Thermal decomposition kinetics of
biomass wastes used in
energy co-generation
C.SASIKUMAR & K.K.S. GAUTAM
Department of MSME, MANIT, Bhopal
T.C.ALEX & S.SRIKANTH
National Metallurgical Laboratory, (CSIR), Jamshedpur
Kinetics studies of biomass materials
and its complexity
Rate at which a chemical process occurs.
Besides information about the speed at which reactions
occur, kinetics also sheds light on the reaction
mechanism (exactly how the reaction occurs).
d
dt


E
 A . exp  
 . f ( ).  k ( T ) f ( )
Nk B T 

Biomass wastes - hemi-cellulose, cellulose and lignin
Possibility of change in reaction mechanism with temperature
Complex multiple reactions - series, parallel or independent
overlapping reactions
Program on decomposition Studies of
biomass Materials
Rise Husk
Groundnut Shell
Coffee Husk
Bagasse
Cotton Flower
Wood - chips
Various conditions of Thermal
decomposition of sugarcane bagasse
Argon
Atmospheric air
Oxygen
Biomass
Biomass + Coal
Atmosphere
Fuel mix
0.5 to 100 0C/min
Isothermal
Non-isothermal
• Linear heating
• Non-linear heating
Heating rate
Heating method
Thermogravimetric Studies of Sugarcane bagasse
S.NO
1.
2.
3.
Material
Sugar cane
bagasse
E.I.D. Parry (India)
Limited, Nellikuppam,
Tamil Nadu, India.
Sugar cane
bagasse
Sugar cane
bagasse
Atmosphere
Argon
Atmospheric
Air
Oxygen
Heating
Rate
(0C/min)
2
5
10
30
2
5
10
30
2
5
10
30
TG/DTA analyzer
(Seiko, Japan, Model No.
A320)
chemical composition (%w/w) of the bagasse
Constituent of sugarcane
S.No
bagasse in dry
Condition
Weight percentage
(Initial)
1
Hemi-Cellulose
33%
2
Cellulose
38%
3
Lignin
22%
4.
Ash
2.3%
5.
Moisture content
4.7%
By murugappa groups R&D, Chennai, India.
TG-DTG Results of Sugarcane bagasse
at Argon atmosphere
1600
Bagasse
Argon atm
0.0
1400
-0.2
DTG (g/min)
Mass loss ()
1200
0
30 C/min
-0.4
0
2 C/min
Bagasse
Argon atm
0
2 C/min
0
5 C/min
0
10 C/min
0
30 C/min
1000
800
600
400
-0.6
200
0
5 C/min
-0.8
0
0
10 C/min
-1.0
400
400
600
800
0
Temperature ( K)
1000
600
800
0
Temperature ( K)
1000
DTA -Sugarcane bagasse
Argon atmosphere
40
30
Bagasse
Argon atm
T
20
10
0
30 C/min
0
0
10 C/min
-10
0
2 C/min
-20
400
600
800
0
Temperature ( K/min)
0
5 C/min
1000
TG & DTG Results of Sugarcane bagasse
in static air
Bagasse
Static air atm
0.0
1000
Bagasse
Static air atm
900
-0.2
800
-0.4
DTG (g/min)
mass loss 
700
0
30 C/min
-0.6
0
5 C/min
600
500
0
30 C/min
0
10 C/min
400
300
0
5 C/min
200
-0.8
100
0
2 C/min
-1.0
200
400
0
0
10 C/min
600
0
Temperature ( C)
800
-100
0
2 C/min
200
400
600
0
Temperature ( C)
800
TG & DTG Results of Sugarcane bagasse
in Oxygen atmosphere
Bagasse
Oxygen atm
-0.2
-0.4
0
30 C/min
-0.6
0
-0.8
0
30 C/min
600
DTG, g/min
Fraction of mass loss, 
0.0
Bagasse
Oxygen atm
800
2 C/min
0
5 C/min
400
0
5 C/min
200
0
10 C/min
0
10 C/min
-1.0
200
400
600
0
Tempearure ( C)
800
0
0
2 C/min
200
400
600
0
Tempearure ( C)
800
The integral and differential from of
various reaction models
S.No
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Reaction Model
f(α)
g(α)
Reaction order and geometrical contraction models
Mampel (first order)
1- α
-ln(1- α)
nth Second Order
(1- α)n
1-(1- α) 1-n /(1-n)
Contracting cylinder
2(1- α)1/2
1- (1- α) 1/2
Contracting Sphere
3(1- α)2/3
1- (1- α) 1/3
Diffusion models
One dimensional Diffusion
1/2 α-1
α2
2(1- α)2/3[1-(1Diffusion control (Janders)
-1 [1-(1- α) 1/3]2
1/3
α) ]
Diffusion control (Crank)
3/2[(1- α) -1/3 -1] -1
1-2/3 α – (1- α) 2/3
Nucleation models
Power Law
4α3/4
α1/4
Power Law
3 α2/3
α 1/3
Power Law
2 α1/2
α 1/2
Avrami-Erofeev
4(1- α)[-ln(1- α)]3/4
[-ln(1- α)]1/4
Avrami-Erofeev
3(1- α)[-ln(1- α)]2/3
[-ln(1- α)]1/3
Avrami-Erofeev
2(1- α)[-ln(1- α)]1/2
[-ln(1- α)]1/2
Decomposition of sugarcane bagasse
- Reaction Mechanism
T
 E
g ( ) 
exp 

