Method for producing polyamides from dinitriles and diamines

A continuous process for preparing a polyamide by reacting at least one dinitrile and at least one diamine with water, which comprises:

• (1) reacting at least one dinitrile and at least one diamine with water at a temperature from 90 to 400° C. and a pressure from 0.1 to 35×106 Pa in a flow tube containing a Brönsted 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 a temperature from 150 to 400° C. and a pressure which is lower than the pressure instage 1 in the presence or absence of a Brönsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or 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 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 or the 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 a temperature from 150 to 370° C. and a pressure from 0.1 to 30×106 Pa to obtain a product mixture.

A continuous process for preparing a polyamide by reacting at least one dinitrile and at least one diamine with water, which comprises:

• (1) reacting at least one dinitrile and at least one diamine with water at a temperature from 90 to 400° C. and a pressure from 0.1 to 35×106 Pa in a flow tube containing a Brönsted 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 a temperature from 150 to 400° C. and a pressure which is lower than the pressure in stage 1 in the presence or absence of a Brönsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or 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 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 or the 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 a temperature from 150 to 370° C. and a pressure from 0.1 to 30×106 Pa in a flow tube containing a Brönsted 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 product mixture.

A continuous process for preparing a polyamide by reacting at least one dinitrile and at least one diamine with water, which comprises:

• (1) reacting at least one dinitrile and at least one diamine with water at a temperature from 90 to 400° C. and a pressure from 0.1 to 35×106 Pa in a flow tube containing a Brönsted 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 a temperature from 150 to 400° C. and a pressure which is lower than the pressure in stage 1 in the presence or absence of a Brönsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or 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 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 or the first solid phase or from the mixture of first liquid and first solid phases, and
• (4) postcondensing the first liquid or the first solid phase phase or the mixture of first liquid and first solid phases at a temperature from 200 to 350° C. and a pressure which is lower than the pressure in stage 3, the temperature and pressure being selected so as to obtain a second, water- and ammonia-containing gas phase and a second liquid or second solid phase or a mixture of second liquid and second solid phases, which each include(s) the polyamide.