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用吡啶吸附 IR 测定了锌改性的 ZSM-5沸石上的 L_(1616)酸的强度分布。结果表明,L_(1616)酸是很强的 Lewis 酸,各种强度的 L_(1616)酸量随 ZnZSM-5上锌含量的增加而增加,经过一极值然后下降。采用吡啶、2,6-二甲基吡啶和2,4-二甲基喹啉脉冲中毒和脉冲微反活性测定相结合的方法,研究了三种不同方法制备的 ZnZSM-5的脉冲中毒曲线。结果表明,ZnZSM-5的活性中心主要分布在 ZSM-5沸石的通道内,在外表面分布的数量决定于锌改性的方法。制备方法也强烈影响ZnZSM-5沸石通道内的酸位分布。讨论了活性中心在 ZSM-5通道内的位置及制备方法对 ZnZSM-5芳构化稳定活性的可能影响.
The intensity distribution of L 1616 acid on zinc-modified ZSM-5 zeolite was determined by pyridine adsorption IR. The results showed that L1616 acid was a strong Lewis acid. The amount of L1616 acid increased with the increase of zinc content on ZnZSM-5, and then decreased after an extreme value. The pulse poisoning curves of ZnZSM-5 prepared by three different methods were studied by the combination of pyridine, 2,6-lutidine and 2,4-dimethylquinoline pulse poisoning and pulse microreactivity assay. The results show that the active center of ZnZSM-5 is mainly distributed in the channel of ZSM-5 zeolite, and the number of ZnZSM-5 distributed on the outer surface is determined by the method of zinc modification. The preparation method also strongly influenced the acid site distribution in the ZnZSM-5 zeolite channel. The location of the active site in the ZSM-5 channel and the possible influence of preparation methods on the stability of aZn-5-aromatization of ZnZSM-5 were discussed.