NON-CATALYTIC METHOD FOR PRODUCTION OF HIGH-PURITY MELAMINE AT HIGH PRESSURE Russian patent published in 2001 - IPC

FIELD: industrial organic synthesis. SUBSTANCE: more than 99%- purity melamine is prepared in urea-pyrolysis reactor at pressure 1700-3500 lb/sq. inch and temperature approximately 670 to 850OF, after which reaction product, containing liquid melamine, carbon dioxide, and ammonia, is fed in the form of mixed stream into separator wherein essentially the same pressure and temperature as in reactor are maintained. Mixture is separated there into liquid melamine and carbon dioxide/ammonia gas mixture containing melamine vapors. Gas mixture is sent into scrubber operated under the same conditions as above, wherein gas is washed with molten urea to be cooled and to remove melamine admixture. Melamine-free gas mixture comes out of scrubber at temperature approximately 350-450OF. Preheated urea is returned into reactor and liquid melamine, loosing overpressure, is introduced into cooler, wherein it is sharply cooled by a liquid medium, which vaporizes when acquires temperature of liquid melamine in cooler. Method is distinguished by that pressure in indicated cooler is maintained equal to 600 lb/sq.inch. EFFECT: increased yield and purity of product and simplified technology. 5 cl, 2 dwg, 1 tbl