Nanoparticle proximity controls selectivity in benzaldehyde hydrogenation

Abstract

Disentangling the effects of nanoparticle proximity and size on thermal catalytic performance is challenging with traditional synthetic methods. Here, we adopt a modular raspberry-colloid-templating approach to tune the average interparticle distance, while preserving all other physicochemical characteristics, including nanoparticle size. By controlling the metal loading and placement of pre-formed nanoparticles within a 3D macroporous support and using the hydrogenation of benzaldehyde to benzyl alcohol and toluene as our probe reaction, we report that increasing the interparticle distance (12 to 21 nm) substantially enhances selectivity towards benzyl alcohol (54 to 99%) without compromising catalytic activity or stability. Combining electron tomography, kinetic evaluation, and simulations, we show that interparticle distance modulates the local benzyl alcohol concentration profile between active sites, consequently affecting benzyl alcohol readsorption, which promotes hydrogenolysis to toluene. Our results illustrate the relevance of proximity effects as a mesoscale tool to control the adsorption of intermediates and hence, catalytic performance.