不同负载量VO_X/Mg-Al-O催化剂表面物种分析及其环己烷氧化脱氢性能研究  

Characterization of VO_X/Mg-Al-O Catalyst and Catalytic Activity in Oxidative Dehydrogenation of Cyclohexane to Cyclohexene

作　　者：方健[1] 路平[1] 余国贤[1] 晋梅[1] 

机构地区：[1]江汉大学化学与环境工程学院,湖北武汉430056

出　　处：《江汉大学学报（自然科学版）》2016年第1期52-57,共6页Journal of Jianghan University：Natural Science Edition

基　　金：武汉市科技计划项目(2015061701011597)

摘　　要：采用等体积浸渍法制备了不同钒负载量的VOX/Mg-Al-O催化剂,采用XRD、氮气吸附-脱附、FT-IR、H2-TPR等催化剂表征方法对所制备的催化剂进行分析表征,并将催化剂用于环己烷脱氢的催化反应,以研究催化剂表面物种性质与其氧化脱氢反应性能之间的关系。结果表明:当钒负载量为4%左右时,催化剂表面以还原性能好、单层分散的孤立态和聚合态钒氧物种为主;当钒负载量高于4%时,催化剂表面开始形成还原性能较差的镁钒酸盐物种。当采用4 VOX/Mg-Al-O催化剂、反应温度475℃、烃氧比为2、空气流量100 m L/min的操作条件下,在催化剂表面所形成的低价钒氧物种为环己烷脱氢反应的活性物种,可获得较好的环己烷氧化脱氢制取环己烯的催化性能。Hydrotalcite-type materials of VOX/Mg-Al-O with different V： （Mg＋Al） ratios have been prepared with isometric impregnation method, and characterized by X-ray diffraction, N2-adsorption-desorption, FT-IR and H2-TPR techniques. The relationship between catalysts＇ surface properties and the oxidative dehydrogenation performance of cyclohexane to cyclohexene was investigated in detail. The experimental results showed that the isolated and polymeric VO4 species on the catalyst surface were present at low vanadium loading of lower than 4 wt%, which could be reduced more easily than samples with higher vanadium loading. With the increasing of vanadium loading, mixed magnesium vanadate compounds appeared on the catalyst surface, which were difficult to be reduced by hydrogen. Under the experimental conditions of 475 ℃ , hydrocarbon oxygen ration of 2 , airflow 100 mL/min and the vanadium loading of 4 wt%, a better catalytic performance of cyclohexane oxidative dehydrogenation to cyclohexene could be obtained. It can be suggested that low VOx species on the surface are the active sites for the reaction.

关 键 词：类水滑石催化剂 VOX/Mg-Al-O 负载量 氧化脱氢 氧物种 

分 类 号：O643.36[理学—物理化学]