Reducibility and Catalytic Activity of Nickel Oxide-Chromia Composite Catalysts

Abstract

The reduction characteristics of silica supported nickel oxide-chromia composite catalysts were investigated by the thermal analysis method. The catalysts were prepared with impregnation and coprecipitation. The reduction peak of chromia appeared at 300° C. The thermal analytical data of the nickel oxide-chromia composite catalyst showed that this reduction peak is attributed to the reduction of CrOe contained in Cr2O^2- and that the peak shifts 300° C to 150-170° C due to hydrogen on a small amount of nickel in a reduced state. The reduction curves of impregna tion catalysts differ markedly from those of coprecipitation catalysts at higher temperatures, . The surface of impregnation catalysts consists of a mixture of nickel oxide and oliromia, while that of coprecipitation catalysts consists mainly of nickel silicate. The results of the -chemi sorption mesurements and the reduction curves showed that the surface of imPregnation catalysts is covered with kactive elements more than that of coprecipi%ation catalysts. The in terrelation for the relation between the amount of the active element and its catalytic activity was tested hydrogenation of acetone. The results showed that the catalytic activity depends on the amount of the active element.