Acidic eco-catalysts derived from coffee husks in the acetylation of glycerol

The transformation of coffee husks into solid acid catalysts (eco-catalysts) was studied. The synthesis of the materials consisted of the elaboration of carbonaceous supports by thermal means [graphitic carbon (Cp) and biochar ( Cc )], followed by functionalization with sulfonic groups, by means of two techniques: i) in situ diazotization with sulfanilic acid (S D ) or ii) direct sulfonation with sulfuric acid (S A ). The density of acid sites (-SO 3 H) present in the materials was determined by elemental analysis and additionally characterizations such as TGA, XRD, TEM and FTIR spectroscopy were performed. The catalytic properties of eco-catalysts in the glycerol acetylation reaction were studied and compared with a commercial sulfonic resin, i.e. Amberlyst® 15. It was found that all of them were more active compared to Amberlyst ® 15. CpS A showed the highest conversion and selectivity towards triacetin, the product of interest.