Sulzer Chemtech Ag

Sulzcr Chemtech Ag

Resitec Participacoes Ltda

Andrzej Kuszlik

Manfred Stepanski

Francois Loviat

François Loviat

Florian Lippuner

Axel König

Rodolfo Rohr

Herbert Engstler

Ali Nikzad

Matthias Schäfer

Matthias Schaefer

A process and an apparatus for the purification of a crude acrylic acid composition containing maleic anhydride as an impurity comprising the following steps: (a) carrying out at least one dynamic melt crystallization stage () with the crude acrylic acid composition to prepare a first purified acrylic acid composition and a first residue containing at least 3.5% by weight maleic anhydride, (b) adding a solvent () which is capable of dissolving maleic anhydride to the first residue in an amount that the weight ratio of the solvent to the maleic anhydride is 0.3 or more to prepare a ratio-adjusted residue and (c) carrying out at least one further dynamic melt crystallization stage and/or at least one static melt crystallization stage () with the ratio-adjusted residue to prepare a second purified acrylic acid composition and a second residue.

Process and apparatus for purification of acrylic acid

Disclosed is a method to prepare a polylactic acid comprising the steps of performing a ring opening polymerization using a catalyst and either a catalyst killer compound or an endcapping additive to obtain a raw polylactic acid of MW greater than 10,000 g/mol, purifying the raw polylactic acid by removing and separating low boiling compounds comprising lactide and impurities from the raw polylactic acid by devolatization of the low boiling compounds as a gas phase stream, and purifying the lactide from the devolatization and removing the impurities from the gas phase stream of evaporated low boiling compounds by means of crystallization by desublimation from the gas phase, wherein the lactide is purified and the removed impurities include a catalyst residue and a compound containing at least one hydroxyl group such that the purified lactide is then polymerized by feeding it back into the ring opening polymerization. The invention further relates to an apparatus for carrying out the method comprising a polymerization reactor for performing a ring opening polymerization to obtain a raw polylactic acid, a devolatization apparatus for separating low boiling compounds comprising lactide and impurities from a raw polylactic acid, and a crystallization apparatus for purifying a lactide and removing impurities by means of a desublimation and a crystallization in the same crystallization apparatus.

Method for the manufacture of a polyhydroxy-carboxylic acid

The present invention relates to a method for the purification of an ionic liquid by means of fractional crystallization in which a part of the ionic liquid is crystallized and the crystallizate formed is separated from the liquid remainder. In this respect the ionic liquid is charged with a certain amount of at least one entrainer substance.

Method of purifying ionic liquids

This invention relates to a method and a device for purifying and/or separating preferably high melting organic raw products or compound mixtures containing, in particular, high melting and/or degradable sterols, by layer crystallization on first heat exchanger surfaces. The raw product is received in a solvent or solvent mixture, and then brought into contact with heat exchanger surfaces. The desired product crystallizes on the heat exchanger surfaces by slow cooling. Solvent evaporating during the crystallization or sweating process is condensed and returned to the mixture.

Method and device for purifying high melting organic raw products or compound mixtures by means of fractionated melting crystallisation from solvent mixtures

Growing community of inventors

Buchs, Switzerland

Andrzej Kuszlik