阅读说明：本技术 一种利用间歇模拟移动床色谱同时制取木糖、***糖和半乳糖的方法 (Method for simultaneously preparing xylose, arabinose and galactose by using intermittent simulated moving bed chromatography ) 是由 张军伟 贾彩敬 袁苗新 于 2020-07-08 设计创作，主要内容包括：本发明公开了一种利用间歇模拟移动床色谱同时制取木糖、阿拉伯糖和半乳糖的方法,属于食品工业分离技术领域。该方法包括以下步骤：(1)木糖母液预处理；(2)间歇模拟移动床色谱分离木糖、阿拉伯糖和半乳糖。本发明不仅能以高纯度和高产率从木糖母液或木糖发酵液中同时制取木糖、阿拉伯糖和半乳糖,克服糖组分回收率不高、常规色谱不满足分离要求、现有色谱多组分分离系统复杂、固定相需求量大、分离功能区交叉污染等问题,还解决了因半乳糖导致木糖和阿拉伯糖结晶收率较低、发酵法难以消耗掉半乳糖等问题,实现了高价值糖类的充分回收,提高了资源利用率。(The invention discloses a method for simultaneously preparing xylose, arabinose and galactose by using an intermittent simulated moving bed chromatography, belonging to the technical field of separation in the food industry. The method comprises the following steps: (1) pretreating xylose mother liquor; (2) and (3) separating xylose, arabinose and galactose by using intermittent simulated moving bed chromatography. The method can simultaneously prepare xylose, arabinose and galactose from the xylose mother liquor or the xylose fermentation liquor with high purity and high yield, overcomes the problems that the recovery rate of sugar components is not high, the conventional chromatogram does not meet the separation requirement, the existing chromatographic multi-component separation system is complex, the stationary phase requirement is large, the separation functional area is cross-polluted and the like, also solves the problems that the crystallization yield of the xylose and the arabinose is low, the galactose is difficult to be consumed by a fermentation method and the like due to the galactose, realizes the full recovery of high-value saccharides, and improves the resource utilization rate.)

1. A method for simultaneously preparing xylose, arabinose and galactose by using a batch simulated moving bed chromatography, which is characterized by comprising the following steps:

(1) pretreatment of xylose mother liquor: diluting the xylose mother liquor, fermenting by using yeast to remove glucose, cellobiose and mannose, and filtering to remove colloids, proteins, hyphae and solid matters to obtain xylose fermentation liquor; removing color and luster substances and inorganic ions in the xylose fermentation liquor by using activated carbon in combination with anion-cation exchange resin to obtain sugar liquor with the light transmittance higher than 80%, performing rotary evaporation, controlling the temperature to be 65-80 ℃, and performing evaporation concentration on the sugar liquor until the refractive concentration is 40-60% to obtain a raw material;

(2) and (3) intermittent simulated moving bed chromatographic separation: separating the raw materials obtained in the step (1) by intermittent simulated moving bed chromatography to prepare xylose, arabinose and galactose; the intermittent simulated moving bed chromatography takes calcium-type or lead-type strong acid cation resin as a stationary phase and deionized water as an eluent, and the working temperature is 50-75 ℃;

the intermittent simulated moving bed chromatogram comprises a No. 1 chromatographic column, a No. 2 chromatographic column, a No. 3 chromatographic column, a No. 4 chromatographic column, a No. 5 chromatographic column and a No. 6 chromatographic column which are sequentially connected in series, and comprises a zone I, a zone II, a zone III and a zone IV, wherein the zone I, the zone II and the zone III respectively contain 2 chromatographic columns which are sequentially connected in series, and the zone IV contains 6 chromatographic columns which are sequentially connected in series; said zone I is located between the eluent port and the feed port; the II zone is located between the feed port and the xylose component port; the III zone is between the xylose component port and the arabinose component port, and the IV zone is between the eluent port and the galactose component port.

