Aqueous-Phase Reforming of Guaiacol: Coproduction of Phenol and Green Hydrogen

Lignin, a methoxy-rich aromatic biopolymer, represents a promising renewable feedstock for the sustainable production of fuels and chemicals. However, achieving high catalytic activity and selectivity for the upgrading conversion of lignin derivatives without external hydrogen input remains a challenge. Herein, we report an inverse-encapsulated NiMgAl IE catalyst synthesized via hydrothermal etching, which enables the selective demethoxylation of guaiacol into phenol while simultaneously generating hydrogen through in situ aqueous-phase reforming of dissociated methoxy groups. Under mild reaction conditions (180 °C and 1 MPa), guaiacol conversion reaches 91.6%, with a phenol selectivity of 88.9% and a hydrogen production rate of 429.6 μmol g –1 h –1 . An in-depth investigation based on kinetic isotope effect studies, in situ spectroscopies, and DFT calculations substantiates that the Ni 0 –Ni v –AlO x interface serves as the intrinsic active site, in which the surface Ni 0 sites facilitate water dissociation, the adjacent nickel vacancies promote guaiacol adsorption, and the AlO x coating layer assists in C–O bond activation. Techno-economic analysis confirms the pronounced economic feasibility and promising industrial scalability of phenol–hydrogen coproduction from guaiacol through aqueous-phase reforming (ROI, 20%; payback, 3.9 years). This study highlights a green, cost-effective, and scalable aqueous strategy for the coproduction of phenol and green hydrogen, providing mechanistic insights and design principles for advanced biomass valorization catalysts.