Verfahren zur Herstellung von Sorbitol

摘要

Preparation of sorbitol comprising hydrogenation of an aqueous glucose solution to give a 40-50% sorbitol solution (SS) having a sorbitol content of 98-99% based on dry substance and comprising: (a) subjecting salt-free SS one after the other at a bed volume of 0.2-0.25 per cycle to chromatography at a flow rate of 0.4-0.6 m/hr from top to bottom using a multiple shot chromatographic column having a total length of 1.8-2 metres, warmed to 60-65 deg C, filled with a strongly acidic cationic exchanger of medium degree of polymerisation, average particle size 0.25-0.4 mm and in the calcium form, such that in each shot 8-12% freeboard remains and the elution water is in amount 4-5 times that of the SS; (b) obtaining three fractions: the first fraction is almost sorbitol free and contains separated unwanted components of SS; the second fraction is a 10-15% sorbitol solution having a purity of 95-98%; the third fraction is an 18-25% sorbitol solution having a purity of 99.5-99.7% and containing 85-95% of the total SS subjected to chromatography; the transition from one fraction to the other is established using the refractive index of the eluant; the chromatography is adjusted for the third fraction when the proof for the presence of glucose can no more be established; (c) the first fraction which is used to dilute the 70% glucose syrup is used as the raw material for the hydrogenation process; the second is either pooled with the first fraction and used to dilute the glucose syrup followed by hydrogenation as above or is evaporated to be used for the preparation of a 70% sorbitol solution. Preferably purity of sorbitol is at least 99.5 (preferably 99.7)% with a maximum of 0.02% glucose, 0.15% total sugar, 0.20% and 0.25% mannitol.