2. The method as claimed in claim 1, wherein the xylose mother liquor is a viscous sugar liquor left after the production of crystalline xylose from agricultural and forestry waste corncobs, bagasse, straw, eucalyptus or birch; the total sugar refractive concentration of the xylose mother liquor is 50-60%, wherein the xylose content is 45-52%, the arabinose content is 20-23%, the galactose content is 7-10%, the glucose content is 12-13.5%, and the cellobiose and mannose content is 2-5% by mass fraction.

3. The method according to claim 1, wherein the cross-linking agent of the stationary phase is polyene benzene, the cross-linking level is 6-15%, the calcium or lead rate is more than 95%, and the particle size of the resin is 120-250 μm.

4. The method according to claim 1, wherein the eluent flows through a number 1 to a number 6 chromatographic column, and the simulated moving direction of the stationary phase is a number 6 to a number 1 chromatographic column; a multi-channel rotary valve which is servo by a motor is arranged in front of and behind each chromatographic column, and the multi-channel rotary valves are arranged at the eluent port, the feeding port, the xylose component port, the arabinose component port and the galactose component port.

5. The method according to claim 4, wherein a flow meter is arranged in front of the feed port and the eluent port, and a conductivity meter, a flow meter and a flow regulating valve are arranged behind the xylose component port, the arabinose component port and the galactose component port; the chromatographic columns are connected by pipelines; the height-diameter ratio of the chromatographic column is as follows: 15: 1-25: 1.

6. The method of claim 4, wherein the chromatographic column is insulated with a circulating water jacket at a temperature of 50 ℃ to 75 ℃; the positions and the opening or the closing of designated ports on a multichannel rotary valve servo by motors at the front and the rear of the chromatographic column are controlled by a PLC program, so that the raw materials, the eluent and the sugar components are fed, and the stationary phase is simulated to move.

7. The method of claim 4, wherein there are two substeps in each cycle of the method for simultaneously producing xylose, arabinose and galactose: substeps one and two; after each period of operation, each port position moves forward one chromatographic column along the flowing direction of the eluent, and the port position is restored to the initial position after all the ports are operated circularly.

8. The method according to claim 7, characterized in that the specific steps of said two sub-steps are as follows:

(a) the first substep: respectively opening an eluent port and a feeding port on a multi-channel rotary valve in front of a No. 1 chromatographic column and a No. 3 chromatographic column, respectively flowing eluent and raw materials, wherein the affinity between a fixed phase and different sugar components in the raw materials is different, the migration speed of a xylose component is higher than that of other components under the driving of the eluent, and the xylose component flows out from a xylose component port at the end of the No. 4 chromatographic column; the strong reserved component arabinose of the last period flows out from the arabinose component port at the end of the No. 6 chromatographic column;

(b) and a second substep: after the operation of the first substep is finished, closing a feeding port in front of the No. 3 chromatographic column, closing a xylose component port at the end of the No. 4 chromatographic column, and forming an independent chromatographic separation area, namely an IV zone, from the No. 1 chromatographic column to the No. 6 chromatographic column by using the No. 1 chromatographic column and an eluent in the flowing direction, wherein a galactose component and an arabinose component in the period migrate to the end of the No. 6 chromatographic column; the arabinose component has strong affinity with the stationary phase, the migration speed of the arabinose component is slower than that of galactose, and the galactose component flows out from a galactose component port at the end of the No. 6 chromatographic column;

when the operation of the sub-step two is finished, the eluent port is switched from the front end of the No. 1 chromatographic column to the front end of the No. 2 chromatographic column; the feeding port is switched from the front end of the No. 3 chromatographic column to the front end of the No. 4 chromatographic column; the xylose component port is switched from the end of the No. 4 chromatographic column to the end of the No. 5 chromatographic column; the arabinose component port is switched from the end of the No. 6 chromatographic column to the end of the No. 1 chromatographic column; after each period of operation is finished, each port position moves forward one chromatographic column along the flowing direction of the eluent, all the ports are recovered to the initial position of the port after operation circulation is finished, and the substep I and the substep II are repeatedly operated to respectively collect xylose components, arabinose components and galactose components.

