The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 26, 2019
Filed:
Jul. 30, 2015
Sulzer Chemtech Ag, Winterthur, CH;
Matthias Schäfer, Kreuzlingen, CH;
Andrzej Kuszlik, Buchs, CH;
Florian Lippuner, Gams, CH;
Herbert Engstler, Frastanz, AT;
Sulzer Chemtech AG, Winterthur, CH;
Abstract
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.