Hydrogen production for the synergistic catalytic of modified-titanium dioxide supported nickel catalyst with potassium carbonate catalyst by supercritical water gasification of coal

Supercritical water gasification (SCWG) is a novel energy utilization technology for converting coal into hydrogen (H₂)-rich gas products. Constructing a synergistic catalytic system is crucial for the enhanced production of H₂ in the SCWG of coal. This work constructed a novel synergistic catalytic system, Mo, Co, and Cu were employed to modify titanium dioxide-supported nickel (Ni/TiO₂) catalysts which were added to separate reaction zones independent with potassium carbonate (K₂CO₃) to exhibit synergistic effects, thereby enhancing H₂ yield. The modification of Ni/TiO₂ can improve the stability of the catalyst by causing lattice shrinkage of TiO₂, and the synergistic catalytic system exerted much higher carbon gasification efficiency (CGE) and H₂ yield than the non-catalytic condition in this way. Among all the Ni/TiO₂ catalysts, synergistic Ni–Cu/TiO₂ with K₂CO₃, which has the smallest Ni particle size, maximized the CGE and H₂ yield from 30.82% to 15.48 mol kg⁻¹ to 95.43% and 81.42 mol kg⁻¹, respectively. The synergistic catalytic mechanism was further revealed, providing theoretical support for the regulation of hydrogen production from SCWG of coal.