9. The method according to claim 8, wherein the eluent has a flow rate of 4-5 mL/min, the raw material flow rate is 2-3 mL/min, the xylose component flow rate is 2-4 mL/min, the arabinose component flow rate is 3-5 mL/min, the galactose component flow rate is 4-6 mL/min, the time of the first sub-step is 5-6 min, and the time of the second sub-step is 8-11 min.

Technical Field

The invention belongs to the technical field of separation in the food industry, and relates to a method for simultaneously preparing xylose, arabinose and galactose by using an intermittent simulated moving bed chromatography.

Background

Xylose is a pentose, also known as pentaaldose, and is mainly present in plants in the form of heteropolysaccharide. Xylose is a low calorie sugar sweetener (sweetness is 72% of sucrose and is close to glucose), and has effects of promoting production of Bacillus bifidus and intestinal peristalsis, and resisting dental caries. The product of xylose after catalytic hydrogenation (i.e. xylitol) is a healthy sweetener, the sweetness is equivalent to that of sucrose, and the xylitol has similar physiological efficacy to that of xylose.

Arabinose is a five-carbon sugar, also called arabinose, which is mainly present in plant pulp, hemicellulose and the like in the form of heteropolysaccharide. Arabinose, a novel low calorie sweetener, has been approved by the united states, japan, etc. as a health food additive, and its representative physiological effect is to selectively affect sucrase that digests sucrose in enterodisaccharide hydrolase, and to restrict the conversion of sucrose and glucose into glycogen to be absorbed by the liver.

Galactose is a caloric six-carbon aldose, an important component of mammalian milk and glycoproteins, and a component constituting cerebroside in the cranial nervous system. Galactose is present in plant kingdom in the form of polysaccharides in plant gums or ivy berries. In the semi-fiber branch structure of the plant cell wall, the side chain substituent contains galactose units, and the galactose units are dissolved out of the plant cell wall in a monosaccharide form during the hydrolysis of the semi-fiber acid.

Three kinds of saccharides with special effects are initially used in the nutritional health care and food industries, and are gradually developed into non-food fields such as chemical industry, pharmacy, cosmetics, biorefinery, petroleum and the like.

In industry, agricultural and forestry wastes such as corncobs, straws, bagasse, eucalyptus and the like are hydrolyzed or enzymolyzed by dilute acid to obtain primary sugar liquid, and then refined, concentrated and crystallized to prepare xylose (or xylitol is prepared by hydrogenation) and arabinose, wherein a large amount of xylose mother liquor is generated in the process. However, the existing production of xylose or arabinose can only show scientific and commercial value after reaching higher purity, so the separation and purification are very important links in the production and manufacturing process.

The xylose mother liquor is viscous liquid remained after xylose crystallization, generally contains xylose, arabinose, glucose, galactose and a small amount of other impurities, and has slightly different component contents according to different raw materials and processes, wherein the component contents are that the xylose contains 40-52 percent, the arabinose contains 25-32 percent, the glucose contains 10-18 percent, the galactose contains 10-16 percent and the impurities contain 3-7 percent according to mass fraction. After the xylose is crystallized, the ratio of galactose to glucose in the mother liquor is increased, and the traditional crystallization process cannot extract the xylose and the arabinose. For this problem, xylose mother liquor is generally fermented to remove glucose, and then the xylose and arabinose are extracted by chromatographic separation, and other components are taken as heterosugars. And returning the xylose-rich component obtained by chromatographic separation to the upstream for xylose crystallization, and refining, concentrating and crystallizing the arabinose-rich component to obtain a crystal substance.

In Chinese patent publication No. CN1699587A, xylose hydrolysate or xylose mother liquor is used as raw material, Saccharomyces cerevisiae is used for fermentation to remove glucose, and simulated moving bed chromatography is used for separating impurity sugars such as target component xylose and arabinose, to obtain xylose-rich component for recrystallization. Chinese patent (publication No. CN104086607A) uses active dry yeast to remove glucose, and after decolouring, ion-exchange and evaporation, uses continuous chromatography to separate the component rich in arabinose and xylose, and crystallizes to obtain arabinose and xylose. Chinese patent (publication No. CN107142337A) discloses that bagasse is used as raw material to prepare xylose and arabinose, 0.2-2% yeast is used to ferment xylose crystallization mother liquor, and a chromatographic separation device is used to separate the xylose-rich component and the arabinose-rich component. Glucose is removed from xylose mother liquor through fermentation, arabinose and xylose are separated and extracted, other galactose and the like are contained as heterosugar, galactose with high content and high added value in the mother liquor cannot be extracted, and the heterosugar is only treated at low price.

