Bifunctional hydrogen buffer catalytic system forenhanced hydrodeoxygenation of guaiacol under mild conditions

Abstract

Developing stable, high-performance catalysts for hydrodeoxygenation (HDO) reactions under mild conditions is crucial for advancing biomass conversion into high-value chemicals. This study introduces a bifunctional catalytic system consisting of a glucose-modified Ni-MOF-74-derived carbon catalyst (Ni/C-G) and silicotungstic acid (SiW 12 ) as a hydrogen buffer and carrier. Compared to phosphotungstic acid (PWA) and phosphomolybdic acid (PMO), SiW 12 exhibits superior performance, attributed to its reversible redox cycle, stability, and efficient hydrogen transfer capacity. The glucose modification of Ni-MOF-74 enhances the dispersion of nickel nanoparticles (Ni NPs), reduces agglomeration, enhances the hydrogen spillover, and introduces additional porosity while forming protective carbon layers (∼3.072 nm thick) around the active Ni NPs. These layers stabilize the catalyst in aqueous environments, enabling consistent catalytic performance over five cycles without activity loss. The system achieved a guaiacol HDO conversion of 74.93 % and cyclohexanol selectivity of 66.03 % under mild reaction conditions (95 °C, 1 MPa H 2 , 1 h). The key reaction pathways for SiW 12 -induced HDO, including demethoxylation and aromatic ring hydrogenation, facilitate selective cyclohexanol production. The synergistic interaction between Ni/C-G and SiW 12 boosts hydrogen transfer and enhances the catalyst’s stability, making this system a highly effective solution for upgrading bio-oil and enabling sustainable biomass conversion under mild conditions.

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