论文部分内容阅读
分子筛催化剂上的积碳是导致失活的主要原因.本文以甲苯-乙醇在固定床积分反应器中的乙基化反应作探针,研究ZSM-5分子筛上的积碳情况.结果表明,对于HZSM-5,反应时间t<4.5h时,积碳较快,催化剂活性(C_t)、乙基甲苯产率(Y_(ET))和对乙基甲苯选择性(S_(P-ET))均有较大幅度的变化;t>4.5h时,积碳减慢,催化剂性能的变化也较小.对MgHZSM-5,各种催化性能的变化则较小.进一步分析表明,HZSM-5分子筛的积碳主要在外表面(占95%),而MgHZSM-5的积碳主要在孔内.阐明了保持积碳C/H比较低的条件下,采取加入添加剂抑制积碳生成的办法,可望收到延长催化剂寿命的效果.对含有适量添加剂A和B的HZSM-5催化剂,进料200h后催化剂仍有较高活性和选择性.
Molecular sieve catalyst carbon deposition is the main reason leading to deactivation.In this paper, toluene-ethanol in fixed-bed integral reactor ethylation reaction probe for ZSM-5 zeolite carbon deposition on the results show that for HZSM-5, the reaction time t <4.5h, carbon deposition faster, catalyst activity (C_t), ethyl toluene yield (Y_ (ET)) and para-ethyl toluene selectivity (S_ And the change of catalyst performance is small.While MgHZSM-5, the change of various catalytic properties is small.Further analysis shows that the HZSM-5 molecular sieve Carbon deposition is mainly on the outer surface (95%), while the carbon deposition of MgHZSM-5 is mainly in the pores. It is shown that keeping the C / H ratio of coke under low conditions can be expected by adding additives to inhibit carbon deposition To prolong the life of catalyst.For HZSM-5 catalyst containing appropriate amount of additives A and B, the catalyst still has higher activity and selectivity after feeding for 200h.