Silica/polyethyleneimine composite adsorbent S-PEI for CO2 capture by vacuum swing adsorption (VSA)

Gregory P. Knowles, Paul A. Webley, Zhijian Liang, Alan L. Chaffee

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SBA15 type mesoporous silica was combined with a pore volume equivalent of branched polyethyleneimine PEI (MW 1200) to prepare a high capacity adsorbent S-PEI for the selective capture of CO2 from post combustion flue gas via pressure / vacuum swing adsorption (VSA). The adsorbent was characterized by helium pycnometry, N2 adsorption / desorption at 77 K, powder X-ray diffraction XRD and thermogravimetric analysis. The potential of S-PEI for CO2 capture via VSA was assessed by both CO2 partial pressure swing adsorption (PPSA) studies via combined thermogravimetric analysis (TGA) / differential thermal analysis (DTA), and by CO2 pressure / vacuum swing adsorption (VSA) studies via a custom bench gas sorption analyzer. The CO2 sorption capacities determined by partial pressure swings were consistent with those determined by pressure / vacuum swings as expected by the Henry gas law and therefore demonstrate the validity of PPSA to estimate VSA process working capacities. S-PEI was found to exhibit greater working CO2 capacity than zeolite 13X at 105 °C under key process conditions (0.05 - 0.15 atm CO2) from either anhydrous or humidified (̃1 % H2O) process gas. The amine adsorbent was also found to exhibit a higher Hads(CO2) (70-90 kJ.mol-1 than zeolite 13X (30-40 kJ.mol-1) as was expected for a chemisorption process. Zeolite 13X however was found to exhibit faster sorption kinetics under anhydrous process conditions consistent with its lower Hads(CO 2). Pelletized S-PEI exhibited the same good sorption kinetics as the powder, however with slightly reduced CO2 working capacity, 2.5 wt% at 105 °C, and minimal void volume, equivalent to 29.3 g of CO2 per L of sorbent bed. S-PEI was thus found to be attractive for CO2 capture from post combustion flue gas via VSA.

Original languageEnglish
Title of host publicationRecent Advances in Post-Combustion CO2 Capture Chemistry
EditorsMoetaz I Attalla
Place of PublicationWashington DC USA
PublisherAmerican Chemical Society
Number of pages29
ISBN (Print)9780841226210
Publication statusPublished - 2012
EventSymposium at the International Chemical Congress of Pacific Basin Societies (Pacifichem) 2010 - Hawaii Convention Center, Honolulu, United States of America
Duration: 15 Dec 201020 Dec 2010
Conference number: 6th

Publication series

NameACS Symposium Series
PublisherAmerican Chemical Society
ISSN (Print)0097-6156
ISSN (Electronic)1947-5918


ConferenceSymposium at the International Chemical Congress of Pacific Basin Societies (Pacifichem) 2010
Abbreviated titlePacifichem 2010
Country/TerritoryUnited States of America
Internet address

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