Melamine of improved purity produced by high-pressure, non-catalytic process

A continuous process for producing melamine from urea comprising pyrolyzing urea in a reactor at a pressure at from about 1500 to 3500 psi and at a temperature at from about 670.degree. to 850.degree. F. to produce a reaction product containing liquid melamine, CO.sub.2 and NH.sub.3 ;

• transferring, under pressure, said reaction product as a mixed stream to a separator unit;
• maintaining said separator unit at substantially the same pressure and temperature as said reactor;
• separating said reaction product in said separator unit into CO.sub.2 and NH.sub.3 offgases containing melamine vapors and liquid melamine;
• simultaneously transferring
• (a) said CO.sub.2 and NH.sub.3 offgases containing melamine at a temperature and pressure substantially the same as said temperature and pressure of said separator unit to a scrubber unit and scrubbing said offgases with molten urea to preheat said urea and cool said offgases and remove therefrom said melamine, and thereafter removing NH.sub.3 and CO.sub.2 gases from said scrubber unit at a temperature of from about 350.degree. to about 450.degree. F. and feeding said preheated molten urea containing said melamine to said reactor, and
• (b) said liquid melamine to a product cooling unit;
• and depressurizing and quenching said liquid melamine with a liquid medium which will form a gas at the temperature of said liquid melamine in said product cooling unit, said cooling unit being at a pressure in excess of 600 psi to produce a commercially useful solid melamine product having a purity in excess of 99% without washing or further purification.