Novel Effects of K-Addition to Ru/SiO2 on Conversion of Cyclohexane

Abstract The effects of the addition of alkalis to a Ru/SiO2 catalyst upon the conversion (hydrogenolysis and dehydrogenation) of cyclohexane, hydrogenolysis of butane, and hydrogenations of benzene and CO were studied. The addition of K or Cs slightly enhanced the catalytic activity for the hydrogenolysis of cyclohexane, whereas dehydrogenation to benzene was markedly suppressed. This result is contrary to the effect of the addition of Cu or Au to group-VIII metals, as reported in the literature. Changes in the activities became less significant as the atomic number of the added alkali decreased. From a systematic examination by varying the alkali content, it was revealed that dehydrogenation and CO hydrogenation were very sensitively suppressed by an electronic effect imposed by the alkalis, whereas changes in the activities of hydrogenolysis and benzene hydrogenation were not great.