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以γ-Al2O3为载体,采用浸渍法制备了以V和K为主活性组分、碱土元素为助剂的催化剂M-3%V-6%K/γ-Al2O3(M=Mg、Ca、Sr、Ba),考察了该催化剂在环己烷氧化脱氢制环己烯反应中的催化活性,并采用X射线衍射(XRD)、N2吸附(BET)、氢-程序升温还原(H2-TPR)、氨-程序升温脱附(NH3-TPD)和X射线光电子能谱(XPS)方法对催化剂进行了理化表征.H2-TPR和NH3-TPD的表征结果显示碱土助剂的添加会影响催化剂的氧化还原能力和酸性;XPS表征结果表明碱土金属的添加影响了催化剂上钒物种和氧物种的组成,其中添加助剂Ca和Ba后,催化剂上钒钾物种的相对浓度升高,且催化剂表面晶格氧物种的含量增加.活性评价结果表明经碱土助剂Ca和Ba修饰后的3%V-6%K/γ-Al2O3催化剂均具有较好的催化性能,在425℃反应时环己烯的选择性均达56%以上;催化剂也表现出较好的催化稳定性和再生性能.
The catalysts M-3% V-6% K / γ-Al2O3 (M = Mg, Ca, Sr) with V and K as active components and alkaline earth as additives were prepared by impregnation method using γ- , Ba). The catalytic activity of the catalyst in the cyclohexene oxidation to cyclohexene was investigated. The catalysts were characterized by XRD, N2, H2-TPR, , Ammonia-temperature programmed desorption (NH3-TPD) and X-ray photoelectron spectroscopy (XPS) .H2-TPR and NH3-TPD characterization results show that the addition of alkaline earth additives will affect the oxidation of the catalyst Reduction ability and acidity. XPS characterization results showed that the addition of alkaline earth metal affected the composition of vanadium species and oxygen species on the catalyst, and the relative concentrations of vanadium and potassium species on the catalyst increased with the addition of additives Ca and Ba, Oxygen species content increased.The activity evaluation results show that the alkaline catalyst Ca and Ba modified 3% V-6% K / γ-Al2O3 catalyst has good catalytic performance, reaction of 425 ℃ cyclohexene selection The average of more than 56%; catalyst also showed good catalytic stability and regeneration performance.