申请人:BOCK Michael
公开号:US20110178329A1
公开(公告)日:2011-07-21
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.
本发明涉及一种通过热解氨基甲酸酯并通过蒸馏从氨基甲酸酯解离反应混合物中分离出相应的异氰酸酯和相应的醇的过程,其中通过具有富集段(V)和剥离段(A)的塔(K)蒸馏,将氨基甲酸酯(1)引入富集段(V)和剥离段(A)之间,并将异氰酸酯作为底流(2)的组分和醇作为塔(K)的顶流(3)的组分取出,存在惰性溶剂的情况下,其中使用具有沸点介于异氰酸酯和醇的沸点之间的中间沸腾剂作为惰性溶剂,并以液态形式作为外部回流(4)在富集段(V)的上部区域中以>95%重量纯度的形式投入,并作为气态过热流(5)在剥离段(A)的下部区域中的一个或多个点投入。