In order to reduce the types and the content of sugar components in the xylose mother liquor, biological fermentation or enzyme method-assisted purification is used, and specific microorganisms or enzymes are used for selectively converting unnecessary sugars in the xylose hydrolysate or the xylose mother liquor, so that the relative purity of target monosaccharide is improved.

Chinese patent (publication No. CN101555503A) uses specific microorganism, namely red yeast to metabolize monosaccharide in xylose mother liquor except arabinose so as to purify the xylose mother liquor and separate the arabinose. Chinese patent (publication No. CN101497904A) inoculates specific Candida tropicalis into detoxified hemicellulose hydrolysate, and xylose is converted into xylitol, thereby improving chromatographic separation efficiency and purity of the obtained components. Chinese patent (publication No. CN101665523A) utilizes the cooperation of various specific bacteria to convert xylose hydrolysis or sugar components in xylose mother liquor except xylose and arabinose into ethanol, ribose or lemon, and then extracts xylose and arabinose by chromatographic separation. However, specific microbial or fungoid invert sugar components are present: 1) the implementation conditions are strict and the period is long; 2) non-target sugar component resources cannot be recovered, and the due value of the non-target sugar component resources cannot be realized; 3) substances generated by the synergistic transformation of multiple strains influence the chromatographic separation and extraction of xylose and arabinose.

To overcome the disadvantages of specific microbial fermentation processes, non-target sugar components in the xylose mother liquor are chemically reduced to improve the purity and yield of the chromatographically separated components.

Chinese patent publication No. CN102093435A (kokai) utilizes the difference between the characteristics of sugar dissolution in organic solvents with different water contents and cooling crystallization to extract arabinose from mixed sugar, and the used organic solvents include alcohols, ethers, ketones, carboxylic acids, nitrogen-containing organic solvents, etc. U.S. Pat. No. 3, 7498430, 2 discloses the use of a monosaccharide reacted with a ketone or aldehyde to form a glycoaldehyde, and the separation of xylose and arabinose in a mixture is achieved based on the difference in solubility of the glycoaldehyde in polar and non-polar organic solvents. However, the disadvantages of the use of organic solvents in industrial processes are obvious, in particular in the food industry, with the risk of safety.

For this reason, many scholars or inventors have optimized or improved the refining or separation and extraction process of xylose mother liquor in order to achieve efficient extraction of target sugar components and maximum recovery of high-value sugar components.

Chinese patent publication No. CN101792822A discloses that after the hemicellulose hydrolysate is subjected to electrodialysis and membrane filtration preconcentration, xylose and arabinose are separated by sequencing batch simulated moving bed chromatography, as shown in fig. 1. However, in the above patent: 1) how glucose, galactose and other components are treated is not described; 2) the sequencing batch simulated moving bed can only realize the separation and extraction of two components. Chinese patent (publication No. CN107142337A) discloses a method for preparing xylose and arabinose by using bagasse as a raw material, which comprises the steps of firstly carrying out decoloration, deionization and separation on concentrated solution by using a decoloration, deionization and separation mixing device to obtain xylose-rich liquid and arabinose-rich liquid, refining and then recrystallizing to obtain crystalline xylose and crystalline arabinose, and then separating mother liquor of the xylose and the arabinose by using a simulated moving bed. However, no other sugar components than xylose and arabinose are mentioned herein; and when the simulated moving bed separates the xylose mother liquor and the arabinose mother liquor, the structure and the operation mode of the simulated moving bed are not described.

