| abstract |
Process for delignifying lignocellulosic materials and for effectively separating their constituent from each other. These materials which, optionally, can be prehydrolyzed, are heated in an aqueous acid medium in the presence of phenol compounds, the liquid / solid weight ratio being at least 0.5. In the case of low liquid / solid ratios, i.e. less than about 4: 1, more aqueous liquid is added to the reaction mass after pulping to aid filtration and drainage. After isolation of the purified solid cellulose pulp, the liquid phase separates into two layers: an aqueous layer rich in pentose and an organic layer rich in phenols and lignin, the latter providing, by distillation and pyrolysis of the residues, an amount of phenols at least equal to the quantity of phenols used in the delignification or elimination phase of lignin. |