CuCrO_2和CuCr_2O_4间相互作用对体系结构及催化性能的影响  

Influence of Phase-to-Phase Interaction between CuCrO_2 and CuCr_2O_4 on Their Structure and Catalytic Activity

作　　者：赵峰[1] 李国英[1] 李能[1] 刘英骏[1] 林炳雄[1] 

机构地区：[1]北京大学化学与分子工程学院,北京100871

出　　处：《催化学报》2003年第1期11-16,共6页

摘　　要：以柠檬酸络合法制备了CuCrO2 和CuCr2 O4 两相共生的Cu Cr O催化剂体系 .由于两相共生而相互作用 ,两相组成的样品中 ,样品颗粒较小 ,比表面积增大 ,催化CO O2 反应的活性提高 .当样品中n(Cu) /n(Cr) =0 7时 ,两相含量最为接近 ,显示出最高的催化活性 .CO O2 反应过程中 ,气相中的CO与样品表面的氧原子作用 .在两相共生而相互作用的过程中 ,CuCrO2和CuCr2 O4 的体相结构没有变化 .各样品催化活性的不同是由其表面性质的差异引起的 .TPR和XPS分析结果表明 :两相共生而相互作用 ,修饰了样品的表面性质 ,使样品表面含有更多的活性氧 。Catalysts consisting of CuCrO_2 and CuCr_2O_4 phases (Cu-Cr-O catalysts) were prepared by amorphous citrate precursor method. Phase-to-phase interaction results in increase in surface area and catalytic activity of the catalysts for CO-O_2 reaction. The samples consisting of CuCrO_2 and CuCr_2O_4 phases give better performance. The sample with n(Cu)/n(Cr)=0.7 (Cu70), in which n(CuCrO_2)/n(CuCr_2O_4) is much closer to 1 than in the others, shows the highest catalytic activity. However, in mechanical mixture of CuCrO_2 and CuCr_2O_4, the interaction cannot be observed. Particles of Cu70 are much smaller and more regular than those of single-phase CuCr_2O_4 (Cu50) and CuCrO_2 (Cu100) samples. The particle size of Cu70 is around 200 nm, while that of Cu50 and Cu100 is above 500 and 250 nm respectively. The interaction does not show evident influence on the bulk phase structure. Crystalline parameters of CuCrO_2 and CuCr_2O_4 structure in all samples are almost the same. CO weak adsorption on Cu-Cr-O catalysts occurs at room temperature, while at 100 ℃ and above, it could no longer be detected. During CO-O_2 reaction over Cu-Cr-O catalysts, the gaseous CO reacts with surface oxygen atoms. The reactivity of surface oxygen is the criterion for catalytic activity. In TPR profile, the reduction peak of the Cu-Cr-O catalyst near 460 ℃ corresponds to the surface reduction. Two-phase samples, especially Cu70, tend to be reduced more easily than single-phase samples below 460 ℃. This signifies that two-phase samples, especially Cu70, contain more active surface oxygen, and show higher catalytic activity. The binding energy of surface oxygen atoms over two-phase samples is lower than that of single-phase samples. The reason for the better performance of two-phase samples for CO-O_2 reaction is that phase-to-phase interaction activates surface oxygen atoms, resulting in catalytic activity enhancement. Nevertheless, this interaction only functions at the surface and does not influence the bulk phase structure.

关 键 词：CuCrO2 CuCr2O4 催化性能 一氧化碳 燃烧反应 铜 铬 复合氧化物 程序升温还原 两相相互作用 金属载体强相互作用 催化剂 尾气净化 

分 类 号：O643.3[理学—物理化学]