In the hydrogenation of soybean and rapeseed oils with fresh copper chromite catalyst, the rate of reaction −d(IV)/dt varies extensively with time. These variations are ascribable to changes in phase composition of the catalyst during its reduction. This reduction is not restricted to an initial period but proceeds in two steps during the major part of a normal hydrogenation for the reduction of the linolenate content of the oil. Variations of the catalyst activity followed by experimental measurements have been related to the changes of the catalyst composition.

The influence of poisoning of ruthenium catalysing the selective hydrogenation of benzene to cyclohexene has been studied. Both the yield of cyclohexene and the rate of hydrogenation are greatly affected by the degree of poisoning (e.g. FeS04, FeCla, Tic13 and oxygen), and may also be optimised. A reproducible catalyst has been prepared by precipitating the catalyst precursor, as the hydroxide, in a glass vessel at 353 K without influence ofcorrosion products from the reactor material. The influence of the hydrogen pressure on activity has also been investigated. An optimum pressure for maximum yield of cyclohexene was obtained and a rate expression was formulated which could account for reaction orders varying with hydrogen pressure.

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