Mechanistic insights into solvent-assisted BHMF hydrogenation: diatomic catalysts beyond conventional pathways

Abstract

Unraveling the dynamic coupling between catalytic sites and solvent-mediated hydrogen transport is essential for understanding selective hydrogenation under realistic conditions. In this work, we investigate the hydrogenation mechanism of 2,5-bis(hydroxymethyl)furan (BHMF) on dual-atom catalysts (DACs) using first-principles Quantum Mechanics calculations combined with molecular dynamics simulations that incorporate explicit solvent effects. Hydrogen molecules dissociate at a single metal site, with the subsequent migration of atomic hydrogen significantly facilitated by formation of a transient hydrogen-bond network in ethanol. This solvent-assisted H diffusion emerges as the most solvent-sensitive step in the reaction, highlighting the critical role of the liquid environment. BHMF is then hydrogenated via two competing pathways: (1) ring hydrogenation to form 2,5-bis(hydroxymethyl)tetrahydrofuran (BHMTHF) and (2) side-chain hydrogenation to yield 5-methylfurfuryl alcohol (5-MFA). Both Mo and Ru DAC have good performance but DFT calculations and microkinetics modeling reveal that the Ru DAC catalyst exhibits higher selectivity toward the ring hydrogenation product BHMTHF than Mo DAC across the range 300–550 K. Specifically, the selectivity on Ru DAC decreases only slightly from 99.9% to 96.2%, whereas on Mo DAC, it drops markedly from 86.1% to 43.4%. This underscores that product selectivity is jointly governed by the synergistic effects of the dual-metal centers and the structure of the surrounding solvent environment.