| 摘要 |
<p>Prepn. of xylose and xylitol from waste cellulosic materials e.g. almond and hazelnut shells by (a) washing the waste materials with water at 100 degrees C, contg. 0.1-1% strong alkali; (b) hydrolysing the washed materials at 140-145 degrees C and 4-4.5 atm. with a 1.5% aqs. H2SO4 soln; (c) decolourising the hydrolysate, hydrolysing it again at 100-110 degrees C.; neutralising to pH 3.5, deionising, concentrating or 15% original volume and crystallising xylose by addn. of viscous CH3OH and (d) catalytically hydrogenating the xylose solns. to yield xylitol. In stage (a); ratio of water (l): cellulosic material (kg) is almost 2; in (b); ratio of water (Hl.) : cellulosic material (kg) is between 125 and 150. Xylose and xylitols which are used in sweeteners and diabetic foods and as chemical intermediates are easily obtained in good yield and high purity from waste products.</p> |
