Insights Into The Role Of Dual-Interfacial Sites In Cu/Zro2 Catalysts In 5-Hmf Hydrogenolysis With Isopropanol

In this work, we synthesized a series of Cu/ZrO2 catalysts with tunable V-o-Cu-0 (oxygen vacancy adjacent to Cu metal) and V-Zr-Cu delta+ (zirconium vacancy adjacent to electron-deficient Cu species) dual-interface sites and investigated the role of the dual-interface sites in the 5-hydroxymethylfurfural (5-HMF) hydrogenolysis reaction with isopropanol as the hydrogen source. By combining a series of in situ infrared characterization and catalytic performance analysis, it is identified that V-o-Cu-0 interface sites were responsible for activating isopropanol dehydrogenation and C = O dissociation of 5-HMF, while the V-Zr-Cu delta+ interface sites were responsible for the dehydroxylation of an intermediate product 5-methyl-2-furfuryl alcohol (5-MFA). Specifically, C-OH was first deprotonated on the V-Zr at the V-Zr-Cu delta+ interface site to reduce the activation energy of 5-MFA dehydroxylation and then adjacent Cu delta+ promoted the dissociation of the C-O bond by enhancing the adsorption energy while elongating the C-O bond, as confirmed by the density functional theory calculations. Because the dual-interface sites provided separate sites for activating intermediate products and reactants, the coupling reaction caused by competitive adsorption is thus well avoided. Therefore, the optimized Cu/ZrO2 catalyst with the most V-Zr-Cu delta+ and moderate V-o-Cu-0 sites exhibited 98.4% of 2,5-dimethylfuran yield under the conditions of 180 degrees C and self-vapor pressure.