Chinese patent publication No. CN1699587A discloses a method for extracting xylose or xylitol from xylose mother liquor or xylose hydrolysate by four-zone simulated moving bed chromatographic separation, which is provided with an extraction zone, an enrichment zone, an analysis zone and a circulation zone, and can separate xylose from the xylose mother liquor or separate xylitol from the xylitol mother liquor as shown in figure 2. However, the separation and extraction of sugar components other than xylose or xylitol is not mentioned. Chinese patent (publication No. CN102924538A) discloses a method for separating xylose, arabinose and galactose by six-zone simulated moving bed chromatography (as shown in figure 3), which takes special resin special for sugar alcohol as a stationary phase, and has the purity of 84-95 percent of xylose, 73-87 percent of arabinose, 55-68 percent of galactose and the yield of 80-90 percent of three components. However, the above patents exist: 1) the number of valves, pipelines and control sites are large, and the stationary phase resin is large in demand due to more chromatographic partitions; 2) when a plurality of components are separated and extracted, cross contamination of components in pipelines is easy to occur, the purity of the components is influenced, and the subsequent crystallization process is influenced; 3) the proportion of feed water is high, and the problem of excessive dilution of components is inevitable.

In summary, xylose mother liquor is mainly pretreated by fermentation process, refined, concentrated and crystallized to obtain crystalline xylose and crystalline arabinose. The existing simulated moving bed chromatographic method cannot effectively recover the galactose in the xylose mother liquor, and the specific strains and conditions for removing the galactose by the fermentation method are strict, so that the operation cost of the subsequent treatment process is increased, the product yield in the subsequent xylose and arabinose crystallization process is reduced, and the resource utilization rate is reduced.

The intermittent simulated moving bed is a novel chromatographic separation method, and has four chromatographic functional areas, and four ports are arranged in a structural mode similar to a conventional four-zone simulated moving bed. A method for simultaneously preparing xylose, arabinose and galactose by applying novel four-zone intermittent simulated moving bed chromatography is explored, and the defects of the conventional four-zone or sequential simulated moving bed chromatography, five-zone or above simulated moving bed chromatography and the like are overcome.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a method for simultaneously preparing xylose, arabinose and galactose by using intermittent simulated moving bed chromatography. By using the method provided by the invention, xylose, arabinose and galactose can be continuously and effectively separated from the xylose mother liquor.

The technical scheme of the invention is as follows:

a method for simultaneously preparing xylose, arabinose and galactose by using a batch simulated moving bed chromatography comprises the following steps:

(1) pretreatment of xylose mother liquor: diluting the xylose mother liquor, fermenting by using yeast to remove glucose, cellobiose and mannose, and filtering to remove colloids, proteins, hyphae and solid matters to obtain xylose fermentation liquor; removing color and luster substances and inorganic ions in the xylose fermentation liquor by using activated carbon in combination with anion-cation exchange resin to obtain sugar liquor with the light transmittance higher than 80%, performing rotary evaporation, controlling the temperature to be 65-80 ℃, and evaporating and concentrating the sugar liquor until the refractive concentration is 40-60% (measured by an Abbe photometer) to obtain a raw material;

(2) and (3) intermittent simulated moving bed chromatographic separation: separating the raw materials obtained in the step (1) by intermittent simulated moving bed chromatography to prepare xylose, arabinose and galactose; the intermittent simulated moving bed chromatography takes calcium-type or lead-type strong acid cation resin as a stationary phase and deionized water as an eluent, and the working temperature is 50-75 ℃;

the intermittent simulated moving bed chromatogram comprises a No. 1 chromatographic column, a No. 2 chromatographic column, a No. 3 chromatographic column, a No. 4 chromatographic column, a No. 5 chromatographic column and a No. 6 chromatographic column which are sequentially connected in series, and comprises a zone I, a zone II, a zone III and a zone IV, wherein the zone I, the zone II and the zone III respectively contain 2 chromatographic columns which are sequentially connected in series, and the zone IV contains 6 chromatographic columns which are sequentially connected in series; said zone I is located between the eluent port and the feed port; the II zone is located between the feed port and the xylose component port; the III zone is between the xylose component port and the arabinose component port, and the IV zone is between the eluent port and the galactose component port.

