柠檬酸改性H-beta催化甲苯和叔丁醇烷基化

采用不同浓度的柠檬酸（HCA）对H-beta分子筛样品进行改性，通过XRD、SEM、TEM、FTIR、N₂物理吸脱附、NH₃-TPD及吡啶Py-IR等手段对改性分子筛进行了表征。实验结果表明，适宜浓度的柠檬酸改性不但没有破坏H-beta分子筛的骨架结构，而且在脱铝的同时兼具补铝功能。改性后的H-beta分子筛孔道更加畅通，虽然总酸量有所下降，但对烷基化有利的中强酸量和B酸含量却明显增加，催化活性增强。但柠檬酸浓度过高会脱除骨架铝，破坏晶格结构，导致催化活性降低。催化剂的甲苯叔丁基化活性评价表明，适宜的柠檬酸处理浓度为0.25mol/L。在0.25HCA/H-beta催化剂作用下，甲苯转化率为67.0%，对叔丁基甲苯的选择性高达80.4%。

Alkylation of toluene with tert-butyl alcohol catalyzed by citric acid modified H-beta zeolite

A series of citric acid (HCA) modified H-beta zeolites were prepared and characterized by XRD, SEM, TEM, FTIR, N₂ physical adsorption and desorption, NH₃-TPD, and Py-IR. The experimental results showed citric acid treatment did not damage the skeleton structure of H-beta, but had the function of both dealuminization and realuminization. The channel was more open due to removal of non-framework aluminum. Though the total acid decreased, the content of medium strong acid and Bronsted acid were increased, therefore the catalytic activity was enhanced. However, high concentration of citric acid removed the skeleton aluminum, damaging the lattice structure and reducing the catalytic activity. The performance assessment of catalysts in butylation of toluene showed that the suitable citric acid concentration for the modification was 0.25mol/L. The highest conversion of toluene could reach 67.0% and the selectivity of PTBT was 80.4% under 0.25HCA/H-beta.