Design and testing of sorbents for CO2 separation of post-combustion and natural gas sweetening applications

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1 Engineering Conferences International ECI Digital Archives CO2 Summit II: Technologies and Opportunities Proceedings Spring Design and testing of sorbents for CO2 separation of post-combustion and natural gas sweetening applications Jiajun He Stanford University John To Stanford University Peter Psarras Stanford University Jianguo Mei Stanford University Jen Wilcox Stanford University Follow this and additional works at: Part of the Environmental Engineering Commons Recommended Citation Jiajun He, John To, Peter Psarras, Jianguo Mei, and Jen Wilcox, "Design and testing of sorbents for CO2 separation of post-combustion and natural gas sweetening applications" in "CO2 Summit II: Technologies and Opportunities", Holly Krutka, Tri-State Generation & Transmission Association Inc. Frank Zhu, UOP/Honeywell Eds, ECI Symposium Series, (2016). co2_summit2/34 This Abstract and Presentation is brought to you for free and open access by the Proceedings at ECI Digital Archives. It has been accepted for inclusion in CO2 Summit II: Technologies and Opportunities by an authorized administrator of ECI Digital Archives. For more information, please contact

2 S O R B E N T D E S I G N AND T E S T I N G F O R CO 2 S E PA R AT I O N F O R P O S T - C O M B U S T I O N AND N AT U R A L G A S S W E E T E N I N G A P P L I C AT I O N S CO 2 S U M M I T I I : T E C H N O L O G I E S A N D O P P O R T U N I T I E S A P R I L , S A N TA A NA P U E B L O, N EW M E X I C O J E N N I F E R W I L C O X

3 The Team Coupled Experiments and Theory Synthesis, Characterization, Testing and Monte Carlo PhD Students Jiajun He John To Chris Lyons Postgrad Researchers Peter Psarras

4 Objectives Develop porous carbons targeting specific CO 2 capture processes Optimize the carbon properties for enhanced capture performance Investigate the roles of the sorbent s textures and functionalities in the capture performance Post-combustion capture 1 Natural gas sweetening N 2 Flue gas CO 2 separation Natural gas Low CO 2 partial pressures CO 2 Trace acid gas (SOx, NOx, etc.) CO CH 2 4 CO separation 2 High CO 2 partial pressures Sometimes contains H 2 S 1 To et al., J. Amer. Chem. Soc.,

5 Closer Look at Heat Properties Assume: Heat of regeneration = C p ΔT + ΔH heating up all material in system from T 1 to T 2 + breaking the CO 2 interaction 3

6 Sorbent Design Depends on Application optimal pore size depends upon dilution Air Capture 400 ppm Natural Gas Plants 4-6% Coal Plants 12-14% 100 Air Capture 300 Air Capture 4

7 2 Mechanisms Impacting CO 2 Uptake Natural Gas Plants 4-6% Coal Plants 12-14% CO 2 -Surface Surface Chemistry CO 2 -CO 2 Thermodynamic 5

8 Hierarchal Carbons as a CO 2 Adsorbent Tunable pore sizes and distribution Optimal heat properties High surface area and pore volume Flexibility on surface functionalization Physical adsorption not chemical Chemical stability Earth-abundant and low cost 6

9 Soft-Template Synthesis Micelle formation Micelle assembly Polymerization Monomersurfactant solution Monomertemplate coassembly Carbonization Activation Monomer = Surfactant = PEO-PPO-PEO Hierarchically porous carbon 7

10 Cumulative PV (cm 3 g -1 ) dv(logd) (cm 3 g -1 ) Pore Analysis Pore Size Distribution (PSD) 1.2 SU-MAC SU-MAC SU-MAC-600 SU-MAC CO 2 PSD N 2 PSD SU-MAC-600 SU-MAC CO 2 PSD N 2 PSD Pore Diameter, d (nm) Pore Diameter, d (nm) BET surface area (SU-MAC-500, 600, 800): 942, 1500 and 2369 m 2 g -1 Higher act. temperature higher surface area and total pore volume 8

