B-oriented MFI zeolite membranes for xylene isomer separation - Effect of xylene activity on separation performance
B-oriented MFI zeolite membranes for xylene isomer separation - Effect of xylene activity on separation performance
复制标题
用于二甲苯异构体分离的 B 取向 MFI 沸石膜 - 二甲苯活性对分离性能的影响
DOI：
10.1016/j.memsci.2022.120492
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发表时间：
2022
影响因子：
9.5
通讯作者：
Jerry Y.S. Lin
中科院分区：
文献类型：
--
作者：
Fateme Banihashemi;Jerry Y.S. Lin
MFI沸石膜，特别是b取向沸石膜，在低蒸汽压条件下对二甲苯异构体的分离表现出优异的蒸汽渗透/分离性能。在工业应用中，这些膜应在蒸汽分离模式下的高二甲苯蒸汽压力下操作，或在渗透蒸发模式下与液体进料一起操作。本文报道了二甲苯活性对b取向MFI沸石膜对二甲苯汽液渗透/分离性能的影响。采用有机模板法在改性二氧化硅衬底上合成了高质量的b取向MFI沸石膜。对于二元p/邻二甲苯进料的蒸汽渗透，对二甲苯和邻二甲苯的渗透系数和对邻二甲苯的分离系数均增大，在150℃时分离系数达到最大值515，随后由于扩散系数和吸附的温度依赖性的共同作用而随温度的升高而减小。随着二甲苯活性（或蒸气压）的增加，二甲苯的蒸气透过率和分离系数均单调降低。在渗透蒸发模式下，对/邻二甲苯的分离系数最低，约为2。与用有机模板合成的随机取向MFI沸石膜相比，b取向MFI沸石膜具有更好的蒸汽渗透/分离性能，二甲苯活性对分离因子的负面影响较小。然而，当在渗透蒸发模式下操作时，b取向和随机取向的MFI沸石膜都表现出类似的差分离因子。
MFI zeolite membranes, especially b-oriented ones, show superb vapor permeation/separation performance for xylene isomer separation at low vapor pressures. In industrial applications these membranes should be operated at high xylene vapor pressures in the vapor separation mode or with liquid feed in the pervaporation mode. This paper reports the influence of xylene activity on xylene vapor and liquid permeation/separation performance of b-oriented MFI zeolite membranes. High quality b-oriented MFI zeolite membranes were synthesized with an organic template on modified silica substrates. For vapor permeation with binary p/o-xylene feed, both permeance (for p-xylene and o-xylene) and p-/o-xylene separation factor increase, with separation factor reaching maximum of 515 at 150oC, then decreases with increasing temperature due to combined effects of temperature dependence of diffusivity and adsorption. The vapor permeance for both xylenes and separation factor decrease monotonically with increasing xylene activity (or vapor pressure). Lowest separation factor is observed when operated in the pervaporation mode giving p-/o-xylene separation factor of about 2. Compared to randomly oriented MFI zeolite membranes synthesized with an organic template, the b-oriented MFI zeolite membranes show better vapor permeation/separation performance and less negative effect of xylene activity on separation factor. However, both b- and randomly oriented MFI zeolite membranes exhibit a similarly poor separation factor when operated in the pervaporation mode.