ZSM-5分子筛结构对苯烷基化反应性能影响的数值模拟研究  

Effect of ZSM-5 zeolite structure on the reaction performance of benzene alkylation:a computational study

作　　者：黄静茹 陈佳轩 张群锋 阮晋 朱来 叶光华[1] 周兴贵[1] HUANG Jingru;CHEN Jiaxuan;ZHANG Qunfeng;RUAN Jin;ZHU Lai;YE Guanghua;ZHOU Xinggui(State Key Laboratory of Chemical Engineering,East China University of Science and Technology,Shanghai 200237,China)

机构地区：[1]华东理工大学化学工程联合国家重点实验室,上海200237

出　　处：《化工学报》2024年第7期2544-2555,共12页CIESC Journal

基　　金：国家自然科学基金项目(22078090);上海市自然科学基金项目(21ZR1418100)。

摘　　要：以ZSM-5分子筛催化苯和乙烯烷基化为体系,建立并验证了一种三维各向异性扩散-反应数学模型,该模型考虑了分子筛形貌、孔结构和扩散各向异性的影响。模拟发现当分子筛颗粒体积和abc轴尺寸保持不变时,改变分子筛形貌并不会显著影响其表观活性,因而该情况下无须调控分子筛形貌;而当分子筛颗粒体积不变时,仅缩短b轴尺寸才能显著降低扩散阻力,提高催化剂表观活性,因而合成ZSM-5分子筛时缩短b轴尺寸最有利于扩散和反应。在分子筛颗粒中引入大孔可显著提高分子筛催化剂利用率和表观活性,保持大孔孔隙率不变时,减小大孔孔径更有利。存在最优大孔孔隙率以平衡扩散阻力和活性材料含量,当分子筛粒径4μm、大孔孔径300 nm时,最优大孔孔隙率0.16,对应最高表观反应速率80.5 mol/(m^(3)·s)。另外,由于分子筛内扩散各向异性的影响,当大孔取向平行于c轴时最有利。结果可为苯和乙烯烷基化ZSM-5分子筛催化剂乃至其他分子筛催化剂的设计优化提供一定的理论指导。This paper uses ZSM-5 zeolite to catalyze the alkylation of benzene and ethylene as a system to establish and verify a three-dimensional anisotropic diffusion-reaction mathematical model.This model takes into account the influence of zeolite morphology,pore structure and diffusion anisotropy.The simulation results show that changing zeolite particle shape would not significantly affect the apparent activity when the zeolite particle volume and sizes in a-,b-,and c-axis keep unchanged,indicating modifying zeolite particle shape is unnecessary in this case.When the particle volume remains constant,only shortening the size in b-axis could importantly reduce diffusion resistance and then enhance apparent catalytic activity,indicating that decreasing the size in b-axis is most favorable for diffusion and reaction in the preparation of ZSM-5 zeolites.When the particle size is 4μm and the large pore diameter is 300 nm,the optimal large pore porosity that balances diffusion resistance and active material content is 0.16,corresponding to a maximum apparent reaction rate of 80.5 mol/(m^(3)·s).Besides,due to the influence of diffusion anisotropy,introducing the macropores being parallel to c-axis is most favorable.These results provide some theoretical guidance for the optimal design of ZSM-5 zeolite catalysts for benzene alkylation with ethylene and other zeolite catalysts.

关 键 词：苯烷基化 ZSM-5分子筛 扩散-反应模型 孔道 扩散各向异性 颗粒形貌 

分 类 号：TQ021.4[化学工程]