摘要
为观察C4烯烃转化制丙烯过程中影响催化剂稳定性的因素,对经历不同反应时间(即新鲜、反应48h、反应650h、反应650h后再生和再生后再进行反应48h)的系列ZSM-5分子筛催化剂进行了表征。结果表明,经历长期反应后,催化剂微孔体积和B JH吸附累积孔体积明显降低;再生后,孔体积可以恢复到新鲜催化剂的初始值。与此同时,NH3-TPD酸量不仅降低,而且再生后也不能得到恢复。与高温水蒸气处理的催化剂相比较,27A lMAS NMR表征结果说明,积炭因素对催化剂孔体积的影响可通过再生消除,而分子筛骨架铝丢失和分子筛晶胞参数的降低对催化剂酸量的持续减少起主要作用。长期在高温水蒸气条件下运行后,催化剂酸量可维持在一定水平,使催化剂长期稳定运行成为可能。
A series of ZSM-5-based catalysts with different reaction durations,i.e.fresh,used for 48h,used for 650h,used for 650h and then regenerated,as well as the regenerated one reused for another 48h,were characterized to investigate the factors that influence the stability of ZSM-5-based catalyst for the conversion of C4 olefin to propylene.The results indicted that both of the micropore volume and the BJH adsorption cumulative volume of pores are dropped after long term reaction;after regeneration,they are nearly recovered to the original values of the fresh catalyst.Meanwhile,the acid amount determined by NH3-TPD is also decreased,but it cannot be recovered after regeneration.Comparing with the results of the catalyst pretreated by steam at the same temperature,the 27Al MAS NMR results suggested that the effect of coke deposition on the pore volume can be completely eliminated through regeneration,however,the dealuminum of zeolite and the decrease of cell parameters may lead to the permanent loss of the catalyst activity.After a long duration under high temperature and water steam,the acid amount of the ZSM-5-based catalyst can be maintained at a relatively stable level,which then makes a long term stable reaction operation possible.
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
2011年第7期533-537,共5页
Journal of Fuel Chemistry and Technology
基金
中国石油化工股份有限公司项目(405106)
关键词
ZSM-5分子筛
积炭
脱铝
晶胞参数
稳定性
ZSM-5-based catalyst
coke deposit
dealuminum
cell parameter
stability
