Tailoring Re-Loaded Core-Shell Ni Constructions Embedded in Mesoporous Silica for the Selective Transformation of Levulinic Acid into γ-Valerolactone

Abstract

Heterogeneous core-shell catalysts have attracted significant interest because they integrate multiple catalytic functions within a single, precisely engineered architecture. In this work, we report the rational synthesis and catalytic evaluation of a Re-loaded Ni core-shell catalyst embedded in mesoporous silica for the efficient hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). The core-shell configuration enables effective confinement of Ni nanoparticles within the porous silica matrix and stabilizes spatially separated Ni and ReOX species with complementary catalytic functions. Comprehensive physicochemical characterizations confirmed the successful formation of the core-shell structure, its high structural stability, and the presence of confined metallic Ni sites responsible for H2 activation and oxophilic ReOX-derived acid sites for oxygenate activation. Under optimized conditions, the Ni12Re1.63-CS catalyst achieved complete LA conversion with a GVL yield exceeding 94% within 2 h, outperforming non-core-shell catalysts. The catalyst also displayed high intrinsic activity, with a turnover frequency of up to ~36 h-1, and maintained excellent GVL selectivity of approximately 80% during recycling, despite a gradual decrease in LA conversion. These findings demonstrate that spatial separation of hydrogenation and oxophilic adsorption sites within a core-shell architecture is critical for enhancing activity and selectivity in biomass-derived platform molecule upgrading.