CATALYSIS BY MIXED OXIDE PEROVSKITES - 1. HYDROGENOLYSIS OF ETHYLENE AND ETHANE ON LaCoO3.

Article abstract of DOI:10.1246/bcsj.53.3044

Catalysis by a mixed oxide with a perovskite structure, LaCoO//2, was studied for the hydrogenolysis of ethylene and ethane at temperatures 300-600 K using the hydrogen-excess mixtures. The high and stable activity was obtained by evacuating LaCoO//3 at 600 K. Ethylene hydrogenolysis above 420 K proceeded consecutively via the intermediate, ethane, to produce methane, whereas only the hydrogenation to form ethane occurred below 420 K. Different temperature dependence of the rate was observed, i. e. , the activation energy of minus 19. 3 kJ:mol** minus **1 in the range 420-600 K and 33. 6 kJ multiplied by (times) mol** minus **1 in the range 300-420 K. The mechanistic analysis and tracer study using D//2 showed that the slow step of the hydrogenation shifts, with increasing temperature, from the adsorption of hydrogen to the surface reaction between hydrogen atom and ethyl radical.