It was found during the studies on the hydrogenolysis pulping, that solvolysis with the solvent system cresol-water can promote pulping without hydrogen and catalyst. If the proportion of waterin the solvent system increases, solvolysis competes with hydrogenolysis, and the solvent mixturecontaining over 20% water needs not hydrogenolysis for deligninfication. In this paper, pulping of birch with the cresol-water system of various ratios is reported. The results obtained are as follows :
1) The solvolysis pulping has more merits than the hydrogenolysis one. The process without hydrogen and catalyst simplifies the plant and the operation.
2) By solvolysis with cresol-water mixture at 180°C, in 6090min., birch chips are easily pulped, and the strength properties of the pulp sheet are almost the same as those of kraft pulp.
3) The ratio of cresol and water is an important factor for solvolysis pulping, and within the results obtained so far, the ratio of 8 : 2 solvent mixture gave the effective delignification and the pulp with the most satisfactory properties.
4) Among other solvolysis (organosolv) pulping processes, cresol-water system may be less energy intensive, because the heat of evaporation of cresol is lowest within them.
5) The process is advantageous for biomass processing. After cooling, reaction liquor separates into two phases, water and cresol layers. In the former, hemicellulose sugars are dissolved, and over 60% of them are composed of xylose. The latter disolves slightly degraded lignin. These two wood components can be usable as feedstock for chemical conversions after further processing.
6) The solvent, cresol can be suplied from the degradation products of lignin by hydrogenolysis or pyrolysis.
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