Method for preparing melamine

Abstract

Method for preparing melamine from urea via a high-pressure process in which solid melamine is obtained by transferring the reactor product comprising liquid melamine, CO2 and NH3 to a gas / liquid separator and subsequently transferring the melamine melt coming from the separator to a vessel where the melamine melt is cooled with an evaporating cooling medium, characterized in that, the gas / liquid separation is conducted by addition of 5.10<-4> - 2.10<-2> mole of water per mole of melamine.

Description

technical field [0001] The present invention relates to a method for preparing melamine from urea under high pressure, wherein by including liquid melamine, CO 2 and NH 3 The reactor product is transferred to the vapor-liquid separator, and then the melamine melt coming out of the vapor-liquid separator is transferred to a container, wherein the melamine melt is cooled with a cooling medium to obtain a melamine solid. Background technique [0002] This method is described, inter alia, in European patent EP-A-747366. This document describes a process for the high-pressure preparation of melamine from urea. Specifically, EP-A-747366 describes how urea is thermally decomposed in a reactor at a pressure of 10.34-24.13 MPa at a temperature of 354 to 454° C. to obtain a reactor product. The obtained reactor products include liquid melamine, CO 2 and NH 3 , the product is transferred to a vapor-liquid separator under the pressure of the mixed vapor. In the vapor-liquid separa...

AI Technical Summary

Problems solved by technology

[0003] According to EP-A-747366, the purity of the final product of melamine is above 98.5%, but this result is difficult to continuously maintain at a constant level in large-scale industrial production

This is a disadvantage of this method, especially when melamine is used to prepare melamine-formaldehyde resins for laminates and / or coatings