Fe-Doping Ru-ZrO_<i>x</i> Catalyst for Improving the Ratio of Dihydric Alcohol/Methane during the Hydrogenolysis of Biomass Polyols

Fe was doped into Ru-ZrOx catalysts to suppress methane generation and improve the selectivity of functionalized products during the hydrogenolysis of polyols. The performance test showed that the doping of Fe in Ru catalysts effectively reduced the methane generation compared to that without Fe. The higher the Fe amount, the lower the methane yield, and the higher the selectivity of 1,2-propanediol and ethylene glycol. Characterizations showed that there was a strong interaction between Ru and Fe, which facilitated the reduction of Ru. The electron donation from Fe increased the electron density of Ru, which suppressed the formation and activation of carbonyl. The activation of the C–C bond attached to the carbonyl was also suppressed, which, in turn, reduced methane generation. DFT calculations confirmed that the pathway of methane generation through the decarbonylation pathway would encounter a higher energy barrier over Fe-containing Ru catalysts. The Fe-containing catalysts also exhibited stable performance in the recycle runs and hydrogenolysis of other polyols. These results provide a mechanistic understanding of reducing methane generation over Ru catalysts and would be helpful in designing the Ru catalysts for polyol hydrogenolysis.