Acetylation of glycerol catalyzed by different solid acids

This work describes the acetylation of glycerol with acetic acid catalyzed by different solid acids. Reactions were carried out in batch mode under reflux. The kinetics of glycerol transformation and selectivity to the products, notably mono, di and triacetyl esters, were determined within 30 min of reaction time to observe the primary products. The results showed that the acid exchange resin, Amberlyst-15, was the most active catalyst, achieving 97% conversion in this period, followed by K-10 montmorillonite, niobic acid, HZSM-5 and HUSY. The selectivity varied for each catalyst and conversion degree, but the yield of di and triacetylated products increased with increasing conversion and reaction time. In all cases, the formation of alpha-hydroxy-acetone (acetol) was observed and associated with the glycerol dehydration. The poor performance of the zeolites might be related to diffusion problems of the acetylated esters inside the cavities. (C) 2007 Elsevier B.V. All rights reserved.