Catalysts based on transition metals are employed for hydrodeoxygenation in biofuel processes. However, the limitations are over-hydrogenation of arenes and contaminated product issue. Here, we report the metal-free nitrogen-assembly carbons (NACs) and single-atom catalysts (SACs) as sustainable catalysts to replace metals in hydrogenolysis and hydrogenation. This work combines both experiment and density functional theory (DFT) calculations. We find that synergies of graphitic nitrogen-assembled atoms on graphene are active and selective for hydrogenolysis of alkylarenes. DFT calculation shows that the nitrogen-assembled atoms localized charge densities at neighboring carbon atoms which allows H2 molecule to dissociate. The activation barriers of H2 dissociation on clustered N sites are from 1.1 to 2.4 eV, and dissociative adsorption energies are between -0.8 and 0.8 eV. In addition, SACs of Fe, Co, Ni, Cu, Ru, Pd and Pt for H2 activation were studied based on DFT calculations. We show that Frontier orbital provided by density of state (DOS) are well correlated to the activities of SACs. In particular, Fe and Co SACs show the most catalytic activity for dissociation of H2. This study provides tailored designs of new promising catalysts for challenging chemical reactions.

Metal-free carbocatalyst and single atom catalysts for hydrodeoxygenation

ACS Spring Meeting 2021

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