CN1032940A - The preparation method of crystalline xylose - Google Patents

Abstract

A kind of preparation method of crystalline xylose, it is characterized in that at first the raw material bagasse being carried out water pretreatment, the dehydration back is that catalyzer is hydrolyzed with acid, hydrolyzed solution carries out once concentration and gets syrup after passing through Zeo-karb, granular active carbon decolorizing column, anionite-exchange resin, and the filtration syrup is removed throw out wherein, make it pass through the granular active carbon decolorizing column again, continue afterwards to concentrate to make it reach supersaturation, last Crystallization Separation promptly obtains highly purified crystalline xylose.

Description

The preparation method of crystalline xylose

The present invention relates to the raw material that a kind of usefulness is rich in pentosan, particularly prepare the method for wood sugar with bagasse.

Along with the widespread use of Xylitol as diabetics's therapeutical agent, and Xylitol is as the exploitation of chewing gum for preventing decayed tooth, and as the production technology of Xylitol basic raw material wood sugar, also extremely each side payes attention to.Chromatography isolation technique on the post is puted forth effort to have studied by developed country over past ten years, obtains purity of xylose with it.A kind of method for preparing wood sugar is disclosed as U.S. Pat 4008285, be be rich in the natural phant of defending sugar of contracting more be raw material through acid hydrolysis, step such as chromatographic separation prepares purity of xylose on ion eliminating, ion-exchange, activated carbon decolorizing, the post.This method contains more impurity with the raw material direct hydrolysis in the hydrolyzed solution, bring certain difficulty for the purification of hydrolyzed solution.The chromatography isolation technique can obtain good refining effect on the post though adopt, but it is not ideal enough as its economical effectiveness of suitability for industrialized production, because chromatographic separation needs the selectivity exchange resin of an input price costliness on the post, and operation is very tight complicated, wayward, accurate Automation Control Instruments must be arranged, some mixtures are successfully separated, and each component of sepn process can not be singly from, can only substep " cutting " thus this method cost very high.

The objective of the invention is weak point, provide a kind of simple technological process to prepare the highly purified crystalline xylose of economical rationality at the aforesaid method existence.

The object of the present invention is achieved like this: bagasse is carried out water pretreatment, the dehydration back is that catalyzer carries out acid hydrolysis with sulfuric acid or hydrochloric acid, hydrolyzed solution is removed iron ion wherein etc. by Zeo-karb, again by the granular active carbon decolorizing column, remove pigment wherein, colloid etc., hydrolyzed solution passes through anionite-exchange resin afterwards, remove the mineral acid in the hydrolyzed solution, hydrolyzed solution is carried out once concentration get syrup, the filtration syrup is removed throw out wherein, make it pass through the activated carbon decolorizing post again, remove the pigment that concentration process produces, syrup is continued to concentrate, make it reach supersaturation, last Crystallization Separation promptly obtains highly purified crystalline xylose.

The present invention is raw material with the bagasse, and this raw material has concentrated on sugar refinery as everyone knows, does not need special purchase, so be cheap as the industrial waste price.

The present invention carries out water pretreatment with the raw material bagasse before hydrolysis, flush away a large amount of colloids, water-soluble impurities such as pigment, ash, six charcoal sugar.Significantly reduced the pollution of the non-sugared impurity of hydrolytic process, be next step ion-exchange, scavenging process such as decolouring have alleviated load, thereby have simplified technological process.

The present invention changes powdered carbon into granular active carbon, in the decolorizing column of packing into, can use repeatedly, improves than nonrecoverable powdered carbon economic benefit, and labor condition also is greatly improved.

Accompanying drawing 1 is a schematic flow sheet of the present invention.

The present invention is described in detail below in conjunction with accompanying drawing.

