Hydrogen-Free Deoxygenation of Oleic Acid and Industrial Vegetable Oil Waste on CuNiAl Catalysts for Biofuel Production

The pyrolysis of vegetable oil waste is an alternative way to convert biomass into high-quality second-generation biofuels, with social, economic and environmental sustainability. The present work deals with the pyrolysis of oleic acid as a model compound and an industrial vegetable oil residue on CuNiAl mixed oxide catalysts, derived from layered double hydroxides. Reactions of the oils pre-adsorbed on the catalysts (catalyst:oil mass ratio of 5:1) were performed at 550 & DEG;C on a micro-pyrolysis system and the analyses of volatile products were carried out online using GC/MS. Copper addition to NiAl catalysts increased the cracking of oleic acid. Increasing copper content also decreased the formation of aromatics and coke precursors, as well as oxygenated compounds. The CuNiAl catalyst with a Cu/Ni ratio of 0.4 showed strong catalytic activity in the conversion of an industrial vegetable oil residue with a high volume of free fatty acids produced. Compared to the non-catalytic reaction, the catalyst reduced the content of oxygenates and increased the content of hydrocarbons, particularly in the gasoline range (C5-C9). The CuNiAl oxide catalyst was able to convert vegetable oil residues into hydrocarbons in the range of gasoline, kerosene and diesel, and also linear alkylbenzenes as chemical precursors for surfactant production.

Automated summary

The pyrolysis of vegetable oil waste can be an effective method to convert biomass into high-quality biofuels. In this study, CuNiAl mixed oxide catalysts derived from layered double hydroxides were used to pyrolyze oleic acid and industrial vegetable oil residue. The addition of copper to the catalysts increased the cracking of oleic acid and reduced the formation of aromatics and oxygenated compounds. The CuNiAl catalyst with a Cu/Ni ratio of 0.4 showed strong catalytic activity in converting vegetable oil residue with a high volume of free fatty acids into hydrocarbons.