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51.
CuCrO2和CrCr2O4间相互作用对体系结构和催化性能的影响 总被引:3,自引:0,他引:3
以柠檬酸络合法制备了CuCrO2和CuCr2O4两相共生的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CuCr2O4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,提高了样品的催化活性. 相似文献
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It is well known that γ-Fe_2O_3 is a very active and selective catalyst for okidative dehydrogenation ofbutene to butadiene. It is hard, however, to distingulsh between ferrite spinels and therefore to identify its existence in ferrite-ferric oxide catalysts using XRD. On the IR spectra γ-Fe_2O_3 has characteristic bands in the range of 600~800 cm~(-1), which do not exist for α-Fe_2O_3, Fe3O4, ZnFe_2O_4 and MgFe_2O_4. But these bands are too weak to deterAnne for the small amount of γ-Fe_2O_3, e g. less than 30% (mass fraction), in catalysts.
Usually using second derivative IR spectra can increase the analytical sensitivity substantially. The mechanical mixtures of γ-Fe_2O_3 and MgFe_2O_4 in different ratio were prepared and their second derivative IR spectra were taken. It was found that the bands 730 and 695 cm~(-1) were characteristic of γ-Fe_2O_3 and their intensities increased with the content of γ-Fe_2O_3 in the mixtures. A staight line with R=0.994 can describe the relation between γ-Fe_2O_3 content and the peak area of band 695 cm~(-1). The lowest detectable content of γ-Fe_2O_3 is about 1% (mass fraction). The existence of γ-Fe_2O_3 in the used B-02 comercial catalyst was identified by this method. 相似文献
Usually using second derivative IR spectra can increase the analytical sensitivity substantially. The mechanical mixtures of γ-Fe_2O_3 and MgFe_2O_4 in different ratio were prepared and their second derivative IR spectra were taken. It was found that the bands 730 and 695 cm~(-1) were characteristic of γ-Fe_2O_3 and their intensities increased with the content of γ-Fe_2O_3 in the mixtures. A staight line with R=0.994 can describe the relation between γ-Fe_2O_3 content and the peak area of band 695 cm~(-1). The lowest detectable content of γ-Fe_2O_3 is about 1% (mass fraction). The existence of γ-Fe_2O_3 in the used B-02 comercial catalyst was identified by this method. 相似文献
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