PROCESS FOR ACIDIC HYDROLYSIS OF A PARTICULATE SOLID MATERIAL CONTAINING CELLULOSE， LIGNIN， AND HEMICELLULOSE， WHEREIN THE LATTER HAS A HIGH CONTENT OF XYLOSE

A process for hydrolyzing at least part of the hemicellulose and at least part of the cellulose of a particulate solid material comprising cellulose， lignin， and from 10 to 60% by weight of hemicellulose， wherein said hemicellulose comprises xylose in an amount of from 40 to 100% by weight， on the basis of hemicellulose， said process being conducted in at least one reactor comprising said particulate solid material and interstitial space. The process comprises two hydrolysis steps using hydrochloric acid， separated by a displacement step wherein a water-immiscible displacement fluid displaces part of the hydrochloric acid containing hydrolysate products from the interstitial space in the reactor. In the present process， a particulate solid material is used of which the hemicellulose is high in xylose (xylan).