The effect of tetramethylurea and hexamethylphosphoramide on the dissolution of coal
by Christina Ichioka
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in
Chemical Engineering
Montana State University
© Copyright by Christina Ichioka (1985)
Abstract:
Coal liquefaction by tetramethyl urea (TMli) and hex-amethylphosphoramide (HMPA) has potentially
significant process advantages over coal-liquefaction systems currently under development. In this
investigation, the effects of solvent type, temperature, and time on coal conversion behavior are
determined. Experiments were conducted on Kittanning coal in a batch reactor at atmospheric pressure
under nitrogen purge and temperatures below the boiling points of the solvents.
Coal conversion to 41% was achieved using a 1:1 mixture of the solvents for 40 minutes at 320 degrees
Fahrenheit. The maximum dissolution using pure TMU, 23%, was observed after 12 hours at 320
degrees Fahrenheit. Pure HMPA as the solvent produced a colloidal suspension that blocked separation
of residue and liquid product.
Dissolution and initial dissolution rate tended to increase with increasing run temperature. Dissolution
rate was fast until condensation reactions dominated. Maximum dissolution was achieved at shorter
times with increasing run temperatures.
Solvent retention levels increased with increasing run temperature. Substantial amounts of TMU and
HMPA were incorporated into the residue, probably at least in part as solvent fragments. THE EFFECT OF
TETRAMETHYLUREA AND HEXAMETHYLPHOSPHORAMIDE
ON THE DISSOLUTION OF COAL
by
C h r i s t i n a Ic hi oka
A t h e s i s s ubmi t t e d in p a r t i a l f u l f i l l m e n t
o f t he r e qui r e me nt s f o r t he de gr ee
of
Mast er o f S c i e n c e
Chemical
Engi ne e r i ng
MONTANA STATE UNIVERSITY
B o z e ma n Mo n t a n a
August 1985
^ 7 2
APPROVAL
of a t h e s i s
s u b m i t t e d by
Christina Ichioka
T h i s t h e s i s has been r e a d by each member of t h e t h e s i s
c o mmi t t e e and has been f ound t o be s a t i s f a c t o r y r e g a r d i n g
c o n t e n t , English u sa ge , f o r m a t , c i t a t i o n s ,
bibliographic
s t y l e , and c o n s i s t e n c y , and i s r e a d y f o r s u b m i s s i o n t o t h e
Co l l e g e of Gr aduat e S t u d i e s .
Date/
^nmrperson
G r a d u a t e Commi t t ee
Appr oved f o r t h e Ma j or De p a r t me n t
Datoy^
Maj or De p a r t me n t
Appr oved f o r t h e C o l l e g e o f Gr a d u a t e S t u d i e s
Dat e
G r a d u a t e Dean
STATEMENT OF PERMISSION TO USE
In p r e s e n t i n g t h i s t h e s i s in p a r t i a l
r e qui r e me nt s
sity,
for a master' s
I agr e e
that
t he
de gr e e at Montana S t a t e Uni ve r ­
Li brary
shall
borrowers under r u l e s o f t he Li br ar y.
this
thesis
are
allowable
f u l f i l l m e n t of t he
wi thout
make i t
available
to
B r i e f q u o t a t i o n s from
special
permi ssi on,
pro­
vi de d t h a t a c c u r a t e acknowl edgement o f s our c e i s made.
P e r mi s s i o n f o r e x t e n s i v e q u o t a t i o n from or r e p r o d uc t i o n
of
this
t h e s i s may be gr ant e d by my major p r o f e s s o r , or in
h i s a b s e n c e , by t he D i r e c t o r o f L i b r a r i e s when, i n t he o p i n ­
ion
of
either,
scholarly
this
the
proposed
purposes.
thesis
Si g n a t ur e
Date
of
the
material
is
Any c opyi ng or use o f t he ma t e r i a l
for f i na n c i a l
my w r i t t e n p e r mi s s i o n .
use
gai n s h a l l
for
in
not be a l l o we d wi t ho u t
ACKNOWLEDGEMENT
The
Sears
for
aut hor
his
expresses
her
appreciation
s upport and gui danc e
and p r e p a r a t i o n o f t h i s t h e s i s .
Montana S t a t e
wor ke r s ,
University
wi t h
t hr oughout
Dr.
t he
John T.
research
Thanks are a l s o ext ended to
t he f a c u l t y and s t a f f o f t he Chemical
at
to
En g i n e e r i ng Department
special
I Usi ng Tsao and Timothy Ward.
t hanks
to my c o ­
- V -
TABLE OF CONTENTS
Page
1.
LIST OF TABLES ..................................................................................
2.
LIST OF F I G U R E S ...................................................................................v i i i
3.
ABSTRACT................................................................................................
Ix
4.
INTRODUCTION ......................................................................................
I
Te t r ame t hyl ur e a
........................................................................
Hexamethyl phosphorami de
.....................................................
TMU v s . HMPA............................................................................. .
Pr o c e s s Advantages .......................................... . . . . .
P r e l i mi n a r y Experi ment s
.....................................................
Mechanisms o f Coal L i q u e f a c t i o n ...................................
E f f e c t o f Phy s i c a l P r o p e r t i e s o f S o l v e n t s
on L i q u e f a c t i o n ......................................
E f f e c t o f Chemical S t r u c t u r e o f S o l v e n t s
on L i q u e f a c t i o n ...................................................................
E f f e c t o f Coal Rank on L i q u e f a c t i o n ........................
I n f l u e n c e o f Coal Pr e t r e a t me n t on L i q u e f a c t i o n .
I n f l u e n c e o f E x t r a c t i o n Co n di t i o ns
on L i q u e f a c t i o n ....................................................
Research Ob j e c t i v e . . . . .
..................................... .
5.
EXPERIMENTAL .................... . . . . .
.......................................
R e s o u r c e s ............................
P r o c e d u r e ......................................
6.
R E S U L T S ..................................................... ....
vii
I
6
ii
14
15
16
20
22
23
24
25
27
28
28
29
. .
....................
E x t r a c t i o n R e s u l t s ......................................
Re t e n t i o n Re s u l t s
. ...............................................
H/C and 0/C R e s u l t s .......................
32
32
47
66
7.
DISCUSSION.......................................................................
68
8.
SUMMARY............................
83
9.
REFERENCES CITED .......................................
. . . . . . . .
85
- vi -
TABLE OF CONTENTS - - Cont i nued
Page
APPENDICES................................................
Appendi x A - Raw d a t a ..........................................................
Appendix B - Raw r e s u l t s
................... ....
Appendix C - Equat i on d e r i v a t i o n s
............................
D e r i v a t i o n o f Equat i on (4) . . . . . . . . . .
Deri v a t i o n o f Equat i on (
5
.
89
90
93
97
98
100
-
vii
-
LIST OF TABLES
Page
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
Ph y s i c a l p r o p e r t i e s o f TMU . . . . .
.............................
P h y s i c a l p r o p e r t i e s o f H M P A ................................................
Ki t t a n n i n g coal chunk a n a l y s e s ...........................................
E f f e c t o f s t a r t u p pr oc edur e on d i s s o l u t i o n . . . .
Coal d i s s o l u t i o n r e s u l t s ..........................................................
Resi due as h i ng r e s u l t s ..............................................................
TMU r e t e n t i o n r e s u l t s ....................
Tot al s o l v e n t r e t e n t i o n
ass umi ng 1:1 s o l v e n t i n c o r p o r a t i o n .............................
HMPA r e t e n t i o n
assumi ng 1: 1 s o l v e n t i n c o r p o r a t i o n .............................
TMU r e t e n t i o n
assumi ng 1:1 s o l v e n t i n c o r p o r a t i o n .............................
Total s o l v e n t r e t e n t i o n
based on. phosphorus d a t a .....................................................
HMPA r e t e n t i o n
based on phosphorus d a t a .....................................................
TMU r e t e n t i o n
based on phosphorus d a t a .....................................................
Raw dat a f o r TMU r u n s ..............................................................
Raw dat a f o r TMU+HMPA r u n s .....................................................
Raw r e s u l t s f o r TMU r u n s ..........................................................
Raw r e s u l t s f o r TMU+HMPA runs
ass umi ng 1:1 s o l v e n t i n c o r p o r a t i o n .............................
Raw r e s u l t s f or TMU+HMPA runs
based on phosphorus d a t a .....................................................
2
7
29
33
36
38
49
53
54
55
56
57
57
91
92
94
95
96
viii
LIST OF FIGURES
Page
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
De c ompos i t i on o f t he r a d i c a l - a n i o n o f TMU. . . .
D i s s o l u t i o n apparat us ...............................................................
Apparent d i s s o l u t i o n v s . t i m e ...............................
40
Apparent d i s s o l u t i o n v s . s h o r t - c o n t a c t t i me . . .
Actual d i s s o l u t i o n v s . t i m e ....................................
42
Act ual d i s s o l u t i o n v s . s h o r t - c o n t a c t t i me . . . .
45
D i s s o l u t i o n based on ash t e s t s v s . t i m e .......
TMU r e t e n t i o n v s . t i me f or TMU r u n s .................
50
TMU r e t e n t i o n v s . d i s s o l u t i o n f or TMU runs
. . .
Tot al r e t e n t i o n v s . t i m e .........................................
58
Tot al r e t e n t i o n v s . d i s s o l u t i o n ............................. .... .
HMPA r e t e n t i o n v s . t i m e ..............................................
61
62
HMPA r e t e n t i o n v s . d i s s o l u t i o n ..........................
TMU r e t e n t i o n v s . t i m e ...........................................
TMU r e t e n t i o n v s . d i s s o l u t i o n ...............................
64
I oni c mechanism o f coal r e d u c t i o n ......................
79
TMU as a hydri de t r a n s f e r a g e n t ..........................
79
14
30
41
43
52
59
63
\
ABSTRACT
Coal l i q u e f a c t i o n by t e t r a me t h y l urea (TMli) and hexa me t h y l phosphorami de (HMPA) has p o t e n t i a l l y s i g n i f i c a n t pr o­
c e s s a dv a n t a g e s ove r c o a l - l i q u e f a c t i o n s ys t e ms c u r r e n t l y
under de v e l o pme nt .
In t h i s i n v e s t i g a t i o n , t he e f f e c t s of
s o l v e n t t y p e , t e m p e r a t u r e , and t i me on c o a l c o n v e r s i o n
b e ha v i o r are d e t e r mi n e d . Experi ment s were conduc t e d on K i t ­
t anning coal in a batch r e a c t o r a t atmospheri c pressure
unde r n i t r o g e n pu r g e and t e m p e r a t u r e s b e l o w t h e b o i l i n g
p o i n t s o f t he s o l v e n t s .
Coal c o n v e r s i o n t o 41% was ac hi e ve d u s i n g a 1:1 mi xt ure
o f t he s o l v e n t s f o r 40 mi nut e s a t 320 d e g r e e s F a h r e n h e i t .
The maximum d i s s o l u t i o n u s i n g pure TMU, 23%, was obs erved
a f t e r 12 hours a t 320 d e g r e e s F a h r e n h e i t .
Pure HMPA as t he
s o l v e n t produced a c o l l o i d a l s u s p e n s i o n t h a t bl o c ke d s e pa r a ­
t i o n o f r e s i d u e and l i q u i d pr oduc t .
D i s s o l u t i o n and i n i t i a l d i s s o l u t i o n r a t e t e n d e d t o
i n c r e a s e wi t h i n c r e a s i n g run t e mpe r a t ur e .
Di ss ol ut i on rate
was f a s t u n t i l c o n d e n s a t i o n r e a c t i o n s domi nat ed.
Maximum
d i s s o l u t i o n was a c h i e v e d a t s h o r t e r t i mes wi t h i n c r e a s i n g
run t e mp e r a t u r e s .
S o l v e n t r e t e n t i o n l e v e l s i n c r e a s e d wi t h i n c r e a s i n g run
temperature.
S u b s t a n t i a l amount s o f TMU and HMPA were
i n c o r p o r a t e d i n t o t he r e s i d u e , probabl y at l e a s t in part as
s o l v e n t f r a g me n t s .
I
INTRODUCTION
Sears
which t h i s
tially
[1]
has
suggested
investigation
is
a coal-conversion
ba s e d.
method
on
Thi s method has p o t e n ­
s i g n i f i c a n t p r o c e s s advant age s over c o a l - I i q u e f a c t i o n
s ys t ems
currently
under
de ve l opme nt .
s o l v e d under mi l d c o n d i t i o n s
In i t ,
coal
is
dis­
o f t emper at ur e and pr e s s u r e by
a c l a s s o f s o l v e n t s r e p r e s e n t e d by t he f ormul a
0
Il
R - M- N - R
n i l
3
R
R
I
2
where M i s
cally,
a c a r b o n , p h o s p h o r u s , or s u l f u r atom.
t e t r a m e t h y l urea
and
Specifi­
he xame t hyl phosphorami de
were
found t o be e f f e c t i v e in d i s s o l v i n g bi t umi nous c o a l .
Te t r ame t hyl ur e a
Te t r a me t h y l ur e a
( 1 , 1 , 3 , 3-Tetramethylurea,
t e mur , TMU) ,
one of t he few ureas t h a t i s l i q u i d at room t e mpe r a t ur e ,
a wi de l i q u i d - p h a s e
ur e a
derivatives.
l i s t e d i n Tabl e I .
t emper at ur e
Some
range which i s
physical
properties
has
uncommon f or
of
TMU ar e
- 2 -
Tabl e I .
Physical
p r o p e r t i e s o f t e t r a m e t h y l urea [ 2 ] .
O
Il
HC
C
CH
3 \ / \ / 3
N
N
I
I
CH CH
3
3
Structure
Mol e cul ar f ormul a
CH
NO
5 12 2
Mol e cul ar we i g ht
1 16. 16
Bo i I i n g p o i n t ( C)
1 7 6 . 5 (I atm)
Mel t i ng p o i n t (C)
-
1. 2
De n s i t y ( g / m l )
0 . 9 6 1 9 (25 C)
Viscosity (poise)
0 . 01401
D i e l e c t r i c constant
23.45
Di pol e moment (Debye)
3. 3 7
B a s i c i t y ( aqueous pKg
)
(25 C)
12
-8
< 2 x 10
Specific conductivity
( mho/cm)
The
specific
conductivity
l ow, as e x p e c t e d .
i ng
suitably
TMU,
an
aprotic
solvent,
is
An a p r o t i c s o l v e n t i s i n c a p a b l e of donat ­
labile
wi t h a p p r o p r i a t e
of
(25 C)
hydrogen
species
[3].
i ng t he f our carbon a t o ms ) ,
atoms
to form hydrogen
bonds
A c opl anar mo l e c u l e ( i n c l u d ­
TMU e x h i b i t s , maximum r e s o n a n c e .
- 3 The
three
electronegative
h e t e r o - a t o ms
are
s y mme t r i c a l l y
bonded to t he more p o s i t i v e l y - c h a r g e d carbon atom due to the
amide r e s onanc e
gen
atoms
urea
[2].
I n c r e a s i n g t he s u b s t i t u t i o n o f hydro­
by methyl
results
groups
in d e c r e a s i n g
to
form l i n e a r
both t he
total
derivatives
electron
a t t he C=O bond and t he C-N bond s t r e n g t h [ 4 ] .
o f t he u s u a l l y
of
density
The abs ence
s t r o ng a s s o c i a t i o n o f amides ( hydrogen bond­
i ng i n v o l v i n g t he hydrogen on t he amide n i t r o g e n ) makes TMU
act
onl y
hi gh
as
a hydrogen- bond
boiling
point
and
dipole
strong di po l e a s s o c i a t i o n ,
t he f our methyl
The
dipole
acceptor
[2].
moment,
The
howe ve r ,
relatively
indicate
d e s p i t e t he e x p e c t e d hi ndrance by
groups.
capacity
for
i on
solvation
moment and d i e l e c t r i c
is
de t er mi ne d
constant
Si nc e TMU has a l ower d i e l e c t r i c
of
by
a species
power
of
TMU f o r
c o n s t a n t than o t h e r si mpl e
strongly
ionic
a ppr oxi mat i ng t h a t o f a c e t o n e .
As e x p e c t e d ,
power
moderat e
is
and poor
fates.
good
for
for
t he
alkali
iodides,
and a l k a l i n e
The f a c t t h a t n i t r a t e s
cates
that
power.
anion
Al t hough
solvation
alkali
the
[2].
carboxami des wi t h a pp r o x i ma t e l y t he same d i p o l e moment,
dissolving
a
e ar t h
salts
is
for
t he
bromi des,
chlorides
cyanides,
affects
l ow,
t he d i s s o l v i n g
and s u l ­
have good s o l u b i l i t i e s
also
the
the
cyanates,
indi­
dissolving
thiosulfates,
and a c e t a t e s e x h i b i t l ow s o l u b i l i t i e s , many s a l t s o f t r a n s i ­
tion
metal s
electron
have
density
good
in
solubilities
the
ami de
in
group,
TMU.
The hi gh
especially
in
pithe
4
pi-orbital
o f t he carbonyl
s o l v a t i o n o f a l k a l i metal
Li ke
and a l l
pyridine,
oxygen, explains
t he e x c e p t i o n a l
ions.
TMU i s
c o mp l e t e l y
common o r g a ni c s o l v e n t s .
miscible
wi t h
wat er
The optimum hydr at i on con­
d i t i o n s occur a t a wat e r: TMU mol ar r a t i o of 6 : 1 , which pro­
duce a water/TMU mi xt ur e o f maximum d e n s i t y [ 2 ] .
TMU has a
high
Al t h o u g h
solvent
significant
t he
power f o r
electron
interaction
is
not
Lu t t r i n g h a u s
dissolving
power i s
g r oups ,
of
TMU,
and t he
strong
t he
point,
enough
by
t he
van
der
interactions
Waals
speculate
forces
between t he
In i t s
over
charge
that
homologues,
it
of
t he
t he methyl
r e s o na nc e
However, TMU has
TMU i s
a more
convenient
has
sys t ems
d i s s o l v i n g power and mi s ­
pyridine:
The good d i s s o l v i n g
not accom­
boiling
t he
power o f TMU can be e x p l a i n e d
ellipsoid
form o f t he po l a r l i q u i d .
ellipsoid
f o r m,
unde r e qua l
spherical
form,
produces
a higher
the
molecule
is
of
wh i c h
hydrocarbons
groups
in
probabl y due to t he f a v o r a b l e mo l e c ul a r
adv a nt a g e s
by c o n s i d e r i n g
groups
[2]
result
and i t can be made al mos t anhydrous by s i mpl e d i s t i l ­
lation.
surface
to
in both s p e c i e s ,
TMU i s most s i m i l a r to p y r i d i n e .
following
panied
oc c ur s
and Di rksen
o f t he s o l v e n t and s o l u t e .
cibility,
hydrocarbons.
delocalization
transfer.
structure
aromatic
shield
accounts
[5].
t he
for
conditions
Although
carbonyl
power.
f ormed
the
high
the
oxygen
polarity
dissolving
mostly
the
of
dissolving
four
to
by
as a
The
met hyl
power f o r
lipophilic
a large
An
met hyl
extent,
the.
5
good
solubility
compounds
i mpai red
[23.
ability
t he
readily.
wi t h
of
acids
t he
is
of
strong
polyvalent
hydroxy
due to t he onl y s l i g h t l y
carbonyl
TMU s i n c e
oxygen
to
acids,
hydrogen
TMU i s
t he mechanism has
N , N - d i a l k y l ami des
but
and
bond
pr ot onat e d
assumed t h a t p r o t o n a t i o n on t he oxygen atom
t he carbonyl
pounds
of
presence
It is
f o r both
univalent
and c a r b o x y l i c
In
occurs
of
and u r e a .
group p r e v e n t s
can
not
wi t h s t a n d
demons t rat ed
The s t r o n g
reaction
attack
been
wi t h
shielding
Gri gnard com­
from l i t h i u m
and most
o r g a n o s o d i urn compounds, which are more r e a c t i v e .
TMU has been found to be u s e f u l
as a non- aqueous medium
f o r many chemi cal
reactions.
solvent
has a good d i s s o l v i n g
since
bases,
it
gives
Targe
ies,
is
TMU
accelerates
shifts
the
easily
potential
purified,
ability
to
formed
carbonyl
chloride
indicate
f or me d.
hydrogen
t he
are
good r e c o v e r ­
prototropic
power f o r a l k a l i
bond w i t h
reaction
suitable
doubl e- bond
the
[2].
as
i ons wi t h
interfering
TMU and
a c y l a t i o n medi a;
kinetic
t h e hydrogen c h l o r i d e
from t e r t i a r y p h o s p h i n e s .
diazonium
hexafluorophosphates,
s our c e
hy d r i d e
of
recommended as
hydrogen
diluent
in
in t he
free
of
t h a t TMU combi nes wi t h
Mi xt ure s
TMU i s used t o prepare mono- and d i f u n c t i o n a l
phonium s a l t s
and
and i s c omme r c i al l y a v a i l a b l e [ 5 ] .
base-catalysed
in
titration
power f o r a c i d s
breaks, affords
by combi ni ng a s o l v a t i n g
alcohol
dat a
I t i s an e x c e p t i o n a l
In t he r e d uc t i o n o f
TMU has
an i o n i c
phos-
be e n
us e d
mechani sm.
