Palladium Hydride Catalyst for CO-Tolerant Formate Production

The patent changes the chemical state of palladium from metallic Pd(0) to palladium hydride Pd-H by controlling hydrogen content (x in PdHx) during synthesis. This parameter change transforms the catalyst's electronic structure and surface properties, enabling it to maintain high formate selectivity while developing enhanced CO tolerance and stability. The hydrogen content is precisely controlled at 0.2-0.8 equivalents per Pd atom to achieve optimal performance.

The patent creates a composite catalyst system where palladium hydride nanoparticles are supported on carbon materials (such as carbon nanotubes, graphene, or activated carbon). This composite structure combines the high formate selectivity of Pd-H with the stability and CO tolerance provided by the carbon support, preventing Pd aggregation and enhancing overall catalyst durability.

The patent converts the harmful effect of CO adsorption on Pd surfaces into a beneficial outcome. By forming Pd-H species, the catalyst develops enhanced CO tolerance where CO molecules no longer strongly poison the surface. The hydrogen-rich environment actually protects the catalyst from CO deactivation, extending operational lifetime while maintaining high faradaic efficiency for formate production.

The patent performs preliminary hydrogenation of palladium during the catalyst synthesis process, creating Pd-H species before the actual CO2 reduction reaction begins. This preliminary action of introducing hydrogen into the Pd lattice pre-configures the catalyst with enhanced stability and CO tolerance, preventing deactivation during subsequent long-term operation.