Production process and equipment for purifying xylose from xylose hydrolysate and application

Abstract

The invention discloses a production process and equipment for purifying xylose from xylose hydrolysate and application, and belongs to the technical field of xylose production. The process comprises the following steps: pretreating xylose hydrolysate, and conveying the pretreated xylose hydrolysate to a tubular ultrafiltration membrane for filtration; filtering and decolorizing the clear liquid obtained by filtering with the tubular ultrafiltration membrane through a roll-type ultrafiltration membrane; carrying out hardness removal treatment on clear liquid obtained by decoloring through a cation hardness removal resin device; concentrating and deacidifying the effluent after hardness removal through a high-pressure nanofiltration membrane; concentrating the deacidified clear liquid through an acid-resistant high-pressure RO (Reverse Osmosis) membrane; the deacidified concentrated liquor is treated by a cation exchange resin device, the obtained effluent is conveyed to an anion exchange resin device to further adsorb anions in the solution, and the obtained effluent is treated by an evaporative crystallization drying system to obtain a xylose product.

Description

Technical Field

[0001] The present invention relates to the technical field of xylose production, and particularly relates to a production process, equipment and application for purifying xylose from xylose hydrolysis solution. Background Art

[0002] Xylose is a pentose sugar with the following characteristics and uses:

[0003] 1. Basic properties:

[0004] - Appearance: white crystals or crystalline powder.

[0005] - Solubility: readily soluble in water.

[0006] - Molecular formula: C4H9O4CHO.

[0007] - Source: It is a component of xylan, which is widely present in plants. Xylose also exists in heparin, chondroitin and glycoproteins of animals. It is the connecting unit between the sugar chain and serine (or threonine) in some glycoproteins. Free xylose has not been found in nature.

[0008] 2. Physiological functions:

[0009] - Prebiotic effect: It cannot be absorbed by the small intestine, but will be fermented and utilized by beneficial bacteria such as Bifidobacterium in the large intestine, promoting the growth and reproduction of beneficial bacteria, improving the human microbial environment and enhancing the body's immune capacity.

[0010] - Assisting in calcium supplementation: When ingested simultaneously with calcium, it can increase the absorption rate and retention rate of calcium in the human body, and can also prevent constipation to a certain extent.

[0011] - Special metabolic pathway: Conventional enzymes in the human body are difficult to decompose xylose, and it usually directly reaches the intestine.

[0012] 3. Application fields:

[0013] - Food industry:

[0014] - As a calorie-free sweetener, it is suitable for obese and diabetic patients, and can also be used as a raw material for making caramel and for preparing spices such as pork through the Maillard reaction.

[0015] - Due to its obvious flavor-enhancing effect, it can be used in the spice and pet food industries; due to its obvious color-enhancing effect, it can be used for the golden-brown coloring of the food industry, such as the coloring of butter and bread.

[0016] - Pharmaceutical field: It can be used as a pharmaceutical raw material and pharmaceutical intermediate.

[0017] - Other fields: It also has certain uses in light industry and chemical industry, such as for the production of xylitol, etc.

[0018] China is a major producer of xylose. The traditional purification process of xylose production usually includes the following steps:

[0019] Raw material pretreatment: Agricultural wastes such as corncobs, bagasse, and cottonseed hulls are crushed and screened for pretreatment to remove impurities.

[0020] Hydrolysis: The pretreated raw materials are mixed with catalysts such as sulfuric acid and subjected to hydrolysis reaction under high temperature and high pressure to hydrolyze the hemicellulose in the raw materials into xylose.

[0021] Neutralization: The hydrolyzed solution is neutralized to adjust the pH value to neutral.

[0022] Decolorization: The neutralized solution is decolorized with decolorizing agents such as activated carbon to remove impurities such as pigments.

[0023] Primary purification: The decolorized solution is purified for the first time through ion exchange resins and other means to remove impurity ions and the like.

[0024] Primary evaporation and concentration: The solution after primary purification is evaporated and concentrated to increase the concentration of xylose.

[0025] Secondary purification: The solution after primary evaporation and concentration is purified for the second time to further remove impurities.

[0026] Secondary evaporation and concentration: The solution after secondary purification is evaporated and concentrated to obtain a high-concentration xylose solution.

[0027] Crystallization: The high-concentration xylose solution is cooled and crystallized to obtain xylose crystals.

[0028] Centrifugation: The crystallized xylose crystals are centrifuged to separate the mother liquor.

[0029] Drying: The centrifuged xylose crystals are dried to obtain the finished xylose.

[0030] The traditional purification process of xylose production has problems such as complex process, many equipment, large consumption of ion exchange resins, high consumption of acids and alkalis for resin regeneration, large amount of wastewater discharge, serious environmental pollution, large consumption of steam, high cost, and long production cycle. Therefore, the present invention explores and improves the xylose production and purification process to improve production efficiency, reduce costs, and reduce environmental pollution. Summary of the Invention

[0031] In view of the deficiencies of the prior art, the present invention provides a production process, equipment and application for purifying xylose from xylose hydrolysis solution.

[0032] The object of the present invention can be achieved by the following technical solutions:

[0033] The first aspect of the present invention relates to a process for purifying xylose from xylose hydrolysis solution, comprising the following steps:

[0034] Pre-treat the xylose hydrolysis solution and transport it to tubular ultrafiltration membrane filtration;

[0035] The clear liquid obtained from tubular ultrafiltration membrane filtration is decolorized by spiral ultrafiltration membrane filtration;

[0036] The clear liquid obtained after decolorization is subjected to hardness removal treatment by a cationic hardness removal resin device;

[0037] The effluent after hardness removal is concentrated and deacidified by a high-pressure nanofiltration membrane;

[0038] The clear liquid after deacidification is concentrated by an acid-resistant high-pressure RO membrane; the concentrated liquid after deacidification is treated by a cation exchange resin device, and the obtained effluent is transported to an anion exchange resin device to further adsorb anions in the solution. The obtained effluent is treated by an evaporation crystallization drying system to obtain a xylose product.