11 Adsorbed Amount (mmol g -1 ) Adsorbed Amount (mmol g -1 ) Henry s Law CO 2 /N 2 Selectivity SU-MAC-500 CO 2 initial slope 2E-2 1E-2 8E-3 4E-3 y = x R² = E-2 4E-2 3E-2 2E-2 1E-2 N 2 initial slope y = x R² = E+0 0E+0 5E-5 1E-4 2E-4 Pressure (bar) 0E+0 0E+0 5E-2 1E-1 Pressure (bar) Sample CO 2 Capacity (mmol g -1 ) 273 K 298 K 323 K 298 K N 2 Capacity (mmol g -1 ) CO 2 /N 2 Selectivity SU-MAC :1 SU-MAC :1 SU-MAC :1 9

12 Literature Selectivity for AC Activated Carbon CO 2 Capacity 25 C, 1 bar (mmol/g) CO 2 /N 2 Selectivity Reference CP Sevilla et al. Adv. Funct. Mater AS Sevilla et al. Energy Environ. Sci VR-93-M Wahby et al. ChemSusChem 2010 CN Ma et al. J. Mater. Chem NPC Wang et al. J. Mater. Chem. A 2013 NG Kemp et al. Nanotech Bamboo Wei et al. ChemSusChem 2012 Petro. Coke Hu et al. Environ. Sci. Technol Polypyrrole Chandra et al. Chem. Commun Polyfurfuryl alcohol Sevilla et al. J. Colloid Interface Sci SU-MAC This work 10

13 CO 2 /N 2 Selectivity Comparison of CO 2 Capture Potential CO 2 Capacity (mmol g -1 ) SU-MAC-500 Carbons Polymers MOFs Zeolites (1) Wei et al. Adv. Funct Mater (2) Hao et al. J. Am. Chem. Soc (3) Chandra et al. Chem. Comm (4) Xiang et al. Nat. Commun (5) Ma et al. J Mater Chem A (6) Patel et al. Adv. Funct.l Mater (7) Patel et al. Nat Commun 2013.

14 Cumulative V (cm 3 g -1 ) dv(logd) (cm 3 g -1 ) CO 2 /N 2 Selectivity Factors Affecting Selectivity: Ultra-Microporosity PSD by DFT method (CO K) Correlation of selectivity vs. PV (d < 0.5 nm) SU-MAC-500 SU-MAC-600 SU-MAC Pore Diameter, d (nm) PV (d < 0.5 nm) (cm 3 g -1 ) Decreased ultra-small pore volume with increasing activation temperature Enhanced CO 2 adsorption potential in narrow pores 12

15 MFC MFC Dynamic Column Breakthrough Experimental Setup P P Bypass line FM BPR Sorbate Carrier CO 2 N 2 Adsorption column Heating Jacket Detector MS MFC: mass flow controller P: MFC: pressure Mass flow gauge controller FM: flow Flow meter MS: BPR: mass Back spectrometer pressure regulator 10% CO % N 2, 1 bar and 298 K Humidity and acidic impurities added to simulate various coal flue gases 13

16 CO 2 Capacity (mmol g -1 ) Cyclability dry humid acid impurities Cycle Regeneration: N 2 purge at 25 C (dry) 10 cycles: fully recovered CO 2 capacity Excellent cyclability 14

17 Density (mmol cm 3 ) Density (mmol cm -3 ) Effect of Nitrogen Functionalities Pyridonic nitrogen (PN) *PG = perfect graphite PG, 0.8 nm PN, 0.8 nm QN, 0.8 nm PG, 2 nm PN, 2 nm QN, 2 nm PG, 10 nm PN, 10 nm QN, 10 nm 15 Quaternary nitrogen (QN) Pressure (bar) N enhances CO 2 uptakes when pore size is small and/or at low pressure QN leads to higher CO 2 uptakes than PN Pressure (bar) 15

18 Total Adsorption (mmol g -1 ) GCMC Simulations versus Experiments 0.3 nm 0.4 nm 0.5 nm 0.6 nm z y PG PN QN Exp. Data Pressure (bar) 16

19 Major Findings Hierarchal nitrogen-doped porous carbon was made with designed pyrrole monomer via a soft-templating approach Promising CO 2 capture capacity and CO 2 /N 2 selectivity Selectivity as a function of the pore size and nitrogen functionalities Potential in post-combustion capture (cyclability, regeneration requirements, stability towards moisture and acidic impurities, etc.) Computational modeling can serve as an excellent screening tool for new sorbent design Acknowledgements 17