 0
 RT
A
g ( ) 
A RT

E
2

 .dT

2 RT 

 E 
1

.
exp




E 

 RT 
 AR   E 
 g ( ) 
ln 

ln


2


 T

  E   RT 
The plot of ln[g(α)/T2] and 1/T yields a straight line with a slope of –E/R.
Selection of suitable reaction model for overall
decomposition reaction of sugarcane bagasse at 2 K/min.
0
Bagasse, Argon atm, 2 C/min
2.72
overall decomposition
CR -Integral Method
2
ln [g()/T ]
0.37
Stage II
0.05
0.01
0.00
con.sphr
con.cylin
sec.order
DC Crank
DC jander
1D diff
Avrami
power law
Mample (I rst order)
0.0012
0.0014
Stage I
0.0016
0.0018
-1
1/T (K )
0.0020
0.0022
Separation of hemi-cellulose, cellulose
and lignin decomposition reactions
0.012
Bagasse
Argon,5 K/min
0.008
I 
I 
Overall
I 
I 
I
d/dT
I
I
0.000
I

I
I
I
I 
I
I

I

I

I

I

I

I

I

I
Hemi-cellulose

I

Cellulose
I
I
I
I
I
I
I
I
I

I
I
I

Lignin
I
I
I
I
I
I
 I
 I
 II
 I
 II
 II
 II

II

IIII

IIIII

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

IIIIIIIIIIIIIII





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


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
500


I

I
I

I
I I
II I I

II I III I I
IIIIIIIIIIIIIIIII
II
II III I
I
II

II I II II I
II
III I I I
II
I

II
I
I
I

I
I
I

I
I
I

I
I
I

I
I
I

I
I

I
I

I
I
I

I
I

I
I

I
I

I
I
I

I
I

I
I

I
I

I
I

I
I

I

II

II

II

II
I
I

II

II

II

III


IIII

IIII


IIIII

IIIIII


IIIIIIIIIII


IIIIIIIIIIIIIIIIIIIIIIIIIIIIII

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII




IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII



400

I 
I 
I
0.004
Experimental
IIII
II II
I
I
I
I
I
I
I
I
I
I


I 


 I

I  
 I
I 


I 
I
I
I 
600
700
800
Tempearture (K)
 d 



 dT  Sugarcane
Bagasse
AH
wH
  2 (T  TCH
. Exp 
2

wH


2
  2 (T  TCC ) 
  2 (T  TCL ) 
)
AC
AL




. Exp 
.
Exp
2
2





wC
wL
 w 



 w 
C
L
2
2
Mass loss reactions of hemi-cellulose,
cellulose and lignin of sugarcane
Bagasse
Argon, 5 K/min
n
Lig
in
Cellulose
0.4
i-cell
ulose
0.6
Hem
Fraction decomposed, 
0.8
0.2
0.0
400
500
600
700
Temperature (K)
800
Selection of suitable reaction model after resolution
- decomposition reaction of hemi cellulose in sugarcane
bagasse at 2 K/min.
0.006
g()=1- (1- )
n=1.5
0.1
(1-n)
/(1-n)
Diffusion control-Jander
g()=-1 [1-(1- )
Power law
0.04
1/3 2
]
1/3
g()= 
0.003
0.02
th
n order
0.000
ln (g())/T
2
0.01
0.00
0.12
0.08
0.006
contracting cylinder
g()=1- (1- )
1/2
Diffusion Control- Crank
0.004
0.04
0.002
0.00
0.000
Avarami
0.4
(2/3)
1/3
g() = [-ln(1- )]
0.2
0.0
0.08
0.06
g()=1-2/3  - (1- )
0.24
Mample (1 rst order)
contracting sphere
g()=1- (1- )
1/3
0.6
ID diffusion
g()=-ln(1- )
0.16
0.04
0.4
2
g()= 
0.08
0.02
0.2
0.00
0.00
0.0019
0.0020
0.0021
0.0019
0.0020
0.0021
-1
1/T(K )
0.0019
0.0020
0.0021
Comparison of experimental and reconstructed α-T plots
of hemi-cellulose decomposition at 2 K/min.
Fraction decomposed,
1.2
Sugarcane bagasse - Hemi-cellulose
0
1.0 Argon atm, 2 C/min
0.8
ln A = 22.98
E = 134.17
1-n
g()= 1-(1-) /(1-n)
n=1.5
0.6
0.4
0.2
Reconstructed
Experimental
0.0
300
400
500
Temperature (K)
600
700
