Abstract
Silicoaluminophosphate (SAPO) membranes with Si/Al gel ratios from 0.05 to 0.3 were synthesized by in situ crystallization onto porous, tubular stainless steel support. Pure SAPO-34 membranes were obtained when the Si/Al ratio was 0.15 or higher. The adsorbate polarizability correlated with the adsorption capacity on SAPO-34, and the amounts of gases adsorbed were in the order: CO 2 > CH 4 > N 2 > H 2. The Si/Al ratio did not affect the pore volume significantly, but it changed the CO 2 and CH 4 adsorption equilibrium constants. The SAPO-34 membranes effectively separated CO 2 from CH 4 for feed pressures up to 7 MPa. At 295 K, for a pressure drop of 138 kPa and a 50/50 feed, the CO 2/CH 4 selectivity was 170 for a membrane with a Si/Al gel ratio of 0.15. At 7 MPa, the CO 2/CH 4 selectivity was 100 and the CO 2 permeance was 4 × 10 −8 mol/(m 2 · s · Pa) at 295 K. This membrane was also separated CO 2/N 2 (selectivity = 21) and H 2/CH 4 (selectivity = 32) mixtures at 295 K and a pressure drop of 138 kPa. Competitive adsorption and difference in diffusivities are responsible for CO 2/CH 4 and CO 2/N 2 separations, whereas the H 2/CH 4 separation was due to diffusivity differences. For a membrane with Si/Al gel ratio of 0.1, a mixture of SAPO-34 and SAPO-5 formed, and the CO 2/CH 4 selectivity was lower.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