1, water pretreatment:

Except that the moisture content of pentosan that contains about 25-28% and 50-60%, still contain impurity such as six charcoal sugar, pigment, colloid, nitrogenous thing and ash in the bagasse.Especially through after the fermentation of stockyard, produce lot of organic acids, matter etc. is planted in corruption.Water pretreatment is removed the impurity beyond the pentosan as far as possible.Water pretreatment comprises that mechanical process is cleaned and method such as hot water (fresh water or add small amount of acid or alkali).It is in a container that propeller blade high-speed stirring (450-1500 rev/min) arranged that mechanical process is cleaned, by big liquor ratio (〉=1: 10) consumingly beat wash continuously by fresh water for bagasse, the portion water solubility impurity that the flush away bagasse is contained, with the dehydration of fourdrinier wire water extracter, bagasse is moisture to be no more than 80% afterwards.According to the quality of bagasse, if quality is better, it is rotten not go rotten, and then only carries out the mechanical process cleaning and just can meet the demands.If bagasse when containing more impurity, also needs the hot water with≤130 ℃ to embathe in hydrolytic decomposition pot through stacking downgrade.Experimental result shows that vegetable fibres such as bagasse, corn cob are through water pretreatment, and are leachable to over dry raw material 3-5%(weight) the water solubles, mouldy bagasse, the water solubles are removed and are reached 10%.After bagasse embathes, discard and embathe water, add a small amount of fresh water washing again, be hydrolyzed then.

2, acid hydrolysis:

The pentosan that is present in the bagasse hemicellulose, under 110 ℃ of-140 ℃ of temperature, be catalyzer with hydrochloric acid or sulfuric acid, being hydrolyzed into monose, under 140 ℃ of temperature, is catalyzer with hydrochloric acid or sulfuric acid wherein, be hydrolyzed into monose, wherein 85-90% is a wood sugar.Diluted acid method hydrolysis temperature is lower than 110 ℃, and hydrolysis is incomplete, is higher than 140 ℃, is easy to generate furfural.

The hydrolysis reaction formula is:

The acid hydrolysis solid-to-liquid ratio is that 1: 8～10(is to dried slag)

Acid amount 1.2～1.8%(is to dried slag)

Hydrolyzed solution contains reducing sugar 2.7～3.5%, purity 75～78%.

3, filter:

Residual a lot of thin chaffs are very muddy in the hydrolyzed solution, for transparent hydrolyzed solution is provided to next step, must filter.Filtration is carried out in utmost point frame pressure filter.

4, cationic exchange:

By Zeo-karb, speed is 1 to hydrolyzed solution: 1-1: 0.5(resin volume from top to bottom: flow/hour), can remove the metal ions such as iron calcium in the hydrolyzed solution, to reduce the ash in the crystalline xylose.Cationic exchange is carried out in exchange column, and resin can select 732 for use ^#The type Zeo-karb.Exchange terminal point purity 〉=82%, Fe ²⁺≤ 15PPM.

5, once decolouring

Remove pigment in the hydrolyzed solution, colloid etc., to guarantee the colour standard of crystalline xylose, decolouring is carried out in the granular active carbon decolorizing column.Speed is 1: 1.

Granularity 28-42 order accounts for more than 80%.

6, anionresin:

From top to bottom by anionite-exchange resin, speed is 1: 1.5-1: 2(resin volume through the hydrolyzed solution of decolouring: flow/hour), remove the mineral acid in the hydrolyzed solution, guaranteeing material PH about 3.5, and improve hydrolyzed solution purity.Negative resin can be selected 703 type anionite-exchange resin for use.Exchange liquid reducing sugar yield 〉=95%, purity 86-90%.

7, once concentration

Hydrolyzed solution is evaporated in triple effect vacuum-evaporation jar, obtain the syrup of concentration 20-30%.

8, syrup filters:

Syrup through once concentration filters by plate-and-frame filter press, and the throw out in the concentration process is leached.

9, secondary decolourization:

Make the raw sugar slurry by the decolorizing with activated carbon post, remove the pigment that concentration process produces.The employed activated carbon and the identical of use of once decolouring, flow velocity is also identical.

10, secondary concentration:

After filtration, clear syrup that decolouring is good continues concentratedly in vacuum pan, reaches supersaturation, is referred to as sugared lamb.Sugar lamb concentration 82-88%, purity 80-92%.

11, crystallization:

Sugared lamb is introduced crystallizer, be cooled to 55-50 ℃.Input is lowered the temperature to the crystal seed of sugared 0.1-0.03%, per hour lowers the temperature 1-2 ℃, growing the grain.

12, separate:

With mother liquor in the sugared lamb and crystal grain centrifugation, drying promptly gets the high purity wood sugar.

