Achieving Product Control in Furfural Hydrogenation Using Intermetallic Catalysts

Intermetallic nanoparticles (iNPs) have garnered much attention as effective catalysts, but the impact of tuning surface properties to induce steric effects is relatively unexplored. Here, we report on the strategy of governing steric hindrance in bimetallic catalysts as a method to alter product selectivity in furfural hydrogenation using Rh-based iNPs by varying the size of the secondary metal atoms. RhGa, RhIn, and RhBi nanoparticles were synthesized within confined mesoporous silica wells (MSWs) and assessed for the vapor-phase hydrogenation of furfural. RhGa and RhIn iNPs enable product control with an enhanced selectivity to furan and furfuryl alcohol (>90%) compared to the monometallic Rh@MSW. Adding Bi to Rh inhibits the transformation of furfural almost entirely. In situ diffuse reflectance infrared Fourier transform spectroscopy studies and density functional theory-based machine-learning accelerated molecular dynamics simulations reveal that the secondary metal’s identity strongly impacts the preferred furfural adsorption mode on the active sites, leading to the observed catalysis control. The mesoporous silica shell of the RhM@MSW catalyst provides protection against NP aggregation under reaction and regeneration conditions, as supported by good stability during recycling studies.