还原温度对Ni／Al_2O_3催化剂上H_2、CO吸附的影响  

Effect of Reduction Temperature on the Adsorption Performance of H 2 and CO on Ni/Al 2O 3 Catalyst

作　　者：胡常伟[1] 陈豫[1] 田安民[1] 

机构地区：[1]四川大学化学系

出　　处：《分子催化》1996年第5期345-349,共5页Journal of Molecular Catalysis(China)

基　　金：国家自然科学基金

摘　　要：采用程序升温还原与程序升温逐步活化、Ｈ２、ＣＯ室温吸附、Ｈ２程序升温脱附相结合的方法，研究了Ｎｉ／Ａｌ２Ｏ３催化剂上还原活化温度对其吸脱附性能的影响．实验发现，Ｎｉ／Ａｌ２Ｏ３催化剂上，在不同温度还原的不同Ｎｉ氧化物物种，经相应温度活化后可形成不同性质的Ｈ２、ＣＯ吸附中心．催化剂经５２３Ｋ及５７３Ｋ活化后可形成极细的与Ａｌ２Ｏ３有一定相互作用的吸附中心，在这类中心上，Ｈ２的室温吸附量极小，但有一定的高温Ｈ２吸附量，且高温吸附的Ｈ２要在较高温度下才能脱附，ＣＯ在其上则可能是按单金属中心多ＣＯ方式吸附的．催化剂经６７３Ｋ和７２３Ｋ活化后均形成较强的Ｈ２、ＣＯ吸附中心，ＣＯ在这些中心上可能是按线式和桥式两种方式吸附的．催化剂经６７３Ｋ活化后，形成的中心上吸附的Ｈ２可在相对较低的温度下脱附．Ｎｉ／Ａｌ２Ｏ３经７７３Ｋ处理会发生烧结，因而丧失室温Ｈ２、ＣＯ吸附能力．Temperature programmed reduction and stepwise activation, H 2 and CO adsorption at room temperature, and temperature programmed desorption of H 2 were combined to investigate the effect of reduction temperature on adsorption desorption properties of Ni/Al 2O 3 catalyst. It was found that on Ni/Al 2O 3 catalysts different kinds of H 2 and CO adsorption sites can be formed from different Ni oxide species after reduced at different temperatures. The sites formed on the catalyst reduced at 523 K or/ and 573 K could be nickel species of very fine particle size which could interact with Al 2O 3. Carbonyl adspecies might be formed when CO was adsorbed on this kind of sites. H 2 uptake at room temperature on this kind of sites was very small whereas that at higher tmeperature was larger. The catalyst reduced at 673 K and 723 K adsorbed more H 2 and CO at room temperature, the ratio of the adsorbed CO and H(q′/q) indicated that CO might be adsorbed in linear, carbonyl and bridged forms. H 2 adsorbed on the sites formed on the catalyst reduced at 673 K desorbed at lower temperature than those adsorbed on the catalyst reduced at 523 K and 573 K. Sintering of the catalyst might occur when it was treated at 773 K.

关 键 词：还原 温度影响 催化剂 吸附 金属催化剂 

分 类 号：O643.36[理学—物理化学] O621.254.2[理学—化学]