Descarboxilação redutiva catalisada por níquel para produção de biocombustíveis drop-in

Abstract

Drop-in biofuels emerge as alternatives to petroleum derivatives to reduce CO2 emissions into the atmosphere, contributing to energy transition to a low carbon economy. These fuels are formed by mixture of renewable hydrocarbons that can be obtained from deoxygenation of biomass. Currently, hydrotreatment is main process applied for this purpose, however, use of high temperatures and consumption of hydrogen gas is desirable look for other methods. For this, the present work proposed to develop methodology for deoxygenation of fatty acids, under mild conditions, using nickel complex as catalyst and low-cost silane as alternative source of hydrogen. Therefore, fatty acids were converted into redox-active esters and optimization study was carried out using lauric acid ester as model compound. Different parameters of system were investigated and after 175 reactions it was possible to find best set of reaction conditions, which allowed the decarboxylation of lauric ester to be carried out at 40°C, in open atmosphere and without specific reactors. The scope of method was extended to convert esters derived from other fatty acids, including synthetic mixture, and results obtained by GC-FID indicated production of hydrocarbons in range of green diesel and aviation biokerosene with high selectivity and yields 33-67%, under free-hydrogen conditions. Finally, application of method in one-pot reactions was satisfactory to directly convert some of tested fatty acids, indicating that ester isolation step could be dispensed, increasing efficiency of developed protocol.