| 摘要 |
Microcrystalline cellulose has many applications in the pharmaceutical, food, paper and structural composite industries. Level off DP (Degree of Polymerization) microcrystalline cellulose is made up of a chain of about 250 glucose molecules in the form of microcrystal. In nature, several microcrystals are hinged together and surrounded by amorphous cellulose to form a cellulose microfibril. If the amorphous cellulose is removed, the resultant product is called level off DP (Degree of Polymerization) microcrystalline cellulose. When lignocellulosic material is processed according to applicant's earlier processes (Canadian Pat. Nos. 1,096,374 and 1,141,376), the dissociated material is partitioned by removing the lignin and the xylan leaving a low DP (320) cellulose fraction. This material can be converted to level off DP microcrystalline cellulose and glucose by soaking the cellulose in an acid solution, dewatering it, returning the acid-impregnated cellulose to the reactor, introducing high pressure steam (300-700 psi) and when substantially all of the material reaches a temperature of the order of 215 DEG C., releasing it instantly to atmosphere. This procedure will produce a mixture of level off DP microcrystalline cellulose and glucose. If the acid solution employed is sulfuric acid and the temperature of the cellulose is allowed to reach a uniform temperature of 234 DEG C. before instant release to atmosphere, the procedure will produce substantially all glucose.
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