Isokinetic effects in ethane hydrogenolysis and their relation to the mechanism of the reaction

Abstract

Literature data on the kinetics of ethane hydrogenolysis over metal catalysts are used to indicate the existence of isokinetic temperatures, Θ. For platinum Θ = 725 K, for Ni Θ is probably in the same temperature range. For Fe and Co on the other hand Θ is found at much lower values, about 330 K for Fe and 320 K for Co. From an analysis of the model of selective energy transfer, these values support the proposition of Sinfelt that the elements of high atomic number in one and the same transition metal series favour the splitting of the carbon-carbon bond as rate determining step, whereas those elements that have lower atomic numbers cause the splitting of the metal-carbon bond to be the rate determining step.