InNi₃C_0.5/Fe₃O₄ catalyst for the CO₂ hydrogenation to methanol: Co-precipitation preparation, performance and mechanistic insight

Efficient conversion of CO₂ to methanol using a renewable source of H₂ is a feasible strategy to achieve the goal of carbon neutrality. A qualified InNi₃C_0.5/Fe₃O₄ catalyst system was developed by the co-precipitation method. The effects of catalyst preparation were investigated systematically on the catalyst performance. Well-formation of InNi₃C_0.5 nano-intermetallic is essential to a high activity/selectivity of catalyst, which is strongly dependent on the catalyst calcination/carburization temperatures. The catalytic-relevant electronic metal-support interaction is tightly linked with the InNi₃C_0.5 particle size that is tunable with In-loading. The 5InNi₃C_0.5/Fe₃O₄-400/425 catalyst (5 wt% In, calcined at 400 °C and carburized at 425 °C), with a high turnover frequency of 513 h⁻¹ and promising stability, achieves 12.3 % or 6.8 % CO₂ conversion and 95.6 % or > 99.8 % methanol selectivity without CH₄ formation at 250 or 200 °C, 4.0 MPa and 12,000 mL g_cat ⁻¹h⁻¹, for H₂/CO₂ = 5/1. A high methanol space–time-yield of 2.62 g_MeOH g_cat ⁻¹h⁻¹ is obtainable at 250 °C and 6.0 MPa. A pathway of CO₂-to-CO*-to-HCO*-to-CH₂O*-to-CH₂OH*-to-CH₃OH* is proposed for the CO₂ hydrogenation to methanol over our InNi₃C_0.5/Fe₃O₄ catalyst.