Sulfonated Reduced Graphene Oxide: An Acid Catalyst that Efficiently Promotes the Esterification of Glycerol

Abstract

A sulfonated graphene catalyst was designed and tested in the acetylation of glycerol. The catalyst was synthesized using graphite as starting material and comprised three stages, which included: (i) synthesis the graphene oxide by means of a modified Hummers method, (ii) reduction with ascorbic acid, and (iii) functionalization of the material with sulfanilic acid by in situ diazotization. Structural, morphological and chemical properties were characterized by SEM, XRD, and FT-IR spectroscopy. The acidity was determined by elemental analysis. The catalytic properties of catalyst in the glycerol acetylation were studied and compared with a commercial sulfonic resin, i.e. Amberlyst® 15. The sulfonated graphene presents attractive features in the catalytic transformation of glycerol, allowing for significant increase in the reaction rate at low temperature, and achieving at optimum activity and greater selectivity towards triacetin.