摘要
在HZSM-5分子筛催化乙醇脱水反应中观察到了停料效应:即当停止乙醇-水进料一定时间,恢复进料后乙烯选择性明显提高。通过考察不同反应条件下的停料效应,发现乙醇质量分数控制在55%附近、延长停料时间、升高反应温度和降低乙醇进料空速会提高停料效应强度,并较长时间维持高乙烯选择性。500 h的催化剂稳定性测试表明,停料效应可有效延长催化剂的使用寿命。结合含水乙醇脱水反应机理和实验结果,推测HZSM-5催化乙醇脱水停料效应产生的原因是停料时乙氧基中间体的积累和催化活性空位的再生。
The stop-effect phenomenon on the catalytic dehydration of ethanol over HZSM-5 zeolite was observed. That is,when stopping ethanol-water feed for a period of time and restoring the feed,a dramatic increase on ethylene selectivity could be found. At different reaction conditions,it was found that the stop-effect was enhanced by increasing the stop time and reaction temperature or decreasing the feed speed. When the ethanol concentration was kept at 55%,the stop-effect could be strengthened and the high ethylene selectivity was maintained at long time. 500 h catalyst stability test showed that the stop-effect can improve the life span of the catalyst effectively. By studying the aqueous ethanol dehydration mechanism and experimental results,the preliminary conclusion is that causes of the stop-effect on the catalytic dehydration of ethanol over HZSM-5 is the accumulation of ethoxy intermediate and regeneration of empty catalytic active sites in stop operation.
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
2013年第12期1495-1501,共7页
Journal of Fuel Chemistry and Technology
基金
江苏省自然科学基金(BK2009494)
中石化科技开发项目(L411003)
材料化学工程国家重点实验室自主研究课题重点资助项目(ZK200815)
