SPECIFIC CATALYTIC ACTIVITY OF NICKEL IN HYDROGENATION OF CARBON DIOXIDE TO METHANE

This paper deals with the correlation between activity of nickel catalysts and their structure. The structure of nickel, chromium (III) oxide, and a model series of Ni Cr2O3 catalysts was studied by low-temperature adsorption of nitrogen and oxygen chemisorption at 22 °C. Oxygen uptake in the rapid stage of adsorption was found to be a proper measure of the number of nickel surface atoms in the samples. The chosen test reaction proceeds on all samples investigated according to the equation r = kcCO2 1 2. Chromium(III) oxide alone is inactive in the given reaction. The catalytic activity was expressed as a rate constant related to 1 g of the sample (kg) as well as a rate constant related to 1 m2 of nickel of the sample (kSNi). While the kg values varied in dependence on the composition about thirtyfold, the kSNi values varied less than twofold, so that it was possible to represent them for all the samples investigated by one Arrhenius straight line. The results obtained show that only nickel is the active component of the catalysts under study, whereas Cr2O3 is a structural promoter. In this paper an attempt is also made to characterize the present state of investigation of specific activity and its significance in catalysis. © 1968.