Patent ID: 6252074
Filing Date: 2001-06-26
Classification: C07D

Abstract:
A high-pressure melamine manufacturing process starting from urea and having high yields and conversion rates comprising the steps of:a) feeding urea to a first reactor containing molten melamine, said first reactor operating continuously and being kept at a temperature in a range of 360 to 420.degree. C. and at a pressure higher than about 7.times.10.sup.3 kPa while a vigorous mixing is provided by evolving gases;b) recovering a reaction liquid product comprising 85 to 95% melamine and removing a gaseous phase comprising CO.sub.2 and NH.sub.3 ;c) feeding said recovered reaction liquid product continuously together with fresh NH.sub.3 to a first tubular reactor, whereby a substantially whole volume of said tubular reactor is occupied by the recovered reaction liquid product without any mixing of the reaction liquid product with any reactants or intermediate products, said recovered reaction liquid product is maintained at a temperature in a range of 360 to 450.degree. C. and at a pressure higher than about 7.times.10.sup.3 kPa for a residence time sufficient to complete a reaction; andd) collecting melamine from an outlet of the first tubular reactor.