苯与1,2,4-三甲苯在纳米HZSM-5上的烷基转移反应

TRANSALKYLATION OF BENZENE AND 1,2,4-TRIMETHYLBENZENE OVER NANOSIZED HZSM-5

研究了硅酸乙酯或吡啶改性对纳米HZSM-5分子筛催化剂上苯与1,2,4-三甲苯反应体系中各反应的影响。结果表明:在苯与1,2,4-三甲苯反应体系中,1,2,4-三甲苯的脱烷基反应、烷基转移反应及异构化反应等一次反应主要在纳米HZSM-5外表面及孔口酸位上进行;苯与二甲苯之间的烷基转移反应、二甲苯的脱烷基反应等二次反应主要在纳米HZSM-5内表面酸位上进行;各反应均由B酸催化。

In the present study, nanosized HZSM-5 was treated by tetraethoxysilane and pyridine respectively to study the effect on the reactions in benzene and 1,2,4-trimethylbenzene （1,2,4-TMB） system. It was found that the primary reactions, such as transalkylation of benzene and 1,2,4-TMB, dealkylation of 1,2,4-TMB and isomerization of 1,2,4-TMB occurred at the acid sites of the external surface and pore opening near by. Secondary reactions, such as dealkylation of xylenes, transalkylation of benzene and xylenes occurred at acid sites of the internal surface. These reactions were catalyzed by Bronsted acid sites.