中文摘要：

通过N2吸附、X射线衍射（XRD）、X射线光电子能谱（XPS）、H2程序升温还原（H2-TPR）、CO2程序升温脱附（CO2-TPD）和热重分析（TGA）等多种表征手段和催化反应性能评价，研究了铈助剂的添加对V/SiO2催化CO2氧化乙苯脱氢性能的影响. 结果表明，Ce助剂不仅提高了催化剂活性组分分散性和氧化还原性能，抑制了钒物种的深度还原，而且增强了催化剂碱性和CO2吸附能力，减缓了积炭生成，从而显著提高了V-Ce/SiO2对CO2氧化乙苯脱氢反应的催化活性和稳定性. 在本实验中，V（0.8）-Ce（0.25）/SiO2催化剂表现出最佳的催化性能，苯乙烯（ST）收率可达55.6%，选择性为98.5%，反应12 h 后，催化剂活性基本不变，与惰性N2气氛比较，CO2明显促进了乙苯脱氢反应，归因于CO2能保持催化剂表面钒物种的高价态.

英文摘要：

The effect of a Ce promoter on the catalytic properties of V/SiO2 was investigated for the oxidative dehydrogenation of ethylbenzene （EB） to styrene （ST） with CO2 （CO2-ODEB）. The catalysts were characterized by nitrogen adsorption, X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, H2 temperature-programmed reduction （H2-TPR）, CO2 temperature-programmed desorption （CO2-TPD）, and thermogravimetric analyses （TGA）. It was found that incorporation of Ce into V/SiO2 increased the dispersion of active V species, enhanced the redox properties of the system, and inhibited deep V reduction of V^5＋ to V^3＋. The Ce promoter also improves the basicity of V/SiO2 and CO2 adsorption on the catalyst, and suppresses coke formation. The addition of a Ce promoter greatly improves the catalytic activity and stability of V/SiO2 towards CO2-ODEB. The ST yield and selectivity reach 55.6% and 98.5%, respectively, for CO2-ODEB over the most efficient catalyst, V（0.8）Ce（0.25）/SiO2, at 550 ℃, and a COJEB molar ratio of 20. Moreover, after reaction for 12 h, the V（0.8）Ce（0.25）/SiO2 still shows stable catalytic activity. The ST yield in CO2 is higher than that in an inert N2 atmosphere, showing the significant promoting effect of CO2 on EB dehydrogenation; this is because CO2 is a soft oxidant and can effectively keep/regain the high valence of V for high activity with CO2-ODEB.