1
ZEOLITES
Group 7
Kristen Losensky
Trenton Wood
9-28-12
2
Summary
• Synthesis of ultrasmall and nanosized EMT Zeolites
without the use of an organic template or Organic
Structure-Directing Agent (OSDA)
• DLS used to determine particle size
• X-Ray Diffraction used to investigate structure
• X-Ray Diffraction used to examine nucleation
• Analyzed crystallinity of EMT zeolites
3
Introduction: What is a Zeolite?
• A highly porous, low
density material
• Composed of silicon,
aluminum and oxygen
lattice
• Molecular framework
creates cages, cavities,
and/or channels
http://www.bestzeolites.com/
4
Industrial Use
• Adsorption and Separation
- Molecular sieving based on limiting pore size and steric effects within the
zeolite
- A good desiccant, drying
• Ion exchange
- The negatively charged lattice can be used absorb heavy meatals or
radioactive isotopes
- Already present interstitial cations can be replaced with others in solution
- Different insterstitial cations also influence molecular sieving
• Catalytic
- Presence of interstitial cations and Lewis acid Al sites can provide
necessary electrons for reactions.
- Specific shape of cavity leads to specialized products with less isomers
5
Petrochemical
• Zeolites are attractive for
the separation of smaller
hydrocarbons due to pore
size
• Gasoline yields increase in
cracking compared to
Silica-Alumina gels
• Zeolites can reduce
unwanted product and/or
isomers by their pore
structure
http://www.dtic.mil/dtic/tr/fulltext/u2/p011209.pdf
6
Wastewater Treatment
• Zeolites can also utilize Ion exchange in softening
water, by absorbing calcium and magnesium and
releasing a sodium
• It is even good at removing ammonia
http://www.asdn.net/asdn/chemistry/zeolites.shtml
7
Basic Principles: Structure
• Aluminosilicate
• Each Si and Al are bound
to four tetrahedrally
arranged oxygens
• Aluminum sites can
function as Lewis acids or
act with water to create a
Brønsted acid
http://www.cheresources.com/zeolitezz.sht
ml
http://www.gizmag.com/european-synchrotron-radiationfacility-succesfully-analyzes-zeolites/9544/
8
Basic Principles: Structure
• Zeolite frameworks:
40 naturally occurring
>191 synthetically made
Characteristics
• Porosity
• Si/Al ratio (lowest = 1)
http://en.wikipedia.org/wiki/File:Zeolite-ZSM-5-3D-vdW.png
9
Basic Principles: Structure
• Faujasite structures
contain spherical
pores called
supercages
• Different connectivity
leads to different
specializations
http://www.dtic.mil/dtic/tr/fulltext/u2/p011209.pdf
10
http://www.asdn.net/asdn/chemistry/zeoli
tes.shtml
11
Basic Principles: Dynamic Light Scattering (DLS)
• Measures the intensity of the
reflected incident light from a
suspended solution as a
function of time.
• Sharper fluctuations correspond
with more molecular movement
and correlate with smaller
particles.
• If temperature and solvent are
constant, the intensity is only a
function of particle size and can
be experimentally determined.
http://en.wikipedia.org/wiki/File:DLS.svg
12
Basic Principles: X-ray Diffraction
The Diffractometer
• A crystalline sample is rotated to
determine the angles at which
light is the least scattered.
• Information about the crystalline
structure can be experimentally
determined by the values of the
angles at intense peaks.
http://www.asdlib.org/onlineArticles/ecourseware/Bullen_
XRD/XRDModule_Theory_Instrument%20Design_3.htm
13
Basic Principles: X-ray Diffraction
Bragg’s Law
• Two different light beams
are scattered at the same
angle on a crystalline
structure
• The interatomic distance
between the planes of
atoms can be determined
by the extra distance
traveled by the second
beam
http://photonicswiki.org/index.php?title=Xray_Diffraction
14
Previous Work
• EMT-FAU intergrown phases
• Pure EMT type zeolite by templating with 18-crown-6-
ether and using tightly controlled conditions
• Recycle the template
• SINTEF tumbling approach
• Steam-assisted crystallization
• Surfactants / other organic and inorganic additives
• Nanosized molecular sieves assembled at moderate
temperatures
http://pediatrics.about.com/od/yourbabyweekbyweek/ss/baby_wk_eighten_6.htm
15
Materials Used
• NaAlO2 (Strem-chemicals, 56.7% Al2O3, 39.5% Na2O)
• NaOH (Merck, 99%)
• Na2SiO3 (Prolabo, 29% SiO2, 8% Na2O, 28.85 g)
http://www.tootoo.com/buy-al2o3_powder/
16
Fabrication Methods
Ultrasmall EMT Zeolite (6-15 nm)
Precursor Suspension
5.15 SiO2: 1 Al2O3 : 18.45 Na2O : 240.3 H2O
Continuously Stir
10 min, at Room Temperature
Keep Product at 30 °C
36 hr
17
