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 (H 2 )-rich gas products. Constructing a synergistic catalytic system is crucial for the enhanced production of H 2 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/TiO 2 ) catalysts which were added to separate reaction zones independent with potassium carbonate (K 2 CO 3 ) to exhibit synergistic effects , thereby enhancing H 2 yield. The modification of Ni/TiO 2 can improve the stability of the catalyst by causing lattice shrinkage of TiO 2 , and the synergistic catalytic system exerted much higher carbon gasification efficiency (CGE) and H 2 yield than the non-catalytic condition in this way. Among all the Ni/TiO 2 catalysts, synergistic Ni–Cu/TiO 2 with K 2 CO 3 , which has the smallest Ni particle size, maximized the CGE and H 2 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. • A novel synergistic catalytic system for supercritical water gasification was created. • Transition metals modified Ni/TiO 2 catalysts were synthesized. • NiCu alloy boosts the hydrothermal stability of Ni–Cu/TiO 2 in supercritical water. • Ni–Cu/TiO 2 synergized with K 2 CO 3 achieved an H 2 yield of 81.42 mol kg −1 . • A comprehensive synergistic catalytic mechanism was revealed.