The production of diesel-like hydrocarbons from palmitic acid over HZSM-22 supported nickel phosphide catalysts

[Display omitted] •High quality diesel with a heat value of 46.4MJkg−1 was obtained.•The mechanism of the catalytic deoxygenation of palmitic acid was proposed.•Ni12P5 was mainly responsible for the decarbonylation and decarboxylation.•HZSM-22 exhibited activity in the isomerization and cracking of palmitic acid. We have synthesized the nickel phosphides supported on the commercial HZSM-22 catalysts, which were used to convert palmitic acid to diesel-like hydrocarbons under ambient pressure in the absence of any solvents. The deoxygenation reactions of palmitic acid were studied in a fixed-bed reactor over HZSM-22, NixP/HZSM-22, Ni2P/HZSM-22, the unsupported NixP and the unsupported Ni12P5 catalysts. The conversion of palmitic acid and the hydrocarbon yield were found to be 99.6% and 42.9%, respectively, for the best catalyst, 40 NixP/HZSM-22. The heat value of the resulting hydrocarbons was 46.4MJkg−1. Ketones and aldehydes were identified as reaction intermediates, which were subsequently converted into hydrocarbons. In addition, short-chain hydrocarbons and aromatic hydrocarbons were generated, suggesting the presence of cracking and isomerization reactions. Our mechanistic exploration and the NH3 adsorption–desorption DRIFT spectra suggest that the decarbonylation and decarboxylation are facilitated by NixP, whereas Brønsted acid sites on HZSM-22 play a crucial role in the isomerization reactions and Lewis acids sites on catalysts are responsible for the cracking reactions. The present study demonstrates that the catalysts such as NixP supported on commercial HZSM-22 can serve as a practical modus with excellent catalytic activity to produce diesel-like hydrocarbons from biomass-based oil.