A robust Co/SiO2 catalyst for sustainable sorbitol production: from batch to continuous flow

Abstract

The development of efficient non-noble metal catalysts for glucose hydrogenation to sorbitol is essential for sustainable biomass valorization. Herein, a robust Co/SiO₂ catalyst prepared by incipient wetness impregnation is reported. The catalyst with 50 wt% Co loading exhibits a dominant mesoporous structure and moderate metal–support interaction, which stabilizes uniformly dispersed Co₃O₄ nanoparticles. Under optimized batch conditions (145 °C, 5 MPa H₂), complete conversion and a 99.2% sorbitol yield were achieved within 1 h. In situ FTIR DRIFTS reveals a synergistic mechanism wherein Co–O–Si interfacial sites facilitate glucose adsorption and activation, while adjacent metallic Co⁰ sites provide active hydrogen, effectively suppressing decarbonylation side reactions. The catalyst demonstrated good stability, retaining 88.1% of its initial activity after five cycles. In continuous-flow operation, the catalyst achieved 98.8% conversion with 97.6% yield under optimal conditions, with a gradual decline to approximately 85% conversion after 120 h on stream. This work provides fundamental insights into the structure–activity relationship of Co-based catalysts and demonstrates their potential for industrial sorbitol production, while identifying areas for further improvement in long-term stability.