Enhanced Aqueous-Phase Hydrodeoxygenation of Fatty Acids over CoP Anchored on P–N Co-Doped Carbon

Abstract The aqueous-phase hydrodeoxygenation of biomass-derived fatty acids offers an alternative route for the production of diesel-range hydrocarbons, but remains a major challenge. Herein, we report a hydrophobic CoP catalyst anchored on P–N co-doped carbon spheres (CoP@PNC-900), which exhibits high performance for the aqueous-phase hydrodeoxygenation of palmitic acid at 270 °C and 2 MPa H2, delivering nearly complete conversion together with over 99% yield of C15+C16 alkanes. The enhanced performance arises from the synergy between CoP active sites and the hydrophobic interface, which promotes C–O bond cleavage while enhancing the contact between hydrophobic substrates and catalytic sites. Isotopic-labeling experiments demonstrate that water acts exclusively as the reaction medium rather than a hydrogen source. In situ FT-IR–MS analysis combined with DFT calculations confirms the hydrodeoxygenation- and decarbonylation-related pathways, with C–O bond cleavage of the alcohol intermediate identified as the rate-determining step in the hydrodeoxygenation pathway. Moreover, the catalyst exhibits a broad substrate scope for various fatty acids and esters as well as stable recyclability under hydrothermal conditions. Finally, a preliminary life cycle assessment (LCA) highlights the potential environmental benefits of the aqueous-phase catalytic process. This work establishes an effective strategy that integrates active-site engineering with interfacial hydrophobic microenvironment regulation for the aqueous-phase valorization of biomass-derived fatty acids.