Further, in the step (1), the xylose mother liquor is diluted by deionized water, the refractive concentration after dilution is 20-25%, active dry yeast powder is inoculated into the xylose mother liquor according to the proportion of 0.1-0.3% (m/V), air blowing oxygenation is carried out, the temperature is controlled to be 25-35 ℃, fermentation is carried out for 15-30 hours, the glucose content in the fermented xylose liquor after fermentation is lower than 2%, and the content of impurity sugar is lower than 0.5%.

Further, the xylose mother liquor is viscous sugar liquor left after the agricultural and forestry wastes such as corncobs, bagasse, straws, eucalyptus or birch are used for producing crystallized xylose; the total sugar refractive concentration of the xylose mother liquor is 50-60%, wherein the xylose content is 45-52%, the arabinose content is 20-23%, the galactose content is 7-10%, the glucose content is 12-13.5%, and the cellobiose and mannose content is 2-5% by mass fraction.

Furthermore, the cross-linking agent of the stationary phase is polyene benzene, the cross-linking level is 6-15%, the calcium type or lead type rate is more than 95%, and the particle size of the resin is 120-250 μm.

Further, the flowing direction of the eluent is from No. 1 to No. 6, and the simulated moving direction of the stationary phase is from No. 6 to No. 1; a multi-channel rotary valve which is servo by a motor is arranged in front of and behind each chromatographic column, and the multi-channel rotary valves are arranged at the eluent port, the feeding port, the xylose component port, the arabinose component port and the galactose component port.

Furthermore, flow meters are arranged in front of the feed port and the eluent port, and a conductivity meter, a flow meter and a flow regulating valve are arranged behind the xylose component port, the arabinose component port and the galactose component port; the chromatographic columns are connected by pipelines; the height-diameter ratio of the chromatographic column is as follows: 15: 1-25: 1.

Further, the chromatographic column is heated and insulated by a jacket, and the temperature is 50-75 ℃; the positions and the opening or the closing of designated ports on a multichannel rotary valve servo by motors at the front and the rear of the chromatographic column are controlled by a PLC program, so that the raw materials, the eluent and the sugar components are fed, and the stationary phase is simulated to move.

Further, the method has two substeps in each period for simultaneously preparing xylose, arabinose and galactose: substeps one and two; after each period of operation, each port position moves forward one chromatographic column along the flowing direction of the eluent, and the port position is restored to the initial position after all the ports are operated circularly.

Further, each period for simultaneously preparing xylose, arabinose and galactose by the batch simulated moving bed chromatography has two substeps, and the specific steps are as follows:

(1) the first substep: respectively opening an eluent port and a feeding port on a multi-channel rotary valve in front of a No. 1 chromatographic column and a No. 3 chromatographic column, respectively flowing eluent and raw materials, under the pushing of the eluent, enabling the affinity between a fixed phase and different sugar components in the raw materials to have difference, enabling the migration speed of the xylose component to be faster than that of other components, and enabling the xylose component to flow out from a xylose component port at the end of the No. 4 chromatographic column; the strong reserved component arabinose of the last period flows out from the arabinose component port at the end of the No. 6 chromatographic column; because the No. 1 chromatographic column and the No. 6 chromatographic column are discontinuous, namely the discharged material from the zone III does not enter the zone I any more, the problems of cross contamination or component dilution do not exist;

(2) and a second substep: after the operation of the first substep is finished, closing a feeding port in front of the No. 3 chromatographic column, closing a xylose component port at the end of the No. 4 chromatographic column, and forming an independent chromatographic separation area, namely an IV zone, from the No. 1 chromatographic column to the No. 6 chromatographic column by using the No. 1 chromatographic column and an eluent in the flowing direction, wherein a galactose component and an arabinose component in the period migrate to the end of the No. 6 chromatographic column; the arabinose component has strong affinity with the stationary phase, the migration speed of the arabinose component is slower than that of galactose, and the galactose component flows out from a galactose component port at the end of the No. 6 chromatographic column;

