Process for the production of high purity melamine from urea
View Patent ↗A method for purifying melamine comprising impurities like ureido-melamine, oxotriazines, melam, melem, comprises the step of putting into contact at a temperature comprised between 340° C. and 410° C. and at a pressure comprised between 8 and 17 MPa a melamine melt with a bed of a catalyst thus obtaininig melamine with a purity of at least 99%.
1. Method for purifying melamine comprising impurities characterized in that a melamine melt is put into contact at a temperature comprised between 340° C. and 410° C. and at a pressure comprised between 8 and 17 MPa with a bed of a catalyst thus obtaining melamine with a purity of at least 99%.
2. Method according to claim 1 , characterized in that said catalyst is selected from the group comprising alumina, silica, alumina/silica, molecular sieves, mixtures and derivatives thereof.
3. Method according to claim 1 , characterized in that said catalyst adsorptive properties.
4. Method according to claim 1 , characterized in that said melamine containing impurities is obtained from urea by a high-pressure non-catalytic process.
5. Method according to claim 1 , characterized in that the contact between said melamine melt with the bed of catalyst is carried out in the presence of NH 3 .
6. Method according to claim 5 , characterized in that said NH 3 is dissolved in said melamine.
7. Method according to claim 1 , characterized in that said melamine melt is fed with a continuous flow to a purification unit comprising at least one bed of said catalyst.
8. Method according to claim 7 , characterized in said continuous flow of melamine melt is fed to said purification unit with a flow rate comprised between 0.5 and 10 Kg of melamine melt/(litre catalyst×hour).
9. Method according to claim 7 , characterized in that said melamine melt is obtained from a high-pressure non-catalytic process and directly fed to said purification unit.
10. Method for purifying melamine comprising impurities characterized in that a melamine melt is put into contact at a temperature comprised between 340° C. and 410° C. and at a pressure comprised between 8 and 17 MPa with a bed of an adsorbent material.
11. Method according to claim 10 , characterized in that said adsorbent material is selected from the group comprising alumina silica, alumina/silica, active carbon, natural clays, molecular sieves, mixtures and derivatives thereof.
12. High-pressure non-catalytic process for the production of a melamine from urea characterized by, in a purification step, putting a melamine melt into contact at a temperature comprised between 340° C. and 410° C. and at a pressure comprised between 8 and 17 MPa with a catalyst or an adsorbent material thus obtaining melamine with high purity.
13. Method according to claim 8 , characterized in said continuous flow of melamine melt is fed to said purification unit with a flow rate comprised between 1 and 10 Kg of melamine melt/(liter catalyst×hour).
14. Method according to claim 10 characterized in that the impurities are one or more of melam, melem or melon.
15. Method according to claim 1 characterized in that the impurities are one or more of ureido-melamine, oxotriazines, melam or melem.