STUDY ON HYDROGENATION OF CARBON OXIDES ON SUPPORTED METAL-CATALYSTS .2. SURFACE-REACTIONS IN METHANATION OF CARBON-MONOXIDE AND CARBON-DIOXIDE ON NI-SIO2 CATALYST

By using a pulse technique, CO and CO2 methanations were studied on a Ni/SiO2 catalyst at around 200°C. Gas chromatogram of the products obtained from CO and CO2 methanations showed the pronounced tailing of the CH4 peak, as shown in Fig. 2. In methanation from the mixture of CO and H2 or CO2 and H2 using He as a carrier gas, the tailing of the CH4 peak was not observed, and the amount of the product was less than that formed m H2 carrier gas by a factor of about 100. These results indicated that the stable adsorbed intermediate, (X)ad, formed on the catalyst from CO or CO2 was methanated slowly. From the kinetic studies of these tailings, the rate constants of the surface reaction and the activation energies in CO and CO2 methanations were determined. In both reactions the rate constants of the surface reactions were in good agreement with each other and the activation energies were 19kcal/mol, as shown in Fig. 5, indicating that CO2 methanation proceeded through the same intermediate as that in CO methanation. By adding the results of CO disproportionate, it seemed more probable that (X)ad was M-CHOH rather than M-C or M-CO. © 1979, The Chemical Society of Japan. All rights reserved.