Abstract: Preparation of ethylene from ethanol dehydration catalyzed by HZSM-5 molecular sieve modified with Zn and Mn was studied. The effects of modified solution, Si/Al ratio of HZSM-5, and modified conditions, such as concentration of modified solution, modification reaction time and temperature, and calcination temperature, were investigated. The results showed that when the Si/Al ratio of ZSM-5 was 25, modification temperature was 40℃, the concentrations of Zn(NO3)2 and MnCl2 were 2% and 6% respectively, the modification time was 1 h, and the calcination temperature was 550℃, the catalytic activity of modified HZSM-5 was higher. The HZSM-5 and modified ZSM-5 were characterized by XRD, BET, SEM and FT-IR techniques. The result indicated that Zn2+ and Mn2+ were located in the zeolite frame, and the crystalline structure of the modified zeolites was not changed, in addition B acid sites were decreased slightly and L acid sites increased greatly, which were favorable to catalytic dehydration of ethanol to ethylene.

Key words: HZSM-5, modification, ethanol, dehydration, ethylene

摘要： 对浸渍法锌锰复合改性HZSM-5分子筛用于催化低浓度乙醇脱水制备乙烯进行了研究. 探讨了改性溶液类型、HZSM-5原粉硅/铝比和改性条件(改性溶液浓度、浸渍时间、浸渍温度、焙烧温度)对Zn/Mn/ZSM-5催化乙醇脱水效果的影响，通过XRD、孔体积与比表面积、微观形貌分析等方法对改性前后的HZSM-5进行了表征. 结果表明，当HZSM-5原粉硅/铝比为25，改性温度为40℃, Zn(NO3)2和MnCl2浓度分别为2%和6%条件下改性1 h，再于550℃焙烧获得的分子筛催化效果最好，乙醇转化率和乙烯选择性分别达到99%和92%以上. 表征结果表明，Zn2+和Mn2+进入了分子筛骨架中，分子筛能很好地保持原有的结构，并且B酸中心量减少，L酸中心量增多，这有利于乙醇催化脱水制乙烯.

关键词: HZSM-5, 改性, 乙醇, 脱水, 乙烯