Fabrication Methods
Nanosized EMT Zeolite (50-70 nm)
Precursor Suspension
5 SiO2: 1 Al2O3 : 17.48 Na2O : 340.3 H2O
Continuously Stir
10 min, at Room Temperature
Age at Room Temperature (~ 23 °C)
14 hr
Heat in Microwave Oven
Anton Paar Synthos 3000
4 min at 30 °C (200 W)
Heat in Conventional Oven
36 hr at 30 °C
18
Results
• Synthesis of ultrasmall and nanoscale EMT crystals from
colloidal suspensions without organic template
HRTEM images of ultrasmall EMT zeolites
Made from colloidal suspensions
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems. Science 2012, 335
19
Results
• Synthesis of ultrasmall and nanoscale EMT crystals from
colloidal suspensions without organic template
SEM image of
nanosized EMT zeolites
prepared from colloidal
suspension
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems. Science 2012, 335
20
Results
• Conditions were adjusted to avoid
phase transformations and to
stabilize the EMT crystals
• more stable and more dense
hydroxysodalite (SOD)
• FAU-type phase observed in
precursor suspensions
• 63% Yield of ultrasmall hexagonal
EMT zeolite (Si/Al = 1.4)
• Channels in a highly ordered
hexagonal arrangement
TEM images showing the formation of
fully crystalline ultrasmall EMT zeolite
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems. Science 2012, 335
21
Results: X ray Diffraction of Precursor
Suspension
(A) Samples extracted from a precursor
suspension with a molar ratio of 5.15 SiO2:
1Al2O3: 18.45 Na2O: 240.3 H2O after (a) 24
h, (b) 36 h, (c) 42 h, (d) 48 h, and (e) 54 h
synthesis in comparison with (f) pur
sodalite (SOD).
(B) Intermediate EMT-FAU synthesized from a
precursor suspension with a molar ratio of
5 SiO2 : 1 Al2O3: 20 Na2O: 700 H2O for (b)
20 h, (c) 36 h, (d) 42 h and (e) pure FAU 50
h, in comparison to (a) pure EMT
synthesized from the original suspension
(5.15 SiO2: 1Al2O3: 18.45 Na2O: 240.3
H2O) for 36 h.
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems. Science 2012, 335
22
Results: Zeolite Size
• The size of the zeolites produced was analyzed using
Dynamic Light Scattering (DLS)
(a) Ultrasmall EMT zeolites prepared with conventional heating
(b) Nanosized EMT zeolites prepared with microwave heating
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems. Science 2012, 335
23
Results: Formation of Crystals
XRD patterns of ultrasmall
EMT crystals from
template-free precursor
suspensions for (A) 8
hours, (B) 14 hours, (C) 24
hours and (D) 36 hours
Indexed using hexagonal
EMT structure
P63/mmc space group
RW = 1.5%
RB = 1.12%
Rexp 0.62%
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems. Science 2012, 335
Crystallite sizes and shapes are calculated based on the XRD data
24
Results: Zeolites X and Y?
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems. Science 2012, 335
25
Results: Zeolites X and Y?
• Poor fit between data and zeolite X
and Y models
• Refined cell parameters:
• a = 1.7616(1) nm
• C = 2.838(2) nm
• Refined shape: hexagonal crystal
• 10 mn [100], 15nm [110], 2.0 nm
[001]
http://www.chegg.com/homework-help/questions-and-answers/determineindices-directions-shown-following-hexagonal-unit-cells-q2865110
http://www.chem1.com/acad/webtext/states/crystals-ext.html
26
Results: Nucleation Analysis (8-14 h)
XRD patterns of ultrasmall EMT crystals from
template-free precursor suspensions for (A) 8
hours, (B) 14 hours, (C) 24 hours and (D) 36
hours
• 2-10 nm amorphous
objects
• 8h, no Bragg peaks
• 14h, mixture of
amorphous and
nanocrystalline EMT
zeolite
• 30% crystalline
• Unit cell c/a = 1.44
• Reitveld = entirely
amorphous
• Anisotropic shapes
with mostly developed
plate-like form
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems.
Science 2012, 335
27
Results: Nucleation Analysis (8h)
Reitveld fitting of EMT sample (8h)
(a) EMT crystals with isotropic sizes (harmonic
development only up to P0), (b) EMT crystals with
anisotropic shapes (harmonic development up to P1),
(c) EMT crystals with anisotropic shapes (harmonic
development of P0, P1, and P4), (e) FAU crystals with
isotropic shapes, (f) FAU crystals with with anisotropic
shape (harmonic development up to P1), (g) FAU
crystals with anisotropic shape (harmonic development
up to P2), and (h) FAU crystals with anisotropic shape
(harmonic development up to P4).
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems. Science 2012, 335
28
Results: Nucleation Analysis
Characteristic of the
starting of EMT
growth
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems.
