InNi3C0.5/Fe3O4 catalyst for the CO2 hydrogenation to methanol: Co-precipitation preparation, performance and mechanistic insight

Efficient conversion of CO 2 to methanol using a renewable source of H 2 is a feasible strategy to achieve the goal of carbon neutrality. A qualified InNi 3 C 0.5 /Fe 3 O 4 catalyst system was developed by the co-precipitation method. The effects of catalyst preparation were investigated systematically on the catalyst performance. Well-formation of InNi 3 C 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 InNi 3 C 0.5 particle size that is tunable with In-loading. The 5InNi 3 C 0.5 /Fe 3 O 4 -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 % CO 2 conversion and 95.6 % or > 99.8 % methanol selectivity without CH 4 formation at 250 or 200 °C, 4.0 MPa and 12,000 mL g cat −1 h −1 , for H 2 /CO 2  = 5/1. A high methanol space–time-yield of 2.62 g MeOH g cat −1 h −1 is obtainable at 250 °C and 6.0 MPa. A pathway of CO 2 -to-CO*-to-HCO*-to-CH 2 O*-to-CH 2 OH*-to-CH 3 OH* is proposed for the CO 2 hydrogenation to methanol over our InNi 3 C 0.5 /Fe 3 O 4 catalyst.