Process for the preparation of fatty acid esters and thus obtained high purity esters

摘要

The process enables the simultaneous production of a 6-26C ester composition and glycerin from primary products such as used frying oils by reaction with a 1-4C monoalcohol. The ester composition can be used as a gas oil fuel substitute. The composition of 6-26C linear monocarboxylic esters is obtained as follows: (a) the vegetable or animal oil (optionally acidic) is reacted with an excess of a 1-4C aliphatic mono-alcohol in the presence of a heterogeneous catalyst, with the elimination of excess monoalcohol and separation of glycerin : a crude ester product containing fatty acid esters and residual monoglycerides is obtained; (b) the crude ester is submitted to reaction of transesterification or esterification of residual monoglycerides into di- and possibly tri-glycerides in the presence of a similar heterogeneous catalyst by the fatty acid esters or an added 6-26C fatty acid; and (c) the ester composition is evaporated under reduced pressure and the residue , containing di-and triglycerides recycled to (a). An Independent claim is also included for the ester composition obtained by the process.