芳烃官能化有机硅膜的制备及丙烯/丙烷分离性能

Fabrication of aromatic functionalized organosilica membranes and gas separation performance

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C_(3)H_(6)渗透速率为3.4×10^(-9)mol/(m^(2)·s·Pa),C_(3)H_(6)/C_(3)H_(8)选择性为9.6;BTESBPh膜的C_(3)H_(6)渗透速率为1.7×10^(-8)mol/(m^(2)·s·Pa),C_(3)H_(6)/C_(3)H_(8)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C_(3)H_(6)中的碳碳双键产生π-π相互作用,有利于C_(3)H_(6)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C_(3)H_(6)/C_(3)H_(8)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。

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 C_(3)H_(6)permeance of 3.4×10^(-9)mol/(m^(2)·s·Pa)and C_(3)H_(6)/C_(3)H_(8)selectivity of 9.6.Nevertheless,BTESBPh membrane showed a C_(3)H_(6)permeance of 1.7×10^(-8)mol/(m^(2)·s·Pa)and a comparable C_(3)H_(6)/C_(3)H_(8)selectivity of 10.5.BTESBPh membrane networks with biphenyl bridged structures were much looser and could achieve higher gas permeance.Theπ-πinteractions occurred between the bigπbond in the benzene ring and the C==C bond in the C_(3)H_(6)molecules,which was beneficial for the preferential adsorption and permeation of the C_(3)H_(6)molecules.The biphenyl bridges in BTESBPh membranes enhanced the adsorption and permeation process,as evidenced by the increased C_(3)H_(6)/C_(3)H_(8)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.