The kinetic parameters of overall decomposition &
hemi-cellulose decomposition derived with different
reaction models.
Overall decomposition- Stage II
E (kJ/
Ln A
R2
mol)
Hemi-cellulose decomposition
E (kJ/
Ln A
R2
mol)
Reaction order and geometrical contraction models
Contracting
Sphere
Contracting
Cylinder
6.12
54.68
1.00
18.65
108.73
0.88
6.11
53.04
1.00
18.39
106.04
0.87
nth Order
n=1.5
Mample First
Order
Diffusion Models
Diffusion
Control (Crank)
Diffusion
Control
(Janders)
One
Dimensional
Diffusion
Nucleation Models
10.94
69.39
0.99
22.98
134.17
0.98
8.10
58.09
1.00
21.15
114.43
0.89
17.29
114.21
1.00
41.01
220.32
0.87
18.35
118.55
1.00
42.56
226.57
0.88
17.46
105.94
0.99
39.86
206.36
0.85
Avrami-Erofeev
0.42
24.45
1.00
7.51
52.66
0.87
Power Law
-4.06
9.98
0.97
1.18
26.76
0.77
MODEL FREE METHODS – HEMI CELLULOSE, CELLULOSE & LIGNIN
2.5
0
1.0
Flynn, Wall and Ozawa method - Bagasse - Argon atm - 2, 5, 30 c/min
Friedman method - Bagasse - Argon atm - hemicellulose
fraction of decomposition () - Hemicellulose
fraction of decomposition () - Hemicellulose
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
2.0
0.5
0.0
1
1
A
a
a
3
C
3
log (.d/dT)
c
log ()
1.5
A
1.0
C
-0.5
c
-1.0
2
B
b
-1.5
1
b
B
A
2
a
-2.0
0.5
a
A
1
-2.5
0.00165
0.0
0.00165
0.00170
0.00175
0.00180
0.00185
0.00190
0.00170
0.00175
0.00195
0.00180
0.00185
0.00190
0.00195
-1
1/T (k )
1/T
0.04
Cellulose
Bagasse, Argon atm
Friedman
350
Cellulose
300
Activation energy (kJ/mol)
d/dT
0.03
0.02
0
= 2 C/min
0.01
0
= 5 C/min
e
250
200
Hem
ulos
i-cell
r
all
er
Ov
on
cti
ea
150
nin
Lig
100
0
= 30 C/min
50
0.00
0.2
0.0
0.2
0.4
0.6
Fraction reacted,
0.8
1.0
0.4
0.6
0.8
Fraction reacted,
Variation of activation energy with fraction reacted for hemi-cellulose, cellulose
and lignin decomposition reactions and overall decomposition reaction of
sugarcane bagasse.
The kinetic parameters of hemi-cellulose, cellulose and lignin derived
with model free iso-conversional methods.
α
Ln A*
E(kJ/mo
l)
R2
0.1
43.81
207.13
0.99
Flyn, Wall and Ozawa
Method
E(kJ/mo
Ln A*
R2
l)
54.41
221.63
0.99
0.2
51.43
242.28
0.99
57.80
234.82
0.99
0.3
54.38
256.45
0.99
62.53
248.11
0.99
0.4
55.78
263.71
0.99
67.89
255.23
0.99
0.5
57.95
274.52
0.99
72.13
265.17
0.99
0.7
59.83
283.95
0.99
81.83
270.24
0.99
Constituent
Hemicellulose
cellulose
Lignin
Friedman Method
0.1
68.68
349.55
0.99
80.40
385.90
0.99
0.2
62.86
320.52
0.99
73.24
352.87
0.99
0.3
60.60
308.97
0.99
70.32
339.36
0.99
0.4
58.34
297.40
0.99
67.77
327.08
0.99
0.5
56.61
288.27
0.99
65.93
317.69
0.99
0.7
55.37
281.55
0.99
64.86
311.84
0.99
0.1
0.2
0.3
0.4
38.38
50.11
81.86
99.10
119.38
0.99
0.99
0.99
0.99
0.99
10.41
13.22
16.19
19.49
24.65
38.90
55.86
73.63
94.41
118.83
0.99
0.99
0.99
0.99
0.5
16.94
19.04
11.12
14.27
17.73
0.7
22.52
147.38
0.99
26.24
150.25
0.99
* - Derived by assuming f(α) =(1-α)1.5
0.99
Kissinger method
Ln A*
E(kJ/mo
l)
R2
55.50
255.54
0.99
64.65
322.71
0.99
18.36
109.23
0.98
NON-LINEAR LEAST SQUARE MINIMZATION METHOD
M
OF 
N
j
  (( d 
j 1
exp t
/ dT ) ij
 ( d  / dT ) ij
calc
2
) /N
j
i 1
( d  / dT )