Science 2012, 335
29
Results: Nucleation Analysis (24 h)
XRD patterns of ultrasmall EMT crystals from
template-free precursor suspensions for (A) 8
hours, (B) 14 hours, (C) 24 hours and (D) 36
hours
• Ultrasmall
crystallites of
zeolite EMT
appear
• Amorphous matter
and low intense
Bragg peaks
• Crystalline
particles exhibit
hexagonal shape
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems.
Science 2012, 335
30
Results: Nucleation Analysis (36 h)
XRD patterns of ultrasmall EMT crystals from
template-free precursor suspensions for (A) 8
hours, (B) 14 hours, (C) 24 hours and (D) 36
hours
• Entirely crystalline
matter
• Well-formed
hexagonal particles
with crystalline
fringes
• Size and hexagonal
arrangement of
micropores
correspond to the
EMT zeolite
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems.
Science 2012, 335
31
Results: Crystallinity
27Al
NMR spectra of
(a) ultrasmall ( 30 °C,
36 h) and (b)
nanosized EMT (30
°C, 4 min)
N2 Sorption Isotherm for Ultrasmall EMT crystals
synthesized in a conventional oven
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems.
Science 2012, 335
32
Results: TEM and SAED
• Characteristic hexagonal plate-like morphology
• Selected-Area Electron Diffraction pattern of nanosized EMT
exhibits sixfold symmetry
• ABABAB stacking of the faujasite sheets
• Nanosized EMT grow favorably in the a direction rather than the c
direction
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova, S., Capturing Ultrasmall EMT Zeolite from Template-Free Systems. Science 2012, 335
33
Analysis
• Why has EMT never been observed in organic-free
synthesis methods before?
• Proposed: heating the solution for extended periods of time or at
higher temperatures causes EMT to convert into FAU and SOD
structures
• EMT is the first kinetic metastable product
• Perhaps it is possible to capture other zeolite phases by
exploiting early stages of synthesis
34
Analysis
• The results of the different techniques used to
determine composition and structure of the
crystals/solutions were consistent
• All possible models were considered
• Impact on Industry and the Environment
http://www.ccrg.info/environment.htm
http://science.howstuffworks.com/environmental/energy/oil-refining3.htm
35
Further Research
• Catalytic and ion exchange properties of EMT zeolites
prepared without OSDA
• Effect of microwave heating vs. effect of conventional
heating on catalytic and ion exchange properties of the
zeolites
• Applicability to other zeolite phases
http://blogs.worldbank.org/developmenttalk/wholesaling-research-for-development
36
References
1.
2.
3.
4.
5.
6.
Ng, Eng-Poh; Chateigner, D.; Bein, T.; Valtchev, V.; Mintova,
S., Capturing Ultrasmall EMT Zeolite from Template-Free
Systems. Science 2012, 335
Callister, William D., Jr., and David G. Rethwisch.
Fundamentals of Materials Science and Engineering: An
Integrated Approach. 4th ed. N.p.: Wiley, 2008. Print
Wittcoff, Harold A., Bryan G. Reuben, and Jeffrey S. Plotkin.
Industrial Organic Chemicals. 2nd ed. Hoboken: Wiley Interscience, 2004. Print.
Vermeriren W., Gilson J.P. “Impact of Zeolites on the
Petroleum and Petrochemical Industry” Springer
Science+Business Media (2009) Web. 26 September 2012.
http://www.springerlink.com/content/4445388030721270/fullt
ext.pdf
http://www.asdn.net/asdn/chemistry/zeolites.shtml
37
References (Pictures)
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
http://www.tootoo.com/buy-al2o3_powder/
http://pediatrics.about.com/od/yourbabyweekbyweek/ss/baby_wk_eighten_6.htm
http://www.ccrg.info/environment.htm
http://science.howstuffworks.com/environmental/energy/oil-refining3.htm
http://blogs.worldbank.org/developmenttalk/wholesaling-research-for-development
http://www.bestzeolites.com/
http://www.cheresources.com/zeolitezz.shtml
http://www.gizmag.com/european-synchrotron-radiation-facility-succesfully-analyzeszeolites/9544/
http://en.wikipedia.org/wiki/File:Zeolite-ZSM-5-3D-vdW.png
http://www.dtic.mil/dtic/tr/fulltext/u2/p011209.pdf
http://www.asdn.net/asdn/chemistry/zeolites.shtml
http://www.dtic.mil/dtic/tr/fulltext/u2/p011209.pdf
http://www.asdn.net/asdn/chemistry/zeolites.shtml
http://en.wikipedia.org/wiki/File:DLS.svg
http://www.asdlib.org/onlineArticles/ecourseware/Bullen_XRD/XRDModule_Theory_Instrument%
20Design_3.htm
http://photonicswiki.org/index.php?title=X-ray_Diffraction
http://www.chem1.com/acad/webtext/states/crystals-ext.html
http://www.chegg.com/homework-help/questions-and-answers/determine-indices-directionsshown-following-hexagonal-unit-cells-q2865110
38
Questions ?