Patent ID: 7375223
Filing Date: 2008-05-20
Classification: B01J,C07D,Y02P

Abstract:
1. A high-pressure process for preparing pure melamine by pyrolysis of urea in a vertical synthesis reactor, wherein the synthesis reactor has three stages arranged vertically one on top of another, and a) in the first, uppermost stage, a smaller portion of a total amount of urea is introduced into a central tube of a first tank reactor and a first melamine-containing reaction medium is formed, b) in the second, middle stage, the first melamine-containing reaction medium and a larger portion of the total amount of urea is introduced into a central tube of a second tank reactor and a second melamine-containing reaction medium is formed, and then c) in the third, lowermost stage, the second melamine-containing reaction medium is introduced into a vertical flow tube reactor and a crude melamine melt is formed which is subsequently worked up in any desired manner and pure melamine is obtained.