β沸石催化甲苯-丙烯烷基化反应

Alkylation of Toluene-Propylene over Zeolite

研究了不同硅铝比及磷、锡氧化物和水汽改性β沸石上甲苯与丙烯烷基化反应和产物IPT各异构体分布,发现具宽敞三维通道结构的β沸石的中强酸位是烷基化反应的活性中心,酸密度高的低硅铝比β沸石催化所得IPT混合液中邻位异构体少,引起烷基化反应降活的主要因素是甲苯的多烷基化物.通过水汽或氧化锡改性Hβ(26),在充分保留酸密度的同时,减弱酸强度和适度调低B/L酸位数比例,可以达到降低IPT混合液中o-IPT低于3.3%和抑制甲苯多烷化物,满足生产m-或p-甲酚所需原料IPT的质量要求.为将现在通用的甲苯-丙烯烷基化后接烷基化产物异构化的二步法生产工艺简化为一步法工艺提供了催化科学基础.

Zeolites β with different molar ratio of SiO2 to Al2O3 modified by phosphors oxide, Sn oxide or steaming were used to investigate alkylation of toluene-propylene and their products＇ IPT isomer distribution respectively. Mild strength acidic sites of zeolite β with wide 3D channel structure was found to be the active center of alkylation reaction and the key factor to influence isomerization of alkalized products. Less o-IPT was produced with high acid density, low SiO2/Al2O3 ratio zeolite β. Multi-alkylates of toluene was considered as one of the major factors of deactivation of alkylation. Concentration of o-IPT can be lowered to 3.3% with Hβ（26） modified by steaming and Sn oxide, which weakened acid strength and properly lowered B/L acid sites ratio, and maintained acid density simultaneously. In addition, by limiting multi-alkylates of toluene, quality requirement for production of IPT which is raw material of producing m- or p- cresol can be satisfied. General two-step production technics of alkylates isomerization after toluene-propylene alkylation can be simplified to one step process.