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 H-2 is a feasible strategy to achieve the goal of carbon neutrality. A qualified InNi3C0.5/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 InNi3C0.5 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 InNi3C0.5 particle size that is tunable with In-loading. The 5InNi(3)C(0.5)/Fe3O4-400/425 catalyst (5 wt% In, calcined at 400 degrees C and carburized at 425 degrees 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 degrees C, 4.0 MPa and 12,000 mL g(cat)(-1)h(-1), for H-2/CO2 = 5/1. A high methanol space-time-yield of 2.62 g(MeOH) g(cat)(-1)h(-1) is obtainable at 250 degrees 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 InNi3C0.5/Fe3O4 catalyst.