Sorbitol, also known as sorbitol. It is white hygroscopic powder or crystalline powder, flakes or granules, odorless. Depending on the crystallization conditions, the melting point changes in the range of 88~102℃, and the relative density is about 1.49. Easily soluble in water (1g dissolves in about 0.45mL water), slightly soluble in ethanol and acetic acid. It has a refreshing sweetness, the sweetness is about half that of sucrose, and its caloric value is similar to that of sucrose. In the food industry, it is mostly sorbitol liquid with a content of 69~71%.
The industrial production methods of sorbitol include a decomposition reduction method and a catalytic hydrogenation method. Since the electrolytic reduction method consumes a lot of energy, intermittent or continuous high-pressure catalytic hydrogenation technology is currently mainly used, and nickel-containing catalysts are generally used. The following suppliers of sorbitol are introduced to you:
1. Intermittent method:
The concentration is 50% glucose aqueous solution, heated with a stirrer In the kettle, hydrogenation is continued for 2 to 4 hours at 120~150°C, hydrogen pressure is 7MPa, pH value is 6, catalyst dosage is 3%~6% (based on glucose), and then the catalyst is separated by sedimentation and filtered. After decolorization by ion exchange or activated carbon, the aqueous solution with a content of 70% is obtained by vacuum evaporation. The sorbitol yield is 96%~98%.
2. Continuous method:
The continuous method uses paddle reactors or fixed bed reactors, which can achieve large-scale industrial production. Convenient for automated control. In addition to supported nickel or Raney nickel, catalysts can also use copper, chromium, cobalt, palladium and ruthenium, among which supported ruthenium catalysts (such as Ru/Al2O3, Ru/c, Ru/TiO2, etc.) are studied. It has attracted particular attention in recent years. Ruthenium catalyst not only has good hydrogenation catalytic activity, but its price is only 1/10 of platinum and palladium. The investment using this technology is reduced by 20% compared with traditional methods. At the same time, due to the lower reaction temperature and pressure, side reactions such as coking are also suppressed, which increases the yield of sorbitol.
In addition, homogeneous hydrogenation technology has also been used for the synthesis of sorbitol. The catalyst is a complex of dichlorotriphenylphosphine and ruthenium. The reaction is carried out in the presence of strong acid. The reaction temperature is 110°C, the hydrogen pressure is 12.3MPa, and the conversion rate is 90%. There are also new developments in research on other synthesis methods of sorbitol, such as continuous hydrolysis of starch, cellulose or sucrose as raw materials, hydrogenation technology, glucose electrolytic reduction method, etc.
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