Abstract: The reducibility of hydrocarbon-steam reforming catalysts has been studies by temperature programmed reduction (TPR) method. We found that the reduction mechanism of these catalysts is in accordance with nucleation model. The interaction between nickel and other components present in catalysts affects their reduction property. Addition of MgO and cement into those catalysts lead to an increase in their reduction temperature. A decrease in reduction temperature, however, has been observed by adding rare earth oxides.
The reduction kinetic parameters of Ni catalysts with or without CeO_2 have been obtained from the peak analysis of their TPR curves. It has been found that CeO_2 promotes the reduction process by decreasing its activation energy. There is a good correlation between the reduction activation energy and the degree of dispersion of Ni, the higher the dispersion, the lower the activation energy. A mechanism of the promoting effect on reduction by CeO_2 has been suggested.