Noble-metal-free Co4N derived from Co3O4 nanosphere as an effective catalyst for water gas shift reaction

Water gas shift (WGS) reaction is crucial for removing CO impurity in industrial hydrogen production. Noble-metal-free Co-based species mainly serve as a support rather than dominant sites for this reaction. Here, a bulk Co 4 N nanospheres (Co 4 N-NS) catalyst is prepared via temperature programmed nitriding using Co 3 O 4 nanosphere precursor for low-temperature WGS reaction. It is found that the CO conversion can achieve 97.6% at 240°C, and the thermodynamic equilibrium conversion is reached at 250°C, which is unprecedentedly reported for Co-based catalysts. Moreover, the reaction rate reaches 19.84 mmol CO g cat −1 h −1 with a better stability, 4.5 times higher than that on Co 4 N-C from commercial Co 3 O 4 precursor. The characterizations and kinetic studies show that Co 4 N-NS enhances the H 2 O activation and promotes the CO adsorption, which renders a lower activation energy compared to Co 4 N-C for the WGS reaction. This study offers insights for designing cost-effective WGS catalysts with transition metal nitrides.