Metal oxide compositing tailors H2 affinity on carbon-supported catalysts for boosted gas-liquid-solid hydrogenation

Gas–liquid–solid catalytic hydrogenation over carbon-supported catalysts is typically performed at elevated temperatures and high hydrogen pressures, primarily because hydrogen is poorly soluble in the liquid phase. Enhancing the H 2 affinity of catalysts, thereby increasing the surface coverage of active hydrogen species, is an effective strategy; however, it remains challenging. Herein, we demonstrate that the H 2 affinity of carbon-supported catalysts can be optimized by introducing metal oxides into the carbon support, thereby increasing the surface hydrogen coverage on carbon-supported catalysts and ultimately enhancing their hydrogenation performance. As a proof of concept, cobalt supported on a homogeneous composite of d-Al 2 O 3 and N-doped carbon (Co/Al 2 O 3 –NC) has been prepared. The d-Al 2 O 3 component, possessing high H 2 affinity, promotes local H 2 concentration and stabilizes the dissociated hydrogen through the formation of O–H δ+ and Al–H δ- . Consequently, Co/Al 2 O 3 –NC exhibits significantly enhanced hydrogenation performance (TOF = 343 h −1 ) across hydrogenation of p -chloronitrobenzene compared to those of Co/NC (TOF = 32 h −1 ) and Co/Al 2 O 3 (TOF = 53 h −1 ) catalysts under 100 °C and 5 bar H 2 . These findings provide new insights for designing efficient catalysts for gas–liquid–solid catalytic hydrogenation reactions over carbon-supported catalysts.