CN1353310A - Process for preparing cellopolyose reagents series simultaneously - Google Patents

Abstract

A process for preparing a series of cellopolyase reagents simultaneously includes such steps as continuously hydrolyzing cellulose in supercritical/near critical water to generate liquid mixture of cellopolyose and separating the liquid mixture by serially connected ion exchange column and gel osmosis column while prepairng the said reagents. Its advantages include simple process and convenient operation.

Description

Simultaneous preparation method of cellopolysaccharide series reagents

The invention relates to polysaccharides, in particular to a simultaneous preparation method of a series of fiber polysaccharide reagents.

Cellopolysaccharide series reagents refer to five reagents with certain solubility in water, including cellobiose, cellotriose, cellotetraose, cellopentaose and cellohexaose. Cellopolysaccharides can be used as biochemical reagents (such as cellobiose as a substrate for cellobiase), bacteriological reagents, and analytical standards (widely used to study the hydrolysis of material resources, such as acid hydrolysis, enzymatic hydrolysis, and paper industry and food industry, etc.). In addition, due to the linear structure of cellulopolysaccharide, it can be used as a model substance to study the physical properties of polymers. However, currently only cellobiose reagents are produced in China.

When cellobiose is prepared separately, organic synthesis method is used. Firstly, cellulose is reacted with acetic anhydride in the presence of concentrated sulfuric acid to produce α-cellobiose octaacetate, then the acetic acid group is removed, and finally it is prepared by decolorization and solvent recrystallization. . This reaction process is long and the cost is high. For the simultaneous preparation of cellulosic polysaccharide reagents, the method of hydrolyzing cellulose with fuming hydrochloric acid is currently used abroad to obtain a mixed solution of cellulosic polysaccharides, and then the single component of cellulosic polysaccharides is separated by column chromatography. Due to severe corrosion of fuming hydrochloric acid and difficulty in operation control, the mixed solution obtained from cellulosic polysaccharides needs to be neutralized with alkali, and the generated salt seriously affects the subsequent separation process.

The purpose of the present invention is to provide a simultaneous preparation method of cellopolysaccharide series reagents with simple process and convenient operation.

In order to achieve the above object the present invention takes the following measures:

The steps of simultaneous preparation method of fiber polysaccharide series reagents are as follows: 1) Continuous hydrolysis of cellulose in super/near critical water to generate fiber polysaccharide mixture, the reaction conditions are temperature 200-600°C, pressure 1.6-40MPa, residence time 0-600s ; 2) Utilize ion-exchange column and gel permeation column series method to separate fiber polysaccharide mixed solution, effluent liquid detects export product on-line with differential refraction (RI) detector after shunting, collects different cuts according to the peak situation, different cuts pass through Cellopolysaccharide series reagents with a purity greater than 95% can be obtained at the same time after freeze-drying. Column chromatography conditions: the mobile phase is water, the column temperature is 0-80°C, and the empty column flow rate is 0.3-6.4 cm/min.

The invention has the advantages of simple process and convenient operation. The composition of the cellulosic polysaccharide in the product can be controlled by adjusting the reaction conditions as required. Due to the high content of fiber polysaccharide in the fiber polysaccharide mixed raw material and the absence of salt, the separation process is relatively simple.

The present invention is described in detail below in conjunction with embodiment.

The critical temperature of water is 374°C, and the critical pressure is 22.0 MPa. Supercritical water refers to a state where the temperature is above the critical temperature and the pressure is above the critical pressure. Near critical water refers to compressed liquid water with a temperature between 200°C and 350°C. The present invention utilizes the feature that cellulose can be decomposed quickly and selectively without adding a catalyst in super/near-critical water (Lü Xiuyang (Lu Xiuyang), Sakoda, A, Suzuki, M. Decomposition of cellulose by continuous near-critical water reactions.Chinese J.Chem.Eng., 2000, 8(4), in press; Lu Xiuyang, Sakoda, A, Suzuki, M. Study on decomposition kinetics and product distribution of cellulose in near-critical water, Acta Chemical Society, accepted) and solid Advances in continuous feeding technology of materials under high pressure (Lu Xiuyang, Xia Wenli, Liu Tianchun, Sakoda, A, Suzuki, M. Research on high-pressure continuous transportation of biomass resources, Journal of Agricultural Machinery, accepted), using super/near critical water continuous The method of hydrolyzing cellulose (Lu Xiuyang, Sakoda, A, Suzuki, M. Development of a continuous decomposition device for solid waste in super/near critical water, Journal of Chemical Engineering of Universities, accepted) to prepare fiber polysaccharide mixed raw materials. A single pure product of cellulopolysaccharide is isolated from this raw material.

The products of cellulose hydrolysis in super/near critical water include monosaccharides (glucose and fructose), secondary decomposition products of monosaccharides (acetoglyoxal, 5-hydroxymethylfurfural, furfural, glyceraldehyde, hydroxyl Acetaldehyde, erythrose, anhydroglucose, dihydroxyacetone, etc.) and organic acids (formic acid, acetic acid, sugar acid, etc.). According to the characteristics of this raw material, the ion exchange column and the gel permeation column are connected in series to separate.

Ion-exchange column chromatography adopts macroporous anion-exchange resin, which can be strongly alkaline or weakly alkaline according to the raw materials. It is used to separate organic acids from other components, and its mobile phase is water; gel Permeation column chromatography separates solute molecules according to their size, and has the advantages of low requirements on mobile phase, relatively mild experimental conditions, good repeatability, fast speed, and high solute recovery rate. For this system, except for the cellopolysaccharide, the molecular weights of the other components are all less than 180.1 (glucose), and the molecular weight of the cellopolysaccharide is shown in Table 1.