calc
  EH 
 d   A H
. Exp 
 1  a H

  
 dT   
 RT 

 AC
  EC 
. Exp 
 1  a C

RT



 n 1   

E 

. exp  
 . f ( )

RT


A

 AL
  EL 
. Exp 
 1  a L
 RT 
 
 n 2   


 n 3 

The derivation of kinetic parameters of hemi-cellulose, cellulose
and lignin in sugarcane bagasse using a non-linear least square
minimization method.
0.012
Non-linear least square minimization
0
2 C/min
0
5 C/min
0
30 C/min
Calculated
da/dT
0.008
0.004
Suagarcane bagasse
Argon atm
0.000
400
500
600
700
Temperature (K)
800
900
Reconstruction of fraction reacted (α) vs temperature plot using the
kinetic parameters derived from integral method for hemi-cellulose
decomposition
0.004
0.20
Least square
minimization
Experimental
Reconstructed
Kissinger
0.15
0.10
0.002
0.05
0.00
da/dT
0.000
0.004
KD Differential
80000
0.002
40000
0.000
0
0.004
CR Integral
0.04
0.002
0.02
0.000
0.00
450
500
550
600
650
Ozawa, Flynn, Wall
Friedman
500
Temperatute (K)
550
600
650
Conclusions
About 70-80 percent mass loss was occurred at argon atmosphere.
The separation of overall reaction showed about 92-96% of hemi-cellulose,
91-95.5% cellulose and 94-97% lignin decomposition.
The decomposition of cellulose and hemi-cellulose occurred rapidly while
decomposition of lignin was sluggish in nature.
The selection of suitable reaction model was possible after separation of
hemi-cellulose, cellulose and lignin decomposition reactions.
The reaction order model f(α) = (1- α)1.5, better described the kinetics of
hemi-cellulose, cellulose and lignin decomposition.
The activation energy of hemi-cellulose and lignin increased with heating
rate, while the activation energy of cellulose decreased with heating rate.
The non-linear least square minimization method showed better results