Ullmann s y n t h e s i s
as
a
TMU i s
of b i aryls
6
f rom a r y l
needed,
halides
since
when h i g h e r
reaction
temperatures
t he b o i l i n g p o i n t o f TMU i s
ar e
23 d e g r e e s Ce n t i ­
grade hi g h e r than t h a t o f d i m e t h y l formarnide, which i s norm­
ally used.
TMU s i g n i f i c a n t l y a c c e l e r a t e s the m e t a l l a t i o n of
t r i phenyl methane wi t h sodami de.
Good y i e l d s o f hi gh p u r i t y
2)
have been a c h i e v e d in t he a l k y l a t i o n o f t e r t i a r y h e t e r o c y ­
clic
ami nes
in
TMU.
TMU has
been
used
as
s o l v e n t s ys t e ms f o r paper c hr omat ogr aphy.
TMU i s
their
in
t he
analysis
derivatives
have
of
proteins,
significant
a component
of
A p o s s i b l e use of
since
amino a c i d s
differences
in
and
solubil­
ity.
Hexamet hyl phosphorami de
Hexamethyl phosphorami de
oxide,
HMPT,
aprotic
solvent of all
i ng TMU [ 6 ] .
Ta b l e
HMPA) i s
2.
moment and hi gh
are
caused
charge
ove r
the
by
t he
donor and p o l a r
solvents,
includ­
HMPA has a l a r g e
(electron-donating
symmetrical
NgP groupi ng
on t he oxygen atom.
electron
p r o p e r t i e s of HMPA are l i s t e d in
molecule,
basicity
the
best
t he common a p r o t i c
Some p h y s i c a l
A pyrimidal
( t r i s ( d i me t h y l ami no) phos phi ne
ability)
distribution
of
and t he hi gh e l e c t r o n
dipole
which
positive
density
7
Ta bl e 2.
Physical
p r o p e r t i e s o f HMPA [ 6 ] .
HC
3 \
Structure
0
CH
/ 3
Il
N - P - N
HC
3
/
I
HC
3
CH
3
CH
3
M o l e c u l a r f o r mu l a
CH
N PO
6 18 3
Mo l e c u l a r w e i g h t
1 79. 20
B o i l i n g p o i n t (C)
235 (I atm)
Me l t i n g p o i n t (C)
7.20
Density,
1 . 0253
20 C/4 C
\
N
/ \
Dynamic v i s c o s i t y
3. 5 CS (60 C)
Dielectric constant
30 (20 C)
Di p o l e moment (Debye)
5 . 37 (25 C)
Vapor p r e s s u r e
0 . 0 7 mm (30 C)
HMPA i s m i s c i b l e wi t h w a t e r i n a l l
p r o p o r t i o n s and wi t h
many p o l a r and n o n p o l a r o r g a n i c s o l v e n t s , b u t n o t wi t h s a t u ­
rated
and
hydrocarbons
d i phenols,
mono-
[6].
alcohols
and d i c a r b o x y l i c
crystalline
Unsaturated
and
acids
stoichiometric
aromatic
hydrocarbons,
a mi n e s ,
glycols,
r e a c t wi t h HMPA t o
c o mp l e x e s ,
p o i n t s up t o 200 d e g r e e s C e l s i u s .
some
phenols
and
form s t a b l e
wi t h
melting
HMPA a l s o f or ms c ompl exe s
8
wi t h
metal
salts
have
salts
very
a l k a l i metal s
chlorinated
Al k a l i
in HMPA.
HMPA d i s s o l v e s
Lewis
that
acids
contains
react
wi t h
radical-anions.
HMPA.
An a c i d ,
c a u s e s A t o r e p l a c e one or more N(CH3 ) 2 gr oups .
proposed
metal
Na, K) by a c c e p t i n g an e l e c t r o n to form a
solution
and
solvents.
good s o l u b i l i t i e s
( Li ,
paramagnet i c
Brons t ed
and
a mechanism i n v o l v i n g
a 1:1
compl ex
H+A-,
Normant [ 6 ]
of
t he
acid,
HA, hydrogen bonded to t he oxygen atom of HMPA.
Si n c e
it
is
one o f
t he most powerf ul
cati on^- sol v a t o r s
known [ 7 ] ,
HMPA has been used as a s o l v e n t f or e l e c t r o l y s i s .
Due t o t he
sterically
polarized
t he
oxygen
steric
atom,
hi ndr anc e
phorus atom p r e v e n t s
ever,
e as y a c c e s s i b i l i t y o f t he n e g a t i v e l y cations
around
are
strongly
s o l v a t e d whi l e
t he
positively-polarized
phos ­
significant
ani on s o l v a t i o n [ 6 1.
How­
reactions involving anions,
such as b i m o l e c u l a r e l i m i ­
n a t i o n and b i mo l e c u l a r n u c l e o p h i l i c s u b s t i t u t i o n ,
erated
polar
by
HMPA s i n c e
aprotic
ani on
solvent.
reactivity
Good y i e l d s
is
are a c c e l ­
increased
of s u b s titu tio n s
bromo- , c h l o r o - ,
and f l uor obe nz e ne s wi t h me r c a pt a ns ,
ary
phenyl a c e t y l e n e s
a mi ne s ,
and
mi l d c o n d i t i o n s
which
t he
in HMPA.
hal oge n
have
been
very
f i r ml y
wi t h Gri gnard compounds RMgX onl y in HMPA.
synthesized
readily
in
HMPA.
The m e t a l l a t i o n
weak as t o l u e n e wi t h a l k a l i metal
of
o c c ur s in HMPA.
t a T l i c compounds o f cadmium, magnesi um, t i n ,
of
under
R1X' ,
bound w i l l
Metal
t he
s e cond­
achieved
Hydrocarbon d e r i v a t i v e s ,
atom X1 i s
in
in
react
k e t y l s are
acids
as
Organome-
and z i n c can be
9
directly
HMPA.
synthesized
Ad di t i o n
f or mat i on
of
a smal l
c a r b o d i i mi d e s
substituent
is
of
from t he
exchange
increased
a t l ow t e mp e r a t ur e s
Excellent
yields
and a l k y l
amount o f
from
between
in HMPA.
me t a l s
halides
HMPA a c c e l e r a t e s
isocyanates.
t r i a l kyl bor ane s
The r at e
in
alkylations
the
of
and 1 - a l kenes
Di s mu t a t i o n o f c h l o r o s i l a n e s
in t he p r e s e n c e o f 0 . 5
in
oc c ur s
t o 15 % of HMPA.
and m o d e r a t e y i e l d s
in
a c y l a t i o n and c a r b o x y l a t i on r e a c t i o n s are o b t a i n e d wi t h HMPA
as
t he
solvent.
HMPA has
been
polymerization
catalysts.
transfer
in
agent
t he
used
as
HMPA i s
dimerization
a Lewi s
us e d
of
base wi t h
as an e l e c t r o n -
styrene
and
al pha-
methyl s t y r e n e .
Ouchi e t a l .
b u t y l alcohol
at
[8]
reduced e i g h t c o a l s by HMPA-sodium-t-
room t e mpe r at ur e
and at mos phe r i c
pressure.
Af t e r r e d u c t i o n , more than 70 we i g h t p e r c e n t o f t he coal was
soluble
cent)
in pyri di ne;
was e x h i b i t e d
carbon c o n t e n t .
H/C r a t i o
content
doubl e
and
olefinic
by c o a l s havi ng about 88 we i g h t pe r c e nt
carbon
slightly
of
theorized
splitting
carbonyl
of
content
higher
structures,
that
ether
groups,
slightly
and t h e
t he o r i g i n a l
t h a t were e x t e n s i v e l y
al .
(90 we i ght pe r ­
The p y r i d i n e - s o l u b l e ma t e r i a l
(the
that
t he maximum s o l u b i l i t y
and
coal),
had
saturated
linkages
where
l o we r ,
was r i c h e r
aromat i c
oxygen
in
be
in a l i p h a t i c
ring
structures
reduction.
coal
or r e d u c t i o n
t-BuOH may
t he
hy d r o g e n c o n t e n t a l m o s t
after
hy dr o g e na t i o n
had a hi ghe r
oc c ur r e d
Ouchi
et
by
t he
o f q u i n o n e and
s our c e
of
hydr oge n.
10
Wooton e t al .
indicating
carbon,
[9]
that
o b t a i n e d n u c l e a r - m a g n e t i c - r e s o n a n c e data
HMPA-solubl e
5.0% hydr oge n,
ar omat i c
in
sulphur
2.3% n i t r o g e n )
character.
is
believed
solvent-refined
is
A het er oat om
to
be
coal
(86.0%
appr o x i ma t e l y 95%
such
incorporated
as
nitrogen
in
some
of
or
the
ar omat i c s t r u c t u r e s .
St e r n b e r g
and Donne [ 1 0 ]
Pocahont as
(low
HMPA wh i l e
90 p e r c e n t was s o l u b l e
in
HMPA by
HMPA.
though
other
volatile
discovered
bi t umi nous )
itself
solvents
is
s uch
coal
3 p e r c e nt
was
soluble
of
in
in a s o l u t i o n o f l i t h i u m
a poor
as
onl y
solvent
for
coal
dimethylsulphoxide
even
and N-
m e t h y l - 2 - p y r r o l i done b e l o n g i n g
to t he same c l a s s o f d i p o l a r
aprotic
proven
solvents
vents.
The
lithium
is
solvated
as
HMPA are
increased
believed
ar omat i c
to
from l i t h i u m
"coal
ani on"
to
i nt ermedi at e
[11]
of
t he
readily
good coal
the
addition
f ormat i on
reacts
in
of
of readily
transfer
nuclei
sol­
of e l e c ­
coal .
wi t h
Thi s
alkylating
into a benzene-soluble material.
treated
t he
wi t h
ar omat i c
coals
o f common s o l v e n t s ,
solubilities
to
be
produced by t he
t he
a g e n t s , c o n v e r t i n g c oal
selection
be due
ani ons
trons
Hombach
solubility
to
coals
in
of
different
i n c l u d i n g HMPA.
t he
pure
rank
wi th
a
Al though t he
solvents
were
l ow,
Hombach obs e r v e d mi x t ur e s o f t he s o l v e n t s wi t h enhanced d i s ­
solving
cited
that
power.
S i mi l a r
by K i e b l e r [ 1 2 ]
the
successive
results
were obs e r ve d by R e i l l y as
and Rybicka [ 1 3 ] .
extraction
of coal
Data [ 1 2 ]
with
indicate
two or more
11
solvents
yield
of d i f f e r e n t
s o l v e n t power w i l l
as woul d be a c h i e v e d
HMPA was
result
by t h e b e t t e r
found to be r e l a t i v e l y
solvent
ineffective
s o l v e n t and a r e duc i ng medium [ 1 1 ] .
in t he same
alone.
as both a coal
I t was p o s t u l a t e d t h a t
t h i s be h a v i o r i s due t o "the poor chemi cal
s t a b i l i t y of t h i s
reagent
t he
gives
since
t he
evidence
e l e me n t a l
for
analysis
incorporation
of
of
solvent
reduced
coal
f r a g me n t s " .
However, Hombach di d not e l a b o r a t e as to t he nat ur e o f the
evidence.
TMU v s .
HMPA
Since
TMU and HMPA be l ong
a p r o t i c s o l v e n t s , many p h y s i c a l
of
t he
solvents
t o t he
same c l a s s
and chemi cal
are c omparabl e.
o f pol ar
characteristics
S i mi l a r p r o p e r t i e s o f TMU
and HMPA i n c l u d e t he f o l l o w i n g [ 2 , 5, 6] :
(i)
N(CHg) 2 groups are s y mme t r i c a l l y arranged about a core
atom.
(ii)
The oxygen
atom bonded
to
t he
core
atom has
a hi gh
e l e c t r o n d e n s i t y wh i l e a p o s i t i v e charge i s d i s t r i b u t e d over
t he c or e atom and t he n i t r o g e n at oms.
(iii)
TMU and HMPA are m i s c i b l e wi t h many p o l a r and nonpo­
l a r o r g a n i c and i n o r g a n i c s o l v e n t s .
( i v)
me t h y l
Si n c e
t he
groups
positive
and
the
c har ge d e n s i t y
electron
s o l v e n t s are good e l e c t r o n donor s .
is
density
s h i e l d e d by t he
is
exposed,
the
12
(v)
Ca t i o n s
are
strongly
drance around t he p o s i t i v e
solvated
wh i l e
t he
steric
hin­
char ge d e n s i t y p r e v e n t s s i g n i f i ­
c a n t ani on s o l v a t i o n .
(vi)
Re a c t i o n s
philic
i n v o l v i n g ani o n s
substitution
(e.g.,
and b i mo l e c u l a r
bi mol ecul ar nucl eo­
elimination
reactions)
are a c c e l e r a t e d by t he s o l v e n t s .
(vii)
The s o l v e n t s are hydrogen- bond a c c e p t o r s and e l e c t r o n
acceptors
and donors but not hydrogen- bond donors or hydro­
gen donor s .
(viii)
tion
In t he p r e s e n c e o f Brons t ed or Lewis a c i d s ,
of
HMPA o c c u r s
N(CH3 ) 2 g r o u p s ;
by
the
replacement
protonation
of
o f TMU o c c u r s
one
p r o t o na ­
or more
either
on t h e
n i t r o g e n or oxygen atom.
(ix)
Both
solvents
and a l k a l i met al
are
t o or ganomagne s i urn compounds
amides and h y d r i d e s .
The e f f e c t i v e n e s s
studied [ 6 ] .
inert
of
TMU r e l a t i v e
to
HMPA has
been
The major d i f f e r e n c e s between t he s o l v e n t s are
as f o l l o w s :
(i)
is
Si n c e
higher
t ron
t he e l e c t r o n
d e n s i t y on t he oxygen atom o f HMPA
than t h a t o f TMU,
donor,
hydrogen- bond
HMPA i s
acceptor,
a more e f f e c t i v e
cation
elec­
solvator,
and
a ccelerat or of reactions involving ani ons.
(ii)
(iii)
HMPA i s not m i s c i b l e wi t h s a t u r a t e d hydroc ar bons .
HMPA i s not ed t o form c ompl exes wi th both or gani c and
inorganic
literature
solvents
wh i l e
relatively
little
ment i on
i s made o f s i m i l a r b e h a v i o r wi t h TMU.
in
t he
13
( i v)
Attack
by n u c l e o p h i l e s
wh i l e
HMPA i s
rarely
disrupted.
duced or produced duri ng
polarized
carbon
in
reactions.
ami des
of
rarely
disrupts
can
phosphorus
solvents
its
to bas es ,
itself.
to
form
Al t hough
pounds
of
affected
alkali
intro­
positivelyremoval
of
stable
than
nucleophiles
hindrance
hy d r o l y s e d
around
the
HMPA s t a b l e
to
in a l k a l i n e media
s o l v e n t f o r r e a c t i o n s wi th
reactants.
polar a pr o t i c
inability
B- ,
a u t o x i d a t i on
of
atom makes
u n l i k e TMU, making HMPA an i d e a l
or b a s i c
pr e s e nc e
steric
not
and
are much more
t he
The
and HMPA i s
stability
t he
in the
substitution,
acids,
HMPA.
positively-polarized
nucleophilic
attack
result
phosphorami des
carboxylic
nucleophiles,
f r a g me n t TMU
These amide i ons then compet e wi th t he
addition,
Si n c e
can
Nucl e o p h i l e s ,
a reaction
atom t h a t
amide i o n s from TMU.
nucleophile
and b a s e s
HMPA i s
s u p e r i o r to o t he r
as an a u t o x i d a t i on medium becaus e o f
unlike
carbanions,
t he
ami des
therefore
strongly
metals
and l a c t a ms ,
basic
typical
reaction
effective
than
TMU as
a solvent
olefins.
TMU and HMPA l o s e
a u t o x i d i z i ng
organomet al I i c
and KOH a t t a c k
under
not
and i t s
TMU, HMPA i s
conditions.
for
t he
com­
HMPA i s
not
more
isomerization
of
t he hydrogen atoms bet a to t he
po l a r group t o ba s e s onl y under ext reme c o n d i t i o n s .
( v)
Ac t i ng
radical-anion
anion
of
as
electron
that
HMPA i s
acceptors,
rapidly
TMU forms
decomposes
considerably
more
wh i l e
stable.
an
unstable
t he
radical-
An e l e c t r o n
d o n o r , TMU can a l s o a c t as an e l e c t r o n a c c e p t o r t o become an
14
unstable
radical-am'on.
stabilized
by c h a r g e
into
two
when
acting
HMPA i s
only
ions
an
I).
a ni o n
acceptor,
than
aprotic
it
Al t hough
electron
much more s t a b l e
known p o l a r
the
delocalization,
(Figure
as
Since
of
TMU c a n n o t
be
rapidly
decomposes
HMPA a l s o
decomposes
the
radical-anion
of
t h a t o f TMU, maki ng HMPA t h e
solvent
t h a t can be us e d f o r
syn­
theses involving dissolved r ea ctiv e metals.
Figure I .
De c o mp o s i t i o n o f t h e r a d i c a l - a n i o n o f TMU.
R - C - N - R
I
I
0-
R
~ r*
R - C - N - R
+ e
K
R - C + N - R
—>
i
H
O- R
O R
I
P r o c e s s Ad v a n t a g e s
W h i t e h u r s t e t al .
lines
that
should
[14]
presented
be c o n s i d e r e d
in
the f o l l o wi n g g u i d e ­
new o r
improved coal
l i q u e f a c t i o n technology:
(i)
The key t o s u c c e s s o f a p r o c e s s i s hydr ogen u t i l i z a t i o n
efficiency.
(Ii)
S o l v e n t s can be o v e r h y d r o g e n a t e d .
(Iii)
The
o p t i ma l
for c a t a l y t i c
(iv)
initial
High
conditions
and t h e r ma l
conversion
dissolution
of
and
intrinsic
selectivities
r e a c t i o n s are d i f f e r e n t .
c oal
to
soluble
products
in
the
s t e p i s n o t n e c e s s a r y when h y d r o g e n - r i c h
l i q u i d s are the f i nal
product.
15
(v)
Solids
separation
presents
probl ems
in
t he
processes
p r e s e n t l y under de ve l opment .
(vi)
Temperat ures are very hi gh and r e a c t i o n t i me s are very
l ong in t h e s e p r o c e s s e s .
(vii)
Denitrogenation
is
t he
most
p r o b l e ma t i c
and
least
unde rs t ood r e a c t i o n .
Based
[1]
on
these
shows
abs ence
guidelines,
potential
of
as
hydrogen
t he
process
a commerci al
overpressure
developed
process.
and s t r o ng
by Sears
Due to
acids,
hy d r o g e n a t i o n i s u n l i k e l y in t he d i s s o l u t i o n s t e p .
n a t i o n o f t he c oal
reactor
c o ul d
optimization
steps.
t he
solvent
Hydroge­
hydrocarbons in a s e p a r a t e hydr oge nat i on
reduce
hydrogen
r equi r e me nt s
o f t he d i s s o l u t i o n
and would a l l o w
and c a t a l y t i c
hydr oge nat i on
The mi l d c o n d i t i o n s o f t emper at ur e and pr e s s u r e used
in Se ar s '
process
shoul d r e s u l t
in e a s i e r s o l i d s
separation
than c u r r e n t p r o c e s s e s .
P r e l i mi n a r y Experi ment s
Sears
volatile
[1]
obtained
bituminous
medium v o l a t i l e
Soxhlet
Sewickley
bituminous
extraction.
on Ba k e r s t o wn
extraction
Si mpl e
coal
using
coal
HMPA was
f o r ma t i o n
used
as
wi t h
Ba k e r s t o wn
extraction
a 1:1
o c c ur r e d
when
solvent.
