Accelerating Semihydrogenation of Cinnamaldehyde by Water over a Au/α-MoC Catalyst

Replacing H2 with H2O as the hydrogen source for the water-involved selective hydrogenation of cinnamaldehyde to cinnamyl alcohol (WSHCC) is very attractive yet is underdeveloped by a much lower H2O conversion rate than H2. Here, we report the realization of a high-efficiency WSHCC process by a synergy of CO adsorption and H2O dissociation over a Au/α-MoC1–x boundary. It shows a specific molar rate of 60.86 mol molAu–1 h–1 to cinnamyl alcohol at 96 °C, which is nearly 12-fold that reported earlier, and maintains a high conversion of over 99% and a high selectivity of 77%. Mechanistic studies indicate that the Au/α-MoC1–x boundary accommodates atomically dispersed Auδ+ sites for adsorbing CO, vacating oxygen-covered α-MoC1–x and thereby creating isolated Mo sites for the preferred adsorption and hydrogenation of C═O bonds over that of C═C bonds. This provides a catalyst design strategy for high-efficiency C═O hydrogenation by water.