Preparation method of melamine

Application Number: 00104974
Application Date: 1997.05.13
Publication Number: 1273243
Publication Date: 2000.11.15
Priority Information: 1996/5/14 NL 1003105/96
International: C07D251/62
Applicant(s) Name: DSM N. V.
Inventor(s) Name: J. G. T. Fanwuk;A. B. Deghan;A. J. Billmans
Patent Agency Code: 72001
Patent Agent: yang liqin
Abstract To recover high-purity melamine from a melamine-containing urea reaction product by a noncatalytic high pressure method. A melamine-containing urea reaction product is separated into a vapor phase and a liquid phase to cool the urea reaction product. Then the liquid phase is transported to a mixing vessel, mixed with a liquid medium, preferably ammonia and a liquid mixture is obtained at such a temperature and under such pressure as to approximately avoid the formation of a solid melamine, namely at about 1-50 deg.C under about 10-100Mpa. Optionally the liquid mixture is pressurized, swollen and the liquid medium is evaporated to give melamine as a dried solid substance. Consequently, melamine can be recovered in an extremely high purity of 99.5-99.95wt.% from the urea reaction product.