高性能甲苯烷基化合成二甲苯催化剂研究

通过对比不同孔结构分子筛的甲苯甲醇烷基化催化性能，发现分子筛孔道尺寸与目标芳烃分子动力学尺寸的有效匹配以及孔道空间限制效应对反应路径的约束管理，对实现高性能烷基化至关重要。并结合XRD、BET、NH₃-TPD和SEM表征分析，通过先后负载La₂O₃和P₂O₅对硅铝比为60的ZSM-5进行复合改性修饰，提升其骨架水热稳定性的同时，选择性地消除内外表面大部分强酸中心，保留弱+中强酸作为烷基化催化活性位，所得MAT-HZSM-5催化该反应表现出很高的甲醇烷基化效率和良好的反应稳定性，在氮气反应气氛下，连续运行500 h无明显失活迹象，甲苯转化率维持在35%-38%，二甲苯选择性60%-77%，甲醇烷基化效率大于90%。

Study on the high performance catalyst for toluene alkylation to xylene

By comparing the catalytic performance of toluene methanol alkylation over zeolites with different pore structure, it was found that the effective matching of the zeolite pore size with the molecular dynamics size of the target aromatic compounds and the constrained management of the reaction path by pore confinement effect are essential for achieving high performance of alkylation. Combined with XRD, BET, NH₃-TPD and SEM characterization, it has been confirmed that ZSM-5 with Si/Al ratio of 60 modified by successively loading La₂O₃ and P₂O₅ had better hydrothermal stability of the frameworks and most of the strong acidic sites on its internal and external surface were selectively eliminated while the weak and medium strong acidic sites were remained as the active sites of alkylation. The obtained MAT-HZSM-5 exhibited high methanol alkylation efficiency and good stability under nitrogen reaction atmosphere. There was no obvious deactivation during 500 h reaction. The conversion of toluene was maintained at 35%-38%, the selectivity of xylene was 60%-77%, and the methanol alkylation efficiency was higher than 90%.