| 摘要 |
Chemical conversion of lignocellulose, with fibre sepn., involves digestion with an aq. solvent mixt. in a wood: liquor wt. ratio of 1:5 to 1:10, using a mixt. of 1-4 vol. low-mol. aliphatic alcohol (MeOH/vol. water, together with a catalyst in a concn. of 0.001-1.0 (0.025-0.10) M and opt. a small amt. of an added mineral acid, pref. with the same anion as the catalyst. Digestion is carried out at 130-210 (180-200) degrees C for max. 2 h to effect partial depolymerisation and dissolution of the lignin, the hemicelluloses and the other cell wall materials, including cellulose fibres. The sepd. fibres are recovered from the liq. residue and the digestion and washing solvent, lignin and sugar are recovered from the spent residual liquor. The process is esp. useful for making pulps with low kappa or rho no, and high fibre strength, in which the cellulose is present almost in its natural, undegraded state. It can be used with wood from gymnosperms and angiosperms and agricultural lignocellulose residues. It gives a high yield of pulp with a low residual lignin content and does not cause water and air pollution. |
