| 초록 |
Here, 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 whose access to the inner part of the crystal can only occur through the 10-ring pores, was found to show a significantly higher xylenes yield and catalyst stability than the cage-based, large-pore zeolite H-Y, the current commercial transalkylation catalyst. GC-MS analyses of the 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 has been proposed and discussed based on both experimental and theoretical results obtained. |
