中文摘要：

石油资源的日趋短缺使天然气和页岩气的开发利用受到重视,因而低碳烷烃脱氢制取低碳烯烃也随之引起了人们越来越多的关注.由于乙烷纯脱氢反应的平衡收率低,能耗高,而氧气氧化脱氢又易将乙烷深度氧化为CO2或CO,因此开发具有反应条件温和、装置投资和操作费用低等优势的CO2气氛下乙烷脱氢的技术路线日益得到重视.CrOx是该反应理想的催化剂之一,CO2的加入可使CrOx对乙烷脱氢的催化活性提升3倍,然而受困于CrOx过小的比表面积,通常将CrOx制备成负载型催化剂使用.CrOx的常见载体有Al2O3,ZrO2和SiO2等氧化物及MCM-41,SBA-15,SBA-1和MSU-x等介孔硅材料,ZSM-5作为载体负载CrOx用于低碳烷烃脱氢的研究则较少,所得结果也不甚理想.我们采用亚微米尺寸的ZSM-5作为载体制备了负载型CrOx催化剂,研究了其在CO2气氛下催化乙烷脱氢反应,发现该催化剂具有非常优异的脱氢活性,高硅铝比和Na型的ZSM-5作载体对反应更加有利,而且在反应进行50 h后,催化剂依然保持很好的活性和很高的乙烯收率,这是在一般负载型CrOx催化剂上所不能实现的.X射线光电子能谱（XPS）表征发现,Na型ZSM-5载体制得的催化剂具有更高的Cr^6＋/Cr^3＋比.一般认为,Cr^6＋是Cr系催化剂进行低碳烷烃脱氢反应时的活性位（或活性位前驱体）,因此可以初步判定,Na型载体具有很好催化效果的原因可能是由它制得的催化剂具有更多的反应活性位.程序升温还原（H2-TPR）表征结果证实了这一点,Na型载体明显具有更高的H2消耗量;也就是说,Na型载体制得的催化剂具有更多的可还原Cr物种,即脱氢活性位.进一步表征发现,反应活性还与Cr物种存在形式有关.文献报道,低聚态的Cr物种和孤立态的Cr物种比Cr2O3有更好的催化活性.通过漫反射紫外-可见光谱（UV-Vis）对Cr物种的存在形态进行表征后发现,Na型载体上Cr主要以四配位形式?

英文摘要：

A series of submicron ZSM-5-supported chromium oxide catalysts were prepared and characterized by XRD, N2 adsorption, 27Al MAS NMR, SEM, XPS, laser Raman spectroscopy and diffuse reflectance UV-Vis spectroscopy. The catalytic performance of these materials during ethane dehydrogenation in the presence of CO2 was investigated. The catalysts exhibited both high activity and stability, with an ethane conversion of-65%and ethylene yield of-49%without any obvious deactivation following 50 h. Characterization results show that the excellent catalytic performance results from the high degree of dispersion of CrOx species on the submicron ZSM-5 surface. Both a high Si/Al ratio and the use of the Na-form of the ZSM-5 support were found to favor CrOx dispersion. The promo-tional effect of CO2 on the dehydrogenation reaction was quite evident and can be attributed to the reverse water-gas shift reaction.