The commercial manufacturing of Xylitol Powder is the acidic hydrolysis of pentosan consisted of in farming item handling waste (such as corn cob, cottonseed hull, bagasse, rice husk) into pentose, and afterwards catalytic conversion to xylitol:
( C5H8O4) n+ WATER [H+] → nCH10O5 [H2] → HOCH2( CHOH) 3CH2OH.
The pretreatment of raw corncobs includes in-tank pretreatment as well as out-of-tank pretreatment. Out-of-tank pretreatment involves screening, wind choice, water washing as well as various other procedures to get rid of mechanical pollutants in basic materials as well as improve the high quality of basic materials. Tank pretreatment consists of water therapy, acid treatment or alkali treatment. The most suitable problem for corn cob treatment in water is 120 ℃ and 2h.
There are two kinds of hydrolysis as well as hydrolysis operation procedures: dilute acid atmospheric pressure hydrolysis (sulfuric acid focus 1.5% to 2.0%, temperature level 100 to 105 ° C )and also reduced acid pressurized hydrolysis (sulfuric acid focus 0.5% to 0.7%, temperature level 120 to 125 ° C). Typically, 700kg of corncobs (equal to 590kg of completely dry material) is added at a time, as well as 100kg of sulfuric acid is added (according to 100%). The acid consumption is 0.48-0.75 kg per kilo of sugar, as well as the hydrolysis time is 2-3 hrs. Neutralization The function of neutralization is to eliminate the sulfuric acid in the hydrolyzate, however keep the natural acid. Lime is generally utilized as a counteracting agent, and the lime is first prepared right into milk of lime with a family member density of 1.10 to 1.15. Add milk of lime under consistent mixing at 80 ° C to elevate the pH worth of the hydrolyzate from 1.0 to 1.5 to 3.5 for about 1 hr, and after that choose 2 hours to finish the neutralization operation. Currently, the web content of inorganic acid in the counteracting remedy is normally 0.03% to 0.08%, and also the sugar loss is regulated listed below 3%.
Decolorization, dissipation, separation and neutralization liquid requirement to experience procedures such as decolorization, evaporation focus and also ion resin exchange to get pure xylose fluid. Include 15% pyrolignin (to the lowered compound) as well as 1% turned on carbon to the hydrolyzed solution, warmth as well as stir at 75 ° C for 45 mins, the decolorization loss is 3% to 5%, the top quality of the decolorized solution: the light transmittance is above 80%, and also the pureness is 75% ～ 80%, ash web content 0.18% ~ 0.22%. The decolorization solution is focused in the main circulating tube evaporator to a sugar web content of 35% ~ 40%. Right here, trace quantities of not natural acids in the decolorization solution can likewise be vaporized, and also the calcium sulfate speed up precipitated throughout evaporation can be removed by purification. The pureness of the focused remedy is usually just 85%. Making use of 732 solid acid cation material as well as strong base multi-porous anion resin (1:1.5) for ion exchange, xylose remedy with a purity of 95% to 97% can be obtained. Xylose hydrogenation and also xylitol formation Adjust the xylose filtration remedy having 12% to 15% sugar to pH 8 with lye, pre-heat it to 90 ° C and also inject it into the high pressure reaction with a high pressure feed pump, at 115 ~ 130 ℃ as well as 7.0-8.0 MPa to hydrogenate and also minimize to obtain a hydrogenated liquid including 12% -15% alcohol. Demands for hydrogenated fluid: refractive index 12% ~ 15%, total acid 0.015% ~ 0.05%, residual sugar 0% ~ 1.5%, ash content 0.1% ~ 0.2%, light transmittance 80% ~ 85%. The hydrogenated solution is decolorized with 0.2% (to alcohol) activated carbon, filtered, as well as pre-concentrated to 50% alcohol, and then further concentrated into xylitol paste having 88% alcohol after filtration. After discharge, the temperature level is gradually lowered from 65 to 70 ° C (1 ° C/h) to 20 to 30 ° C, centrifuged to acquire crystals having 96% alcohol, as well as the mom alcohol is recycled.