It
of
at
42% f or
with
is
HMPA by
room t emperat ure
of
TMU and HMPA
Minimum c o l l o i d a l
a 1:1
high
TMU and 62% f o r
coal
mixture
r e s u l t e d i n a 57% l o s s in w e i g h t .
micelle
values
mi xt ur e
believed
[1]
of
or gani c
TMU and
that this
16
b e ha v i o r
tion
c o ul d c o r r e l a t e
products
observed
Sears,
by
to
the
formi ng
separate
solvent
initially
Uni on
of oil
to
t endency o f
have
Corporation
groups
t he
dissolu­
high oxygen c o n t e n t ,
that
and s o l v e n t .
"stabilize
cage
t he
Ca r b i d e
functional
phas es
t he s o l v e n t s
wi t h
are
and c i t e d
likely
Sears
as
by
to p r e f e r
postulated that
t he pr oduc t s by m o d i f i c a t i o n o f t he
a c c o mo d a t e
the
dissolved
molecule
in
a
stable configuration".
Mechanisms o f Coal
Liquefaction
Al t hough many coal
c o n v e r s i o n mechani sms have been pro­
posed t o d e s c r i b e d i r e c t l i q u e f a c t i o n p r o c e s s e s , most i n v e s ­
tigators
adopt
processes.
insoluble
duce
coal,
three
destroying
products.
depol ymeri zat i on
mechanism
thermal
of
initial
De p o l y me r i z a t i o n
soluble
thermal
one
proposed.
e ne r gy
coal
involves
t he
coal
br e aki ng bonds in t he
mac r omol e c ul e s
For
high-temperature
is
usually
t he
Duri ng
thermal
t he
strengths
exceeds
d e p o l y me r i z a t i o n
to pro­
processes,
d e p o l y me r i z a t i o n
depol ymeri zat i on,
of
some
coal
t he
bonds ,
c a u s i n g t he bonds to c l e a v e h o m o l y t i c a l Iy to produce a r a d i ­
cal
pair.
The
from e i t h e r
a donor
free
radicals
then
abstract
hydrogen
a hydrogen donor p r e s e n t in the s o l v e n t or from
group
which
is
par t
of
t he
coal
to
become
stable
compounds o f l ower mo l e c u l a r we i g ht than t he o r i g i n a l
Cont i nui ng
atoms
thermal
cleavage
of
coal
bonds
produces
coal.
soluble
17
fragments
whi c h
react
further.
The
s uppl y
hydrogen
transfer
medium and may
However,
t he d e p o l y me r i z a t i o n
the
solvent
since
i ntermediates
rate
h o mo l y t i c
which
are
is
solvent
t he
a heat-
reactions.
al mos t i nde pe nde nt of
cleavage
not
to
is
produces
affected
un c h a r g e d
considerably
by
t he
sol v e n t .
Anot her
d e p o l y me r i z a t i o n
mechanism
for
h i g h - t e mp e r a t u r e
processes
coal
bonds f o l l o w e d by a r a d i c a l
is
the
commonly
thermal
proposed
cleavage
c hai n mechani sm.
of
The depo­
l y m e r i z a t i o n r a t e may be dependent on t he d o n o r - s o l ve nt c on­
centration.
Larsen [ 1 5 ] c i t e s Heredy who c onc l ude d t h a t the
rate-determining
s t e p f o r pr oduc t f ormat i on i n v o l v e d hydro­
gen by o b s e r v i n g a d e u t e r i u m - i s o t o p e e f f e c t on t he amount o f
pr oduc t s
a
formed us i ng t e t r a l i n ,
reasonable
when t he
radical-chain
solvent
is
mechanism
can
not
not a hydrogen d o n o r .
processes
are
hydrogen
donor
solvents,
occurs
involving
process
not
a hydrogen d o n o r .
dependent
on
dat a
t he
t he
However,
be
proposed
S i n c e homol yt i c
concentration
indicate
non- hydrogen
that
an
donor
of
non­
alternate
solvent
in
t he r a t e - d e t e r m i n i n g s t e p .
Larsen
[15]
is
currently
investigating
a
compet i t i ve
d e p o l y m e r i z a t i o n mechanism which i s c o n s i s t e n t wi t h obs erved
dat a:
bonds
v e nt
d e p o l y m e r i z a t i o n by d i r e c t s o l v e n t a t t a c k on c o v a l e n t
in
t he
mo l e c u l e
coal
(solvolysis).
participates
in
During s o l v o l y s i s ,
t he
transition
state
a sol­
of
the
18
reaction.
A charged
volved.
Since
than t he
coal
t he
intermediate
transition
and s o l v e n t
may or may n o t be i n ­
state
i s more h i g h l y charged
( as s umi ng
t h a t a ne ut r a l
solvent
mo l e c u l e a t t a c k s a bond in t he c o a l ) ,
t he r e a c t i o n shoul d be
sensitive
t he s o l v e n t ,
tion
to
to
t he o v e r a l l
its
ability
depolymerization
direct
solvent
tions:
merization
on
of
to chemi cal l y a t t a c k .
of coal
attack
( i ) t he
polarity
is
The b e l i e f t h a t
may be due a t l e a s t
based
on
t he
in a d d i ­
in part to
following
observa­
s t r o ng dependence o f the e x t e n t o f d e p o l y ­
the
solvent
conversion of coals
concentration,
( i i ) the
high
t o s o l u b l e pr oduc t s at t e mpe r at ur e s t oo
low f o r t h e r m o l y t i c bond c l e a v a g e t o be t he major depol ymer­
ization
mechani sm,
decreasing
t he
solvent
pr obabl e
(iii)
basicity
covalent
and i n s o l u b l e
coal
t he
decrease
and
bondi ng
products.
in
conversion
nuc l e ophi I i c i t y ,
of
solvents
to
and
both
wi t h
( i v)
soluble
D e t a i l s o f t he c i t e d e v i d e n c e
i s p r e s e n t e d in t he f o l l o w i n g :
(i)
Larsen proposed t he s o l v o l y s i s
t he
dependence
ducts
on
extent
of
or
phenol
coal
the
of
t he
concentration
solvolytic
was
conversion
also
of
p r o c e s s a f t e r o bs e r v i ng
of
pyridine
d e p o l y me r i z a t i o n
found
to
be
coals
to
or
soluble
phenol.
of c o a l s
strongly
pro­
The
in py r i di ne
depe ndent on t he
rank; bi t umi nous c o a l s e x h i b i t e d much h i g h e r e x t r a c t i o n
v a l u e s than s ubbi t umi nous c o a l s .
(i i )
age
Ac cor di ng to At hert on and Kul i k [ 1 6 ] ,
s houl d
not
occur
in
processes
wi t h
homo l y t i c c l e a v ­
t e mp e r a t ur e s
at
or
19
bel ow 550 - 700 d e g r e e s F a h r e n h e i t .
[12,
17,
18,
extraction
19,
20,
of coals
21]
Pr e v i o u s
investigators
have found s i g n i f i c a n t
in a v a r i e t y
of solvents
extents
of
at r e l a t i v e l y
low t e mp e r a t ur e s which can not be r a t i o n a l i z e d by h o mo l y t i c ,
thermal
bond c l e a v a g e .
(iii)
Consistent
wi t h
solvolytic
d e p o l y me r i z a t i o n
princi­
p l e s , coal
c o n v e r s i o n was found to be enhanced when the s o l ­
vent
has
us e d
an a v a i l a b l e
similar
to
pair
nitrogen
on
pyridine
conversions
in
than
but
havi ng
t he
pi
pyridine.
oxygen-containing
electron
group
and
pair
a less
s y s t e m,
solvents
amine b a s e s ,
that
wi t h
are o f t e n
solvolytic
o f coal
electron
unshared
pairs
much
l ower coal
between
electron
some
pai r
in
Ki e b l e r [ 1 2 ] obs erved
of e l e c t r o n s ,
so e f f e c t i v e
especially
in d e p o l y m e r i z i ng coal
bond c l e a v a g e must be o c c u r r i n g .
An a l y s i s
e x t r a c t s i n d i c a t e d t h a t t he e x t r a c t s o r i g i n a t e d as a
result
o f both
coal.
Some
peptization
to
unshared
accessible
bondi ng
t he s o l v e n t i s assumed to oc c ur [ 2 2 ] .
that
Indole,
gives
Chemical
t he
[15] .
produci ng
thermal
solvents
and s o l v e n t
(e.g.
or c o l l o i d a l
apparently
d e p o l y m e r i z a t i o n o f coal
d e p o l y me r i z a t i o n
pyridine)
incited
a pr o c e s s
d i s p e r s i o n o f t he coal
soluble
coal
of t he
of
in addition
products;
solvolytic
was t hought to probabl y occur when
an e x t r a c t c o n t a i n s a mi xt ur e o f o r g a n i c compounds i n c l u d i n g
highly
loids.
c ompl e x,
h i g h - mo l e c u l a r
we i g ht
mol ecul es
and
col­
20
(iv)
Treating
Fahrenheit,
t he
coal
coals
C o l l i n s e t al .
extracts
pyridine
wi th
and
a mi n e s
at
73
-
520
degrees
[ 2 3 ] found amines bonded to both
residues.
can be e x c h a n g e d
While
wi th
bound
unlabeled
14C- 1abe l e d
pyridine,
l a b e l e d t e t r a h y d r o q u i n o l i n e (THQ) bound to t he coal
r e ­
product s
can not be exchanged wi t h u n l a b e l e d THQ.
From t h e s e o b s e r ­
vations,
t he
lently
Collins
et
al.
incorporated
speculated
while
that
Atherton
and
THQ i s
Kulik
cova­
[16]
we nt
f u r t h e r t o h y p o t h e s i z e t h a t THQ p a r t i c i p a t e s in t he chemi cal
r e a c t i o n s i n which c o v a l e n t bonds o f coal
E f f e c t of Physical
Extensive
whi c h,
of
if
t he
any,
P r o p e r t i e s o f S o l v e n t s on L i q u e f a c t i o n
research
has
be e n
solvent properties
solvent
in
are b r o k e n .
c oal
p e r f o r me d
to
determi ne
r e f l e c t t he e f f e c t i v e n e s s
extraction.
No s i n g u l a r
ph y s i c a l
pr ope r t y o f s o l v e n t s can a d e q u a t e l y ac count f o r t he i n t e r a c ­
t i o n s between coal
erties
mo s t
often
and s o l v e n t [ 1 9 ,
considered
effectiveness
are s u r f a c e
pr e s s u r e [ 1 2 ,
22, 2 6 ] .
Internal
tension
Internal
pressure = P
as
22].
The p h y s i c a l
a criterion
[12,
24,
prop­
for solvent
25] and i n t e r n a l
p r e s s u r e i s d e f i n e d as
( a Hv - RT) p
= --------------- i
m
aE
= ---V
(I)
where m i s t he mo l e c ul a r we i g ht o f t he s o l v e n t , ^ i s the den­
sity,
a
Hv
mo l e c u l a r
is
the
vol ume,
latent
and
a
heat
E is
of
vaporization,
V is
t he
t he energy o f v a p o r i z a t i o n
per
21
mol e.
By compari ng coal
eral
investigators,
obs e r ve d
hi gh
c o n v e r s i o n r e s u l t s o b t a i n e d by s e v ­
Ki e b l e r
[12]
cites
a t ende nc y o f enhanced y i e l d
values
of
surface
tension.
Kreul en
wi t h
tension is
al . who
solvents
However,
since
c ompi l e d were o b t a i n e d by v a r i o u s e xpe r i me nt al
dissimilar coals,
et
havi ng
the
data
procedures on
t he t he o r y o f y i e l d dependence on s u r f a c e
i n s u f f i c i e n t l y based [ 1 2 ] .
Ki e b l e r [ 2 7 ] a t t e mp t ­
ed t o de t e r mi ne a r e l a t i o n between t he y i e l d o f coal
extract
and t he
Statis­
tical
physical
nat ure o f s o l v e n t s .
a n a l y s e s were made o f y i e l d s
150 t o 300
of
and chemi cal
t he
t ur e
degrees
solvent,
and
and v a r i o u s
including
that
internal
Celsius
surface
extrapolated
pressure,
o f e x t r a c t o b t a i n e d from
to
dipole
physical
tension
t he
at
extraction
moment,
properties
room t empera­
t e mpe r at ur e ,
dielectric
constant,
l a t e n t he at o f v a p o r i z a t i o n a t t he b o i l i n g p o i n t o f t he s o l ­
vent
and
specific
lation
at
t he
extraction
refraction,
t emperat ure,
refractive
and mo l e c u l a r vol ume.
coefficients,
t he
internal
index,
Based on c o r r e ­
p r e s s u r e o f a s o l v e n t has
t he most s i g n i f i c a n t c o r r e l a t i o n t o y i e l d ;
this relationship
can be e x p r e s s e d as Y = a + bP^ where a and b are c o n s t a n t s
dependent on t e mp e r a t u r e .
internal
solvent
pressure
power,
pressure
dependence
and
t he
is
not
t he
solvolysis.
t he
equations
and t e m p e r a t u r e
on
Ki e b l e r
extent
sole
not ed t h a t
factor
relating
do s u p p o r t
of
However,
bot h
for
al t hough
which
yield
t he
de t er mi ne s
and
internal
t he
theory of y i e l d
thermal
d e p o l y me r i z a t i o n
coal
extraction
sys t ems
22
o p e r a t i n g a t t e mpe r at ur e s bel ow t he normal
t he s o l v e n t ,
tension
Thus,
was
no
has
conversion
relationship
det er mi ne d
single
solvents
moderate
no c o r r e l a t i o n e x i s t s between y i e l d and s u r f a c e
and t h e
pressure
b o i l i n g point of
or
been
to
b e t we e n y i e l d
be
inapplicable
c ombi nat i on
found
s ys t e ms
to
reflect
operating
t e mpe r at ur e
and
of
under
pressure
and i n t e r n a l
[18,
physical
solvent
20,
28].
properties
power
in
of
coal
similar . conditions
as
those
considered
of
in
this investigation.
E f f e c t o f Chemical
S t r u c t u r e o f S o l v e n t s on L i q u e f a c t i o n
I n v e s t i g a t i o n s on t he e f f e c t o f t he chemi cal
structure
o f s o l v e n t s on e x t r a c t i o n have produced s u b s t a n t i a l
Dryden [ 2 2 ]
coal
obs e r ve d
extract
are
t h a t both t he y i e l d
affected
extraction conditions,
solvent.
f o r coal
Si n c e
the
coal
composition
as t he chemi cal
and
nat ure of t he
solvents
have s t r u c t u r e s c o n t a i n i n g a n i t r o g e n atom wi th an
unshared
pair
of
electrons.
nat ur e were found t o c o n s i s t e n t l y
solvent
unshared
interfering
[29]
as wel l
the
and nat ure o f the
Dryden det er mi ne d t h a t t he b e s t s p e c i f i c
available
chemi cal
by
results.
power i s
electron
influences
Solvents
s we l l
of th i s
t he c o a l .
a s s o c i a t e d wi t h the a c c e s s i b i l i t y o f
pair
such
to
as
interact
excessive
with
the
hydrogen
coal,
bondi ng
and p a r t i c i p a t i o n o f t he I one p a i r in r e s o na nc e of t he
molecular
nucleus
[20]
ar e
undesirable.
Although
many
i n v e s t i g a t o r s b e l i e v e t h a t t he e l e c t r o n - d o n o r c h a r a c t e r o f a
23
solvent
reflects
Marzec
et
aI .
solvent
[18]
electron-acceptor
order
of
compiled
pr ope r t y
i mport ance
i n f l u e n c i n g coal
effectiveness
as
of
data
t he
its
in
coal
extraction,
indicating
solvent
is
that
t he
the
same
of
electron-donor
pr ope r t y
in
conversion.
E f f e c t o f Coal Rank on L i q u e f a c t i o n
In c o n j u n c t i o n wi t h t he chemi cal
t he coal
rank d i c t a t e s
obs e r ve d t h a t
coal
effectiveness.
Dryden [ 2 2 ]
t he y i e l d o f e x t r a c t d e c r e a s e s r a p i d l y as t he
rank i n c r e a s e s from 85 t o 89% carbon and becomes n e g l i ­
gible
be y o nd
soluble
some
t he
solvent
nat ure o f t he s o l v e n t ,
coal
92
to
93% c a r b o n .
Howe ve r ,
the
trend
of
c o n t e n t wi t h rank a l s o depends on t he s o l v e n t ;
solvents
such
bi t umi nous
as
range
pyridine
(ca.
produce
a maximum y i e l d
80 t o 93% carbon [ 2 6 ,
30])
in
wh i l e
o t h e r s such as e t h y l e nedi ami ne e x h i b i t a s t e a d i l y d e c r e a s i n g
y i e l d wi t h i n c r e a s i n g rank t hrough t h i s r a n g e .
previously,
HMPA-s o d i urn-1 - but yl a l c o h o l
yield
coals
with
having
about
produces
88 w e i g h t
content [ 8 ] .
Based on c o n v e r s i o n r e s u l t s .
cited
et
Fisher
bi t umi nous
coal
coals
al.
appear
liquefaction
not ed
t he
yields
relative
using
solvent
determined
to
be
processes.
advant age
when
who
of
low
Whi t ehurs t
bituminous
power o f
two
a
solvents
carbon
Wen and Lee [ 3 0 ]
high
volatile
desirable
rank f o r
et
al .
r e qui r e me nt
coals.
maximum
percent
that
t he most
hydrogen
As d i s c u s s e d
[14]
also
f or
hi gh
Occasionally,
may be
reversed
the
by
24
c hangi ng t he t ype o f coal
does
not
mi neral
or
dictate
coal
reactivity.
ma t t e r ai d coal
pyrrhotite
(a
However, rank al one
Catalytic
liquefaction.
a l t hough
effects
Specifically,
n o n s t o i c hi ©me t r i c mi neral
reduction of p y r i t e )
activity
treated [31].
of
pyrite
produced by t he
i s commonly b e l i e v e d to c a us e c a t a l y t i c
ion-exchangeable
i ron may have
catalytic
properties [14].
I n f l u e n c e o f Coal Pr e t r e a t me nt on L i q u e f a c t i o n
Coal
p r e t r e a t me n t
products.
coals
also
Cl ark and Wheeler [ 3 2 ]
before
yields.
extraction
However,
bituminous
coal
coal
ext reme
has
with
thermal
by
yield
of
soluble
pr e he a t e d two bi t umi nous
solvent
p r e t r e a t me n t
et
al.
for
e nha n c e d
a
different
of
[14]
resulted
in
Once d e g r e d a t i o n or r e t r o g r e s s i o n of
occurred,
liquefaction
t he
cold
Whitehurst
decreased c o n v e r s i o n .
the
affects
it
can
conditions
n o t be r e v e r s e d e ve n wi t h
[16].
Dryi ng
coal
in
an
i n e r t at mosphere to s l i g h t l y ove r 212 d e g r e e s Fa hr e nhe i t may
promote
coals
reactions,
[14].
al t hough
Oxi dat i on
pr e domi nant l y
o f coal
wi t h
by e xpos ur e
to
l ow- ranked
air
at tem­
p e r a t u r e s up t o 212 de gr e e s F a h r e n h e i t i n f l u e n c e s the amount
of
obtainable
l owe r s
[22].
t he maximum y i e l d
solvent,
cases
extract
it
since
is
unlikely
t he
effect
Al t hough
when us i ng
that
typically
benzene or p y r i d i n e
a single
of oxi dat i on
oxidation
rule
applies
as
to a l l
depends on t he primary
o x i d a t i o n pr oduc t s and t he s o l u b i l i t y o f c o a l .
25
I n f l u e n c e o f E x t r a c t i o n Co n d i t i o n s on L i q u e f a c t i o n
Extraction
coal
conditions
conversion.
can c o u n t e r
The p r e s e n c e
efforts
to maximize
o f oxygen in t he e x t r a c t i o n
appar at us t e nds to d e c r e a s e t he y i e l d obt a i n e d [ 1 2 , 2 2 ] .
t he abs ence o f c a t a l y s t ,
hydrogen w i l l
wi t h hi gh v o l a t i l e bi t umi nous coal
degrees
coal
Celsius
[30].
conversion
tem i s
not a p p r e c i a b l y r e a c t
a t t e mpe r at ur e s bel ow 500
extraction,
faster
are o b t a i n e d when t he coal
agitated
reduces y i e l d
Duri ng
[22].
However, e x c e s s i v e
[21].
