| 摘要 |
A high yield of a high quality pulp is obtained by cooking fragmented lignocellulose material at a temperature of 180 to 240`C with a mixture of methanol or ethanol and water containing 80 to 98 percent by volume of the alcohol, the mixture containing dissolved from 0.001 to 0.5 molar of an alkaline earth metal salt, and from zero to 0.005 normal/molar of (a) a strong mineral acid, or (b) a weak mineral acid or (c) a weak organic acid or (d) an acid reacting metal salt to aid rapid delignification. In addition, optionally, pressures substantially higher than developed in enclosed spaces by the vapors of the solvent mixture at the cooking temperature are used to further increase the delignification rate and suppressing carbohydrate degradation. Lignin is obtained in powder form by low temperature evaporation of the alcohol from the spent cooking liquor. |
