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The catalytic activity of metallic nickel (Ni) is mainly attributed to its electronic structure, surface properties, and the ability to form intermediates in chemical reactions.
1. Electronic structure characteristics
Unfilled d orbitals: The valence electron configuration of nickel is 3d84s2, and its 3d orbital is not fully filled, which enables interaction with the electron orbitals of reactant molecules (such as H₂, CO, alkenes, etc.). This characteristic makes it easy for nickel to adsorb reactants and form intermediate complexes, reducing the activation energy of the reaction.
2. Variable oxidation states: Nickel can exhibit multiple oxidation states (such as Ni⁰, Ni²⁺, Ni³⁺) during reactions, facilitating electron transfer processes and promoting redox reactions (such as hydrogenation, dehydrogenation reactions). Professor MacMillan has reported on light nickel catalytic reactions, refer to this 10.1126/science.adl5890
3. Surface adsorption and activation ability
Adsorption of reactants: The nickel surface can effectively adsorb small molecules (such as H₂, CO, C=C bonds), and weaken the chemical bonds of these molecules (such as H-H bonds, C=O bonds) to activate them. For example: hydrogen molecules (H₂): At the nickel surface, they dissociate into active hydrogen atoms (H·), used for hydrogenation reactions (such as oil hydrogenation). Carbon monoxide (CO): Nickel can adsorb CO and dissociate it, used for syngas (CO + H₂) conversion or Fischer-Tropsch synthesis.
4. Moderate adsorption strength: The adsorption of reactants by nickel is neither too strong (to avoid poisoning the catalyst) nor too weak (to ensure sufficient activity), belonging to an ideal catalytic material.
