Selective hydrogenolysis of glycerol to 1,3-propanediol over bifunctional Pt/KIT-6 catalysts

Glycerol hydrogenolysis represents an important route for biomass valorization, enabling the sustainable conversion of glycerol, a major byproduct of biodiesel production, into value-added chemicals and thereby improving the utilization of renewable carbon resources. Selective hydrogenolysis of glycerol to 1,3-propanediol represents a critical challenge, as high selectivity requires precise control over competing C–O bond cleavage pathways on bifunctional catalysts. In this work, we establish an active-site-resolved kinetic framework to quantitatively elucidate the respective roles of metal, Brønsted acid, and Lewis acid sites in governing glycerol hydrogenolysis over Pt-based mesoporous catalysts. By systematically decoupling metal and acid site densities while preserving catalyst morphology and transport characteristics, intrinsic reaction rates and turnover frequencies for individual reaction pathways are directly quantified. Rate analysis reveals that both 1,3-propanediol formation and over-hydrogenolysis to 1-propanol are metal-mediated but are distinctly modulated by acid functionality: moderate Brønsted acidity selectively promotes 1,3-propanediol formation, whereas excessive Brønsted acidity shifts selectivity toward undesired pathways, while Lewis acid sites alone exhibit minimal promotional effects. The 0.2 wt% Pt/W–KIT-6 catalyst with a Pt site density of 9.7 × 10 ^−6 kmol kg $^ {-1}_{\mathrm{cat}}$ , a Brønsted acid-site density of 0.27 × 10 ^−6 kmol kg $^ {-1}_{\mathrm{cat}}$ , and a Lewis acid-site density of 0.06 × 10 ^−6 kmol kg $^ {-1}_{\mathrm{cat}}$ exhibits approximately 12% glycerol conversion with ∼80% selectivity to 1,3-propanediol under 200 ^∘ C and 3 MPa H _2 . The Pt-site-normalized turnover frequency for the selective glycerol-to-1,3-PDO pathway is approximately 0.07 s ^−1 . Turnover frequency analysis further demonstrates that Brønsted acid sites act as true kinetic promoters rather than merely increasing apparent activity through surface coverage effects. These findings provide a mechanistically rigorous description of metal–acid cooperation in glycerol hydrogenolysis and establish a generalizable kinetic strategy for resolving active-site contributions in complex bifunctional catalytic systems, extending beyond glycerol valorization to selective hydrogenolysis and upgrading reactions involving multifunctional oxygenates.