THE USE OF NON-ISOBARIC PRE-HYDROLYSIS FOR THE ISOLATION OF ORGANIC-COMPOUNDS FROM WOOD AND BARK

The effect of non-isobaric short-time pre-hydrolysis of Siberian type wood and wood bark (Populus tremula wood, Larix sibirica bark, Abies s ibirica bark) on the isolation of different organic substances was stu died. From Populus tremula wood, activated at 187-240 degrees C and 1. 2-3.4 MPa, cellulose and sugar solution were isolated with yields up t o 50 wt%, and II wt%, respectively. The composition of water-soluble c ompounds was studied by chemical and chromatographic methods. The main compounds were represented by mono- and oligo-saccharides, low molecu lar mass lignin, acetic acid, furfural and other products of sugar des truction. Methanol, isopropanol, propionic acid and hydroxymethylfurfu ral were formed in small amounts. The non-isobaric pre-hydrolysis of c oniferous bark promoted the ct-traction process and increased the yiel d of extracted compounds. Some information on functional composition o f extracts was obtained by NMR and IR spectroscopy. An integrated tech nology for wasteless processing of coniferous wood bark was suggested based on the combination of non-isobaric steam activation of bark, ext ractive isolation of some groups of organic substances, and oxidative pyrolysis of solid residue in a fluidized bed of catalyst. Copyright ( C) 1997 Elsevier Science Ltd.