GB424970A - Improvements in or relating to the hydrolysis of cellulose - Google Patents

Abstract

424,970. Hydrolysis of cellulose. DREYFUS, H., 22, Hanover Square, London. Aug. 30, 1933, No. 24050. [Class 127] In carrying out the hydrolysis of cellulosic material, the material and hydrolyzing agent are fed through a heated reaction zone at such rates that the liquor is in the reaction zone for a shorter period of time than the solid material. Preferably the cellulosic material and hydrolyzing agent are continuously fed into the reaction vessel, and the products of hydrolysis continuously discharged therefrom. The hydrolyzing agent may be fed into the reaction vessel separately from the cellulosic material, and may be discharged separately from the material which has been treated. Dilute sulphuric acid or other dilute acid. or a solution of an acid salt may be employed as the hydrolyzing agent. Preferably sulphuric acid of a concentration less than 1 per cent is used, and the hydrolysis is effected at temperatures between 120 and 200‹ C., under the corresponding increased pressures. After leaving the converter, the acid liquid, whether or not admixed with the solid material, is preferably cooled as rapidly as possible, and such cooling may be effected by heat exchange with water or dilute acid to be used in the process. After discharge from the apparatus, the solid products may be separated from the acid liquor admixed therewith, and may then, if desired, be used as fuel or returned wholly or in part to the process. Good yields of fermentable sugars which may be employed in the manufacture of ethanol &c., are obtained by the process. It is usually necessary first to neutralize the acid remaining after the hydrolysis, if desired after allowing the liquor to stand or using some other means to promote complete hydrolysis. The process may be carried out in a tubular reaction vessel 1, into which cellulosic material from a container 2 is fed through a rotary valve 19. The vessel 1 is provided with a screw 4 for moving the material towards a discharge vessel 3, and with an inlet 6 and outlet 7 for the liquids used in the reaction, communicating with the interior of the vessel through gauze or the like 8. The central section of the vessel is provided with a heating jacket 9, the remainder of the vessel being preferably logged with heat insulating material. The container 2 is provided with an inlet 11 for compressed air. The pitch of the screw 4 is longer between the liquid inlet 6 and outlet 7 so that the material is less tightly packed in the reaction zone. Preferably the material is employed in the form of a pulp with dilute acid or water.