Guin e t
In
rates
of
and s o l v e n t s y s ­
shaki ng someti mes
aI . [cited
in 14,
33]
have
o bs e r ve d t h a t s t i r r i n g r a t e a f f e c t s t he breakage o f the coal
particles.
cles,
t he
Due t o
internal
rapidly-stirred
t he
qui ck
pore
disintegration
volume
reactor.
becomes
Al t hough
have exami ned c o a l - p a r t i c l e - s i z e
and t he
possible
effects
size
Extracting
to
coals
in
a
transport
conversion
limitations,
Based on a l i t e r a t u r e s ur ve y,
be a v a r i a b l e
bi t umi nous
parti­
investigators
on coal
Whi t e hur s t e t a l . [ 1 4 ] c i t e d Kl oepper e t a l .
particle
t he
insignificant
numerous
i mport ance o f mass
t he r e s u l t s are i n c o n s i s t e n t .
of
of
of
72
who c o n s i d e r e d
secondary
to
importance.
240 mesh
B.S.S.
wi t h
ami nes a t room t emper at ur e and near the b o i l i n g p o i n t of t he
solvent*
with
Dryden
decreasing
[22]
particle
pressure e x t r a c t i o n
560
degrees
found
o f coal
Fahrenheit,
y i e l d s when us i n g coal
that
yield
size.
t ended
Exa mi ni ng
to
increase
the
benzene-
at t e mpe r at ur e s between 428 and
Asbury [ 3 4 ]
also
o bs e r v e d enhanced
ground f u r t h e r to mi cron s i z e .
Usi ng
26
a micro-autoclave,
Curran
o f coal
wi t h hydrogen donor s o l v e n t s
conversion
pe r a t u r e
from
range
of
715
wi t h
28
to
runs
those
et
to
al .
825
48
mesh
from c o r r e s p o n d i n g
[ 35] s t u d i e d
in
the tem­
degrees Fahrenheit.
Yi e l d s
particles
runs
us i ng
were
From s h o r t c o n t a c t t i me runs ( l e s s
a t 800
t o 850
degrees
on c o a l s
sized
Fahrenheit
identical
to
100 to 200 mesh p a r t i ­
cles.
vents
t he k i n e t i c s
us i ng
than two mi nut e s )
hydrogen- donor
from 45 to 600 mi c r o n s ,
sol­
Whi t e hurs t e t
a l . [ 1 4 ] obs e r v e d l i t t l e ,
i f a n y , e f f e c t o f p a r t i c l e s i z e on
coal c o n v e r s i o n b e h a v i o r .
I n t r a p a r t i c l e mass t r a n s p o r t l i m ­
itations
we r e
liquefaction
no e f f e c t
concluded
s ys t e ms
of
coal
conversion
was
generally
used,
extraction
is
al.
cited
[14]
extraction
wi t h
t he
tions
of
results
Lee
Anderson
we r e
(117
ultimate
yields
rate
with
noted
was
40
to
who
exami ned
rate
size.
who
189
were
coal
of
in
coal
t he
t e t r a l in
under mi l d c o n d i ­
degrees
Fahrenheit).
identical,
particles.
as c i t e d
220
a
60
mesh
range
investigated
energy
coal
Whi t e hurs t e t
wi t h
by K i e b l e r
coal
the
of
size
o bs e r ve d
Usi ng a r o c k i n g bomb a u t o c l a v e ,
Jenny
that
bi t umi nous
-
Al s o ,
c h e mi s t r y
the p a r t i c l e
al.
ultrasonic
t e mper at ur e
than
et
in coal
solvents.
t he
particle
volatile
of
on
stated
i nde pe nde nt o f
extraction
size
Wi thi n
[30]
a hi gh
insignificant
hydrogen- donor
observed.
t he
particles
using
appear
particle
influence
Al t hough
initial
of
to
to
faster
270 mesh
Similar
by Hoffman [ 2 6 ] .
Whi t ehurs t e t a l . [ 14] c i t e d
conversion
in
tetralin
under
27
hydrogen o v e r p r e s s u r e .
t o 100 mesh t o
However,
t he
decreasing
produce
- 325 mes h,
particle
tigators,
no
Any p a r t i c l e
grinding
decreasing y i e l d s
than
from 40
were obs e r ve d.
c o ul d
be obs e r ve d
wi t h
a better
Co n s i de r i n g t he f i n d i n g s o f t h e s e i n v e s ­
appare nt
i mpl y mass
or
decreased
s i z e was not ed as a f a c t o r , which would
l ower y i e l d s
s y s t e m.
mi neral
size
t ende nc y o f i n c r e a s i n g w e t t i n g r e s i s t a n c e wi t h
agitation
would
As p a r t i c l e
t re nd
transport
size
effect
maceral
and s i z i n g
is
limitations
is
probabl y
contents
or
to
consistently
of
t he
obs er ved
on c oal
due t o
size
differences
that
conversion.
variations
r anges
caused
in
by
in the c o nv e rs i on
pr oc e dur e s [ 1 4 ] .
Research O b j e c t i v e
The
sion
purpos e o f t h i s
behavior
through
he xamethyI phosphorami de
thesis
is
extraction
conver­
by t e t r a m e t h y I urea
and
t e mp e r a t ur e s bel ow t he b o i l i n g p o i n t s o f the s o l v e n t s .
The
for
additional
at mos phe r i c
and
pr e s s u r e
r e s u l t s obtained wi l l
under
t o exami ne coal
be used as a b a s i s by c o - i n v e s t i g a t o r s
studies
aimed
at
opt i mi zi ng
t he
extraction
p r o c e s s in order to u l t i m a t e l y a s s e s s the p r o c e s s p o t e n t i a l .
28
EXPERIMENTAL
Resources
TMU and
Al dr i c h
by t he
HMPA,
Chemical
obtained
or
Bakers
Kittanning
f rom
99% p u r e ,
Company.
Al d r i c h
bituminous
both
Dr,
Ac e t o ne ,
Chemical
coal
tion
at
Ki t t a n n i n g coal
ground,
grade)
supplied
High v o l a t i l e
recently
mi n e d ,
West V i r g i n i a
several
chunk,
to
Celsius
purged wi t h
using
significantly
coal
sized
degrees
was
by t h e
were
University;
The c h o i c e o f coal
to be
i n v e s t i g a t i o n was based on p r e l i mi n a r y d i s s o l u ­
experiments
Kittanning
98% pur e ,
chunks,
Stiller
supplied
Company.
s p e c i f i c a t i o n s were not a v a i l a b l e .
used in t h i s
we re
150 -
nitrogen
dissolved
approximately
200 Ty l e r mesh,
overnight,
nitrogen.
were
bituminous
then
Cy l i n d e r s
filled
coals.
Onl y
in t he s o l v e n t s .
A
7" x 5" x 5",
was
dried
105
stored
in
at
100 -
a dessicator
o f 99.9% pure
(commerci al
by Western Wel di ng.
El emental
a n a l y s e s and ash c o n t e n t s o f t he t h r e e g r i n d i n g bat c he s t h a t
were used are l i s t e d
are
quite
batches
Micro
on
Carl o
different,
Erba
t he
a moisture-
ultimate
Ward w i t h
in Tabl e 3.
analyses
a Ca r l o
Al t hough t he ash c o n t e n t s
e l e me n t a l
and
were
Erba Model
DPllO i n t e g r a t o r ,
contents
ash-free
performed
basis
by
t he
are
Mr.
1100 E l e m e n t a l
and an Osborne
of
three
similar.
Timothy
Analyzer,
L.
a
I computer at
29
Montana
State
f ormed
by
Ont ar i o.
University.
Guel ph
Phosphorus
Che mi c al
The d i s s o l u t i o n
liliter
analyses
Laboratories
Ltd.
were
at
pe r ­
Gue l p h,
apparat us c o n s i s t e d o f a 500 m i l ­
Erl enmeyer f l a s k , a Cenco h o t p l a t e / m a g n e t i c s t i r r e r ,
a condenser,
and a 20 -
680 d e g r e e s
Fa h r e n h e i t
thermometer
( Fi gure 2 ) . *
Tabl e 3.
Batch
%
Ki t t a n n i n g coal
Ash
%
N
chunk a n a l y s e s . *
% C
%
H
I
9.5
1. 45
(1.31)
84.13
(76.14)
5. 61
(5.08)
2
8.9
1. 44
(1.31)
85.47
(77.86)
5 . 69
(5.18)
3
13. 9
1. 45
(1.25)
85. 01
(73.19)
5 . 68
(4.89)
%
0
-
6.30
(5.74)
-
%
P
Run numbers
0.06
(0.05)
14 - 29
0.18
(0.16)
30 - 35
-
36 - 39
* v a l u e s Th p a r e n t h e s e s RTve a mol s t u r e - f r e e TmTl b a s i s ;
o t h e r v a l u e s have a mo i s t u r e - and a s h - f r e e (maf) b a s i s .
Procedure
The bat ch r e a c t o r ,
agitated,
c o n t a i n e d 200 m i l l i l i t e r s
f our grams o f coal .
vol ume)
mi xt ur e
were a t t e mpt e d:
i ng t he
purged wi t h n i t r o g e n and c o n s t a n t l y
of
o f s o l v e n t and t hree to
The s o l v e n t was TMU, HMPA, or a 1:1 (by
TMU and
HMPA.
( I ) combi ni ng coal
Two s t a r t u p
and s o l v e n t be f o r e h e a t ­
sys t em t o run t e mper at ur e and (2)
preheating
procedures
addi ng coal
t he syst em wi t h s o l v e n t to run t e mp e r a t ur e .
after
The
30
Figure 2
Dissolution apparatus.
con denser
thermometer
nitrogen
/ IJ rubber s t o p p e r
Erlenmeyer f l a s k
hotplate/m agnetic s t ir r e r
31
t e mper at ur e
of
t he
sys t em
was
mai nt ai ne d
to
wi t h i n
+/-
5
d e g r e e s F a h r e n h e i t o f the d e s i r e d run t e mp e r a t u r e , which was
either
79,
200,
or 320 d e g r e e s F a h r e n h e i t ^
Hi gher run tem­
p e r a t u r e s were not c o n s i d e r e d t o avoi d s i g n i f i c a n t TMU l o s s
by v a p o r i z a t i o n .
quent
Time and t emper at ur e were r ec orded at f r e ­
intervals.
I mmedi at el y a f t e r
each run was o v e r ,
s l u r r y was quenched and vacuum f i l t e r e d ,
was c o l l e c t e d ,
the
filtrate
pump f o r
t he l i q u i d product
and t he r e s i d u e was washed wi t h a c e t o n e u n t i l
was c l e a r .
under about 0 . 1
cal
t he
The r e s i d u e s
we re vacuum d r i e d
t o r r i n a d e s s i c a t o r a t t a c h e d to a mechani ­
a p p r o x i ma t e l y
one
i n d i c a t e d maximum we i g h t l o s s
week u n t i l
daily
had been a t t a i n e d .
we i g hi ng s
The r e s i ­
due was q u i c k l y wei ghed (due t o t he s i g n i f i c a n t we i ght gai n
o bs e r ve d o f t he vacuumed r e s i d u e on e xpos ure t o a i r )
be i ng sampl ed f o r c ar bon,
phorus ,
and ash
residues
before
we r e
analyses.
weighed
and a f t e r
be i ng
f o r a t l e a s t 24 hours .
in
hydr oge n, n i t r o g e n ,
o x y g e n , phos ­
In t he ash a n a l y s e s ,
crucibles
ashed
in
at
be f o r e
coals
and
room t e m p e r a t u r e
a 700 de gr ee
Celsius
oven
32
RESULTS
Extraction Results
HMPA as
the
solvent
undesirable
produced wi th
tested
an
colloidal
greatly
impeded f i l t r a t i o n .
heating
of
of
suspension
the c o a l s
or
gel
that
Of t he two s t a r t u p p r o c e d u r e s ,
t he sol v e n t - p r e h e a t i n g method i s
simultaneous
all
p r e f e r r e d to t he method o f
solvent
and c o a l
because
in the
l a t t e r method a l ower d i s s o l u t i o n was t y p i c a l l y a t t a i n e d and
an u n p r e d i c t a b l e t i me was needed f o r t he sys t em t o reach t he
run
t emperat ure.
comparison.
Exemplary
For a run t i m e
runs
are
gi ve n
in Tabl e 4 f o r
o f 20 m i n u t e s ,
considerably
hi g h e r d i s s o l u t i o n was o b t a i n e d wi t h pr e he at e d s o l v e n t than
wi t h
s i mu l t a n e o u s
additional
still
solvent
tion
after
run.
after
t he
solvent
Al t hough a c t u a l
and c o a l ,
dissolution
a run t i me o f one hour,
p r e f e r r e d method be c a us e
retained.
are
of
despite
discussed
12 hours
values
(but
with
corresponding
in
became
s o l v e n t preheating i s
of
t he
l ower
amount o f
The d i s a d v a n t a g e s o f hi gh s o l v e n t r e t e n ­
in t he
Re t e n t i o n
Results
section.
di d t he method o f s i mu l t a n e o u s
almost
values
twice
the
produced
by
solvent
the
dissolu­
retention)
me t hod
Only
h e a t i n g pr o ­
duce s i m i l a r appare nt d i s s o l u t i o n and hi g he r a c t u a l
tion
t he
12 mi nut es o f c o n t a c t between s o l v e n t and coal
t he l a t t e r
similar
heating
of
t ha n
solvent
Tabl e 4.
H e a t i ng
Procedure
Run Time Heat i ng Apparent Actual
Sol vent
Run
(mi n)
t l me( mi n) Di s s ( %) Di s s (%) Re t e nt i on* number
sol ve nt
20
+
0
7.4%
11.6%
0. 069
19
TMU+HMPA
200
solvent+coal
20
+ 12
1.5%
6.1%
0. 046
14
TMU+HMPA
200
sol vent
60
+
13.5%
0. 068
27
TMU+HMPA
200
solvent+coal
60
+ 10
4.7%
12.6%
0 . 079
12
TMU+HMPA
200
sol ve nt
720
+
0
20.5%
27.9%
0 . 074
34
TMU+HMPA
200
solvent+coal
720
+ 15
20.8%
CO
0 . 134
15
W
0
Uni t s of s o l v e n t r e t e n t i o n are (g s o l v e n t / g mar c o a l )
**
200
CU
TMU+HMPA
OO
Temp
(F)
O
a*
Solvent
E f f e c t o f s t a r t u p pr ocedure on d i s s o l u t i o n
34
preheating.
us i ng
Dissolution
pr e he a t e d
dat a
were
a c c umul at e d,
therefore,
TMU and a 1:1 pr e he at e d mi xt ur e o f TMU and
HMPA as s o l v e n t .
Apparent d i s s o l u t i o n
i ng f o r mo i s t u r e
( i e .,
d i s s o l u t i o n o f coal
a c c o u nt ­
and ash but not s o l v e n t i n c o r p o r a t i o n )
was
c a l c u l a t e d from
Apparent D i s s .
assumi ng
sius
that
in
t he
=
(g c o a l - g wet r e s i d u e )
-------------------------------------- xlOO
g ash
( i ------------- ) ( g coal )
g coal
i ) dr yi ng t he coal
removed a l l
bonds
[ %)
of
at 100 - 105 de gr e e s Ce l ­
t he mo i s t u r e wi t h o u t a l t e r i n g
coal,
i i ) t he
(2)
actual
ash c o n t e n t
of
chemi cal
the coal
can be de t er mi ne d from t he a s h i n g method pe r f o r me d, and i i i )
acetone
the
has
residue.
be c aus e o f
yses
if
no e f f e c t
Wet r e s i d u e
solvent
t he we i g h t
remove e x c e s s
refers
t he a c t u a l
additional
s o l v e n t mol ecul es
to
incorporation.
( Appendix A) ,
these
except
are
to r e s i d u e
i s we t
From t he e l e me n t a l
anal^
d i s s o l u t i o n can be det ermi ned
assumptions
ar e
incorporated
into
t he
i v)
residue
whol e
and v)
remain c o n s t a n t t hrough t he d i s s o l u t i o n p r o c e s s
so t h a t any
poration
nitrogen
of
t he e l e me n t a l
nitrogen
valid:
i n the coal
in
of
that
from
and phosphorus
change
percents
solvent
and phosphorus c o n t e n t
TMU and/ or
HMPA.
c o n t e n t s o f dry ( s o l v e n t - f r e e )
in Appendix B.
as
dissolution
the
actual
due to i n c o r ­
Based on t h e s e
de t er mi ne d and are l i s t e d
solvent,
is
was
a s s ump t i o n s ,
r e s i d u e s can be
For runs us i ng TMU
calculated
from
35
Actual
Di s s .
( %)
( g c o a l - g dry r e s i d u e )
= --------------------------------------- xlOO
g ash
. ( I --------------- ) ( g coal )
g coal
( 3)
where
g dry r e s i d u e = g wet r e s i d u e
g N
g N
g solvent
g wet r e s i d u e
x ( ............. .............................................)
g N
g N
g solvent
(4)
g coal
For runs us i ng a 1:1 mi xt ur e o f TMU and HMPA as s o l v e n t ,
a c t ua l
t he
d i s s o l u t i o n was c a l c u l a t e d from Equati on ( 3) where
g dry r e s i d u e = g wet r e s i d u e x
(g N/g wet r e s )
( g N/g HMPA)
( g P/ g wet res)
[ I ................. ...................... - + ( ............... .................... 1 ) ( ....................... ................. ) ] /
( g N/g TMU)
(g N/g c o a l )
( g N/g TMU)
(g N/g HMPA)
[ I .............. - .................. +
( g N/g TMU)
--------
(g P/ g HMPA)
(g P/ g c o a l )
- 1,)( — .............. - - - ) ]
( g N/g TMU)
(g P/ g HMPA)
(5).
Apparent and a c t u a l
r e s u l t s are l i s t e d
in Tabl e
5; Equat i ons ( 4) and ( 5) are d e r i v e d in Appendix C.
Observ­
i ng
runs
t he
e xpe ns e
us i ng
phosphorus
of
dissolution
phosphorus
analyses,
onl y
half
of
t he
a 1:1 mi xt ur e o f TMU and HMPA were a nal yz e d f or
content.
from Equat i ons
( 3)
Al I o f
and ( 5)
t he a c t ual
dissolution
results
are s i m i l a r to t h o s e based on a
36
Tabl e 5.
Coal d i s s o l u t i o n r e s u l t s .
S o l v e n t Temp
(F)
TMU
TMU
TMU
TMU
TMU
TMU
TMU
TMU
TMU
TMU
TMU
TMU
Solvent
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
Temp
(F)
79
79
79
200
200
200
200
320
320
320
320
Run t i me
(mi n)
79
79
79
79
200
200
200
200
200
320
320
320
60
60
720
2880
20
40
60
720
2880
20
720
2880
Run t i me
(min)
75
735
2880
20
60
720
2880
10
20
40
720
Apparent
Di s s ( $)
Act ual
Di s s ( %)
5.3$
2.9$
2.4$
4.7$
8.4$
12.4$
3.7$
9.1$
1 5. 5$
1 0. 5$
1 6. 2$
1 0. 1$
Apparent
Di s s ($)
0$
2.6$
6.7$
7.4$
8.0$
20.5$
1.4$
21.5$
1 8. 2$
20.6$
1 5. 2$
5.4$
3.1$
5.2$
5.7$
13.1$
1 8. 3$
9.9$
1 5. 2$
21.2$
1 6. 9$
22.8$
1 9. 3$
Actual
Di s s ($ )#
—
8.0$*
—
1 3. 6$*
27.8$
23.9$
-
3 3. 9$
—
3 0. 0$*
Run
number
21
35
22
31
39
38
23
• 24
30
25
26
32
Actual
Run
Di s s ( $) + numb
2.1$
4.2$
8.0$
1 1. 6$
1 3. 5$
27.9$
23.7$
40.2$
33.7$
41.2$
29.4$
16
17
33
19
27
34
29
37
20
36
28
# Based on n i t r o g e n and phosphorus a n a l y s e s .
+ Based on n i t r o g e n a n a l y s e s and assumi ng 1:1 s o l v e n t
incorporation.
* Data i n d i c a t e n e g a t i v e TMU i n c o r p o r a t i o n i n t o t he r e s i d u e .
37
1:1 (by vol ume) sol v e n t - i n c o r p o r a t i o n as s ump t i o n , which w i l l
now be adopt ed f o r t h o s e runs us i n g both s o l v e n t s .
