纳米Cr_2O_3系列催化剂上CO_2氧化乙烷脱氢制乙烯反应  

Oxidative Dehydrogenation of Ethane with Carbon Dioxide to Ethylene over Nanosized Cr_2O_3 Catalysts

作　　者：邓双[1] 李会泉[1] 张懿[1] 

机构地区：[1]中国科学院过程工程研究所,北京100080

出　　处：《催化学报》2003年第10期744-750,共7页

基　　金：国家 8 63计划资助项目 (2 0 0 1AA0 70 10 )

摘　　要：采用溶胶 凝胶法和共沸蒸馏法耦合技术制备了纳米Cr2 O3 催化剂 ,并采用共沉淀法和共沸蒸馏法耦合技术制备了纳米Cr2 O3 /Al2 O3 ,Cr2 O3 /ZrO2 和Cr2 O3 /MgO复合催化剂 .应用BET ,XRD ,XPS ,TPR和TEM等物理化学方法对催化剂的结构和物化性质进行了表征 ,并考察了该系列催化剂上CO2 氧化乙烷脱氢制乙烯的反应性能 .结果表明 ,纳米Cr2 O3 催化剂上乙烷和CO2 的转化率均明显高于常规Cr2 O3 催化剂 ,但乙烯的选择性低于常规Cr2 O3 催化剂 ;纳米复合催化剂中的复合成分显著影响催化剂的催化性能 .其中 ,10 %Cr2 O3 /MgO纳米复合催化剂在温度为 973K时 ,乙烷转化率和乙烯选择性分别可达到6 1 5 4 %和 94 79% .纳米催化剂表面Cr的还原性以及Cr6+/Cr3The nanosized Cr 2O 3 was prepared by sol gel coupling with azeotropic distillation method. The size distribution of the nanosized Cr 2O 3, statistically determined by TEM, was narrowly ranging from 20 to 40 nm. The nanosized composite catalysts Cr 2O 3/Al 2O 3, Cr 2O 3/ZrO 2 and Cr 2O 3/MgO were prepared by coprecipitation coupling with azeotropic distillation method. Calculated by using Scherrer equation, the average diameters of the nanosized composite catalysts were 8, 12 and 6 nm, respectively. The catalytic performance of these nanosized catalysts in oxidative dehydrogenation of ethane with carbon dioxide to ethylene was investigated. The result showed that the nanosized Cr 2O 3 catalyst exhibited much higher ethane conversion and lower ethylene selectivity than the normal Cr 2O 3 catalyst. The catalytic activity of the nanosized composite catalysts varied with the nature of the composites. Cr 2O 3/ZrO 2 catalyst showed the highest ethane conversion and the lowest ethylene selectivity among the nanosized composite catalysts. The ethylene yield over Cr 2O 3/Al 2O 3 catalyst was very low but it exhibited the highest ethylene selectivity. 10%Cr 2O 3/MgO catalyst exhibited excellent catalytic performance in the reaction, producing 61 54% ethane conversion and 94 79% ethylene selectivity at 973 K. These nanosized catalysts were characterized by BET, XRD, TEM, FT IR, XPS and TPR techniques. The reducibility of Cr and Cr 6+ /Cr 3+ ratio in the nanosized catalysts determined the catalytic performance in the oxidative dehydrogenation of ethane with carbon dioxide.

关 键 词：纳米催化剂 氧化铬 氧化铝 氧化锆 氧化镁 二氧化碳 乙烷 氧化脱氢 乙烯 

分 类 号：O643.3[理学—物理化学]