ZSM-5催化剂在乙醇脱水反应中的失活与再生

Deactivation and Regeneration of ZSM-5 Zeolite Catalysts for Ethanol Dehydration

在固定床反应器中进行了ZSM-5分子筛催化乙醇脱水生成乙烯反应的积碳失活实验,采用X射线衍射、热重、傅里叶变换红外光谱、低温氮吸附和核磁共振等方法对催化剂进行了表征。结果表明,在乙醇脱水反应中,催化剂表面的积碳导致分子筛微孔堵塞是造成催化剂失活的主要原因,积碳物种主要是带有双键的聚合态化合物(或芳香族化合物)。再生后的催化剂仍具有良好的活性和稳定性,在1000h的反应过程中,乙醇转化率始终在99.5%以上,乙烯收率也保持在98%以上。同时再生过程未改变分子筛中铝的状态。

Deactivation and regeneration experiments for ZSM-5 zeolite during ethanol dehydration to ethylene were carried out in a fixed-bed reactor. The catalyst was characterized by XRD, N2 adsorption techniques, TG-DTG, FTIR and NMR. The results show that deactivation of ZSM-5 is due to the coke forming on the catalyst surface which block the pore mouth of zeolite channels for ethanol dehydration. The coke consisted mainly of polymer with double bond （ or aromatic）. Regeneration of ZSM-5 catalyst was studied at appropriate temperature. Regenerated catalyst had high activity and stability for ethanol dehydration, conversion of ethanol is over 99.5% and yield to ethylene is over 98% in 1 000 h. But regeneration can not change the state of aluminum in zeolite.