Lignin product and process for making same
US9879119B2 · kind B2 · utility
Inventors
Key dates
| Filing date | Jan 8, 2016 |
| Grant date | Jan 30, 2018 |
| Priority date | — |
| Expiry date | Jan 9, 2036 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08H6/00
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
There is provided a process for recovery of lignin from black liquor that contains either soluble or dispersed lignin, generating a “liquid-lignin” at high yield. Lignin at elevated pH is precipitated by reducing the pH of the black liquor stream with carbon dioxide, at elevated temperature and pressure, creating two bulk fluid phases: a dense liquid-lignin phase and a light lignin-depleted phase. The dense liquid-lignin phase is separated and washed with a strong acid to displace metal cations from the lignin, creating a low-salt, randomly shaped lignin. If needed, especially for lignin recovered from kraft papermaking black-liquor streams, an oxidation step is included to eliminate negative odor for high value green chemistry applications.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.