Glycerol acetylation catalysed by ion exchange resins

Five types of ion exchange resins (Amberlyst 15, Ambertlyst-36, Dowex 50Wx2, Dowex 50Wx4 and Dowex 50Wx8) have been compared in glycerol acetylation carried out at 378 K and atmospheric pressure. The glycerol: acetic acid molar ratio was set to 8:1. In these conditions the best performances were exhibited by Amberlyst-36 and Dowex-2. The effects of catalyst loading and the pre-treatment were also studied for the latter catalysts, showing that the use of 6.25 g of dry catalyst/l of glycerol resulted in the optimal conditions for our reaction. The catalytic performances of the resins were unaltered after washing with distilled water in a Soxhlet apparatus, showing that sulphonic species were not removed by leaching. Recyclability tests showed that these solids are directly reusable up to 4-5 esterification runs. No homogeneous catalysis was detected in the filtered liquid media obtained after contact with the solids. Resins are not deactivated by the presence of water in the reaction medium. (C) 2012 Elsevier B.V. All rights reserved.