Pulping at atmospheric pressure with aqueous acetic acid containing sulfuric acid: Pulping of Hokkaipopula (improved balsam poplar), Ezonokinuyanagi (Salix pet-susu Kimura) and Nagabayanagi (Salix sachalinensis Fr. Schm.)
1992
Sano, Y. (Hokkaido Univ., Sapporo (Japan). Faculty of Agriculture) | Yamamura, K. | Uraki, Y. | Sasaya, T. | Chiba, S.
In order to use Hokkai-poplar, Ezonokinuyanagi and Nagabayanagi as raw materials for pulp and paper and also for biomass products, the characteristics of these short-rotation hardwoods and the possibilities of atmospheric pulping with aqueous acetic acid containing sulfuric acid were discussed. The samples in 4-year-old tree used were separated into stemwood and bark. The results of their chemical composition showed that the barks had larger quantities of ash (5-6%) and alcohol-benzene extractives (13-16%) than those of the woods, but the content of Klason lignin was slightly higher for poplar bark and clearly higher for salix barks than those of the woods. The content of tannin for the barks varies within species. The bark of Ezonokinuyanagi having 8% of Staisny's tannin may be used as raw materials for tannin. Hokkai-poplar was easily cooked in 90% AcOH with 0.32% H2SO4 for 3h and yielded acetic acid pulp of satisfactory sheet strength. Ezonokinuyanagi and Nagabayabagi gave a large quantity of rejects under the same conditions but they yielded pulps with fewer contents of rejects when cooked in the liquor with small amounts of phenols such as phenol and cresols, or with surface-active reagents such as p-dodecylibenzenesulfonate. Products similar to the phenols and the sulfonate can be prepared from lignins. Acetic acid lignins and water solubles from the reaction liquors were recovered in excellent yields as valuable by-products. The water solubles consisted mainly of xylose, which means that they are useful as sweetening materials and as furfural by chemical conversion. Acetic acid lignins may be used as raw materials for phenolic polymers such as adhesives and also as clean fuels without sulfur compounds
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