Process to obtain a mixture of lower carboxylic mono, di and triesters from raw glycerin

摘要

An process to obtain a mixture of lower carboxylic acid mono, di and triesters, from raw glycerin, a by-product of the process to obtain biodiesel, a transesterification of vegetable raw material with lower alcohols is described. Also described is a process to obtain triacetin or a mixture of mono-, di- and triacetin from that raw glycerin, without prior purification.

主权项

1. A process of obtaining a mixture of mono, di and triesters comprising at least 60% of triesters of C1-C6 carboxylic adds from raw glycerin obtained from the transesterification process of animal-or-vegetable-origin lipids to obtain biodiesel, without prior purification, comprising from 60% to 90% by weight of glycerin, the process comprising the following steps:
a. charging a reactor comprising a rectification column provided with a condenser and a phase separator for liquid, with raw glycerin, C1-C6 carboxylic add and/or its anhydride, one or more azeotropic agents, and one or more esterification catalysts; b. heating until total reflux; c. rectifying and condensing vapors, separating the formed organic and aqueous phase; d. returning the organic phase to the top of the column, withdrawing the aqueous phase; e. performing steps c and d for a period of time sufficient to take the reaction to a content of 80% of triester with respect to the total esters obtainable by the reaction; f. optionally neutralizing the reaction medium at this point; g. removing solids at this point or later, in step k; h. removing the azeotropic agent; i. removing the remaining C1-C6 carboxylic acid; j. neutralizing the reaction medium, if the neutralization of step f was not previously performed; k. removing solids, if item g was not previously performed; l. optionally re-esterifying the product obtained in step k; and m. optionally, distilling the obtained mixture of esters; wherein the step of removing solids is always performed after a step of neutralization.