Effective Deoxygenation of Palmitic Acid to Diesel-Like Hydrocarbons over Ni-Based Catalysts without Added Hydrogen

The lipid-derived carboxylic acids are promising for renewable hydrocarbons, which are alternatives to fossil fuels. In this work, we studied a promising method for obtaining long-chain alkanes from palmitic acid, a model compound for biomass microalga, through decarboxylation under non-hydrogen conditions. Under hydrothermal conditions, it was found that the smaller the Ni particle size, the higher the yield of long-chain alkanes obtained. When the Ni particle size of Ni/ZnO/AlOn-500 reaches 6.5 nm, the highest yield of long-chain alkane is 54.2 mol %. The catalyst recycling experiment showed that the decarboxylation yield of the catalyst recycled twice would decrease. Through XRD analysis of the catalyst, it was found that the particle size of Ni in the catalyst increased significantly after the decarboxylation reaction. This may be the main reason for the decrease in the yield of long-chain alkanes after the catalyst was recycled. In the end, a possible reaction mechanism was proposed by studying the distribution of the reaction products.