Dissolution
e l e me nt al
values
based On as h i ng
results
as wel l
as
a n a l y s e s were c a l c u l a t e d from Equat i on ( 3) where
g dry r e s i d u e
g dry r e s i d u e = g coal x ( --------------------- )
g wet r e s i d u e
(g ash)/(g coal)
x ( ..................- ................................. )
(g a s h ) / ( g wet r e s i d u e )
and are l i s t e d
consistently
to
that
of
in Tabl e 6.
produced a s h e s
t he coal .
uni que c o l o r s
( 6)
Runs us i ng pure TMU as s o l v e n t
o f a l a v e n d e r hue very s i m i l a r
However, phosphorus a n a l y s e s and t he
o f t he as he s from t he h i g h e r - t e mp e r a t u r e runs
us i ng a 1: 1 mi xt ur e o f t he s o l v e n t s i n d i c a t e d t h a t t he HMPA
incorporated
into
t he
residues
di d
not
c o mp l e t e l y
combust
(up t o 21 we i g h t p e r c e n t phosphorus was p r e s e n t in the ashed
residue).
gram o f
tion
Also,
residue
results.
duplicate
runs
as hi ng
di d not c o n s i s t e n t l y
Therefore,
there
is
appr o x i ma t e l y
have s i m i l a r
doubt
that
one
dissolu­
t he
as hi ng
t e c h n i q u e used a d e q u a t e l y r e p r e s e n t s t he t rue ash c o n t e n t o f
t he
residues.
These
compl icat ions
force
t he
dissolution
r e s u l t s based on ash t e s t s to be c o n s i d e r e d s e c ondar y to the
dissolution
results
based on we i ghi ng t he
and b a c k - c a l c u l a t i n g t he ne t we i g h t l o s s .
coal
and r e s i d u e
38
Tabl e 6.
Resi due as h i ng r e s u l t s .
Sol ve nt Temp
(F)
Run ti me
(min)
TMU
TMU
TMU
TMU
TMU
TMU
TMU
TMU
TMU
TMU
TMU
TMU
79
79
79
79
200
200
200
200
200
320
320
320
60
60
720
2880
20
40
60
720
2880
20
720
2880
Solvent
Temp
(F)
Run ti me
(min)
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
TMU+HMPA
79
79
79
200
200
200
200
320
320
320
320
75
735
2880
20
60
720
2880
10
20
40
720
Dissolution
( sampl e 1 , 2 )
0%,
0$,
0%,
0 %,
6%
0%
0%
3%
Ash c o l o r
( maj or/ mi nor )
Lav e n d e r / g r e y
Lavender
Lavender
Lave nder / or ange
-
0%,
0 %,
7%,
8 %,
15%,
12%,
mm
—
0%
4%
16%
20%
16%
18%
Di s s o l u t i on
( s ampl e 1 , 2 )
0$,
0 $,
3 %,
9%,
13%,
26%,
44%,
0%
4%
7%
11%
20%
38%
45%
La ve nde r / gr e y
Lavender
Lave nde r / or ange
Lavender
Lavender
Lave nde r / gr e y
Ash c o l o r
( maj or/ mi nor )
Lavender
Lavender
Lave nder / or ange
Lave nde r / gr e y
Whit e / p u r p l e
Whit e / p u r p l e
Whit e / p u r p l e
-
44%, 45%
-
62%, 63%
—
White
—
BIue - g r e e n
Run
number
21
35
22
31
39
38
23
24
30
25
26
32
Run
number
16
17
33
19
27
34
29
37
20
36
28
39
Apparent d i s s o l u t i o n r e s u l t s are i l l u s t r a t e d in Fi gure s
3 and 4.
The maximum appare nt e x t r a c t i o n ,
21.5%, i s a c h i e v ­
ed wi t h a 1: 1 r a t i o o f t he s o l v e n t s a t the h i g h e s t t empera­
ture
considered
(320
degrees
F a hr e n he i t )
in
t en
mi nut e s .
The maximum appare nt d i s s o l u t i o n
f or runs us i ng TMU as s o l ­
vent,
same t e mpe r at ur e but a f t e r
16.2%,
12 h o u r s .
is
obs e r ve d a t
Act ual
t he
dissolution
results
assumi ng a 1:1 r a t i o
o f s o l v e n t i n c o r p o r a t i o n f o r runs us i ng a mi x t ur e o f TMU and
HMPA are i l l u s t r a t e d
in F i g u r e s 5 and 6.
solution
dissolution
and i n i t i a l
increasing
pr oc e e ds
t e mp e r a t u r e .
similarly
increased
dissolution
of
t he
attained,
solvents
room t e mp e r a t ur e ,
Fahrenheit,
by t h e
f or
dissolution
presence
41. 2%,
is
40 mi nut e s
dis­
r a t e tend to i n c r e a s e wi t h
dissolution
f o r both s e t s o f s o l v e n t r u n s .
a t 200 and 320 d e g r e e s
cantly
At
As e x p e c t e d ,
of
HMPA.
a c hi e v e d
at
320
us i ng
degrees
is
However,
signifi­
The maximum
a 1:1
ratio
Fahr e nhe i t ;
t he run e x h i b i t i n g t he maximum appare nt d i s s o l u t i o n o f 21.5%
has an a c t u a l
dissolution
t he maximum d i s s o l u t i o n
o f 40.2%.
attained,
d e g r e e s F a h r e n h e i t a f t e r 12 hour s .
Usi ng TMU as s o l v e n t ,
22.8%,
i s obs e r ve d at 320
Both appar e nt and act ual
d i s s o l u t i o n appear t o reach a maximum wi t h i n 12 hours at 320
d e g r e e s F a h r e n h e i t us i ng pure TMU as s o l v e n t and at 200 and
320 d e g r e e s F a h r e n h e i t us i ng a 1:1 mi xt ure o f t he s o l v e n t s .
Maximum
dissolution
is
i ncreasi ng temperatures.
achieved
at
shorter
t i mes
wi t h
The 1: 1 mi xt ure o f TMU and HMPA as
s o l v e n t i s more e f f e c t i v e than pure TMU in d i s s o l v i n g c o a l .
3.
Apparent
d isso lu tio n
vs.
tim e
79 F
200 F
320 F
Apparent Dissolution ( % )
F igu re
Time
(h ou rs)
Figure 4.
Apparent dissolution vs. short-contact time
Apparent Dissolution ( % )
25,------------------------------------------------ ---
o TMU
a
TMU+HMPA
• • • • 79 F
--- 200 F
---
•*—
—SmJ. .*-* <»-* «"
320 F
%*T \ eT
2
Time
(hours)
5.
A ctual
d isso lu tio n
vs.
tim e
Actual Dissolution ( % )
F igu re
Time
(hours)
6.
A ctual
d isso lu tio n
vs.
sh ort-contact
Actual Dissolution ( % )
F igu re
tim e
o TMU
* TMUt-HMRA
Time
(h ou rs)
44
Dissolution calculations
t r a t e d i n Fi gur e 7.
lution
wi t h
ashing
results.
versus
t i me
based on ash t e s t s
are i l l u s ­
The t e nde nc y o f enhanced a c t u a l
increased
t e mpe r at ur e
Whi l e
trends
little
wi t h
is
corroborated
difference
solvent
t ype
are
disso­
by
t he
in d i s s o l u t i o n
obs e r ve d
at
room
t e m p e r a t u r e , t he 1:1 mi xt ur e o f TMU and HMPA used as s o l v e n t
agai n produces h i g h e r d i s s o l u t i o n
peratures.
is
not
The a t t a i n me n t o f maximum d i s s o l u t i o n ,
apparent
previous
in
actual
retention.
for
r uns
than TMU a t e l e v a t e d tem­
the
ashing
dissolution
results
calculations
as
however,
it
is
in
the
based
on
solvent
D i s s o l u t i o n based on ash t e s t s i s markedl y l ower
using
TMU a t
room t e m p e r a t u r e
and 200
degrees
F a h r e n h e i t than c o r r e s p o n d i n g d i s s o l u t i o n c a l c u l a t i o n s based
on n i t r o g e n
tion
bet ween
data.
t he
two
TMU i s i mpr ove d.
as
solvent,
tests
is
nitrogen
are
At 320 de g r e e s
dissolution
slightly
dissolution
calculations
room t emper at ur e
b u t c o mp a r a b l e
data.
dissolution
higher
tions
on
based
at
lower
and phosphorus
increased,
of
t he c o r r e l a ­
f or
For runs us i n g a 1:1 r a t i o of TMU and HMPA
increasingly
63%,
sets
Fahrenheit,
bas ed
on
ash
t o t h a t ba s e d on
As t e mper at ur e and run ti me
tests
becomes
than c o r r e s p o n d i n g d i s s o l u t i o n
calcula­
e l e me nt al
based
analyses.
on
ash
Maximum d i s s o l u t i o n ,
i s obs e r ve d us i ng a 1: 1 mi xt ur e o f t he s o l v e n t s at 320
de g r e e s
Fahrenheit
f or
12
hour s .
stated,
dissolution
calculations
However,
as
previously
based on ash t e s t s
are not
7.
D isso lu tio n
based
on
ash
tests
vs.
Dissolution based on ash tests { % )
F igu re
Time
(h ou rs)
tim e
46
as
accurate
t ho s e
in descri bi ng
bas ed
pho r us
solely
analyses
of
h i g h e r - t e mp e r a t u r e
indicated
not
that
values
tion
results
error
t r ue
e l e me n t a l
the
dissolution
analyses
uniquely
(i)
ashes
phos­
from t h e
runs us i ng a 1:1 mi xt ure o f t he s o l v e n t s
combus t ,
incorrectly
based on ash
c oul d
tests,
into
(it)
analyses
methods o f c a l c u l a t i n g a c t u a l
t he
residues
elevating
di d
t he
dissolu­
reproducible
dissolu­
not be c o n s i s t e n t l y
in t he e l e me n t a l
Considerable
be havi or as
since
colored
t he HMPA i n c o r p o r a t e d
compl etely
tion
on
t he
attained,
and ( i i i )
i s t r a n s m i t t e d through both
dissolution.
dissolution
o f coal
can be a c hi e v e d wi t h
TMU and HMPA a t t e mpe r a t ur e s bel ow t he b o i l i n g p o i n t s o f t he
solvents.
Based
was o b s e r v e d
hours.
t ur e
on e l e me nt a l
using
analyses,
TMU a t 320
Dissolution
22.8% d i s s o l u t i o n
degrees
Fahrenheit
for
12
t o 41.2% was o bs e r ve d us i ng a 1:1 mi x­
o f TMU and HMPA f o r 40 mi nut e s a t 320 d e g r e e s Fahren­
heit.
Although
mi xt ur e
us i ng
until
enhanced
pure
HMPA i n t he
is
produce d.
addi ng
of s o l v e n t
presence
dissolution
a me t hod
ma t e r i a l
before
the
coal
and coal
dissolution
was
additional
and
u n a v o i da b l e
wh i l e
of
at
HMPA i n t h e
t he
dissolution
developed
Solvent
to
hi g h e r
process
was p r e f e r r e d
to
variable
heating
for
run
t i me s
the
run
colloidal
t emperat ure
syst em
pr oc edur e a l ower
under
sol v e n t / c o a l
t he
not f e a s i b l e
over s i mu l t a n e o u s h e a t i n g
be c aus e in t he l a t t e r
attained
solvent
t e mp e r a t u r e s ,
is
separate
preheating
1: 1
12
contact
to
run
hours
and
ti me
was
t e mpe r at ur e .
47
Dissolution
wi t h
and i n i t i a l
increasing
run
dissolution
rate
t e mp e r a t ur e .
t ended to i n c r e a s e
Maximum
yields
were
a t t a i n e d w i t h i n 12 hours a t 320 d e g r e e s F a h r e n h e i t us i ng TMU
as so. l vent and a t 200 and 320 d e g r e e s F a h r e n h e i t us i ng a 1:1
mi xt ur e o f t he s o l v e n t s .
Hi gher run t e mp e r a t ur e s a l l o w max­
imum d i s s o l u t i o n t o be a c hi e v e d a t s h o r t e r t i m e s .
Si nce a l l
o f t he runs a nal yz e d f o r phosphorus c o n t e n t had d i s s o l u t i o n
values
similar
incorporation,
to
those
vol ume)
adopt ed
The
analyses
for
solvent
us i ng a 1:1 mi xt ur e o f TMU and HMPA t o l i m i t e x p e n s e s .
phosphorus
was
(by
runs
t he
as s umpt i on
1:1
t ho s e
purpose o f
t he
ass umi ng
now becomes
to
substan­
t i a t e t he as s umpt i ons made t o de t e r mi ne d i s s o l u t i o n .
Re t e n t i o n R e s u l t s
Coupl ed wi t h d i s s o l u t i o n a n a l y s e s , s o l v e n t r e t e n t i o n i s
anot he r i mpo r t a nt f a c t o r
in a s s e s s i n g t he p o t e n t i a l
c o n v e r s i o n t hrough e x t r a c t i o n
by TMU and HMPA.
o f coal
If s i g n i f i ­
c a n t r e t e n t i o n o c c u r s , t he e x p e n s i v e s o l v e n t s produce a hi gh
cost
penalty
either
from s o l v e n t
loss
t hrough
irrevocable
i n c o r p o r a t i o n i n t o t he r e s i d u e or from a d d i t i o n a l
requirements
to
investigation,
recover
hi gh
the
solvent
solvents,
retention
processing
or b o t h .
is
also
In t h i s
undesirable
be c aus e t he as s umpt i on made o f whol e s o l v e n t mo l e c u l e s bei ng
incorporated
error
into
t he
by
this
caused
estimated,
but
data
residue
was
not
assumption
can
indicate
that
substantiated.
not
solvent
be
The
adequately
fragments
ar e
48
incorporated.
Sears [ 1 ] obs e r ve d t h a t a f t e r e x t r a c t i o n wi t h
HMPA f o l l o w e d by washi ng wi t h
measurement o f
a residue
we i g h t HMPA r e t e n t i o n ,
tial.
alcohol,
a fluorescence
scan
showed onl y a p p r o x i ma t e l y 0.4% by
i n d i c a t i n g e nc our agi ng p r o c e s s p o t e n ­
Based on t he same as s umpt i on used to de t e r mi ne ac t ual
dissolution,
solvent retention
i s c a l c u l a t e d by s u b t r a c t i n g
t he we i g ht o f dry r e s i d u e from t he we i ght o f wet r e s i d u e and
then
dividing
t he
difference,
t he
s o l v e n t , by a n o r ma l i z i n g w e i g h t ,
o f t he c o a l .
coal
ash-free
and a s h - f r e e
are
coal
i ncorporated
such as t he i n i t i a l
dry coal
weight,
dry r e s i d u e w e i g h t .
used
contents
of
we i g ht
Four n o r ma l i z i n g we i g h t s are c o n s i d e r e d :
weight,
bas e s
we i g ht
to
(8. 9%,
obs e r ve
t he
9.5%,
and
results
for
dry
dry r e s i d u e we i g h t ,
Both dry and a s h - f r e e dry
effect
13.9%)
of
of
t he
t he
d i f f e r e n t ash
three
Ki t t a n ni ng
g r i n d s us ed.
Retention
are l i s t e d
i n Tabl e 7.
weight
moisture-free
of
runs
us i ng
pure TMU as
solvent
The maximum TMU r e t e n t i o n ( wi t h t he
coal
as
the
basis)
of
10.3% i s
obs e r ve d a f t e r 12 hours a t t he h i g h e s t t e mpe r at ur e exami ned.
TMU r e t e n t i o n
As
wi t h
dissolution,
increasing
However,
5)
320
i s p l o t t e d as a f u n c t i o n o f t i me i n Fi gure 8.
temperature
whi l e
indicated
degrees
solvent
ac t ual
t he
retention
and e x h i b i t s
increases
wi t h
maximums wi t h
time.
di s s o l u t i o n - v e r s u s - t i m e
plots
a t t a i n me n t o f maximum d i s s o l u t i o n
Fahrenheit
maximum TMU r e t e n t i o n
us i ng
is
pure
TMU,
Fi g ur e
achieved in l e s s
( Fi g ur e
onl y
at
8 indicates
than 48 hours at
Table 7.
TMU r e t e n t i o n r e s u l t s
Sol ve nt Temp
(F)
Run ti me g s o l v e n t g s o l v e n t
(min)
g mf coal g mat coal
g solvent
g solvent
Run
g dry r e s i d u e g at dry res numb
TMU
79
60
0.010
0. 011
0.010
0. 011
21
TMU
79
60
0 . 003
0. 003
0 . 003
0 . 003
35
TMU
79
720
0 . 027
0.030
0 . 028
0. 032
22
TMU
79
2880
0.009
0 . 010
0.010
0. 011
31
TMU
200
20
0.040
0. 047
0.045
0 . 054
39
TMU
200
40
0.050
0 . 059
0.060
0. 072
38
TMU
200
60
0.060
0 . 066
0 . 065
0 . 073
23
TMU
200
720
0 . 074
0. 081
0 . 085
0. 096
24
TMU
200
2880
0. 051
0 . 056
0.064
0. 072
30
TMU
320
20
0 . 086
0. 094
0. 101
0. 114
25
TMU
320
720
0 . 103
0 . 114
0.130
0. 147
26
TMU
320
2880
0 . 095
0 . 104
0 . 115
0. 129
32
F igu re
8.
TMU r e t e n t i o n
vs.
tim e
for
TMU r u n s
TMU Retention
320 F
ZOO F
o TMU
O « e Ivent/g mf cool
O
IVent/a mof eool
Q eolvenl/g dry r e * Idu
g * o Ivent/g of dry re*
79 F
Time
(hours)
51
all
t e mp e r a t ur e s c o n s i d e r e d .
function
of actual
TMU r e t e n t i o n
dissolution
is
in Fi gure 9.
p l o t t e d as a
TMU r e t e n t i o n
t e nds t o i n c r e a s e wi t h i n c r e a s i n g d i s s o l u t i o n ,
wi t h maximums
a t t a i n e d p o s s i b l y a t 79 and 200 de gr e e s F a h r e n h e i t .
Maximum
TMU r e t e n t i o n i s obs e r ve d f o r t he run e x h i b i t i n g t he h i g h e s t
dissolution.
To a s s e s s t he as s umpt i ons made t o de t e r mi ne ac t ual
solution,
solvent
us i ng
solvent retention
incorporation
phosphorus
dat a
results
assumi ng a 1:1 r a t i o o f
( Ta b l e s
8-10)
are
( Ta b l e s
11 - 1 3 )
f or
compared
to
As wi t h ac t ual
results,
appear e s s e n t i a l l y
cal
is
( Ta b l e s 8 and 11,
agai n
obs e r ve d
However,
of
retention
t he
further
runs
content.
retention
Figures
to
analysis
can
to
de t e r mi ne d.
To
in
t he
be
TO and 1 1 ) .
increase
(starred
Due
results
uncove r s
Tabl e
fixed
calculated
satisfy
wi t h
bot h
5)
onl y
a nal yz e d
of
identi­
retention
t e mpe r at ur e .
a compl i cat i on
after
t he
dissolution
Tot al
increasing
s e quence
t ho s e
runs us i ng a mi x­
t ur e o f TMU and HMPA as s o l v e n t .
total
dis­
for
f or h a l f
phosphorus
calculations,
TMU
HMPA r e t e n t i o n
is
nitrogen
and
phosphorus
mass b a l a n c e s wi t h t he s t a t e d a s s u mp t i o n s , t h r e e o f the runs
listed
t he
in Tabl e 13 i n d i c a t e n e g a t i v e TMU i n c o r p o r a t i o n i nt o
residue
coal-solvent
t he
( i . e .,
mo l e c u l e s
interaction)
relatively
hi gh
ment s .
which
nitrogen
compared t o proposed coal
of
TMU are produced
is
i mprobabl e
content
and
from t he
considering
symmetry
s t r u c t u r e s and i s o l a t e d coal
of
TMU
frag­
The n e g a t i v e r e t e n t i o n v a l u e s do not c o r r e l a t e wi t h
F igu re
9.
TMU r e t e n t i o n
vs.
o TMU
d isso lu tio n
for
TMU r u n s
mf coo I
320 F
TMU Retention
of dry r
200 F
79 F
Actual Dissolution ( % )
Tabl e 8.
Total
s o l v e n t r e t e n t i o n assumi ng I ::I s o l v e n t I n c o r p o r a t i o n .
Solvent
Temp
(F)
Run time g s o l v e n t g sol vent
(min)
g mf coal g mat coal
g solvent
g solvent
Run
g dry r e s i d u e g ar dry res number
TMU+HMPA
79
75
0.022
0 . 024
0.022
0.025
16
TMU+HMPA
79
735
0 . 015
0. 016
0.015
0.017
17
TMU+HMPA
79
2880
0. 011
0. 012
0 . 012
0.013
33
TMU+HMPA
200
20
0 . 063
0. 069
0.070
0 . 078
19
TMU+HMPA
200
60
0.062
0 . 068
0. 071
0.079
27
TMU+HMPA
200
720
0 . 067
0. 074
0.090
0 . 102
34
TMU+HMPA
200
2880
0 . 202
0 . 223
0.257
0 . 292
29
TMU+HMPA
320
10
0. 161
0. 187
0 . 246
0 . 312
37
TMU+HMPA
320
20
0 . 142
0. 157
0 . 204
0. 237
20
TMU+HMPA
320
40
0. 177
0. 206
0 . 275
0.350
36
TMU+HMPA
320
720
0.130
0. 143
0.176
0. 203
28
54
Tabl e 9.
