Sulzer Chemtech Ag

Futerro S.a.

Peter Fässler

Philippe Coszach

Manfred Stepanski

The invention relates to a process for purification of a stream containing a cyclic ester of an alpha-hydroxycarboxylic acid of formula (I), wherein each R independently represents hydrogen or an aliphatic hydrocarbon having 1 to 6 carbon atoms comprising the steps of: (a) separating the cyclic ester-containing stream into one or more cyclic ester-containing vapor fractions and one or more cyclic ester-containing liquid fractions; (b) condensing a cyclic ester-containing vaporized fraction as obtained in step (a) to obtain a cyclic ester-containing condensate; (c) subjecting at least part of the cyclic ester-containing condensate as obtained in step (b) to melt crystallization to obtain a purified cyclic ester-containing stream and a residue stream; and (d) recovering the purified cyclic ester-containing stream as obtained in step (c). The invention further relates to an apparatus suitable for carrying out the present process.

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Allschwil, Switzerland

Peter Fässler