Catalyst and Parameter Optimization Study for Slurry-Phase Methanol Synthesis Using Ni-Doped Indium-Based Catalysts

Producing green methanol using renewable hydrogen and CO2 in a slurry reactor is a promising approach for chemical energy storage and to mitigate global warming caused by industry emissions. A slurry reactor using mineral oil as a carrier liquid compensates for fluctuating conditions due to the high heat capacity and thermal stability. In the present study, metal-promoted In2O3/ZrO2 catalysts have been synthesized by various preparation methods in combination with different support materials. Design of experiment studies aimed at finding optimum parameters for slurry-phase CO2 hydrogenation. The Ni-doped In2O3/ZrO2 catalyst prepared by coprecipitation achieved the highest activity and selectivity both for CO and CO2 hydrogenation under industrially relevant conditions. Using industry syngas composition (H2/CO/CO2) with a molar ratio of 70/28/2 at 300 °C and 75 bar, a very high methanol productivity (6.84 gMeOH gmetal–1 h–1) was achieved, being five times more efficient than the commercial Cu-based catalyst (1.25 gMeOH gCu–1 h–1) related to the active metal content. Finally, the stability of the preferred slurry CO2 hydrogenation system was proven over five reaction cycles, recycling both catalyst and carrier liquid in four successive runs, showing further potential for real industrial applications in the near future.