after the substep two is finished, switching the eluent port from the front end of the No. 1 chromatographic column to the front end of the No. 2 chromatographic column; the feeding port is switched from the front end of the No. 3 chromatographic column to the front end of the No. 4 chromatographic column; the xylose component port is switched from the end of the No. 4 chromatographic column to the end of the No. 5 chromatographic column; the arabinose component port is switched from the end of the No. 6 chromatographic column to the end of the No. 1 chromatographic column; after each period of operation is finished, each port position moves forward one chromatographic column along the flowing direction of the eluent, all the ports are recovered to the initial position after operation circulation is finished, and the substep I and the substep II are repeatedly operated to respectively collect xylose components, arabinose components and galactose components.

Further, the flow rate of the eluent is 4-5 mL/min, the flow rate of the raw material is 2-3 mL/min, the flow rate of the xylose component is 2-4 mL/min, the flow rate of the arabinose component is 3-5 mL/min, the flow rate of the galactose component is 4-6 mL/min, the time of the first substep is 5-6 min, and the time of the second substep is 8-11 min.

The working mechanism of the invention is as follows: calcium or lead ions and sulfonic groups on the resin form a coordination type strong acid cation resin chromatographic stationary phase through coordination. Each hydroxyl group on the sugar molecule has a very weak negative charge, and the hydroxyl group on the anomeric carbon can be deprotonated to have a strong negative charge, and the sugar molecule is retained by the interaction of the negative charge on the sugar molecule with the positive charge of the calcium or lead ion on the resin surface. In single column chromatography, xylose molecule retention time is short, galactose retention time is the second, arabinose retention time is the longest, namely arabinose and chromatography fixed affinity is strongest, galactose is the second, xylose is the weakest. And continuously flowing xylose mother liquor or fermentation liquor into a four-section open-loop simulated moving bed chromatographic system consisting of six chromatographic columns, wherein the first substep collects a weak retention component xylose and a strong retention component arabinose of the previous period, and the second substep collects a medium retention component galactose. And then switching ports along the flowing direction of the eluent to simulate the movement of the stationary phase, and continuously and efficiently preparing xylose, arabinose and galactose simultaneously by utilizing the simulated moving bed.

The beneficial technical effects of the invention are as follows:

(1) the method can simultaneously separate and prepare xylose, arabinose and galactose, and the product has higher yield and purity, thereby fully exploiting the value of the sugar component in the xylose mother liquor;

(2) the invention can avoid the dilution of the concentration of the extracting solution and the cross contamination of the chromatographic function separation zone, the concentration of the component outlet is higher than that of the conventional simulated moving bed, and the subsequent treatment cost is reduced; the problems and the defects of the conventional four-zone or sequential simulated moving bed method, five-zone or more simulated moving bed chromatography and the like in the prior art are overcome;

(3) the invention reduces the resin dosage and the number of chromatographic columns, and reduces the investment and the loss; meanwhile, feed liquid back mixing is reduced, so that the purity and yield of the xylose and arabinose are improved, and a galactose component is newly added; the full recovery of high-value sugar components in the xylose mother liquor is realized, and the utilization rate of biomass resources is improved;

(4) the purity of the xylose, arabinose and galactose which can be continuously recovered by the method is 85 to 95 percent, and the yield is higher than 90 percent.

Drawings

FIG. 1 is a schematic diagram of sequential simulated moving bed chromatography for the separation of xylose and arabinose.

FIG. 2 is a schematic diagram of a four-zone simulated moving bed chromatography for separating xylose or arabinose components.

FIG. 3 is a schematic diagram of six-zone simulated moving bed chromatography for separating xylose, arabinose, galactose and heterosugars.

FIG. 4 is a schematic diagram of separation of xylose and galactose by zone I, zone II, and zone III, portport rearrangement batch simulated moving bed chromatography.

FIG. 5 is a schematic of the separation of arabinose by IV zone-ported rearranged batch simulated moving bed chromatography.

