Patent ID: 6531570
Filing Date: 2003-03-11
Classification: C08G

Abstract:
A process for producing a polyamide by reaction of at least one aminonitrile with water, which comprises the following steps:(1) reacting at least one aminonitrile with water at a temperature from 90 to 400Â° C. and a pressure from 0.1 to 35Ã—106 Pa, which reaction can be carried out in the presence of a BrÃ¶nsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst consisting of 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 a temperature from 150 to 400Â° C. and a pressure which is lower than the pressure in step 1, which reaction can be carried out in the presence of a BrÃ¶nsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst consisting of 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 or a first solid phase or a mixture of first solid and first liquid phase, and the first gas phase is separated from the first liquid or the first solid phase or from the mixture of first liquid and first solid phase, and (3) admixing the first liquid or the first solid phase or the mixture of first liquid and first solid phase with a gaseous or liquid phase comprising water at a temperature from 150 to 370Â° C. and a pressure from 0.1 to 30Ã—106 Pa, optionally in the presence of the above catalyst, to obtain a product mixture, wherein the reaction is carried out in at least one of steps (1) and (2) in the presence of lactams, amino carboxylic acids or mixtures thereof in an amount of from 0.3 to 10% by weight, based on the amount of aminonitrile used.