Combined Hydrogen and Alkane Production by Photocatalytic Decarboxylative C–C Homocoupling of Fatty Acid by Constructing a Hydrogen-Deficient Catalytic Interface

Decarboxylation of biomass-derived fatty acids provides an important method for the production of value-added alkane fuels and chemicals. Here, selective decarboxylative C–C homocoupling of fatty acids to obtain long-chain alkanes was achieved by heterogeneous photocatalysis under mild conditions. Hydrogen was cogenerated as the potential energy source. The high selectivity for the coupling product was realized by constructing a hydrogen-deficient catalytic interface through the combined action of Ru nanoparticles supported on TiO₂ and continuous N₂ blow, which can inhibit the hydrogenation of alkyl radicals and enhance the C–C coupling of alkyl radicals. C_2n–2 saturated alkanes (as high as 93%) and hydrogen (as high as 20.3 μmol·mL^–1) are produced from bioderived C₄–C₁₂ fatty acids in high yields under mild reaction conditions (25 °C, N₂ blow). Furthermore, low-value industrial fatty acid mixtures such as coconut oil and Cinnamomum camphora seed kernel oil can be directly applied in this catalytic system and selectively yield long-chain alkanes (up to 80%) in a solvent-free system. Density functional theory (DFT) calculations and various analytical methods were applied to elucidate the possible catalytic mechanism.