Carbon dioxide/methane mixed-gas adsorption, permeation and diffusion in a carbon molecular sieve film: Experimental observation and modeling
KAUST DepartmentAdvanced Membranes and Porous Materials Research Center
Biological and Environmental Science and Engineering (BESE) Division
Chemical Engineering Program
Physical Science and Engineering (PSE) Division
Chemical and Biological Engineering
KAUST Grant NumberBAS/1/1323-01-01
Online Publication Date2021-11-20
Print Publication Date2021-11
Embargo End Date2023-11-20
Permanent link to this recordhttp://hdl.handle.net/10754/673706
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AbstractThe CO2–CH4 pure- and mixed-gas transport properties (at 35 °C) of a carbon molecular sieve (CMS) film obtained by pyrolysis of a 6FDA-mPDA polyimide precursor at 900 °C are reported. The competitive mixed-gas adsorption of CO2 and CH4 was predicted by the Ideal Adsorbed Solution Theory (IAST) model. The CO2/CH4 mixed-gas solubility selectivity of the CMS film was lower than that of relevant glassy polymer films of various nature and increased with pressure. Mixed-gas adsorption data were coupled with gas permeation tests on the same film sample batch used for barometric adsorption measurements to derive concentration-averaged effective diffusion coefficients. Because of its large fraction of ultramicroporous bottlenecks, the diffusion coefficients of the CMS were of the same order of magnitude as those of glassy polymer films of low free volume (e.g., 6FDA-mPDA and CTA). In the range of pressures explored, the pure-gas and multicomponent CO2 diffusion coefficients overlapped; most importantly, the methane diffusion coefficient was enhanced by the presence of CO2. This result suggests that carbon dioxide dilated the sieving domains of the CMS matrix under mixed-gas environment containing highly sorbing gases such as CO2. Consequently, the CMS film lost some of its size-sieving properties as indicated by a drop in mixed-gas CO2/CH4 permselectivity relative to the values obtained under pure-gas conditions.
CitationGenduso, G., Hazazi, K., Ali, Z., Ghanem, B. S., Alhazmi, A., & Pinnau, I. (2021). Carbon dioxide/methane mixed-gas adsorption, permeation and diffusion in a carbon molecular sieve film: Experimental observation and modeling. Journal of Membrane Science, 120114. doi:10.1016/j.memsci.2021.120114
SponsorsThis research was supported by funding (BAS/1/1323-01-01) from King Abdullah University of Science and Technology.
JournalJournal of Membrane Science