               Table 1 Molecular weight of cellulosic polysaccharides

Cellobiose Cellotriose Cellotetraose Cellopentaose Cellohexaose Molecular Weight 342.3 504.4 666.6 828.7 990.9

Therefore, it is suitable for separation by gel permeation column chromatography. The molecular weight ratio (Mn/Mn-1, n represents the number of sugars) between adjacent cellopolysaccharides is shown in Table 2.

Table 2 Molecular weight ratio between adjacent fiber polysaccharides

n n 2 3 3 4 5 6

Mn/M _n-1 1.90 1.47 1.32 1.24 1.20 It can be seen from the above values that as the number of sugars in cellulosic polysaccharide increases, the difficulty of separation by gel permeation chromatography increases. However, because the molecular weight ratio between adjacent cellopolysaccharides is greater than 1.20, gel permeation chromatography can separate this system well. It is advisable to use a hydrophilic gel suitable for water as a solvent, such as glucose gel, polyacrylamide gel, agarose gel, starch gel, porous silica gel, etc.

Example 1

The first step of the preparation of the mixed raw material of fiber polysaccharide adopts a set of super/near critical water continuous reaction device (Lu Xiuyang, Sakoda, A, Suzuki, M. Development of continuous decomposition device for solid waste in super/near critical water, Journal of Chemical Engineering of Universities , has been accepted), the cellulose is continuously supplied to the reactor by mixing slurry with water, the solid content of the slurry is 5% (wt), and the flow rate of the slurry and the preheated water flow ratio is 1:1. The initial concentration of cellulose at the inlet of the device is 2.5% (wt); the reaction is carried out at a temperature of 275° C., a pressure of 25 MPa, and a residence time of 0.4 min. The yield of the water-soluble cellulopolysaccharide in the product reaches 40% (wt). The separation of the second step fiber polysaccharide mixed raw material adopts a set of preparative gel permeation chromatograph, utilizes the AP-2 glass column of two Waters companies, and one is 30cm long, is used for dress ion exchange resin (macroporous strong base) Anionic resin, Shanghai Resin Factory); the other is 60cm long, used to pack gel (Sephadex G-15 from Pharmacia FineChem.Inc., Sweden), two columns are connected in series (the ion exchange resin column is in front), and the outflow After the liquid is divided, the export product is detected online with a differential refractive index (RI) detector, and different fractions are collected according to the peak situation, and the different fractions are freeze-dried to obtain the product. The content of fiber polysaccharide in the fiber polysaccharide mixed solution is about 1% (wt), adopt mobile phase to be water, column temperature is 35 ℃, the flow velocity of mobile phase is 6ml/min, and once-through column injection volume is 10ml, obtains fiber simultaneously The yield and purity of the polysaccharide series reagents are shown in Table 3.

Table 3 Yield and purity of the product of Example 1

Fibrous two -sugar fiber trice sugar fiber triple sugar fiber sibal fiber yield (mg) 23 19 14 10 5 purity ( %) 96.1 96 95.6 95.1 Separational fiber polysaccharide revenue is 71 %.

Example 2

The equipment used is the same as above, the cellulose is reacted at a temperature of 400° C., a pressure of 40 MPa, and a residence time of 0.17 s, and the yield of the water-soluble fiber polysaccharide in the product can reach 60% (wt). The obtained fiber polysaccharide mixed raw material is separated in series through ion exchange resin (macroporous weakly basic anion resin, Shanghai Resin Factory) column and gel permeation column (Sephadex LH-20 of Sweden Pharmacia Fine Chem.Inc.), and the effluent is passed through After splitting, use a differential refractive index (RI) detector to detect the export product online, collect different fractions according to the peak situation, and freeze-dry the different fractions to obtain the product. The content of fiber polysaccharide in the fiber polysaccharide mixed solution is about 1.5% (wt), adopt mobile phase to be water, column temperature is 35 ℃, the flow rate of mobile phase is 8ml/min, once-through column injection volume is 10ml, obtains fiber simultaneously The yield and purity of the polysaccharide series reagents are shown in Table 4.

Table 4 Yield and purity of embodiment 2 product

Fibrous dietary triangular triangular triangular triple sugar fiber five sugar fiber yield (mg) 32 26 19 11 5 purity ( %) 97.0 96.5 95.1 94.8 Separational fiber polysaccharides are 62 %.

Claims (4)

1. The simultaneous preparation method of a kind of fiber polysaccharide series reagent is characterized in that preparation technology is made up of following two steps: 1) cellulose is hydrolyzed continuously in super/near critical water, generates fiber polysaccharide mixed solution, and its reaction condition is that temperature 200 ～600℃, pressure 1.6～40MPa, residence time 0～600s; 2) Use ion exchange column and gel permeation column in series to separate cellopolysaccharide mixture, and use differential refraction detector to detect the export product on-line after the effluent is divided. Collect different fractions according to the peak conditions, and different fractions can be freeze-dried to obtain cellulosic polysaccharide series reagents with a purity greater than 95% at the same time; column chromatography conditions: mobile phase is water, column temperature is 0-80°C, and the empty column flow rate is 0.3 ~6.4cm/min. 2. The simultaneous preparation method of a kind of cellopolysaccharide series reagent according to claim 1, characterized in that said cellopolysaccharide is cellobiose, cellotriose, cellotetraose, cellopentaose, cellohexaose. 3. The simultaneous preparation method of a kind of fiber polysaccharide series reagent according to claim 1 or 2, characterized in that said ion exchange column chromatography adopts macroporous strongly basic or weakly basic anion exchange resin. 4. the simultaneous preparation method of a kind of fiber polysaccharide series reagent according to claim 1 or 2, is characterized in that the gel that said gel permeation column chromatography adopts is glucose gel, polyacrylamide gel, agar Sugar gel, starch gel, porous silica gel.