Abstract:

Two organosilica presursors, 1,4-bis (triethoxysilyl) benzene (BTESB) with benzene bridges and 4,4'-bis (triethoxysilyl) biphenyl (BTESBPh) with biphenyl bridges were utilized for the fabrication of organosilica membranes via the sol-gel strategy. The two membranes were applied to the gas separation. At 25℃, BTESB membrane displayed a C₃H₆ permeance of 3.4×10^-9mol/(m²·s·Pa)and C₃H₆/C₃H₈ selectivity of 9.6. Nevertheless, BTESBPh membrane showed a C₃H₆ permeance of 1.7×10^-8mol/(m²·s·Pa) and a comparable C₃H₆/C₃H₈ selectivity of 10.5. BTESBPh membrane networks with biphenyl bridged structures were much looser and could achieve higher gas permeance. The π-π interactions occurred between the big π bond in the benzene ring and the C\stackrel{}{̿}C bond in the C₃H₆ molecules, which was beneficial for the preferential adsorption and permeation of the C₃H₆ molecules. The biphenyl bridges in BTESBPh membranes enhanced the adsorption and permeation process, as evidenced by the increased C₃H₆/C₃H₈ selectivity of the BTESBPh membrane under low testing temperatures. This study could provide a reference for the development of high-performance propylene/propane separation membranes.

Key words: organosilica membranes, pore size, C₃H₆/C₃H₈ separation, sol-gel method, molecular sieving

摘要：

利用具有单苯和联苯桥联结构的有机硅前体1,4-二(三乙氧基硅基)苯（BTESB）和4,4'-二(三乙氧基硅基)联苯（BTESBPh），通过溶胶-凝胶法制备成有机硅膜并应用于丙烯/丙烷分离。在25℃时，BTESB膜的C₃H₆渗透速率为3.4×10^-9mol/(m²·s·Pa)，C₃H₆/C₃H₈选择性为9.6；BTESBPh膜的C₃H₆渗透速率为1.7×10^-8mol/(m²·s·Pa)，C₃H₆/C₃H₈选择性为10.5。具有联苯桥联结构的BTESBPh膜网络结构更为疏松，可获得更高的气体渗透速率。苯环中大π键与待分离组分C₃H₆中的碳碳双键产生π-π相互作用，有利于C₃H₆组分的优先吸附和渗透。而BTESBPh中联苯结构增强了这一过程，表现为低温测试条件下，BTESBPh膜的C₃H₆/C₃H₈选择性略高于BTESB膜。本研究可为高性能丙烯/丙烷气体分离膜的开发提供参考。

关键词: 有机硅膜, 孔径, 丙烯/丙烷分离, 溶胶-凝胶法, 分子筛分