Abstract
A method of delignifying a lignocellulosic raw-material, which contains lignin with a benzylic ring structure. The method comprises carboxylating at least a part of the benzylic ring structure by contacting the raw material at anhydrous conditions withcarbon dioxide which is maintained in supercriticalconditionto formbenzylic carboxylates. The benzylic carboxylate are leached out in an aqueous medium to remove at least a part of the lignin. The present process can be used as a pre-treatment for producing fine mechanical pulp, or producing cellulose. The new method is environmentally-friendlyin the respect that no sulphur is used, water consumption is small and there might be a reduced need for use of bleaching chemicals.
| Translated title of the contribution | Method of delignifying wood |
|---|---|
| Original language | Finnish |
| Patent number | FI122974 B |
| IPC | D21C 3/00 |
| Priority date | 28/12/07 |
| Filing date | 28/12/07 |
| Publication status | Published - 28 Sept 2012 |
| MoE publication type | H1 Granted patent |