Abstract:

A series of HMCM-22 molecular sieve catalysts modified by MgO were prepared by mechanical wet mixing method. The crystal structure, surface morphology, pore channel change and acid content of the modified catalysts were characterized by means of XRD, SEM, N₂ physical adsorption and desorption, Py-IR and so on. It was found that the addition of MgO could effectively adjust the acidity of HMCM-22 molecular sieve, but the regulation effect on the pore channel was weak. The catalyst performance was evaluated on a microreactor under the conditions of feed ratio of 1∶1, atmospheric pressure, temperature of 400℃, reaction time of 4h, and weight hourly space velocity (WHSV=10h^-1). The catalytic performance of MgO/HMCM-22 with different MgO loading was investigated. It was found that all of MgO/HMCM-22 catalysts with MgO loading from 3% to 6% had excellent catalytic performance, the conversion of benzene was more than 50%, and the toluene selectivity was more than 60%. At the same time, the stability of 3% MgO/HMCM-22 catalyst was also investigated under the same condition. The results showed that the conversion of benzene remained above 50% within 40h, and still up to 23% within 80h and the selectivity of toluene remained about 65%.

Key words: catalyst, benzene, methanol, alkylation, toluene

摘要：

采用机械湿混法制备了一系列MgO改性的HMCM-22分子筛催化剂，通过XRD、SEM、N₂物理吸/脱附、Py-IR等手段对改性催化剂的晶体结构、表面形貌、孔道变化和酸性酸量等性质进行了表征，发现负载MgO能够有效地调变HMCM-22分子筛的酸性，但对其孔道的调节效果较弱。采用微反装置评价催化剂性能，在进料比为1∶1、常压、温度为400℃、反应时间4h、质量空速WHSV=10h^-1的条件下，考察了不同MgO负载量下的MgO/HMCM-22催化性能，研究发现MgO负载量介于3%~6%的MgO/HMCM-22催化剂具有优越的催化性能，苯转化率＞50%，甲苯选择性＞60%。同时在该反应条件下，对3%MgO/HMCM-22催化剂的稳定性进行了考察，结果表明，反应40h内，苯的转化率始终保持在50%以上；反应至第80h时，苯的转化率仍然可达23%，且甲苯选择性始终保持在65%左右。

关键词: 催化剂, 苯, 甲醇, 烷基化, 甲苯