镁改性ZSM-5分子筛的制备及其催化苯与甲醇烷基化反应性能

制备了不同镁负载量的镁改性多级孔ZSM-5催化剂，采用X射线衍射、N₂吸附-脱附、NH₃程序升温脱附等分析手段对镁改性ZSM-5催化剂进行表征，考察了反应温度、质量空速、原料配比、镁负载量对镁改性ZSM-5催化剂催化苯与甲醇烷基化反应性能的影响，并对催化剂稳定性进行评价。结果表明：镁改性ZSM-5催化剂催化苯与甲醇烷基化反应最佳的工艺条件为：反应温度470 ℃，质量空速2.0 h^-1，苯与甲醇摩尔比1∶1；在最佳工艺条件下，镁负载量（w）为3%的改性ZSM-5催化剂可连续运行1 300 h，苯平均转化率大于54%，甲苯和二甲苯的平均选择性大于90%，乙苯平均选择性低于1.5%；催化剂再生后的反应活性和稳定性与新鲜催化剂相当；催化剂经过了工业试验验证，具备工业应用前景。

PREPARATION OF MAGNESIUM MODIFIED ZSM-5 CATALYST AND ITS CATALYTIC PERFORMANCE FOR ALKYLATION OF BENZENE WITH METHANOL

The magnesium-modified hierarchical porous ZSM-5 catalysts with different magnesium loadings were prepared and characterized by XRD, N₂ adsorption-desorption and NH₃-TPD. The effects of reaction temperature, mass space velocity, raw material ratio and magnesium loading on the performance of magnesium-modified ZSM-5 catalyst for the alkylation of benzene with methanol were investigated. The results showed that the optimal process conditions for the alkylation of benzene with methanol over Mg-modified ZSM-5 catalyst covered a reaction temperature of 470℃, a mass space velocity of 2.0 h^-1,and a molar ratio of benzene to methanol of 1∶1. The modified ZSM-5 catalyst with 3% magnesium loading (w) could run continuously for 1300h with the average conversion of benzene over 54%, the average selectivity of toluene and xylene over 90%, and the average selectivity of ethylbenzene below 1.5%. The activity and stability of the regenerated catalyst was similar to that of the fresh catalyst. The catalyst had been tested and verified by industrial experiments, and showed the prospect of industrial application.