分子筛在异丁烷/丁烯烷基化中的应用研究进展

Advances in isobutene/butene alkylation used zeolite

阐述了分子筛在异丁烷/丁烯烷基化中的应用研究,包括分子筛酸性、孔道结构与烷基化反应的关系,负载金属对催化剂烷基化反应性能和再生性能的影响。文章总结了前人的研究成果,归纳得出以下结论:中强B酸是烷基化反应中心,它在总酸中的比例越高,越有利于提高烷基化反应选择性,增强催化剂稳定性。具有较大微孔的十二元环分子筛有很好的烷基化选择性,而介孔分子筛没有显示出更高的烷基化性能。另外,规整的孔道结构有利于提高催化剂稳定性,大超笼结构中易结焦。碱金属/碱土金属的电负性可调变催化剂酸性。稀土金属可提高分子筛B酸中心浓度,提高催化剂烷基化性能。负载贵金属可使催化剂在临氢条件下恢复活性。虽然分子筛催化剂具有较好的烷基化性能,但其寿命普遍很短,改进的空间还很大。

Advances in isobutene/butene alkylation used zeolite were reviewed,contained the links between acidity or structure of zeolite and alkylation reaction and also the modification with rare earth,alkali metal,alkaline earth metal and noble metal to zeolite alkylation catalysts.The conclusions can be made:Alkylation reaction occurs at moderate brnsted acid site.The more the ratio of moderate brnsted acid in total acid,the higher the alkylate selectivity was,the higher the stability the catalysts showed.The zeolites those have bigger micopore with 12 membered ring had higher alkylate selectivity.The mesoporous zeolites were not better than microporous zeolites in alkylation.In addition,the regular pores were in favor of enhancing the stability of catalysts in alkylation and carbon deposits easily formed in supercage.Alkali metal or alkaline can adjust the acidity of zeolite.Rare earth can increase the concentration of brnsted acid site which promotes the performances of catalysts in alkylation.The activities of the zeolites supported precious metal can be recovered in H2.Although the zeolite catalysts showed better performances in alkylation,their lifetime were very short.They leave much to be desired.