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1. Predicting The Right Material For The Job:
A Molecular Modeling Approach To Separations
Dalar Nazarian, Ph.D.
Development Specialist R&D, Praxair Inc.
Georgia Institute of Technology, 2016
Harvey Mudd College, 2012

2. Mixtures are Easier to Make, Harder to Separate!

3. Mixtures are Easier to Make, Harder to Separate!
Air Sea
Water
Clean Drinking
Water
T-shirts
Books
O2(Hospitals, Steel )
N2(Food, Electronic)

4. Separations Require Energy! A Lot of Energy!
Over 250,000 MWh/day
to separate oxygen

5. Selective Adsorption: Work Smarter, Not Harder
Selective adsorption
on solid adsorbents
Mixture
Pure
Operate at ambient
temperatures and
pressures

6. There is a Right Material for Every Separation
Zeolites Activated Carbon Novel Materials

7. Question
How can we accurately and quickly
choose the best materials for a
specific separation?

8. Experimentally determining promising materials is
unrealistic
Experimentally
Synthesized
Materials
Computational
Screening
1.
2.

9. Employ modeling tools to quickly and accurately
identify promising materials
for separation applications.
Natural
Gas
Gas Turbine
Air
Intake
?
Published Research
Gases

10. High Quality High Throughput Modeling
of Separations in Nanoporous Materials
Nat
ural
Gas
Gas
Tur
bine
Air
Int
ak
e
?
Published Research
Gases
MOFs
High Throughput
High Quality
Example

11. MOFs High Throughput High Quality Example
Metal :
Cu Salt
Organic Ligand :
Trimesic acid
Nanoporous Crystal : HKUST-1
Metal-organic frameworks (MOFs)
The tinker toys of materials
?

12. Metal :
V Salt
Organic Ligand :
Terephthalic
acid
Nanoporous Crystal : MIL-47
• Tunable
• High Selectivity
• High Surface Area
MOFs High Throughput High Quality Example
Metal-organic frameworks (MOFs)
The tinker toys of materials
?

13. Thousands of already synthesized
MOFs offer vast diversity
MOFs High Throughput High Quality Predictions
?
a

14. MOFs are ideal candidate for high
throughput computational screening
MOFs High Throughput High Quality Example
?
Experimentally
Synthesized
MOFS
Computational
Screening
1.
2.

15. Reduce the number of candidates while
increasing complexity of calculations
MOFs High Throughput High Quality Example
?
KineticBarriers
Selectivity
+
SaturationLoading
Selective for
A over B
Database of Crystallographic
Structure Information
Dilute
Realistic

16. Henry’s selectivity & heat of adsorption
MOFs High Throughput High Quality Example
?
BA
DiluteDilute

17. Selectivity and loading at real conditions
MOFs High Throughput High Quality Example
?
Ideal GasAdsorbate and Adsorbent
RealisticRealistic

18. Reduce the number of candidates while
increasing complexity of calculations
MOFs High Throughput High Quality Example
?
1.
2.
KineticBarriers
Selectivity
+
SaturationLoading
Synthesis
+
Structural
Properties
Selective for
A over B
Database of Crystallographic
Structure Information

19. Assess assumptions to insure high
quality calculations
MOFs High Throughput High Quality Example
?
Accurate
Structures
Raw Data Assumed Data But really!

20. Assess assumptions to insure high
quality calculations
MOFs High Throughput High Quality Example
?
Accurate
Structures DF
T
Database of DFT Optimized
Crystallographic Structure
Information

21. Assess assumptions to insure high
quality calculations
MOFs High Throughput High Quality Example
?
Accurate
Structures
D
F
T

22. Assess assumptions to insure high
quality calculations
MOFs High Throughput High Quality Example
?
Accurate
Structures
Structure accuracy is not guaranteed. Precision
is important for adsorption property prediction!

23. Assess assumptions to insure high
quality calculations
MOFs High Throughput High Quality Example
?
Accurate
Structures
Electrostatic
Interactions

24. Assess assumptions to insure high
quality calculations
MOFs High Throughput High Quality Example
?
Accurate
Structures
Electrostatic
Interactions

25. Assess assumptions to insure high
quality calculations
MOFs High Throughput High Quality Example
?
Accurate
Structures
Electrostatic
Interactions
We DON’T have a q
force field

26. Assess assumptions to insure high
quality calculations
MOFs High Throughput High Quality Example
?
Accurate
Structures
Electrostatic
Interactions
Database of DFT Optimized
Crystallographic Structure Information
with DDEC point charges
Created a database of point changes for
3,000 structures!
Precision important for adsorption property
prediction!

27. Assess assumptions to insure high
quality calculations
MOFs High Throughput High Quality Example
?
Accurate
Structures
Electrostatic
Interactions
Rigid
Structure

28. Assess assumptions to insure high
quality calculations
MOFs High Throughput High Quality Example
?
Accurate
Structures
Precision important for adsorption
property prediction!
Electrostatic
Interactions
Created a database of point changes for
3,000 structures!
Rigid
Structure
Framework flexibility can significantly
impact on adsorption properties!

29. Finding the best MOFs to remove
corrosive TBM form natural gas
MOFs High Throughput High Quality Example
?
Natural
Gas
Gas
Turbine
Air
Intake
?

30. Finding the best MOFs to remove
corrosive TBM form natural gas
MOFs High Throughput High Quality Example
?
Discarded MOFs with with SHenry < 103 and qads < -70 kJ/mol

31. Finding the best MOFs to remove
corrosive TBM form natural gas
MOFs High Throughput High Quality Example
?
• Top performing materials have
binary selectivities ~ 105, on
the order of experimental
measurements
• Recommend MOFs with
saturation loading higher than
200 mg of TBM per g of MOF as
promising candidates

32. High Quality High Throughput Modeling
of Separations in Nanoporous Materials
Nat
ural
Gas
Gas
Tur
bine
Air
Int
ak
e
?
Published Research
Gases DFT Optimized
Database
DDEC Point Charges
Database
Outlined Screening
Procedure

33. Use EFFICIENT ways to
find the most EFICIENT materials for
an EFFICENT way to separate mixtures.

34. Thank You!
Dr. David Sholl
Committee Members:
Dr. Ganesh Panchapakesan
Dr. Ryan Lively
Dr. Krista S. Walton
Dr. Angus P. Wilkinson
Sholl Group
Greg Chung

35. Motivation
Separation technology critical to our future.
Separation of fluid mixture are energy intensive.
Adsorption is a potential answer.
There is a right material for every separation.

38. Reduce the number of candidates while
increasing complexity of calculations
MOFs High Throughput High Quality Predictions
?
1.
2.
KineticBarriers
Selectivity
+
SaturationLoading
Synthesis
+
Structural
Properties
Selective for
A over B
Database of Crystallographic
Structure Information