Detailed Description

The batch simulated moving bed chromatography described in the following examples is shown in fig. 4 and fig. 5, and comprises a chromatographic column 1, a chromatographic column 2, a chromatographic column 3, a chromatographic column 4, a chromatographic column 5 and a chromatographic column 6 which are sequentially connected in series, and comprises a zone I, a zone II, a zone III and a zone IV, wherein the zone I, the zone II and the zone III respectively contain 2 chromatographic columns which are sequentially replaced in series, and the zone IV contains 6 chromatographic columns which are sequentially replaced in series; said zone I is located between the eluent port and the feed port; the II zone is located between the feed port and the xylose component port; the III zone is between the xylose component port and the arabinose component port, and the IV zone is between the eluent port and the galactose component port. The flowing direction of the eluent is from No. 1 to No. 6, and the simulated moving direction of the stationary phase is from No. 6 to No. 1; a multi-channel rotary valve which is servo by a motor is arranged in front of and behind each chromatographic column, and the multi-channel rotary valves are arranged at the eluent port, the feeding port, the xylose component port, the arabinose component port and the galactose component port. Flowmeters are arranged in front of the feed port and the eluent port, conductivity meters, flowmeters and flow regulating valves are arranged behind the xylose component port, the arabinose component port and the galactose component port, and running data is recorded by a PLC program; the chromatographic columns are connected by pipelines; the height-diameter ratio of the chromatographic column is as follows: 15: 1-25: 1. The chromatographic column is heated and insulated by a jacket, and the temperature is 50-75 ℃; the positions and the opening or the closing of designated ports on a multichannel rotary valve servo by motors at the front and the rear of the chromatographic column are controlled by a PLC program, so that the raw materials, the eluent and each sugar component are fed, and the chromatographic stationary phase is simulated to move.

The method for simultaneously preparing xylose, arabinose and galactose by using the batch simulated moving bed chromatography in the following examples has two substeps in each period, and comprises the following specific steps:

(1) the first substep: respectively opening an eluent port and a feeding port on a multi-channel rotary valve in front of a No. 1 chromatographic column and a No. 3 chromatographic column, respectively flowing eluent and raw materials, under the pushing of the eluent, enabling the affinity between a fixed phase and different sugar components in the raw materials to have difference, enabling the migration speed of the xylose component to be faster than that of other components, and enabling the xylose component to flow out from a xylose component port at the end of the No. 4 chromatographic column; the strong reserved component arabinose of the last period flows out from the arabinose component port at the end of the No. 6 chromatographic column; because the No. 1 chromatographic column and the No. 6 chromatographic column are discontinuous, namely the discharged material from the zone III does not enter the zone I any more, the problems of cross contamination or component dilution do not exist;

(2) and a second substep: after the operation of the first substep is finished, closing a feeding port in front of the No. 3 chromatographic column, closing a xylose component port at the end of the No. 4 chromatographic column, and forming an independent chromatographic separation area, namely an IV zone, from the No. 1 chromatographic column to the No. 6 chromatographic column by using the No. 1 chromatographic column and an eluent in the flowing direction, wherein a galactose component and an arabinose component in the period migrate to the end of the No. 6 chromatographic column; the arabinose component has strong affinity with the stationary phase, the migration speed of the arabinose component is slower than that of galactose, and the galactose component flows out from a galactose component port at the end of the No. 6 chromatographic column;

after the substep two is finished, switching the eluent port from the front end of the No. 1 chromatographic column to the front end of the No. 2 chromatographic column; the feeding port is switched from the front end of the No. 3 chromatographic column to the front end of the No. 4 chromatographic column; the xylose component port is switched from the end of the No. 4 chromatographic column to the end of the No. 5 chromatographic column; the arabinose component port is switched from the end of the No. 6 chromatographic column to the end of the No. 1 chromatographic column; after each period of operation is finished, each port position moves forward one chromatographic column along the flowing direction of the eluent, all the ports are recovered to the initial position after operation circulation is finished, and the substep I and the substep II are repeatedly operated to respectively collect xylose components, arabinose components and galactose components.

The "about" ranges mentioned in the examples below are given as a percentage of the numerical values ± 1%.