Supra-Strong Metal-Support Interaction in Oxide-Solid-Solution-Derived Transition Metal Catalysts

Transition metal catalysts with electron-deficient active sites (M^δ+) can exhibit unique activity and selectivity in hydrogenation reactions but are prone to deactivation under high-temperature reaction conditions due to the reduction of M^δ+. Here the existence of a supra-strong metal-support-interaction in oxide-solid-solution-derived nickel catalysts are reported, which greatly enhances the stability of Ni^δ+ against reduction. It is found that the reduction of Ni species from solid solutions of NiO and magnesium aluminum spinel occurs at higher temperatures compare to pristine NiO, which is attributed to the strengthened binding of Ni atoms to ligand oxygen atoms for the former. The strength of the metal-support interaction in the final catalysts can be tuned by controlling the calcination temperature of the impregnation process and thus the degree of solid solution formation from separated oxide precursors. Notably, the optimized Ni catalyst with durable electron-deficient sites exhibits a sustained CO output with a 100% selectivity and ≈30% CO₂ conversion at 600 °C in catalyzing the reverse water-gas shift reaction.