We report the catalytic properties of a series of large-pore (H-Y, H-beta, H-mordenite, and H-UZM-35) and medium-pore (H-NU-87, H-TNU-9, and H-ZSM-5) zeolites with different framework structures for the transalkylation of 1,2,4-trimethylbenzene (1,2,4-TMB) with toluene. H-NU-87 with intersecting 10- and 12-ring channels, but in which access to the inner part of the crystal can only occur through the 10-ring pores, was found to show a significantly higher xylene yield (40% vs. 23% at 673 K and 10 h on stream) and catalyst stability (31% vs. 17% 1,2,4-TMB conversion after 30 h on stream at 673 K) than the cage-based large-pore zeolite H-Y, the current commercial transalkylation catalyst. GC–MS analyses of organic species occluded in used zeolite catalysts reveal that the type of diphenylmethane derivatives serving as key reaction intermediates of 1,2,4-TMB-toluene transalkylation is strongly influenced by the pore architecture of the zeolite catalyst. A bimolecular diphenylmethane-mediated reaction mechanism for this transalkylation is proposed and discussed based on both experimental and theoretical results.

我们报告了一系列大孔（HY，H-β，H-丝光沸石和H-UZM-35）和中孔（H-NU-87，H-TNU-9和H-具有不同骨架结构的ZSM-5）沸石，用于1,2,4-三甲基苯（1,2,4-TMB）与甲苯的烷基转移。发现具有相交的10环和12环通道的H-NU-87，但只能通过10环孔进入晶体内部，显示出明显更高的二甲苯收率（40％vs. 10％）。与笼式大孔沸石HY相比，在673 K下30 h运转时23％的催化剂）和催化剂稳定性（在673 K下30 h运转后的1,2,4-TMB转化率分别为31％和17％）。目前的市售烷基转移催化剂。对使用过的沸石催化剂中所含有机物的GC-MS分析表明，用作1的关键反应中间体的二苯甲烷衍生物的类型 2,4-TMB-甲苯烷基转移反应受到沸石催化剂的孔结构的强烈影响。基于实验和理论结果，提出并讨论了双分子二苯甲烷介导的这种烷基转移反应的机理。