The dependence of the C−C hydrogenolysis activity on reaction parameters and the structure of the substrate alkanes was investigated for Ru/CeO2catalyst with very small (dispersion: H/Ru=0.89) Ru particles. The substrate concentration and reaction temperature did not have a significant effect on the selectivity pattern, except that methane production was promoted at high temperatures. However, the hydrogen pressure had a marked effect on the selectivity pattern. Ctertiary−C bond dissociation, terminal Csecondary−Cprimarybond dissociation, and fragmentation to form excess methane had negative reaction order with respect to hydrogen partial pressure, whereas Csecondary−Csecondarybond dissociation had an approximately zero reaction order. Therefore, a high hydrogen pressure is essential for the regioselective hydrogenolysis of Csecondary−Csecondarybonds in squalane. Ru/SiO2catalyst with larger Ru particles showed similar changes in the product distribution during the change in hydrogen pressure. The reaction mechanism for each type of C−C bond dissociation is proposed based on reactivity trends and DFT calculations. The proposed intermediate species for the internal Csecondary−Csecondarydissociation, terminal Csecondary−Cprimarydissociation, and Ctertiary−C dissociation is alkyls, alkylidynes, and alkenes, respectively.
- surface species