In this technology, decolorizing with activated carbon and exchange process are in conjunction with carrying out.Can be to use activated carbon decolorizing earlier, back sun-Yinchiao (abdomen, Ren 7) changes, or first sun-Yinchiao (abdomen, Ren 7) changes rear decoloring.But preferably the positive resins exchange of elder generation then carries out decolouring on the particle charcoal post, carries out the negative resin exchange at last again.The particle charcoal is between the positive negative resin.The sun resin and can be removed partial pigment than anti-pollution, can improve particle carbon decoloring effect, and the destainer behind the particle carbon decoloring can alleviate the pollution of pigment to negative resin through the exchange of negative resin post, the switching performance of protection negative resin.

Embodiment:

The industrialization bagasse is produced wood sugar, drop into moisture 50%, 60 tons of bagasses that contain pentosan 26%, the jar that have rotating speed 450 rev/min propeller stir in continuously carry out mechanical process at 1: 10 with solid-to-liquid ratio and clean, the fourdrinier wire dehydration, bagasse moisture content remains on 78-80%, drop into hydrolytic decomposition pot then, embathe earlier, discard wash water, after adding a small amount of clear water and washing with about 60 ℃ hot water, add hydrochloric acid and water again, making the interior solid-to-liquid ratio of hydrolytic decomposition pot is 1: 8, and concentration of hydrochloric acid is 0.22%, makes the bagasse hydrolysis, hydrolysis temperature is controlled at about 130 ℃, must contain 200 tons of reducing sugar 3.0% hydrolyzed solutions, purity 76% is behind the filtration hydrolyzed solution, make its with 1: 1 speed by cationic exchange coloum and granular active carbon decolorizing column, by anion-exchange column, exchange the liquid reducing sugar rate of recovery 96%, purity 88% with 1: 1.5 speed.Exchange liquid once concentration gets 18.4 tons in the syrup of concentration 30%, purity 90%, after the filtration again decolouring and concentrate for the second time 6.6 tons of the sugared lambs of concentration 85%, purity 91%, sugared lamb is dropped into crystallizer and is cooled to 55 ℃, drops into 0.1% crystal seed, be cooled to 38 ℃, separation, drying get 2.1 tons of crystalline xyloses, and its physical and chemical index is:

Proterties

Molten shape

Sugar degree

Moisture content

Ash

Heavy metal (ppm)

Water-insoluble mg/kg

The white crystals free from extraneous odour

10% aqueous solution water white transparency

98％

1.4%

0.18%

5ppm

110

Claims (6)

1, a kind of preparation method of crystalline xylose is characterized in that:

A, the raw material bagasse is carried out water pretreatment;

B, will be present in the pentosan acid hydrolysis in the bagasse hemicellulose;

C, hydrolyzed solution filter;

D, hydrolyzed solution pass through Zeo-karb;

E, hydrolyzed solution are by the granular active carbon decolorizing column;

F, hydrolyzed solution pass through anionite-exchange resin;

G, hydrolyzed solution is carried out once concentration get syrup;

H, filtration syrup;

I, syrup are by the granular active carbon decolorizing column;

J, syrup is continued to be concentrated into supersaturation;

K, with supersaturation syrup Crystallization Separation.

2, method according to claim 1, it is characterized in that said water pretreatment is included in the container that propeller blade high-speed stirring (450-1500 rev/min) arranged, bagasse continuously by big liquor ratio (〉=1: 10) fresh water beat consumingly wash and use≤130 ℃ hot water embathes bagasse in jar.

3, method according to claim 1 and 2, the order that it is characterized in that hydrolyzed solution ion-exchange and activated carbon decolorizing can be first activated carbon decolorizing, back sun-anionresin, or activated carbon decolorizing after first sun-anionresin.

4, method according to claim 1 is characterized in that said granular active carbon is C ₁₁Particle, its granularity accounts for more than 80% for the 28-42 order.

5, method according to claim 1 is characterized in that the speed of hydrolyzed solution by ion exchange column (resin volume: hydrolyzed solution flow/hour) is:

Cationic exchange 1: 1-1: 0.5

Anionresin 1: 1.5-1: 2

6, method according to claim 1 is characterized in that speed by the granular active carbon decolorizing column of hydrolyzed solution and syrup (activated carbon volume: mass flow/hour) is 1: 1.