Solvent refining method for isocyanate prepared by phosgene method and devices used in same
US9840462B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 11, 2014 |
| Grant date | Dec 12, 2017 |
| Priority date | — |
| Expiry date | Apr 11, 2034 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C263/10
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A solvent refining method for isocyanate prepared by the phosgene method and multistage absorbing towers used in same. Solvent to be refined which contains water, iron, and/or phosgene, hydrogen chloride and other materials with color is dealt by the present method and multistage absorbing towers, which can effectively prevent a drying agent from absorbing water and hardening, partial overheating in the tower and generating channeling. Meanwhile, the pressure drop is effectively lowered. In addition, the content of water is ≦50 ppm, the content of iron is ≦5 ppm, the content of phosgene and hydrogen chloride is ≦20 ppm, Pt—Co chroma is ≦20 in the refined solvent. Therefore, the refined solvent can be used as the solvent for preparing isocyanate in the phosgene method and remarkably improve an L color of isocyanate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.