Emerging catalysis in biomass valorisation: simple Zn(II) catalysts for fatty acids esterification and transesterification

The growing concern about global warming and the consumption of fossil fuels has driven in recent decades the use of biomass as a renewable feedstock. In this context, vegetable oils, the corresponding fatty acids (FAs) and esters (FAEs) have primary importance: their esterification and transesterification lead to innovative products, that find application in several sectors, from biofuels to solvents, from surfactants to cosmetic ingredients and plasticizers. Lewis acid catalysis represents the most accredited methodology for developing processes of esterification and transesterification in line with sustainability requirements. The results available so far reveal the prevalent catalytic role of Zn(II) salts and coordination compounds, due to their beneficial eco-toxicological profile, combined with an appropriate acidity, finely tunable through selective functionalization. This review provides a picture of the state of the art in this important sector of biomass valorization.