(254f) Designing Metal-Substituted Oxide Catalysts for Chemoselective Hydrogenation Reactions

Chemoselective hydrogenation of unsaturated carbon bonds can upgrade compounds into value-added chemicals.¹ Reducible metal oxides can perform selective hydrogenation of unsaturated moieties.² Under hydrogenation reaction conditions, oxygen vacancy sites (O_vac) can form on the reducible oxide surface, inducing repulsive strains between neighboring Lewis acids (i.e., metal cations). On these energetically strained cation sites, metal-bound hydrogen, a hydride, has been identified.³ These hydrides on the oxygen vacancy sites serve as crucial intermediates in C–H bond formation, offering a kinetically feasible pathway.²

To further enhance catalytic performance, we investigate the modification of Lewis acid sites within oxide structures through transition metal cation substitution (i.e., doping). Employing density functional theory methods, we analyze how doping promotes surface reduction, providing active sites for hydrogenation reactions, and influences hydride species formation on the reduced sites. We further investigate doping effects on the activation barriers associated with the hydrogenation of unsaturated C–C or C–O bonds. First-principles-based microkinetic modeling (MKM) is performed to assess selectivity changes induced by doping. Starting with benzoic acid and anatase TiO₂ surfaces, we extend our scope to explore various unsaturated reactants and metal oxides, using density functional theory and thermodynamic data from open databases to guide material selection. This approach identifies descriptors for catalytic performance and develops descriptor-based kinetic models. The derived models establish a rational design framework that links the electronic behavior of reducible metal-substituted oxide catalysts to their potential for facilitating C-H bond formation in reactants of interest.

(1) Wei, J. et al., Catal. Sci. Technol. 2022, 13(5), 1258-1280.

(2) Hwang, M. et al., React. Chem. Eng. 2025

(3) Liu, K. et al., Cell Rep. Phys. Sci. 2022, 3(12), 101190.