Catalytic Behavior of Various Metal Oxides on the Reactior between Carbon and Carbon Dioxide

Abstract

Catalytic effect of the oxides of Cu, Zn, Al, Ti, Zr, Si, Sn, Pb, V, Nb, Ta, Cr, Mn, Fe, Co and Ni on the reaction between carbon and carbon dioxide were invesigated by means of thermogravimetry, temperature programmed X-ray dif-fraction and microscopic analysis.Carbon materials used were chars from phenol-formaldehyde resin and from four coals. They were mixed with each metal oxide of 0.5 atomic % in a mortar grinder for 1 hour.It was found from the TG measurement that the oxides of Sn, Pb, V, Fe, Cu, Ni and Co showed appreciable catalytic action, and among them SnO2 was the most effective additive to all chars. The temperature programmed X-ray diffraction revealed that SnO2, PbO, NiO, CoO and Cu2O were reduced to metallic state and furthermore Sn and Pb melted in the range of the catalytic gasification temperatures. From the microscopic observations, SnO2 and Cu2O were found to give a finer dispersion on char during the reaction than that before the reaction.The catalytic effects of SnO2 and Sn compounds was examined by TG measure-ment. It was found that the weight loss of the char increased with the SnO2 content until 1 atomic %, but after that the degree of reactivity increase with SnO2 content was very small. Similar catalytic activity was obtained with Sn compounds like oxide, oxalate, sulfate and acetate. For Sn acetate, no marked difference in the catalytic activity was recognized between the following two methods of catalyst addition, i. e. physical mixing and impregnation with aqueous solution.