HZSM5-filled cellulose acetate membranes for pervaporation separation of methanol/MTBE mixtures

摘要

HZSM5-filled cellulose acetate (CA) membranes were prepared by incorporating HZSM5 into CA for pervaporation separation of methanol/methyl tertiary butyl ether (MTBE) mixtures. The structural morphology, thermal and mechanical stability, and crystallinity characteristics of these filled membranes were investigated. The effects of HZSM5 content on the sorption, diffusion and pervaporation performance were evaluated. The swelling degree of the HZSM5-filled CA membranes decreased compared with that of CA control membrane. With the increase of HZSM5 content, the permeation flux increased continuously, but the separation factor first increased and then decreased. The CA membrane containing 0.2 wt% HZSM5 showed the highest separation factor of 346 with a permeation flux of 226 g/(m~2 h) for 20 wt% methanol in feed at 303 K. The diffusion coefficients of methanol and MTBE for the HZSM5-filled CA membranes were also estimated. The results showed that the membranes were highly methanol selective. Effects of operating conditions on the pervaporation performance have been systematically assessed. It was found that the permeation flux increased while the separation factor decreased with increasing the amount of methanol in the feed. When increasing temperature from 298 K to 323 K, the permeation flux increased significantly while separation factor decreased only slightly. With the increase of feed flow rate, permeation flux first increased and then decreased while separation factor first decreased and then increased.