Mesoporous sulfonic acids as selective heterogeneous catalysts for the synthesis of monoglycerides

Glycerol was esterified with an equimolar amount of lauric acid to monolaurin using zeolites, sulfonic resins, and sulfonic mesoporous materials as catalysts. The latter were obtained by immobilization of 3-mercaptopropyl groups and oxidation with H2O2. In particular, fatty acid conversions, monoglyceride yields, and selectivities obtained with mesoporous (ordered, amorphous) sulfonic catalysts were compared with those of other heterogeneous or homogeneous catalysts. When using silica gel coated with propylsulfonic acids, high reaction rates are coupled to high monoglyceride yields, e.g., 53% mono yield for a 1:1 glycerol:lauric acid ratio. Minimizing the autocatalytic contribution of the fatty acid reactant is a critical issue. The influence of a number of reaction parameters is investigated. The mesoporous sulfonic catalysts are also employed in the esterification of propanediols and meso-erythritol, and for reactions with other fatty acids. (C) 1999 Academic Press.