On the Role of Cu+ and CuNi Alloy Phases in Mesoporous CuNi Catalyst for Furfural Hydrogenation

Bimetallic catalysts display high reactivity in valorization of biomass-derived chemicals. In this work, KIT-6-templated mesoporous CuNiOx catalysts were synthesized and applied for the selective hydrogenation of furfural (FF) to furfuryl alcohol (FA) under relatively mild reaction conditions. A combination of experimental characterization and density functional theory calculations unveiled the critical role of Cu+ species in hydrogen activation and corroborated a direct experimental correlation between the Cu+ concentration and overall hydrogenation activities. Furthermore, a CuNi alloy phase was attributed as the active adsorption site for FF with a difference in adsorption configurations being responsible for a shift in product selectivity from furfuryl alcohol toward tetrahydrofurfuryl alcohol on Ni-rich phases. Thus, in contrast to pure Cu and Ni catalysts, a close interplay between Cu+ sites and a CuNi alloy phase is proposed to enhance activity of the CuNi catalysts in FF hydrogenation. The structure-activity relationships established in the work clarify the role of bimetallic CuNi catalysts in this important reaction and offer a rationale for similar catalytic systems involving hydrogenation of C=O or/and C=C groups.

Automated summary

In this study, KIT-6-templated mesoporous CuNiOx catalysts were synthesized and used for the selective hydrogenation of furfural to furfuryl alcohol. Experimental characterization and theoretical calculation revealed the critical role of Cu+ species in hydrogen activation and the correlation between Cu+ concentration and hydrogenation activities. The CuNi alloy phase was identified as the active adsorption site for furfural, and the difference in adsorption configurations led to a shift in product selectivity. The interplay between Cu+ sites and CuNi alloy phase was proposed to enhance the activity of CuNi catalysts in furfural hydrogenation. The structure-activity relationships established in this work provide a rationale for similar catalytic systems involving hydrogenation of C=O or/and C=C groups.