载体和添加剂对负载型钯催化剂上CO_2氢化反应的影响  

EFFECT OF SUPPORT AND PROMOTER ON THE HYDR06ENATION OF CO_2 OVER SUPPORTED PALLADIUM CATALYSTS

作　　者：王琳[1] 吴凯[1] 陈焱[1] 陈昌生[2] 姜玄珍[1] 

机构地区：[1]浙江大学化学系 [2]浙江大学物理系

出　　处：《Chinese Journal of Catalysis》1989年第2期130-136,共7页催化学报（英文）

基　　金：国家自然科学基金

摘　　要：进行了Pd/TiO_2,Pd/ZrO_2,Pd/MgO,Pd/La_2O_3,Pd/C,Pd-K/TiO_2及Pd-La/TiO_2的常压CO_2+H_2反应动力学研究。并在同样条件下对Pd/La_2O_3,Pd/ZrO_2和Pd/MgO进行了CO+H_2反应的对比。发现Pd/TiO_2的CO_2加氢活性最高,Pd/ZrO_2的生成甲醇选择性优良。XRD测定催化剂上钯晶粒的数据表明,Pd/TiO_2催化剂有SMSI效应,从而可以解释Pd/TiO_2的高活性。ZrO_2载体具有较短的正电子自由淹没寿命τ_1,说明ZrO_2中存在一种易于提供电子的环境。还采用瞬变应答实验探讨了CO_2+H_2的反应机理,证明CH_4的形成要通过CO_2离解生成表面C~*,而气相CO_2或弱吸附的CO_2才是生成CH_3OH的碳源。The kinetic data of carbon dioxide hydrogenation at atmospheric pressure over Pd/TiO2, Pd/ZrO2,Pd/MgO, Pd/La2O3, Pd/C, Pd-K/TiO2 and Pd-La/ TiO2, were determined. For comparison, the hydrogenation of carbon monoxide over Pd/La2O3, Pd/MgO and Pd/ZrO2 was examined under the same conditions. For CO2+H2 reaction, Pd/TiO2 was proved to be the most active catalyst, and Pd/ZrO2 showed unusually high selectivity for the formation of CH3OH. The particle size of Pd determined by X-ray diffraction method Suggested that there was SMSI effect in Pd/TiO2, and thus the high activity of Pd/TiO2 could be well interpreted. Positron annihilation experiments showed that ZrO2 had a shorter positron free annihilation lifetime which might be connected with a kind of environment of easy providing electrons. The mechanism of CO2 hydrogenation was studied by transient response experiment.lt was proved that the formation of surface carbon C* by the dissociation of CO2 was a necessary step to produce CH4, while the gas phase CO2 or the weak adsorbed CO2 was the carbon source for the formation of CH3OH.

关 键 词：钯催化剂 CO2 氢化 载体 添加剂 

分 类 号：TQ426.81[化学工程]