Synthesis of polyol fatty acid polyesters using column with inert gas

Abstract

Processes for the synthesis of polyol fatty acid polyester by transesterification of a polyol comprise reacting polyol with a first portion of fatty acid lower alkyl ester to provide a first step reaction product in which substantially all of the polyol is reacted with at least one fatty acid lower alkyl ester. The processes then employ a multistage column providing substantial plug flow of liquid therein for further transesterification of the first step reaction product. Partially esterified polyol, a second portion of fatty acid lower alkyl ester and catalyst are fed to the column to form a mixture and cause further transesterification of the partially esterified polyol and fatty acid lower alkyl ester, with lower alkyl alcohol being formed as a by product. The resulting liquid mixture of reactants and product is passed in a first direction between adjacent stages through the column for further reaction of partially esterified polyol with fatty acid lower alkyl ester. An inert stripping or sparging gas is fed through the column in a second direction between adjacent stages, counter current to the flow of the liquid mixture between adjacent stages in the first direction, with radial shear agitation. The lower alkyl alcohol by-product of the polyol-fatty acid lower alkyl ester reaction is transferred from the liquid mixture to the inert gas.