Synergistic catalysis of Ni3P/N@C for efficient hydrodeoxygenation: Unraveling the role of Ni3P-N interactions in hydrogen transfer and C-O bond cleavage

Abstract

The catalytic hydrodeoxygenation (CHDO) of coal-derived oxygenates into high-value aromatic hydrocarbons is pivotal for sustainable coal valorization, yet challenges remain in achieving efficient hydrogen activation and selective C-O bond cleavage. Although the individual catalytic roles of metals and alkaline sites in CHDO are well established, in which metals primarily activate H₂ to form H^…H species and alkaline sites facilitate C-O bond cleavage by providing H⁻ species, the structure-activity relationship and hydrogen transfer dynamics in composite catalysts integrating both components remain inadequately understood. This knowledge gap hinders the rational design of catalysts with enhanced performance in CHDO. In this study, a series of Ni₃P/N@C catalysts, integrating both Ni₃P and N-alkaline functionalities, were synthesized via calcination of Ni₃P precursors at 400–800 °C, resulting in integrates metallic Ni₃P nanoparticles with N-doped carbon supports to synergistically enhance hydrogen transfer and deoxygenation. Among these catalysts, Ni₃P/N@C-600 exhibited superior catalytic activity and stability in CHDO reactions, effectively removing oxygen from the oxygen-containing compounds in the sequential thermal dissolution products, converting 91.6 % of O₄-O₆ class species to lower oxygen class (O₃-O₁) compounds. Structural characterization and mechanistic analysis revealed that the synergistic interaction between Ni₃P and N-alkaline sites enhances hydrogen activation, with Ni₃P facilitating H₂ dissociation and N-alkaline sites providing mobile H⁻ and surface-bound H⁺, thereby promoting selective C-O bond cleavage and accelerating CHDO efficiency. This work offers fundamental insights into the cooperative mechanisms of metal-alkaline catalysts and provides a strategic framework for the design of highly efficient catalysts for coal-derived aromatic hydrocarbon production.