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:
Mar. 25, 2014
Filed:
Jan. 18, 2011
Michael Bock, Ruppertsberg, DE;
Axel Franzke, Mannheim, DE;
Robert Baumann, Mannheim, DE;
Eckhard Stroefer, Mannheim, DE;
Michael Bock, Ruppertsberg, DE;
Axel Franzke, Mannheim, DE;
Robert Baumann, Mannheim, DE;
Eckhard Stroefer, Mannheim, DE;
BASF SE, Ludwigshafen, DE;
Abstract
The invention relates to a process for preparing isocyanates by thermal dissociation of carbamates and separation by distillation of the reaction mixture from the carbamate dissociation, comprising the corresponding isocyanate and the corresponding alcohol, by distillation in a column (K) having an enrichment section (V) and a stripping section (A), where the carbamate (1) is introduced between the enrichment section (V) and the stripping section (A) and the isocyanate is taken off as a constituent of the bottom stream (2) and the alcohol is taken off as a constituent of the overhead stream (3) from the column (K), in the presence of an inert solvent, wherein an intermediate boiler having a boiling point between the boiling point of the isocyanate and the boiling point of the alcohol under the operating conditions of the carbamate dissociation is used as inert solvent and is fed as external runback (4) in liquid form in a purity of >95% by weight, based on the total weight of the external runback (4), in the upper region of the enrichment section (V) and as gaseous, superheated stream (5) into the lower region of stripping section (A) at one or more points.