合成异丙苯催化剂的失活与再生

对苯和丙烯烷基化反应合成异丙苯的QZ-2000烷基化失活催化剂进行了失活原因及再生条件的研究。采用X射线荧光光谱法测定催化剂中元素组成时发现,催化剂失活的原因除积碳外,还有砷化物中毒。根据催化剂积碳和毒物的性质,采用有机酸洗的处理方式脱除砷化物、焙烧的方式烧除积碳,并比较了直接焙烧、先酸洗后焙烧和先焙烧后酸洗再焙烧3种不同再生方案的效果。实验结果表明,柠檬酸的脱砷效果强于甲酸和乙酸;砷化物的脱除率随酸洗处理温度的升高和时间的延长而提高;当处理温度高于80℃、处理时间超过2h后,砷化物的脱除率变化不大;失活催化剂先用质量分数为2%的柠檬酸在80℃下处理4h再焙烧除去积碳,其脱砷率可达到27.4%。氨气程序升温脱附和反应性能评价结果表明,经先酸洗后焙烧处理的失活催化剂的强酸量有明显恢复,并在烷基化反应中表现出很高的活性。

Deactivation and Regeneration of Catalyst Used in Synthesis of Cumene

Deactivation and regeneration of QZ-2000 catalyst for alkylation of benzene and propylene to synthesize cumene were studied. XRF results showed that both coking and arsenic poisoning originated from propylene lead to deactivation of the catalyst. The deactivated catalyst was regenerated by organic acid washing and calcining to remove the arsenic and coke correspondingly. Among acids for washing, namely formic, acetic and citric acid, the last one is most effective for removal of arsenic. The arsenic removal ratio increases with raising of washing temperature not more than 80 ℃ and prolonging of washing time not more than 2 h. By immerging the deactivated catalyst into 2% citric acid at 80 ℃ for 4 h, 27.4% arsenic can be removed. NH3-TPD curves show that strong acid sites on the catalyst can be recovered during acid washing and successive calcinating. The regenerated catalyst exhibited high catalytic activity in the alkylation.