HMPA r e t e n t i o n assumi ng 1: 1 s o l v e n t i n c o r p o r a t i o n .
Run
number
g HMPA
g mf coal
g HMPA
g maf coal
g HMPA
g dry r e s i d u e
g HMPA
g a f dry r es
16
0 . 011
0 . 012
0. 011
0.013
17
0.008
0 . 008
0 . 008
0.009
33
0.006
0 . 006
0. 006
0 . 007
19
0.032
0 . 035
0 . 036
0.040
27
0.032
0.035
0 . 036
0. 041
34
0.034
0 . 038
0. 046
0.052
29
0.104
0 . 115
0.132
0.150
37
0.083
0 . 096
0. 126
0 . 160
20
0.073
0. 081
0.105
0 . 122
36
0. 091
0. 106
0. 141
0 . 180
28
0.067
0.073
0.090
0.104
55
Tabl e 10.
TMU r e t e n t i o n assumi ng 1:1 s o l v e n t I n c o r p o r a t i o n .
Run
number
g TMU
g mf coal
16
0 . 011
0.012
0. 011
0 . 012
17
0.007
0.008
0. 007
0. 008
33
0.005
0.006
0 . 006
0. 006
19
0 . 031
0.034
0 . 034
0. 038
27
0.030
0.033
0.035
0. 038
34
0.033
0.036
0 . 044
0 . 050
29
0.098
0.108
0 . 125
0 . 142
37
0.078
0 . 091
0 . 120
0. 152
20
0.069
0.076
0 . 099
0. 115
36
0.086
0.100
0 . 134
0. 170
28
0.063
0.070
0 . 086
0. 099
g TMU
g maf coal
g TMU
g dry r e s i d u e
g TMU
g a f dry r es
Table 11.
Sol ve nt
Total
Temp
(F)
s o l v e n t r e t e n t i o n based on phosphorus data
Run t i me g s o l v e n t 9 sol vent
(min)
g mf coal 9 maf coal
g solvent
g solvent
Run
g dry r e s i d u e g at ary res number
TMU+HMPA
79
2880
0.012
0.013
0.013
0. 014
33
TMU+HMPA
200
60
0 . 063
0.070
0 . 072
0. 081
27
TMU+HMPA
200
720
0 . 067
0. 074
0.090
0. 102
34
TMU+HMPA
200
2880
0.204
0. 225
0.260
0. 296
29
TMU+HMPA
320
20
0.144
0. 159
0 . 207
0 . 240
20
TMU+HMPA
320
720
0 . 135
0. 149
0.185
0. 212
28
57
Tabl e 12 .
HMPA r e t e n t i o n based on phosphorus d a t a .
Run
number
g HMPA
g mf coal
33
0.028
27
g HMPA
g maf coal
g HMPA
g dry r e s i d u e
g HMPA
g a f dry res
0 . 031
0.030
0. 033
0 . 071
0.079
0. 081
0. 091
34
0.029
0.032
0.039
0. 045
29
0.174
0.192
0 . 222
0. 252
20
0 . 131
0.144
0 . 189
0 . 219
28
0.237
0.262
0. 325'
0. 373
Tabl e 13 .
TMU r e t e n t i o n based on phosphorus d a t a .
Run
number
• g TMU
g mf coal
33
-0.016
-0.018
-0.017
-0.019
27
-0.008
-0.009
-0.010
-0.011
34
0.038
0 . 041
0. 051
0. 057
29
0.030
0.033
0. 038
0 . 044
20
0.013
0 . 014
0.019
0. 022
28
-0.102
-0.113
-0.140
-0.161
g TMU
g maf coal
g TMU
g dry r e s i d u e
g TMU
g a f dry r es
Figure
10.
Total
retention
vs.
time
Total Retention
200 F
20
^
320 F
79 F
A Retwit Ion OKsxim Ing
Q *olvent/g mf coal
g so IVent/g maf coal
I % I Ineorporot Ion
▼ Retention boeed on
phosphorus data
Time
Q « o Ivent/g dry residue
8 s o IVent/g of dry
(hours)
Figure
11.
Total
retention
vs.
d issolu tion
Total .Retention
/
200 F
79 F
A Retent Ion o * « u m Ing
I * I Incorporot Ion
g solvent/g mf cool
g solvent/g maf coal
▼ Retention based on
phosphorus data
g solvent/g dry residue
g solVent/g of dry
Actual
D issolution
(
%
)
320 F
60
t emperat ure,
analyzed
time,
for
or
dissolution.
phosphorus
content
Only
has
one
of
the
runs
TMU r e t e n t i o n
hi gh
enough to be comparabl e to t he c o r r e s p o nd i ng v a l u e s assumi ng
1:1
solvent
results
incorporation.
To c ompens at e ,
HMPA r e t e n t i o n
bas ed on phosphorus a n a l y s e s tend t o be hi gher than
t ho s e based on a 1:1 s o l v e n t i n c o r p o r a t i o n a s s u mp t i o n , s i n c e
total
retention
similar.
lution
calculated
by t he
two methods
are
TMU and HMPA r e t e n t i o n t r e nds wi t h t i me and d i s s o ­
are
expected,
tion
results
illustrated
in
Figures
12
through
15.
As
t he d i s p a r i t y between t he two s e t s o f HMPA r e t e n ­
results
and
increases
wi t h
retention
follows
the
two
sets
increasing
t he
run
of
TMU r e t e n t i o n
t e mp e r a t ur e ,
same t r e n d .
However,
results
since
solvent
no c o r r e l a t i o n
i s e v i d e n t bet ween t he two s e t s o f HMPA r e t e n t i o n r e s u l t s or
t he two s e t s o f TMU r e t e n t i o n r e s u l t s .
The t r e n d s o f s o l v e n t r e t e n t i o n based on t he f our nor­
mal i zi ng
tables
c oal
and r e s i d u e
and g r aphs .
difference
in
r e t e n t i o n r uns .
we i g h t s
As e x p e c t e d ,
retention
values
are
shown in
all
o f t he
t he b a s i s c hos e n makes t he
mo s t
pronounced
in
hi gh
However, s o l v e n t r e t e n t i o n t r e n d s wi t h ti me
and d i s s o l u t i o n are found t o be i nde pe nde nt o f t he no r ma l i z ­
i ng we i g h t
levels
f o r t he
in
chosen.
runs
Total
retention
wi t h moderat e
t horough washi ng o f
to
t he
hi gh
increases
to
unde s i r e d
dissolution.
Except
r e s i d u e wi t h a c e t o n e ,
c e d ur e s t o mi ni mi z e t h i s t e nde nc y were not a t t e mp t e d .
pro­
12.
HMPA r e t e n t i o n
vs.
tim e
HMPA Retention.
Figure
*
t tI
I on euBcvim Ing
I n e o r p o r o t Ion
* Rotcnt Ion booed on
p h o c p h o ru c d o to
1 ‘ * Q coI Vcnt/g
--- 8 coIv«nt/g
8 eol Vent/g
8 *olvcnt/g
"
Time
(hours)
mf coal
mof coal
dry real due
of dry roc
Figure
13.
HMPA r e t e n t i o n
vs.
d issolu tion
320 F
200 F
* Retwnt I on o**xim I ng
I * I Ineorporot Ion
▼ Retention based on
phosphorus data
Actual
D issolution
Q s o IV e n t/o mf cool
fl solvent/y mof cool
a s o I V e n t / g d r y r e s Idu
g solVent/g of dry
(
% )
Figure
.30 —
14«
TMU r e t e n t i o n
vs.
tim e
* Retwit Ien o**um I ng
1*1 Incorporot Ion
TMU Retention
▼ Retwit I on boeed on
phosphorus doto
. 20 -
Ti me
•... Q
_._
a
— — a
.
8
(hours)
«olVwit/g mf cool
*olVwit/g mof cool
colvsnt/o dry residue
eolvcnt/g of dry res
Figure 15.
TMU retention vs. dissolution
AOr------------------------------- ----
.30-
* RetentIen oeeumIng
1*1 IneorporotIen
TMU Retention
▼ Retention based on
phosphorus data
.20
• • • • S «olVent/ q
— ._ Q eolVent/a
— — O eolV e n t / q
9 solV e n t/g
mf cool
mof coal
dry residue
of dry r e s
----- __
320 F
I
at
4^
320 F
%
-L
IO
Actual
J_______________ L
J _______
20
40
D issolution
30
(
%
)
45
65
Low s o l v e n t
this
retention
investigation
Retention
obs e r ve d
to
using
TMU as
at t h e s e c o n d i t i o n s .
t e mper at ur e
times
greater
Fahrenheit
to
e ncouraged
when
not be a t t a i n e d
significant
a moisture-free
solvent
wi t h i n 48 hours a t a l l
t hrough
wi t h
c oul d
for
and
TMU r e t e n t i o n
exhibits
48
de t er mi ne
no t i n g
hours
maximum
that
a maximum wi t h
at
79
was
320 de g r e e s
TMU was a l s o
i n c r e a s e s wi t h
wi t h
t i me
Co n s i d e r a t i o n o f
and
dissolution
TMU r e t e n t i o n
increasing
basis
maximums
t h r e e t e mp e r a t u r e s .
t ha n
at
using
in
dissolution.
coal
12 hours
The maximum d i s s o l u t i o n
increasing
run
runs
10.3% w i t h
Fahrenheit.
attained
for
values
200
degrees
values
possibly
dissolution,
is
pa s s e s
indicating
t h a t l ow r e t e n t i o n may be a t t a i n e d wi t h maximum d i s s o l u t i o n .
However,
gat ed
run t i me s
be c aus e
greater
extraction
feasibility
[14].
as
retention
solvent,
solvent
t i me must be s h o r t
calculations
compared
dat a produced c o n f l i c t i n g
ical.
i ng
f o r commercial
For runs u s i n g a mi xt ure o f TMU and HMPA
incorporation
tion r e s u l t s ,
than 48 hours were not i n v e s t i ­
total
to
results.
assumi ng a 1: 1
t ho s e
using
ratio
of
phosphorus
As wi t h a c t u a l
dissolu­
r e t e n t i o n r e s u l t s are e s s e n t i a l l y i d e n t ­
Re t e n t i o n i s agai n obs e r ve d to i n c r e a s e wi t h i n c r e a s ­
t e mp e r a t u r e .
However,
for
three
runs
negative
solvent
r e t e n t i o n v a l u e s are c a l c u l a t e d based on phosphorus c o n t e n t ,
which can not be modeled by any ass umpt i on o f s ol v e n t - i n c o r ­
poration
ratio.
No c o r r e l a t i o n
i s apparent between the two
66
sets
of
HMPA r e t e n t i o n
results
or
the
two
sets
of
TMU
retention results.
H/C and 0/C Ra t i o s in Resi due
Al t h o u g h
indication
t he
of
dissolution
what
is
occurring
gi ve n by mi cro u l t i m a t e
retention
results
based
mechanism
duri ng
is
t he
not
process
on
be
t he
considered
same
an
may be
a n a l y s i s data c o r r e c t e d f or s o l v e n t
( Ta b l e s 16 and 18 in Appendix B) .
must
known,
questionable
as s umpt i ons
solvent retention values.
made t h a t
However, t h e s e
be c aus e
t hey
produced
negative
A l s o , e r r o r in t he e l e me nt al
are
ana­
l y s e s may c o n t r i b u t e t o produce anomalous H/C and 0/C r a t i o s
[36].
of
Calculated
the
( Tabl e
dry
17
phosphorus
c ar bon,
residues
in
Appendix
dat a
h y d r o g e n , and mol ar H/C c o n t e n t s
assumi ng
1: 1
solvent
B) are
wi t hi n
4% o f
incorporation
those
based
on
( Tabl e 18) wh i l e t he two s e t s o f oxygen and
mol ar 0/C c o n t e n t s d i f f e r by l e s s than 18%.
Hydrogen/ carbon
r a t i o s t end t o d e c r e a s e as a f u n c t i o n of t i me from t he a v e r ­
age i n i t i a l
three
v a l u e o f 0 . 7 9 3 f o r coal
grinds
range
degrees Fahrenhei t .
Fahrenheit,
t he
ature
200
to
0.794)
for
runs a t 320
For runs us i ng pure TMU a t 200 de gr ee s
H/C v a l u e s
oscillate
range b e i ng bel ow t he
coal.
or
from 0 . 7 9 0
( t he H/C v a l u e s f or t he
initial
between
0.767
H/C val ue
and 0 . 7 9 2 ,
f o r Ki t t a n ni ng
However, t he remai ni ng runs us i ng TMU a t room t emper­
or a 1:1 mi xt ur e o f t he s o l v e n t s
degrees
Fahrenheit
produce
a t room t emperat ure
H/C v a l u e s
rangi ng
from
67
0.737
to 0 . 8 4 0 ,
neither
consistently
that of c oa l.
S i m i l a r b e ha v i o r i s
ti on of actual
dissolution.
apparent
t r e nd wi t h
conclusion
pr oduc t s
initially
nor
hi ghe r
than
noted f o r H/C as a f un c ­
Oxygen/ carbon r a t i o s e x h i b i t no
t e mp e r a t ur e ,
can be made as
l ower
t i me ,
or d i s s o l u t i o n .
t o w h e t h e r or n o t
the
No
soluble
have hi gh oxygen c o n t e n t s as proposed by
t he Union Carbi de Cor por at i on and c i t e d by Se ar s [ I ] .
68
DISCUSSION
Based
on
t he
resources
available
to
t he
author,
t he
f o l l o w i n g a s s ump t i o n s are made in order to c a l c u l a t e d i s s o ­
l u t i o n and r e t e n t i o n v a l u e s :
degrees
Celsius
altering
tent
of
overnight
chemi cal
t he
pe r f o r me d,
bonds
coal
iii)
can
dryi ng t he coal
removed a l l
a t 100 - 105
of
t he wat er wi t ho u t
in t he coal , i i )
t he t r u e ash c on­
be
acetone
i)
det er mi ne d
from t he
has no e f f e c t
as h i ng method
o t h e r than t o remove
e x c e s s s o l v e n t from t he r e s i d u e , i v) whole s o l v e n t mo l e c u l e s
are
incorporated
into
t he
residue,
and v)
c e n t s o f n i t r o g e n and phosphorus in the coal
t he
we i g ht
pe r ­
remain c o n s t a n t
t hrough t he d i s s o l u t i o n p r o c e s s so t h a t any change in n i t r o ­
gen and phosphorus
and/ or HMPA.
additional
tion
into
solution
ever,
t he
content
is
due to
incorporation
of
TMU
For runs us i ng a mi xt ur e o f TMU and HMPA, the
as s umpt i on o f
a 1: 1
ratio
of
solvent
incorpora­
t he r e s i d u e was adopt ed a f t e r no t i n g s i m i l a r d i s ­
trends
t o t h o s e bas ed on e l e me nt al
results
based oh t h e s e
t he
dissolution
How­
as s umpt i ons were found to
be i n a c c u r a t e in d e s c r i b i n g t he coal
Al t ho ug h
analyses.
dissolution process.
results
appear
satisfactory,
t he s o l v e n t r e t e n t i o n r e s u l t s i n d i c a t e t h a t t he e r r o r caused
by one or more o f
the
five
enough t o produce n e g a t i v e
initial
assumptions
is
solvent retention values.
large
Si nc e
t he we i g ht p e r c e n t s o f n i t r o g e n i n TMU and HMPA are s i m i l a r
69
(24.12% v s .
are
23. 45%,
virtually
por at e d i n t o
tion
do
of
ratio.
obs e r ve d
that
fluctuates
before
solvent
ratio
Al t hough
affect
of
the
Tsao
t he
and
we i g h t
c aus e d
initially
by
in
run t i me
solvents
results,
of
[37]
have
nitrogen
ass umpt i on
retention
coal
over,
is
will
values:
three
as s umpt i ons
are
recently
in
t he
coal
However, t he
reverse
if
all
onl y
o f t he
assumed
to
be e x t r a c t e d
TMU r e t e n t i o n
is
-0.063
per gram o f m o i s t u r e - f r e e coal
first
analyses
t hey
and t he
grams
f or run 28 which had
t he most n e g a t i v e r e t e n t i o n v a l u e o f t he t h r e e r u n s .
t he
incor­
Cont rary to the
by TMU and HMPA.
this
t he
is
Losinski
percent
t he t h r e e n e g a t i v e
t he
calculations
phosphorus
dissolution
duri ng e x t r a c t i o n
maximum e r r o r
nitrogen
t he
in de t e r mi n i n g s o l v e n t r e t e n t i o n .
assumption,
two o f
of
dissolution
t he r e s i d u e and can be mode l l e d by any assump­
significantly
essential
fifth
i nde pe nde nt
retention
not
respectively),
fifth
Making
ass umpt i on
wi t h
r e s p e c t t o t he phosphorus c o n t e n t probabl y c o n t r i b u t e s l i t ­
tle
to
the
values.
of
the
error,
error
that
produced
Al t hough e x pe r i me nt a l
elemental
previous
analyses
research
negative
retention
t e c h n i q u e and t he i nac c ur ac y
could
of
the
account
HMPA as
for
a coal
some o f t he
solvent [11]
i n d i c a t e s t h a t making t he f o ur t h assumpt i on produces c o n s i d ­
erable
uncertainty.
phosphorus/nitrogen
are
also
If
ratios
incorporated,
fragments
than
TMU
the
of
whole
retention
HMPA w i t h
higher
s o l v e n t mo l e c ul e
(as
whol e
and/ or
70
fragment
solvent
molecules)
be c a l c u l a t e d
negative
for all
i ng t h i s
c o n d i t i o n have o n e , t wo , or a l l
cleaved
( whi ch
before
r uns .
could
can
Examples o f HMPA f ragme nt s s a t i s f y ­
occur
incorporation
in
of
residue.
TMU r e t e n t i o n
unchanged
( as s umi ng
poration)
or
t he
the
remaining
f ragme nt s
increased
(if
are
the
of
dissolution
lated
values
molecules,
values.
a bl e
t he
on
l owest
However,
|re t e n t i on
formed
mol ecul es
which
appare nt
dissolution,
onl y
into
wi t h
the
incor­
steps
and t o t a l
TMU a n d / o r
or
are
retention
limit
be i ng
solvent
would make
than
of
analyses
whol e
actual
calcu­
solvent
dissolution
indicate consider­
a nd / o r
dissolution
t he
t he
whol e
t he appare nt
as
what eve r
HMPA f r a g m e n t s .
l ower
incorporation
t he e l e me n t a l
of
[6])
HMPA l o s s would be
fragmentation
may be h i g h e r
based
an aci d
dependi ng on t he c h a r a c t e r i s t i c s
incorporated
Actual
of
fragment
would i n c r e a s e ,
would i n c r e a s e or d e c r e a s e ,
amount s
t h r e e amide groups
pr e s e nc e
i nde pe nde nt o f t he i n c o r p o r a t i o n s t e p s ) ,
and
as non-
f ragment ed
hi ghe r
constitution
than
of
the
incorporated molecules.
For runs u s i n g pure TMU as s o l v e n t ,
and
fifth
a s s umpt i ons
major par t o f
is
agai n
t he e r r o r ,
content
of
the
functionality
residue
of
e x pe c t e d
Dissolution
would vary dependi ng on ( i )
a do pt i ng t he f our t h
to
a c c o u nt
f or
a
and r e t e n t i o n v a l u e s
t he f l u c t u a t i o n o f t he n i t r o g e n
during
liquefaction
TMU f r a g m e n t a t i o n
and ( i i ) t h e
and r e t e n t i o n
r e s i d u e on t e mp e r a t u r e , t i m e , and d i s s o l u t i o n .
in the
For exampl e.
71
if
TMU a c t s
ionic
as
an
f ragme nt s
electron
formed
acceptor
from
the
duri ng
liquefaction,
de c o mp o s i t i o n
of
t he
r a d i c a l - a n i o n o f TMU c oul d be i n c o r p o r a t e d i n t o t he r e s i d u e .
P r o v i di ng an a l t e r n a t e
philes
produced
duri ng
from TMU [ 6 ] .
de t e r mi ne
s our c e o f s o l v e n t f r a g m e n t s , n u c l e o ­
extraction
Ho w e v e r ,
t he
pr e s e n c e
were not a v a i l a b l e ,
since
of
c oul d
remove
analytical
incorporated
t he s t a t e d a c t u a l
amide
i ons
techniques
solvent
to
f ragment s
d i s s o l u t i o n v a l u e s are
t aken t o be t he b e s t r e p r e s e n t a t i o n s o f t he t r u e v a l u e s .
