Melamine process with a two-stage purification of melamine offgas
US12391655B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 5, 2023 |
| Grant date | Aug 19, 2025 |
| Priority date | — |
| Expiry date | Oct 5, 2043 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07D251/54
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A process for the synthesis of melamine including the purification of the offgas released by the synthesis of melamine by means of a first purification stage followed by a second purification stage (7); in the first purification stage (6) the offgas (3) is contacted with urea melt from the second stage (7) and with a recirculated urea melt (8, 9) containing ammonia and melamine precursors (5); in the second purification stage (7) the offgas from the first stage is contacted with fresh urea melt (15); said recirculated urea melt is withdrawn from bottom of the first stage and cooled in a shell and tube heat exchanger (11) to a temperature of not less than 165° C. preferably in the range 165° C. to 245° C. prior to reintroduction in said first stage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.