Photocatalytic decarboxylation of fatty acids for production of drop-in biofuels
biofuel; photocatalysis; decarboxylation; fatty acids
The growing concern with the progression of the effects of global warming caused by the emission of greenhouse gases (GHG) over the years has aroused interest in diversifying the energy matrix. In this context, there was a growth in demand to produce drop-in biofuels, chemically identical to fossil fuels, to reduce dependence on non-renewable resources and mitigate CO2 emissions. To form a mixture of renewable hydrocarbons, compatible with the structure of the engines, the biomasses to be used need to undergo deoxygenation processes, such as thermocatalytic processes. However, existing methodologies have some operational limitations like high temperatures, high pressures of hydrogen gas, and the need for specific reactors. In this sense, the present work proposes developing a photocatalytic and selective method to deoxygenate fatty acids from vegetable oils under mild conditions, using an organic photocatalyst, at room temperature, in a metal-free process, and without hydrogen gas. After optimizing the reaction conditions for a model compound, lauric acid (C12:0), the major component of some vegetable oils, yields of up to 80% were obtained for the formation of undecane. The evaluated parameters were photocatalyst, hydrogen transfer, base, their respective stoichiometries, reaction concentration, light source, and reaction time, in addition, was the performance of control experiments. Subsequently, the reaction scope will be evaluated when applying the methodology to other pure fatty acids and mixtures, including the one obtained from the hydrolysis of commercial vegetable oils. This new method emerges as a viable alternative to existing deoxygenation processes to produce mild drop-in biofuels with a highly selective formation of Cn-1 hydrocarbons.