Scientists modified nickel catalysts by introducing tin into an ordered intermetallic structure, switching the outcome of carbon dioxide hydrogenation from methane to carbon monoxide. The findings were published in Nature Communications by researchers from East China University of Science and Technology, ShanghaiTech University, and the Norwegian University of Science and Technology.
Nickel catalysts typically favor methanation during carbon dioxide hydrogenation, limiting their use in processes aimed at producing synthesis gas. By creating an ordered Ni3Sn2 intermetallic structure, the team altered the electronic interaction between nickel and carbon monoxide. Measurements using atomic-resolution microscopy and X-ray absorption spectroscopy at the Shanghai Synchrotron Radiation Facility confirmed that tin atoms disrupt extended nickel-nickel ensembles.
Spectroscopic analysis and theoretical calculations showed that hybridization between nickel 3d and tin p orbitals downshifts the nickel 3d band. This shift weakens electron back-donation from nickel into the carbon monoxide 2π* orbital. The weakened bond facilitates carbon monoxide desorption, preventing the molecule from undergoing full hydrogenation into methane.
The Ni3Sn2 material demonstrated carbon dioxide conversion rates approaching thermodynamic equilibrium alongside nearly 100 percent selectivity for carbon monoxide. During laboratory testing, the intermetallic catalyst sustained continuous operation for 300 hours without performance loss. In situ infrared spectroscopy and steady-state isotopic transient kinetic analysis revealed that the pathway relies on hydrogen-assisted carbon dioxide activation alongside spectator-like formate species.
The research team observed corresponding reaction shifts when evaluating nickel-gallium and nickel-indium catalyst configurations. Funding for the research included support from the National Key R&D Program of China and the Natural Science Foundation of China.
