Impact of doping strategy on tungsten-modified nickel aluminate catalysts for glycerol hydrogenolysis via in situ hydrogen generation

Hydrogenolysis of biomass-derived glycerol using in situ generated hydrogen represents a promising pathway for the sustainable production of high-demand bio-based chemicals such as 1,2-propylene glycol. In this work, stoichiometric nickel aluminate spinel was synthesized by citrate sol–gel method and doping it with tungsten (1 wt% W) using two approaches; a one-pot sol−gel method and an impregnation technique. For the latter, two variants were explored, employing either calcined or reduced–passivated nickel aluminate as the support. The catalysts were extensively characterized in calcined and reduced states to establish correlations between synthesis route, structural features, and catalytic performance in continuous glycerol hydrogenolysis (235 °C, 45 bar, 4 h TOS). Tungsten incorporation decreased nickel crystallite size, increased the density of acid sites, and generated additional oxygen vacancies, collectively favoring C O bond cleavage over C C scission and thereby enhancing selectivity toward deoxygenated products. Among the catalysts, the impregnated sample prepared on calcined nickel aluminate exhibited the best performance, achieving 62.8 % glycerol conversion with a 18.5 % yield of 1,2-propylene glycol. Stability tests over 60 h TOS revealed significant deactivation of the undoped catalyst (35 % decay in conversion), whereas W doping via impregnation of calcined nickel aluminate significantly suppressed deactivation and preserved activity. These findings demonstrate that the tungsten incorporation method is a decisive factor in tuning the bifunctionality of nickel aluminate-derived catalysts, enabling efficient and environmentally sustainable glycerol valorization through integrated hydrogen generation and hydrogenolysis. • W doping method modulates metal support interactions and oxygen vacancies. • Balanced C O vs. C C scission by generation of electron-rich Ni W environments. • Surface W doping enhanced selectivity and yield of 1,2-PG yield. • W doping strongly improves stability (60 h on-stream) against sintering and leaching.