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 Ni0–Niv–AlOx interface serves as the intrinsic active site, in which the surface Ni0 sites facilitate water dissociation, the adjacent nickel vacancies promote guaiacol adsorption, and the AlOx 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.