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ZSM-5沸石经Sb_2O_3、CaO等改性后,在甲苯烷基化过程中的对位选择性大为提高.Chen等认为,在改性过程中沸石的孔径变小,阻止分子较大的邻、间位异构体进出孔道,从而提高了对位选择性.我们发现,改性过程对沸石孔径的影响不大.Yashima等则提出,在较低温度下,沸石的内表面不能被有效地利用.因而究竟是什么因素,使沸石改性后的对位选择性得到很大提高,需要对这一问题作进一步的讨论.
ZSM-5 zeolite modified by Sb 2 O 3, CaO and so on, in toluene alkylation process para-selectivity greatly improved.Chen so that the zeolites in the modification process becomes smaller, to prevent the larger molecular neighbors , Meta isomers into and out of the pore, thereby increasing the para-selectivity.We found that the modification process has little effect on the pore size of zeolite Yashima et al proposed that at lower temperatures, the zeolite’s inner surface can not be effectively Therefore, what are the factors that make the para-position selectivity of the zeolite greatly improved, and further discussion on this issue is needed.