Ri gorous
constitutions
por at ed
mass
balances
and
solvent
amounts
have
can
of
been
not
be
applied
dissolved
pr oduct
established.
until
and
To o b t a i n
t he
incor­
results
t h a t a c c u r a t e l y d e s c r i b e t he l i q u e f a c t i o n p r o c e s s , t he e r r o r
caus ed
by making
modifications
model
of
each
t he
t he p r o c e s s .
as s umpt i on
a s s umpt i ons
needs
to
be
assessed
can be made which
so
better
Si n c e n e g a t i v e s o l v e n t r e t e n t i o n v a l u e s
do not c o r r e l a t e wi t h t e m p e r a t u r e , t i m e , or d i s s o l u t i o n ,
any
t r e nd s
can
not
of
be
determined.
conversion
analysis
first
t he magni t ude
assumption
error
Although
studies,
probably
of
t he
is
not
can
be
wi t h
these
commonl y
adopted
first
assumpt i on
true.
The e r r o r
estimated
by
variables
made
in
in
coal
the
i n maki ng t h e
analyzing
by
gas
chromat ography t he vapor r e l e a s e d duri ng dr yi ng and perform­
i ng an e x t e n s i v e a n a l y s i s o f t he coal
r e s o na nc e
( nmr ) , e l e c t r o n
other s p e c t r o s c o p i c
us i ng n u c l e a r magnet i c
paramagnet i c r e s o na nc e
techniques
(epr),
and
duri ng t he dr yi ng p r o c e s s to
72
de t er mi ne
(ii)
if
(i )
t he
process,
t he
t y pe s
of
bonds
between
wat er
wat er
is
c o mp l e t e l y
removed duri ng
and ( i i i )
if
any bonds
o t he r than t h o s e
and c o a l ,
t he
dryi ng
involving
wat er removal are a l t e r e d .
Error
in t he
second as s umpt i on can be det ermi ned wi t h
l e s s d i f f i c u l t y than t h a t in t he o t h e r a s s umpt i ons by s e c u r ­
i ng a r e s p o n s i v e oven c a pa bl e o f as hi ng sampl es ac c or di ng to
ASTM D3174
he at ed
in
( 1973)
s t a n da r ds
a c o l d mu f f l e
one hour and 750 d e g r e e s
[38]:
moisture-free
f ur nac e
to 500 d e g r e e s
Celsius
in two ho u r s ,
coal
is
Celsius
in
f o l l o we d by
h e a t i n g t o c o n s t a n t we i g h t at 750 d e g r e e s C e l s i u s .
heating
rate,
pyrite
is
c o mp l e t e l y
oxidized
e x p e l l e d b e f o r e t he c a l c i t e i s decomposed.
mot i ng t he
-
750
standardization
degrees
Celsius
for
At t h i s
and s u l f u r
is
D i s c u s s i o n s pro­
o f t he as hi ng t e mpe r at ur e at 700
coal
have been underway s i n c e
1978.
Al t hough hi ghe r ash c o n t e n t s may be re c or de d and t he
as h i ng
t i me
mi neral
ashing
would
be
constituents
to
de t e r mi ne
increased,
t he
loss
woul d be r e d u c e d .
yields
on
of
t he
volatile
Low- t emperat ure
a mineral-matter-free
(mmf)
b a s i s was not at t empt ed due t o t he l a r g e r e r r o r a n t i c i p a t e d
in us i ng an oven r a t h e r than an oxygen- pl as ma a s h e r .
I f the
a p p r o p r i a t e equi pment f or I ow- t e mpe rat ure a s h i n g were a v a i l ­
able,
d i s s o l u t i o n v a l u e s on a mmf b a s i s would be hi ghe r than
corresponding values
on an a s h - f r e e b a s i s and t he t h e o r e t i ­
cal maximum c o n v e r s i o n o f 100% c o ul d be a c h i e v e d .
73
S i n c e a c e t o n e has been obs e r ve d to be an i n a c t i v e coal
solvent [28],
is
expected
a c e t o n e wi t h
e r r o r caus ed by adopt i ng t he t h i r d assumpt i on
to
be
t he
small.
residual
Howe ve r ,
TMU and/ or
pr oduc t s duri ng the washi ng s t e p ,
can have enhanced d i s s o l v i n g
it
is
possible
that
HMPA f u r t h e r e x t r a c t s
s i n c e mi x t u r e s o f s o l v e n t s
power [ 1 1 ,
12,
13].
Error in
t he t h i r d as s umpt i on can be a s s e s s e d by d e t e r mi ni ng the com­
ponent s
extracted
residue
for
yields
various
retention
obtained
t he
of
t he
coal-solvent
also
incorporated
into
s t u d y i n g c oal
in
fifth
t he
interactions
same c l a s s
was
wh o l e
residue
liquefaction
calculate yields.
cantly
liquids
a s s u mp t i o n s ,
as s ume d
t he
as s umpt i on
Mi t c h e l l
t he
and c o mp a r i n g t h e
wash
v a l u e s can be c a l c u l a t e d
[19]
vent
analyzing
(including
Be f ore the e r r o r can be e s t i m a t e d , however,
and r e t e n t i o n
al.
liquids,
liquid,
various
modi f y t he f o u r t h and f i f t h
et
wash
o f wash
us i ng
none a t a l l ) .
knowl edge
by
re qui r e d
to
so a c c u r a t e y i e l d s
f or c ompari s on.
solvent
(the
is
f our t h
molecules
Roy
to
as s umpt i on)
be
when
u s i n g DMSO, a p o l a r a p r o t i c s o l ­
of
solvents
adopt ed
as
TMU and HMPA.
by Ki e b l e r
[12]
in
The
order
to
However, P u l l e n [ 3 9 ] c i t e d Whi t ehurs t and
who found
that
nitrogen
in coal
was
not
signifi­
reduced duri ng s o l v e n t e x t r a c t i o n ; in c o n t r a s t ,
Ath^
e r t o n and Kul i k [ 1 6 ] c i t e d r e s e a r c h e r s at t he Mobil Research
and
Devel opment
compounds
stages
of
were
Cor por at i on
concentrated
solvent
extraction
who
in
found
t he
wi t h
coal
t he
that
nitrogen-rich
duri ng
t re nd
the
early
reversing
at
74
e xt e nde d l i q u e f a c t i o n
times.
Error in t he f o u r t h and f i f t h
as s umpt i ons can be det er mi ne d a f t e r
analysis
due s ,
the
us i n g
liquid
fourth
spectroscopic
products,
techniques
on t he c o a l , r e s i ­
and model compounds.
assumption
assumption, s peci al
perf ormi ng an e x t e n s i v e
also
propagates
S i n c e e rr or in
through
the f i f t h
emphasi s s houl d be pl ac e d on unde r s t and­
i ng t he mode o f s o l v e n t r e t e n t i o n .
Condensation
of
the
reactions
is
the
temperature
high
results
coal
products
due t o
c ompet i ng
i n d i c a t e d by t he maximum d i s s o l u t i o n l i m i t s o f
r uns
o b t a i n e d when coal
and by t h e
and s o l v e n t
lower
are
dissolution
he at e d
together
to run t empe r at ur e r a t h e r than when t he s o l v e n t i s pr eheat ed
before
addi ng
coal.
Dryden
[22]
cited
stated
t h a t t he e x t r a c t i o n y i e l d may pass t hrough a maximum
duri ng t he h e a t i n g o f s o l v e n t and coal
pe r a t u r e
due
to
aggregation
Whether or not t h i s
occurs,
or
Te bb e t t
et
al . who
t o g e t h e r t o run tem­
resorption
optimization
of
of
t he
extract.
heating condi­
t i o n s i s i mpor t ant be c aus e d i f f e r e n c e s in p r e h e a t e r product s
can
affect
all
s ubs e que nt
reactions
[39].
Solvolytic
c l e a v a g e i s probabl y o c c u r r i n g in t he p r e h e a t e r s o f p r e s e n t day d i r e c t c o n v e r s i o n p l a n t s [ 1 5 ] .
alters
t he coal
[14],
condensation
Si nc e
s t r u c t u r e and can i n v o l v e s o l v e n t mo l e c u l e s
reactions
d e g r e g a t i o n / r e t r o g r e s s i on
process
[16],
procedure
Si nce e x t r a c t r e s o r p t i o n
affect
of
coal
solvent
is
retention.
an i r r e v e r s i b l e
s o l v e n t p r e h e a t i n g proves to be t he p r e f e r r e d
both
theoretically
and e x p e r i m e n t a l l y .
Ot her
75
investigators
ization
t he
have
also
reactions.
Ki e b l e r
t e nde nc y o f coal
to
light.
not ed
Al t hough
t he o c c u r r e n c e
[12]
extracts
not
cited
to
of
Jostes
r epol ymer­
who obs erved
r e p o l y me r i z e when exposed
experi mentall y
c o n f i r me d ,
Jostes
propos ed t h a t r e p o l y m e r i z a t i o n o f coal e x t r a c t s upon c o o l i n g
does oc c ur ;
later,
experimentally.
Cl arke e t
Yi e l d s
are
al . [ 4 0 ]
support e d t he t he ory
then dependent on t he
t empera­
t ur e a t which t he e x t r a c t s are s e p a r a t e d from t he r e s i d u e s .
Pul l e n [ 3 9 ]
equally
we l l
indicating
initially
e xt e nde d
not ed t h a t i n i t i a l
in
hydrogen-
that
an
external
required.
reaction
and
Af t e r
t i me s
in
c o n v e r s i o n r e a c t i o n s proceed
nonhydrogen- donor
source
mo l e c u l a r
we i g h t
hydrogen
is
not
observing
decreased y i e l d s
wi t h
non- donor
solvents,
[41]
c o nc l ude d t h a t r e c o mbi na t i o n o f coal
hi gh
of
solvents,
substances
Neavel
pr oduc t s i n t o i n s o l u b l e
was
occurring.
Based on
N e a v e V s f i n d i n g s , Whi t e hur s t [ 4 0 ] proposed t h a t t he conden­
sation
reactions
hydroar omat i c
conversion
involved
coal
hydrogen
structure.
involved
a
Hoffman
series
of
and
was
believed
repolymeri zati on
to
exist
processes.
[26]
from t h e
believed
d e p o l y me r i z a t i o n
f o l l o w e d by r e p o l y m e r i z a t i o n s t e p s .
equilibrium
abstraction
coal
steps
At a gi ve n t e mpe r at ur e ,
between
In
this
d e p o l y me r i z a t i o n
investigation
of
coal c o n v e r s i o n by TMU and HMPA, e q u i l i b r i u m does not appear
to
be a t t a i n e d
considered.
wi t h i n
48
hours
a t any xo f
t he
t emper at ur es
76
The
considerable
low f or e x t e n s i v e
dence o f y i e l d
t he major
tion
not
on s o l v e n t
duced
on t he
by
to
assumi ng
given
large
t he
at t e mpt e d due to
by t he
filtration
t he
t i me .
and r e t e n t i o n
but
t he
results.
appar e nt
and
solvolysis
is
stated
assump­
t h a t would be i n t r o ­
initial
uncertainty
reaction
rate
is
Sho r t e r run t i mes were
in d i s s o l u t i o n
The d i f f e r e n c e s
and HMPA t o d i s s o l v e coal
and the depen­
However, a d i s s o l u ­
error
true
too
a c t i v a t i o n e n e r g i e s were
t h a t based on a 10 - 60 mi nut e run.
not
t e mpe r at ur e s
that
data
Initial
t he
that
indicate
mechani sm.
can not be d e r i v e d .
due
at
bond c l e a v a g e
t ype
d e p o l y me r i z a t i o n
evaluated
obtained
t hermol yt i c
mechanism based
tions
yields
in a b i l i t y
caused
o f TMU
are e x e m p l i f i e d by t he d i s s o l u t i o n
Pure
f or mat i on
HMPA appears
of
colloidal
to
solvate
ma t e r i a l
coal
prevents
t he d e t e r mi n a t i o n o f t he magni t ude o f s o l v e n t e f f e c t i v e n e s s .
Al t hough no ment i on was made o f c o l l o i d
investigators
poor coal
bons ,
[10,
solvent.
i mmi s c i b l e
liquid
separation
11]
apparently
effective
coal .
solvent,
a
i n HMPA, are produced which p r e v e n t s o l i d by f i l t r a t i o n ,
dispersed
as
is
I t i s p o s s i b l e t h a t s a t u r a t e d hydrocar­
al t hough
products.
by
t he
a mixture
Because o f c o l l o i d
of
HMPA may a l s o
The c o l l o i d a l
pr e s e nc e
m i s c i b l e wi t h s a t u r a t e d h y d r o c a r b o n s .
as
pr e v i o u s
have not ed t h a t HMPA by i t s e l f
compl exi ng wi t h o t h e r coal
is
f o r ma t i o n ,
of
TMU,
be
mat e r i al
which
TMU by i t s e l f
is
i s not
TMU and HMPA i n d i s s o l v i n g
f or mat i on when us i ng pure HMPA as
i t was not det er mi ne d i f t he e x t r a c t i o n y i e l d us i ng
77
t he
s o l v e n t mi xt ur e
t he
yields
us i ng
is
t he
g r e a t e r than or equal
pure
solvents,
which
t o the sum o f
would
whet her or not TMU and HMPA a c t
independently
coal.
proposed
Other
investigators
have
indicate
in s o l v a t i ng
coal
dissolution
mechani sms which may be a p p l i c a b l e to t h i s p r o c e s s .
al .
wi t h
[19]
believed
"t he
solvation
c oul ombi c
is
forces
hydrogen bond p r o v i d i n g
an e l e c t r o s t a t i c
(ion-dipole,
Roy e t
phenomenon
dipole-dipole)
a major c o n t r i b u t i o n
to
t he
and
solva­
tion process.
S o l v a t i o n pr o c e e ds t hrough donor and a c c e p t o r
properties
one
in
ext reme
t hrough
t he
i ntermedi ate
dipole
a s s o c i a t i o n and f or mat i on o f u n s t a b l e c o o r d i n a t i o n compounds
t o van der Waal ' s i n t e r a c t i o n " .
[16]
not ed t h a t
solvent
(the
some coal
free
radicals
radical
[42]),
heterolysis,
not
pri mary means by which coal
temperatures
at
or
probabl y r e a c t wi t h t he
concentration
f r e e r a d i c a l s per gram o f coal
coal
Al t hough At her t on and Kul i k
is
about
2 x 1019
in a hi gh v o l a t i l e bi t umi nous
h o mo l y s i s ,
is
most l i k e l y
t he
i s decomposed in p r o c e s s e s wi t h
b e l o w 550
-
700
degrees
Fahrenheit.
Si nc e TMU and HMPA s t r o n g l y s o l v a t e and then s h i e l d c a t i o n s
to a c c e l e r a t e
reactions
be e ncouraged
in
strongly
basic
hydroge n- donor
radical
c ha i n
t he
involving
solvents.
s ys t e ms
solvent
at
635
that
mechani sm,
anions,
Af t e r
degrees
c oul d
Ross
and
not
h e t e r o l y s i s would
obtaining
data
Fahrenheit
usi ng
be e x p l a i n e d
Blessing
[17]
from
a
by t he
suggested
t h a t t he o p e r a t i v e mechanism o f coal c o n v e r s i o n was i o n i c in
nature,
involving
hydri de
do na t i o n
by t he
solvent
f o l l o we d
78
- by prot on t r a n s f e r .
itself
[43].
illustrated
anionic
The r e d u c t i o n mechanism and ne t
in
that
liquefaction
oxidants
then l i q u e f i e s
reduction
Fi gure
intermedi ate
hypothesize
other
Hydrogen c oul d be s u p p l i e d by the coal
of
16 where
and coal - H2
major
processes
coal
role
of
hydri de
is
the
reduction
to
unreactive
donors
of
ionic
d e c o mp o s i t i o n
TMU,
highly-reactive
hexafluorophosphates,
the
In the
TMU was
Formed from t he
aryl
cations,
Ar+,
abstract
TMU.
Al t h o u g h
it
in
hydri de
The r e s u l t a n t urea
carboni um i on i s b e l i e v e d to r e a c t wi t h a PFg .
fluorinated
coal
o f a r y l d i azoniurn h e x a f l uorophosphat e
from t he s o l v e n t a c c o r di ng t o Fi gur e 17.
ppg and
They
qui no ne s and
compounds;
used as a s o u r c e o f hydri de hydrogen [ 4 4 ] .
an
in coal
t h e r ma l l y wi t h no hydrogen a d d i t i o n .
a r y l d i azoniurn
are
are
and reduced coal , r e s p e c t i v e l y .
t he
in
coal -H-
reaction
is
Jo r r t o y1 e l d
possible
that
hydri de t r a n s f e r o c c ur s between TMU and coal , no documented
evidence
was
f o und r e g a r d i n g
HMPA as
a hydride
transfer
age nt or s u p p o r t i n g t he hydri de t r a n s f e r mechanism wi th the
sol v e n t s and c o a l .
79
I o ni c mechanism o f coal
Fi gure 16.
reduction.
I
I
H- C- OH
+
OH- —
i
H- C- O-
HO
2
iI
+
c oal
C = O
I
I
coal -H-
—>
+ H - £ - OH
—>
+
H- C - O
I
+ coal -H-
H - (j) - 0-
+ coal - H2
Net r e a c t i o n :
3=
O
O ——
I
3=
+ coal
Fi gure 17.
+
increase
wi t h
and
rates
a l . who f o un d
extraction
ArH
+
expected
dissolution
at
r a t e tend to
hi g h e r
t e mpe r at ur e s
Ki e bl e r [ 1 2 ]
t h a t maximum y i e l d s
is
0
H
HC
C
CH
2 \ / \ /
3
N N
j
j
CH CH
3
3
t emperat ure,
investigation.
t e mper at ur e
t e mpe r at ur e
of
are
+
and i n i t i a l
increasing
exami ned in t h i s
lution
coal - H
2
TMU as a hydri de t r a n s f e r a g e n t .
Since dissolution
values
C = O +
I
0
H
HC
C
CH —*
3 \ / \ / 3
N N
I
I
CH CH
3
3
+
Ar
- ->
slightly
dissolution
above
t hos e
c i t e d Pot t e t
ar e o b t a i n e d when t h e
bel ow t he
de c ompos i t i on
( d e f i n e d as t h a t t emper at ur e where a rapi d e v o ­
gas
o c c u r s ) of
t he
residue,
appr o x i ma t e l y 700 t o
80
750
degrees
tures
can
Fahrenheit.
promote
However,
undesirable
hi ghe r
side
reaction
reactions
t empera­
(e.g.,
excess
gas and coke p r o d u c t i o n ) , make y i e l d s much more s e n s i t i v e to
other r e a c t i o n
variables
such as hydrogen o v e r p r e s s u r e , and
pose equi pment probl ems .
Whi t e hur s t e t a l . [ 1 4 ] and Pot t e t
a l .,
as
cited
us i ng r e a c t i o n
by Ki e b l e r
t e mpe r a t ur e s
bi t umi nous c o a l s .
amount o f
levels
[12],
Also,
interaction
found
little
advant age
in
above 800 d e g r e e s F a hr e n he i t on
retention results
between coal
i n c r e a s e wi t h i n c r e a s i n g
i nd i c a t e a large
and s o l v e n t :
retention
t e mpe r at ur e s and t he i n c o r ­
p o r a t i o n o f s o l v e n t f ragme nt s i n t o t he r e s i d u e i s i n d i c a t e d .
Unabl e
to
remove
incorporated
other i n v e s t i g a t o r s [ 12,
tities
t he
of
electrons
from coal
residues,
16, 23] have a l s o not ed l a r g e quan­
solvent retention.
unpai r ed
solvent
of
Dryden [ 28]
nitrogen
or
hypothesized that
oxygen
in
specific
s o l v e n t s form c ompl exe s wi t h coal m o l e c u l e s , c a u s i n g s o l v e n t
incorporation.
[16]
as
a
result
Al t hough b a s i c
standing
also
ation
swelling
of
the
nitrogen
in d i s s o l v i n g
of
formation
solvents
coal,
coal
has
of
been
these
postulated
complexes.
have been found to be o u t ­
most o f t he i n v e s t i g a t o r s have
not ed t h a t t he c o n s i d e r a b l e s o l v e n t l o s s v i a i n c o r p o r ­
makes
[16].
their
use
i mp r a c t i c a l
in
a commerci al
Un l e s s measures can be t aken t o reduce
solvent
incorporation
offs will
less
The
t ha n
to a c c e p t a b l e l e v e l s ,
pr oc e s s
irreversible
economi c t r a d e ­
d i c t a t e t he optimum d i s s o l u t i o n , which may be much
t h e maximum d i s s o l u t i o n
that
can be o b t a i n e d .
