Patent ID: 6815527
Filing Date: 2004-11-09
Classification: C08G

Abstract:
A continuous process for preparing a polyamide by reacting at least one aminonitrile with water, which comprises:(1) reacting at least one aminonitrile with water in the presence of an organic liquid diluent at from 90 to 400Â° C. and from 0.1 to 35Ã—106 Pa in a flow tube containing a BrÃ¶nsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile and in which up to 40% by weight of the titanium dioxide may be replaced by tungsten oxide, to obtain a reaction mixture, (2) further reacting the reaction mixture at from 150 to 400Â° C. and a pressure which is lower than the preasure in stage 1 in the presence of a BrÃ¶nsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile and in which up to 40% by weight of the titanium dioxide may be replaced by tungsten oxide, the temperature and pressure being selected so as to obtain a first gas phase and a first liquid phase or a first solid phase or a mixture of first solid and first liquid phases and so that the first gas phase is separated from the first liquid phase or first solid phase or from the mixture of first liquid and first solid phases, and (3) admixing the first liquid or the first solid phase or the mixture of first liquid and first solid phases with a gaseous or liquid phase comprising water at from 150 to 370Â° C. and from 0.1 to 30Ã—106 Pa, to obtain a product mixture.