Unpromoted copper supported mesoporous silica nanocatalysts for the selective hydrogenation of biomass-derived levulinic acid to γ-valerolactone

Levulinic acid (LA), derived from lignocellulosic biomass, is an important platform molecule for the production of renewable fuels and value-added chemicals. Its catalytic hydrogenation to γ-valerolactone (GVL), a bio-based compound with applications as a fuel additive, solvent, and precursor to valeric biofuels, represents a promising route for upgrading biomass-derived feedstocks. In this work, we investigate the structure–activity–stability relationships of unpromoted, high-loading (10 wt%) Cu/SBA-15 catalysts prepared by incipient wetness impregnation, glycine-assisted auto-combustion, and deposition–precipitation, respectively. Quantitative N 2 O chemisorption shows that the preparation method strongly affects copper dispersion (9.3–56.5%) and active Cu surface area (5.9–32.5 m 2 Cu g cat −1 ), which correlate with LA-to-GVL hydrogenation productivity (0.26–5.93 h −1 at 150 °C and 30 bar H 2 ). XRD, XPS, and Cu LMM Auger spectroscopy reveal differences in copper reduction and surface speciation, indicating that the Cu 0 /Cu + balance is a contributing factor to the observed GVL selectivity. HAADF-STEM confirms that the deposition–precipitation method produces finely dispersed Cu nanoparticles with sizes below 5 nm within the SBA-15 mesopores. The optimized unpromoted catalyst achieves a GVL productivity of 25.60 h −1 at 175 °C and 30 bar H 2 , which, to the best of our knowledge, is the highest reported for Cu-based catalysts in liquid-phase LA hydrogenation. The catalysts also exhibit good structural and catalytic stability upon recycling, with low Cu leaching (<2 ppm), limited particle growth, and no evidence of severe surface deactivation. Overall, the results demonstrate the potential of unpromoted Cu/SBA-15 catalysts for the efficient conversion of levulinic acid to γ-valerolactone and provide practical guidelines for developing stable, earth-abundant catalysts for biomass valorization.