TH25002A - Process for the production of high-purity melamine - Google Patents

Abstract

Process for producing high-purity melamine Which melamine treatment after composite reaction The steps are as follows: (a) separation of NH3 / CO2 gas mixture from liquid melamine, if appropriate (b) reduction of dissolved CO2 in liquid melamine. By infusing ammonia gas (c), liquid melamine was released for a period equal to the average residence time of 0 to 8 hours at a temperature between 430 ํ and melamine's melting point. And the ammonia sub-pressure of 50 to 400 bar and (d) controlled slow cooling by lowering the temperature from the current temperature in steps (a) (b) (c) each step to 330 to 270 ํ with a cooling rate of 150 ํ / min with an ammonia sub pressure of 50 to 400 bar, the higher the pressure, the faster the cooling rate. And vice versa The lower the pressure, the slower the cooling rate is required. Which in any desired order The reaction vessels are pressurized and cooled to room temperature, and the high purity melamine is obtained as a patent drug powder.

Claims (9)

1.Process for the production of high purity melamine It started with urea replacement. By operating under high pressure Where liquid melamine and NH3 / CO2 gas mixture are formed, consisting of After the transition reaction Conducting post-reaction melamine therapy Consist of step a) The NH3 / CO2 gas mixture may be selected from the liquid melamine. B) The dissolved CO2 reduction in liquid melamine. C) Release of liquid melamine for a period equal to the average residence time of 0 to 8 hours at a temperature between 430 ํ and the melamine melting point. And sub-pressure of 50 to 400 bar of ammonia and d) controlled slow cooling by lowering the temperature from the available temperature in steps (a) (b) and (c) to 350 to 270 ํ at the cooling rate. It cools up to 100 c / min with ammonia sub-pressures of 50 to 400 bar. The higher the pressure in the step (c) the faster the cooling rate. And vice versa The lower the step pressure (c), the slower the cooling rate is required. Which in any desired order Reaction vessels are reduced. Pressure and is cooled to room temperature. And obtain high purity melamine in powder form 2. The procedure for which the claim is made in Clause 1, where the residence time in step (c) is 10 minutes to 4 hours. 3. The process as requested in Claim No. 1, where the temperature in step (c) is between 400 ํ and the melamine melting point. 4. The process as sought by claim 1, where the ammonia sub-pressure at step (c) is between 70 and 200 bar. 5. Process as claimed in claim 1, in which the reaction vessel was cooled in step (d) from 370 ํ to 290 ํ slowly with the controlled cooling rate. 6. The process as requested in Claim No. 1, where the cooling rate in procedure (d) is 100 ํ / min. 7. Process as requested in claim No. 1, in which the cooling rate in procedure (d) is 40 ํ / min. 8. Process as requested in Claim No. 1, with steps (a) and (b) at the same time. 9. Process for claiming of claim No. 1 with steps (a) and (b) respectively 1 0. Process for producing very pure melamine Which consists of making melas The contaminated amine has a temperature between the melamine melting point and 430 ํ at the ammonia sub pressure of 50 to 400 bar. Let the liquid melamine stay at a temperature in this range for a period of 0. To 8 hours, then cool slowly The temperature-controlled model was reduced to 330 to 270 ํ with a cooling rate of 150 ํ / min at the sub-pressure of 50 to 400 bar ammonia. Higher pressures will provide faster cooling rates, and vice versa. The lower the pressure, the slower the cooling rate is required, where at any stage that requires the reaction vessel, the pressure is reduced. It is cooled to room temperature to form high purity melamine in powder form.