Spontaneously polarized ceramic‒carbon-supported Ni–Co for reinforcing water-assisted proton hopping to facilitate catalytic hydrogenation of levulinic acid

Water-assisted proton hopping (WAPH) plays an important role in the aqueous-phase hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). In this study, based on a strategy of spontaneously polarized ceramic (SPCE)-reinforced WAPH, a Ni–Co/SPCE–C catalyst was constructed by high-temperature calcination of a dual mechanical activation-treated precursor. Ni–Co/SPCE–C with favorable structural characteristics, intimate interfacial compatibility, and unique spontaneous polarization effect enhanced the migration efficiency of active hydrogen and activated water to form small water clusters, contributing to outstanding catalytic activity for aqueous-phase hydrogenation of LA to produce GVL at relatively low reaction temperature and H2 pressure. A LA conversion of 99.9% and a GVL yield of 92.3% were achieved at 160°C and 1.5 MPa H2 over the Ni–Co/SPCE–C catalyst, which were significantly higher than those catalyzed by contrastive catalysts. A variety of tests and theoretical calculations reveal that SPCE with far-infrared emission and surface electric field was conducive to the reduction in the hydrogen spillover energy barrier, the stabilization of the transition state, and the facile exchange of H2 and water for accelerating WAPH. Moreover, a reasonable SPCE-reinforced WAPH mechanism was proposed to explain the enhanced aqueous hydrogenation of LA. This research can provide valuable insights into the design and development of high-performance non-noble metal catalysts for aqueous hydrogenation applications.