Reaction of glycerol with fatty acids in the presence of ion-exchange resins: Preparation of monoglycerides

Abstract

The preparation of monoglycerides from glycerol and fatty acids in the presence of ion-exchange resins is studied. A preliminary swelling in the glycerol inhibits the reaction, whereas a swelling of the resin in the oleic acid, before the reaction, increases the activity and the selectivity. This result shows that the competitive adsorption of glycerol and fatty acid influences greatly the esterification rate. Generally, water is an inhibitor of the esterification reaction (catalyst poisoning and thermodynamic equilibrium) and different procedures have already been suggested for its elimination. By using a molecular sieve as a water trap, the oleic acid conversion increases up to 90% without any change of the monoglyceride selectivity (85%). Moreover, owing to the pore structure of the catalyst, it has to be expected that the hydrocarbon chain length of the fatty acid will influence the activity and the selectivity, evidence of which we give in the present study. Finally, if an excess of glycerol increases the selectivity of the monoglycerides, it decreases the activity and can be considered as a selective inhibitor.