Kinetics of heterogeneous liquid hydrogenation under non-agitation (significance of agitation and the role of gas-liquid interface)

Abstract

It was confirmed that even when not applying forced agitation, the rate determining step is the catalytic hydrogenation of ester on a nickel-kieselguhr catalyst and not a spontaneous transportation of the reactants, since the reaction is faster, being zero order with respect to the consumption of substrates, and there is preferential hydrogenation of ethyl linoleate to ethyl oleate. A far faster consumption of hydrogen was observed by the use of a platinum catalyst.State of the catalyst in liquid, suspension, or sedimentation, did not give any effect on the rate. No difference was found in the above phenomena under agitation, except for higher hydrogenation rate.Under this transferral equilibrium, the agitation effect is illustrated in terms of the role of liquid surface, where extra high concentration of hydrogen exists as the surface excess.The rotational agitation used in the present experiment may cause closer approach of more catalysts to the enlarged liquid surface region.Hydrogenation of p-nitrophenol over nickel-catalyst was also controlled by catalysis even under non-agitation.