Abstract:

MFI zeolite membranes were prepared on four-channel α-Al₂O₃ hollow fiber supports (7 cm) with high mechanical strength and high loading density by secondary growth method. The effects of synthetic time, operation temperature, partial pressure of raw material and purge gas flow rate on the membrane separation performance of xylene isomer were investigated. The results showed that the four-channel hollow fiber MFI zeolite membrane prepared by hydrothermal synthesis at 160℃ for 12 h possessed the better separation performance of xylene isomers. The separation factor of p-xylene/o-xylene was up to 878 at 150℃, partial pressure of raw material 2 kPa and purge gas flow rate 20 ml/min. PX permeance was 2.1×10^-8 mol·m^-2·s^-1·Pa^-1. Based on the optimized membrane preparation conditions, the MFI zeolite membranes were further prepared on the 27 cm long four-channel hollow fiber supports. An excellent p-xylene/o-xylene membrane separation performance was obtained, and the as-prepared membrane can run stably for more than 100 h for the separation of xylene isomer mixture. This study laid the foundation for promoting the batch preparation of hollow fiber MFI zeolite membranes and the technical innovation of traditional separation process.

Key words: MFI zeolite membranes, four-channel hollow fiber, xylene isomer, separation, scale-up

摘要：

采用二次生长法在高机械强度、高装填密度的四通道α-Al₂O₃中空纤维载体（7 cm）上制备MFI分子筛膜，探究了膜合成时间、操作温度、原料分压和吹扫气流量等条件对二甲苯异构体膜分离性能的影响。结果表明，160℃水热合成12 h制得的四通道中空纤维MFI分子筛膜对二甲苯异构体分离性能较优，在150℃、原料分压2 kPa、吹扫气流量20 ml/min时对二甲苯/邻二甲苯分离因子高达878，PX渗透性为2.1×10^-8 mol·m^-2·s^-1·Pa^-1。基于优化的制膜及分离操作条件，进一步将MFI分子筛膜制备于27 cm长的四通道中空纤维载体上，也获得了优异的对二甲苯/邻二甲苯膜分离性能，且所制得的膜材料对该体系的分离可稳定运行100 h以上。为推进中空纤维MFI分子筛膜的批量化制备和传统分离工艺的技术革新奠定了基础。

关键词: MFI分子筛膜, 四通道中空纤维, 二甲苯异构体, 分离, 放大