Effective deoxygenation of fatty acids over Ni(OAc)(2) in the absence of H-2 and solvent

Different metal acetate salts were systematically examined for the catalytic deoxygenation of stearic acid in the absence of H-2 and solvent for the first time. Ni(OAc)(2) exhibited the highest activity with 62% yield achieved at 350 degrees C for 4.5 h with only 1 mol% (0.2 wt%) of the catalyst. Even with 0.25 mol% (0.05 wt%) catalyst, around 28% yield was achieved within 2 h at 350 degrees C with 89% selectivity to C17 hydrocarbons. The activity based on C17 yields per Ni was 14.5 mol mol(-1) h(-1), considerably higher than that in previous reports. The catalytically active species were identified to be in situ generated Ni nanoparticles (8-10 nm) formed from the decomposition of the metal precursor with stearic acid as a stabilizer. A new reaction pathway of alkane formation from stearic acid via anhydride intermediate decarbonylation under an inert gas atmosphere was proposed. The excellent stability of the catalyst was demonstrated by re-adding a substrate to the system, during which the activity remained constant through four consecutive runs. The novel catalytic system was found to be applicable to a range of fatty acids and triglycerides with varying activities.