Crystal plane effect of ceria on supported copper catalyst for liquidphase hydrogenation of unsaturated aldehyde

Ceria has been widely used as catalyst support displaying a size- or shape-dependent catalytic performance due to the strong metal-support interaction (SMSI) effect with active metal. Almost all the studies on the SMSI effect of ceria-supported metal catalysts are involved generally in gas-phase reaction, but rarely in the liquid-phase reaction system. In this work, Cu/CeO2-P (copper loaded on nano-polyhedral CeO2 with (1 1 1) terminated surface) was investigated its catalytic performance on liquid-phase hydrogenation and studied the SMSI effect by comparing with the catalysts supported on nano-rod and nanocube CeO2. It was found that Cu was highly dispersed on the external surface of ceria in the Cu/CeO2-P catalyst via a moderate SMSI effect. Furthermore, the degree of the interaction showed great inflfluence on the chemical state of Cu species, and the ratio of (Cu+ +Cu0 )/Cu2+ in Cu/CeO2-P was higher than Cu/ CeO2-R (Cu loaded on nano-rod CeO2 with (1 1 0) plane) and Cu/CeO2-C (Cu loaded on nano-cube CeO2 with (1 0 0) facet). As a result, the Cu/CeO2-P catalyst showed the best catalytic performance among three types of catalysts. Based on series of catalytic investigations, the catalytic performance in liquid-phase hydrogenation was intrinsically relevant to the crystal plane effect and reduced Cu proportion induced by an appropriate SMSI effect, which was completely different from gas-phase hydrogenation.