Highly selective acetalization of glycerol with acetone to solketal over acidic carbon-based catalysts from biodiesel waste

Abstract

The glycerol acetalization reaction in the presence of acetone was evaluated using acidic carbon-based catalysts from biodiesel waste as catalysts. Acidic carbon-based catalysts were prepared with different glycerin: sulfuric acid mass ratios at 457 K for 24 h. The amount of acid groups as well as the acidity (mainly attributed to sulfur groups) enhance with an increase of glycerol: sulfuric acid ratio (1: 2 and 1: 3, named GC-1: 2 and GC-1: 3, respectively), reaching 0.9 mmol g(-1) for sulfur and 3.8 mmol g(-1) for total acidity. Very promising results were obtained when these carbon-based catalysts were tested as catalysts in glycerol acetalization, reaching about 80% of glycerol conversion and about 95% of solketal selectivity, this product has been applied as a fuel additive. Furthermore, the carbon-based catalysts surface groups showed high stability under the reaction conditions tested in this study. These results indicated that acidic carbon-based catalysts derived from glycerin are very attractive catalysts for glycerol acetalization. (C) 2016 Elsevier Ltd. All rights reserved.