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

Abstract

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 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 5InNi3C0.5/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 gcat−1h−1, for H2/CO2 = 5/1. A high methanol space–time-yield of 2.62 gMeOH gcat−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 InNi3C0.5/Fe3O4 catalyst.