Sulfonated hydrothermal carbon: an efficient catalyst for transformations of glycerol and fatty acids

Abstract

[Conclusions]: -Sulfonated hydrothermal carbon (SHTC) is much more active than other sulfonic solids for esterification of fatty acids with alcohols (MeOH or EtOH) and glycerol with carboxylic acids, irrespective from the nature of the sulfonic groups (aliphatic, aromatic, perfluoroaliphatic). -The highest activity of SHTC seems to be related to the high surface density of acidic groups (sulfonic and carboxylic), having a cooperative effect between them. The acidic groups form a dense network of H-bonds, which is open in polar solvents, allowing free access to the catalytic sites. -The high acid density favors deactivation due to reaction with alcohols on the surface. At the same time SHTC is highly tolerant to presence of water in the reaction medium, that significantly improves the recovery of the solid. -New ongoing research: optimization of sites density (maximization of activity, minimization of deactivation) and application to other reactions of interest.