81
T h e r e f o r e , t he r e t e n t i o n r e s u l t s
additional
i n d i c a t e t he need f o r :
(i)
p r o c e s s modi f i c t i o n t o mi ni mi ze s o l v e n t r e t e n t i o n
and ( i i ) a c c e s s
to a n a l y t i c a l
i ns t r ume nt s
not a v a i l a b l e
to
t he aut hor t o e v a l u a t e t he e r r o r in each as s umpt i on made to
c a l c u l a t e actual
To
d i s s o l u t i o n and r e t e n t i o n .
maxi mi ze
t he
process
potential,
t he
following
calculate yields
s h o u l d be
pr oc e dur e s s houl d be c o n s i d e r e d :
(i)
The a s s u m p t i o n s made t o
mo d i f i e d t o b e t t e r model
ticular,
t he l i q u e f a c t i o n p r o c e s s .
In par­
t he c o a l - s o l v e n t i n t e r a c t i o n needs t o be det ermi ned
so a c c u r a t e y i e l d s and r e t e n t i o n v a l u e s can be c a l c u l a t e d .
Hi)
Maximum y i e l d s
s houl d
be
de t e r mi ne d.
The number o f
e x t r a c t i o n s t a g e s s houl d be maxi mi zed s i n c e c ompl e t e e x t r a c ­
tion
t he
can
never
be o b t a i n e d
extraction yield
condensation
reactions
Dryden
cited
[22]
in
a single
from p a s s i n g
duri ng
through
coal
Tebbett et
stage.
To pr e ve nt
a maximum due t o
and s o l v e n t
preheating,
a l . who recommended t h a t
a
S o x h l e t or c o u n t e r c u r r e n t method be used when p o s s i b l e .
(iii)
Solvent
promot i ng
into
recovery
solvent
t he r e s i d u e
residue
loss
s houl d
by
be
maxi mi zed.
f r a g me n t a t i o n
or
Co ndi t i o ns
incorporation
shoul d be avoi de d when p o s s i b l e .
Solvent/
s e p a r a t i o n and r e s i d u e washi ng t e c h n i q u e s shoul d be
t horough and s t a n d a r d i z e d .
D i f f e r e n t wash l i q u i d s shoul d be
considered.
(iv)
Results
compared.
If
us i ng
various
other
bi t umi nous
particle
sizes
coals
are
shoul d
be
considered
to
82
o bs e r v e
possible
mass-transfer
restrictions,
attention
shoul d be g i v e n to mi ni mi ze a t t r i t i o n .
(v)
Inexpensive
solvents
bl ended
wi t h
been used and shoul d be f u r t h e r e x p l o r e d .
less
costly
solvent
dissolution
obs e r ve d
and
results
for
[37].
Bakerstown
10% HMPA i n
At hert on
10
and Kul i k
solvents
c o mb i n a t i o n s
are
used
minutes
not ed
us i ng
at
Ward has prepared
obtained
degrees
wi th
other
[45]
of
pr oduct
solvents
nitrogen
"TMU and
agents
species
whi c h,
t owards coal
t he
that
s we l l i n g / a t t a c k i ng
nitrogen
solvents
in
t he c he mi s ­
U n f o r t u n a t e l y , c o a l s have been found to
absorb
propos ed
10% TMU,
Fahrenheit.
t h a t whenever b a s i c
d i s s o l v i n g c o a l , t he y d i s p r o p o r t i o n a t e l y c o n t r o l
selectively
e nc our agi ng
80% t e t r a l i n ,
320
in c o n j u n c t i o n
t r y o f t he p r o c e s s .
HMPA have
A maximum d i s s o l u t i o n o f 55% was
coal
[16]
and
TMU and
by
and
bas e s
HMPA a c t
that
[14].
most
Ward e t
i mp o r t a n t l y
al ..
as
solvation/stabilization
can be done wi t h a r o ma t i c / h y d r o a r o ma t i c
themselves,
at these conditions".
are
relatively
inactive
- 83
SUMMARY
I•
A 1: 1
mi xt ur e
o f TMU and HMPA i s
pure TMU i n d i s s o l v i n g
more e f f e c t i v e
Ki t t a n n i n g c o a l .
Coal
than
conver­
s i o n t o 41% can be a c h i e v e d us i ng a 1: 1 mi xt ur e of the
s o l v e n t s f o r 40 mi nut e s at 320 d e g r e e s F a h r e n h e i t .
The
maximum d i s s o l u t i o n
was
observed
HMPA
as
after
t he
using
12 h o u r s
solvent
TMU as
solvent,
a t 320 d e g r e e s
apparently
23%,
Fahrenheit.
produced
a colloidal
s u s p e n s i o n t h a t c oul d not be i s o l a t e d .
2.
Dissolution
and
initial
dissolution
rate
tend
to
i n c r e a s e wi t h i n c r e a s i n g run t e mpe r a t ur e .
3.
Dissolution
rate is
fast in itia lly
but t a p e r s o f f when
c o n d e n s a t i o n r e a c t i o n s be gi n t o domi nat e.
4.
Maximum d i s s o l u t i o n
is
achieved at
shorter
t i me s wi t h
i n c r e a s i n g run t e mp e r a t u r e s .
5.
Solvent
retention
levels
increase
wi t h
increasing
run
t e mp e r a t u r e .
6.
Substantial
into
amounts
t he r e s i d u e ,
fragments.
of
TMU and
HMPA are
incorporated
pr obabl y at l e a s t in p a r t as s o l v e n t
84
REFERENCES CITED
85
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[ 3 7 ] P r i v a t e Communi cati on, John T. Sears ( 1 9 8 4 ) .
[ 3 8 ] Kar r , J r . , Cl a r e n c e , e d i t o r . A n a l y t i c a l Methods f or
Coal and Coal P r o d u c t s , Volume I , Academic P r e s s , New York,
1978.
[ 3 9 ] P u l l e n , J a n e t R. , S o l v e n t Ex t r a c t i o n o f Coal ,
Re s e a r c h , London, 1981.
IEA Coal
[ 4 0 ] Wh i t e h u r s t , D. Duayne, e d i t o r . Coal L i q u e f a c t i o n Fundam e n t a l s , American Chemical S o c i e t y , Washi ngt on, D. C. , 1980.
[ 4 1 ] We ave! , Ri chard C. , " Li q u e f a c t i o n of coal in hydrogendonor and non- donor v e h i c l e s " . F u e l , 55, 237 ( 1 9 7 6 ) .
[ 4 2 ] Goul d, Robert F . , e d i t o r , Coal S c i e n c e , American Chemi­
cal S o c i e t y , Washi ngt on, D. C. , 1966.
[ 4 3 ] Cr onaue r , Donald C. , Robert I . McNei l , Donald C. Young,
and R a f f a e l e G. Rube r t o, "Hydrogen/ deut eri um t r a n s f e r in
coal l i q u e f a c t i o n " . F u e l , 61, 610 ( 1 9 8 2 ) .
[ 4 4 ] R u t h e r f o r d , Kenneth G. and Wi l l i am A. Redmond, "Decom­
p o s i t i o n o f aryl di azoni urn h e x a f I u o r o phos phat e s in t e t r ame thylurea.
A new de ami nat i on p r o c e d u r e " , Journal o f Organic
Che mi s t r y, 2 8, 568 ( 1 9 6 3 ) .
[ 4 5 ] Ward, Timothy L . , C h r i s t i n a I c h i o k a , and John I . S e a r s ,
"The E f f e c t s o f Tet ramet hyl urea and Hexamethyl phosphorami de
on D i s s o l u t i o n o f Coal ", Rocky Mountain Fuel S o c i e t y Meet­
i n g , 1984.
APPENDICES
90
APPENDIX A
RAW DATA
0)
O
<
#
3
T«bl« 14.
Raw data for TMU runs.
Temp Run tim e
(F)
(m in)
C oal wt
(p )
R esid u e
wt ( g )
%N
Wet R esid u e
XC
XH
XO
Run
number
TMU
79
60
3. 9925
3. 8361
I. 54
77. 16
5. 12
6. 14
21
TMU
79
60
4. 0029
3. 9016
I. 38
76. 65
5. 42
5. 82
35
TMU
79
720
3. 9850
3. 9068
I. 94
77. 14
5. 20
6. 09
22
TMU
79
2880
3. 9937
3. 8233
I. 54
76. 57
5. 08
5. 73
31
TMU
200
20
4. 0033
3. 7142
2. 24
72. 14
4. 95
39
TMU
200
40
3. 9310
3. 5105
2. 54
71. 55
5. 01
38
TMU
200
60
3. 8833
3. 7674
2. 71
75. 54
5. 31
6. 42
23
TMU
200
720
3. 9705
3. 7172
3. 10
70. 16
5. 21
6. 23
24
TMU
200
2880
4. 0085
3. 4417
2. 68
71. 15
5. 06
6. 51
30
TMU
320
20
3. 9884
3. 7205
3. 40
68. 04
5. 01
6. 57
25
TMU
320
720
4. 0397
3. 6207
3. 93
69. 40
5. 16
6. 66
26
TMU
320
2880
4. 0099
3. 6863
3. 67
70. 75
5. 15
6. 52
32
Table 19.
S o lv e n t
R«w data for TMU+HMPA runs.
Temp Run tim e
(F)
(m in)
Coal wt
<g>
R esid u e
wt ( g )
%N
Wet R esid u e
XC
XH
XO
XP
Run
number
TMU+HMPA
79
79
4. 0060
4. 0187
I. 80
77. 82
9. 23
6. 04
16
TMU+HMPA
79
739
4. 0019
3. 9079
I. 69
75. 79
5. OS
6. 14
17
TMU+HMPA
79
2880
3 9970
3. 7921
I. 98
76. 33
5. 44
9. 72
TMU+HMPA
200
20
2. 9938
2. 8289
2. 78
74. 43
5. 26
6. 37
TMU+HMPA
200
60
4. 0077
3. 7679
2. 79
72. 15
9. 36
9. 88
I. 36
27
TMU+HMPA
200
720
3. 9999
3. 2509
3. 17
73. 66
5. 67
6 13
0. 77
34
TMU+HMPA
200
2880
3. 9979
3. 9461
5. 90
67. 40
5. 93
6. 48
3. 08
29
TMU+HMPA
320
10
3. 9784
3. 2407
9. 70
64. 93
9. 62
TMU+HMPA
320
20
3. 0139
2. 5219
5. 12
63. 19
5. 43
TMU+HMPA
320
40
3. 9881
3. 2797
6. 11
62. 03
5. 62
TMU+HMPA
320
720
3. 9869
3. 4422
4. 68
60. 82
5. OO
0. 67
33
19
37
6. 75
2. 74
20
36
6. 94
4. 78
28
93
APPENDIX B
RAW RESULTS
T«bl» 16.
Raw results for TMU runs.
S o lv e n t Temp Run tim e
(F)
(m in)
%N
XC
Dry R esid u e
XH
XO
H/C
OZC
Run
number
TMU
79
60
I. 31
77. 42
5. 07
6. 06
0. 780
0. 059
21
TMU
79
60
I. 31
76. 72
5. 41
5. 80
0. 840
0. 057
35
TMU
79
720
I 31
7 7 .8 6
5. 05
5. 87
0. 773
0. 037
22
TMU
79
2880
1 .3 1
76. 82
3 .0 3
5. 65
0. 780
0. 055
31
TMU
200
20
I. 25
73. 06
4. 70
0. 767
39
TMU
200
40
I. 23
72. 74
4. 69
0. 768
38
TMU
200
60
I. 31
77. 10
4. 98
5. 94
0. 769
0. 058
23
TMU
200
720
I. 31
71. 73
4. 77
3. 59
0. 792
0. 059
24
TMU
200
2880
I. 31
7 2 .3 9
4. 72
6. 05
0. 777
0. 063
30
TfIU
320
20
I. 31
69. 69
4. 47
5. 84
0. 764
0. 063
23
TMU
320
720
I. 31
71. 70
4. 48
5. 74
0. 744
0. 060
26
TMU
320
2880
I. 31
72. 94
4. 54
5. 69
0. 742
0. 059
32
Table 17
S o lv e n t
Raw results for TMU+HMPA runs assuming 1:1 solvent
Temp Run tim e
(F)
(m in)
XN
XC
Dry R esid u e
XH
XO
XP
incorporation.
H/C
OZC
Run
number
TMU+HMPA
79
73
I. 31
78. 33
3. 12
5. 92
0. 05
0. 777
0. 037
16
TMU+HMPA
79
733
I. 31
7 6 .2 1
5. OO 6. 06
0. 03
0. 782
0. 060
17
TMU+HMPA
79
2880
I. 31
76. 69
5 .3 8
3. 65
0. 16
0. 836
0. 033
33
TMU+HMPA
200
20
I. 31
76. 43
4 .9 1
6. 03
0. 05
0. 765
0. 039
19
TMU+HMPA
200
60
I. 31
74. Ol
3. Ol
5. 50
0. 05
0. 807
0. 036
27
TMU+HMPA
200
720
I. 31
76. 17
5. 26
5. 67
0. 16
0. 822
0. 036
34
TMU+HMPA
200
2880
1 .3 1
72. 93
4. 82
3. 23
0. 05
0. 787
0. 034
29
TMU+HMPA
320
10
1 .2 3
69. 14
4. 48
TMU+HMPA
320
20
1 .3 1
66. 74
4. 44
TMU+HMPA
320
40
I. 23
66. 49
4. 34
TMU+HMPA
320
720
1 .3 1
63. 47
4. 07
0. 772
5. 83
0. 03
0. 793
37
0. 066
0. 778
6. 17
0. 05
0. 764
20
36
0. 073
28
T « b U 18.
S o lv e n t
Raw results for TMU+HMPA runs based on phosphorus data.
Temp Run tim e
(F)
(m in )
%N
XC
Dry r e s id u e
XH
XO
XP
HZC
OZC
Run
number
TMU+HMPA
79
2880
I. 31
76. 52
5. 38
5. 76
0. 16
0. 839
0. 037
33
TMU+HMPA
200
60
I. 31
74. 55
5. 02
5. 71
0. 05
0. 803
0. 038
27
TMU+HMPA
200
720
I. 31
76. 09
5. 25
5. 63
0. 16
0. 823
0. 056
34
TMU+HMPA
200
2880
I. 31
74. 03
4. 83
5. 66
0. 05
0. 777
0. 057
29
TMU+HMPA
320
20
I. 31
67. 73
4. 45
6 .2 1
0. OS
0. 783
0. 069
20
TMU+HMPA
320
720
I. 31
66. 23
4. 10
7. 25
0. OS
0. 737
0. 082
28
97
APPENDIX C
EQUATION DERIVATIONS
98
DERIVATION OF EQUATION (4)
Ni t roge n mass ba l a n c e :
g N in dry r e s = g N in wet res - g N o f s o l v e n t i n c o r p .
Assuming
that
t he
we i g ht
percent
of
nitrogen
in
the
coal
remai ns c o n s t a n t t hrough t he d i s s o l u t i o n p r o c e s s so t h a t any
change
in ni trogen
content
is
due to i n c o r p o r a t i o n of TMU,
then
9 N in dry r e s i d u e = ( g N/g coal H g dry r e s i d u e )
I f X i s d e f i n e d as t he grams o f a c t u a l l y d i s s o l v e d coal
pr o­
duct per gram o f coal , then
9 dry r e s i d u e = ( I - X) (g c o a l )
Si nce
9 N in wet r e s i d u e = (g wet r e s ) ( g N/g wet r e s )
and, ass umi ng whol e s o l v e n t m o l e c u l e s are i n c o r p o r a t e d ,
g N in s o l v e n t i n c o r p o r a t e d =
(g wet r e s i d u e - g dry r e s i d u e ) (g N/g s o l v e n t ) =
[ g wet r e s i d u e - (I - XMg c o a l ) ]
then a l l
give:
(g N/g s o l v e n t )
terms in t he n i t r o g e n bal anc e can be s u b s t i t u t e d to
99
(g N/g c o a l ) ( I - X) ( g c o a l ) =
(g wet r e s i d u e ) ( g N/g wet r e s i d u e )
[ g wet r e s i d u e - (I - X) ( g c o a l ) ]
( g N/g s o l v e n t )
Solving for X gi ves:
(g wet r e s ) ( g N/g s o l v e n t - g N/g wet r e s )
X = I - --------------------------- ------------------------------- - ................
(g c o a l ) ( g N/g s o l v e n t - g N/g c o a l )
Thus, t he e q u a t i o n f or g dry r e s i d u e be c ome s :
g dry r e s i d u e = (I - X ) (g c o a l )
=
( g N/g s o l v e n t - g N/g wet r e s i d u e )
g wet r e s i d u e x -------------------------------------------------------------(g N/g s o l v e n t - g N/g c o a l )
100
DERIVATION OF EQUATION ( 5)
Phosphorus mass ba l a n c e :
9 P o f s o l v e n t i n c o r p . = g P i n wet res - g P in dry res
Si n c e TMU c o n t a i n s no p h o s p h o r u s , a l l
HMPA.
i n c o r p o r a t e d P i s from
Assuming t h a t t he we i g h t pe r c e n t of phosphorus in t he
coal
remai ns
constant
that
any change
t hrough
t he
dissolution
in phosphorus c o n t e n t
is
process
so
due t o i n c o r p o r a ­
t i o n o f HMPA, then
g P i n dry r e s i d u e = (g P/ g c o a l ) ( g dry r e s i d u e )
Assuming whol e s o l v e n t m o l e c u l e s are i n c o r p o r a t e d ,
then
. g P in s o l v e n t i n c o r p o r a t e d = (g HMPA i n c o r p . ) ( g P/g HMPA)
Substituting
these
equations
into
t he
phosphorus
bal anc e
gives:
g HMPA i n c o r p o r a t e d = ( g HMPA/g P) x
[ ( g P/ g wet r e s ) ( g wet r e s ) - ( g P/ g c o a l ) ( g dry r e s ) ]
Ni t r o g e n mass b a l a n c e :
g N in s o l v e n t i ncorp. = g N in wet r es - g N in dry res
Assuming
that
t he
we i g h t
percent
of
nitrogen
in
the
coal
remai ns c o n s t a n t t hrough t he d i s s o l u t i o n p r o c e s s so t h a t any
change
in
nitrogen
content
is
due t o
incorporation
of
TMU
101
and/ or HMPA, then
g N in dry r e s i d u e = ( g N/g c o a l ) ( g dry r e s i d u e )
Assuming whol e s o l v e n t m o l e c u l e s are i n c o r p o r a t e d ,
then
g N in s o l v e n t i n c o r p . =
( g N/g TMU) ( g TMU) + (g N/g HMPAHg HMPA)
Substituting
these
equations
into
t he
nitrogen
bal anc e
gives:
g TMU i n c o r p o r a t e d = (g TMU/g N) x
C(g N/g wet r e s ) ( g wet r e s )
- ( g N/g coal H g dry r e s )
^
Substituting
t he
(g HMPA)
term wi t h
(g
N/g HMPAHg HMPA)]
t he e x p r e s s i o n
de r i v e d
from t he phosphorus mass ba l a nc e g i v e s :
g TMU i n c o r p o r a t e d = (g TMU/g N) x
{ ( g N/g wet r e s ) ( g wet r e s ) - . ( g N/g c o a l ) ( g dry r e s ) (g N/g HMPA)( g HMPA/g P) [ ( g P/ g wet r e s ) ( g wet r e s ) (g P/ g c o a l ) ( g dry r e s ) ] }
Overal l mass b a l a n c e :
g dry r e s i d u e = g wet r e s i d u e - g TMU - g HMPA
S u b s t i t u t i n g t he f i n a l
e q u a t i o n s d e r i v e d from t he phosphorus
and n i t r o g e n mass b a l a n c e s g i v e s :
102
g dry r e s i d u e = g wet r e s i d u e x
(g N/g wet r e s )
(g N/g HMPA)
(g P/ g wet res)
[ I -------------------------------- + ( ----------------------------- ! ) ( - - - ...................................) ] /
(g N/g TMU)
(9 N/g c o a l )
(g
N/ g
TMU)
(g N/g HMPA)
(g P/ g HMPA)
(g P/ g c o a l )
[ I -------------------------- + ( ............ ..........................I M ............... - ............... ) ]
( g N/g TMU)
(g N/g TMU)
(g P/ g HMPA)
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