[0039] Optionally, the clear liquid output by the acid-resistant high-pressure RO membrane is returned to the tubular ultrafiltration membrane and / or the spiral ultrafiltration membrane for use as dialysis water.

[0040] Optionally, the sulfuric acid recovered by the acid-resistant high-pressure RO membrane is returned to the hydrolysis process in xylose production.

[0041] Optionally, the cut-off molecular weight of the tubular ultrafiltration membrane is 200,000 - 300,000 Dalton; the cut-off molecular weight of the spiral ultrafiltration membrane is 1,000 - 5,000 Dalton, and the cut-off molecular weight of the high-pressure nanofiltration membrane is 100 - 300 Dalton.

[0042] Optionally, the concentrated liquids of the tubular ultrafiltration membrane and the spiral ultrafiltration membrane are output to the biochemical system of the sewage treatment plant for treatment.

[0043] The second aspect of the present invention relates to a xylose hydrolysis solution purification device, comprising a tubular ultrafiltration membrane, a spiral ultrafiltration membrane, a cationic hardness removal resin device, a high-pressure nanofiltration membrane, a cation exchange resin device, an anion exchange resin device, and an evaporation crystallization device;

[0044] The clear liquid output end of the tubular ultrafiltration membrane is connected to the input end of the spiral ultrafiltration membrane;

[0045] The clear liquid output end of the spiral ultrafiltration membrane is connected to the input end of the cationic hardness removal resin device;

[0046] The effluent output end of the cationic hardness removal resin device is connected to the input end of the high-pressure nanofiltration membrane;

[0047] The clear liquid output end of the high-pressure nanofiltration membrane is connected to the input end of the acid-resistant high-pressure RO membrane;

[0048] The concentrated liquid output end of the high-pressure nanofiltration membrane is connected to the input end of the cation exchange resin device;

[0049] The effluent output end of the cation exchange resin device is connected to the input end of the anion exchange resin device;

[0050] The effluent output end of the anion exchange resin device is connected to the input end of the evaporation crystallization drying device.

[0051] Optionally, the permeate output end of the acid-resistant high-pressure RO membrane is connected to the dialysis water input end of the tubular ultrafiltration membrane and / or the spiral wound ultrafiltration membrane.

[0052] Optionally, the concentrate output end of the acid-resistant high-pressure RO membrane is connected to the hydrolysis equipment for xylose production.

[0053] Optionally, the molecular weight cut-off of the tubular ultrafiltration membrane is 200,000 - 300,000 Dalton; the molecular weight cut-off of the spiral wound ultrafiltration membrane is 1,000 - 5,000 Dalton, and the molecular weight cut-off of the high-pressure nanofiltration membrane is 100 - 300 Dalton.

[0054] The third aspect of the present invention relates to the application of the above-mentioned process for purifying xylose from xylose hydrolysis solution or the above-mentioned xylose hydrolysis solution purification equipment in xylose purification or production.

[0055] Specifically, the operating pressure of the acid-resistant high-pressure RO membrane is 60 - 80 bar.

[0056] The concentrated liquid obtained by the high-pressure nanofiltration membrane can also obtain xylose crystals after passing through the evaporation crystallization system. After concentration by the high-pressure nanofiltration membrane concentration and deacidification system, the concentration of the xylose concentrated liquid can reach 15 - 20%. The concentrated liquid of the acid-resistant high-pressure RO membrane is the concentrated dilute sulfuric acid solution, and the concentration of the concentrated dilute sulfuric acid is 5 - 10%. The permeate of the acid-resistant high-pressure RO membrane concentration system is desalted water, and its pH is about 4.

[0057] The beneficial effects of the present invention:

[0058] The present invention relates to a purification process for xylose hydrolysis solution. The use of a tubular ultrafiltration membrane system for filtration can remove insoluble substances in the xylose hydrolysis solution, with an efficiency and effect superior to traditional filtration methods, and the recovery rate of active ingredients ≥ 99%; the spiral wound ultrafiltration membrane decolorization system replaces activated carbon decolorization, reducing the loss of xylose, with a recovery rate of active ingredients ≥ 99%, and no solid waste of activated carbon is produced, which is beneficial to maintaining the on-site sanitary environment and is more environmentally friendly; the high-pressure nanofiltration membrane concentration and deacidification system replaces the traditional single evaporation concentration, reducing the equipment investment cost, saving steam energy consumption, greatly improving the concentration efficiency, and inorganic acids are permeated during the concentration process, reducing the anion concentration in the xylose concentrate and extending the service life of the anion exchange resin device. Therefore, the amount of regenerated acid and alkali used is reduced, and the amount of wastewater generated is reduced; the acid-resistant high-pressure RO membrane concentration system realizes the recycling of more than 90% of sulfuric acid and the recycling of more than 90% of desalted water. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The present invention will be further described below with reference to the accompanying drawings.

[0060] Figure 1 It is a flow chart of the process of the present invention.

[0061] Figure 2 It is a schematic diagram of the decolorization treatment result in Experiment 1 of the present invention. From left to right are the original xylose solution, the M7-29 clear solution, and the M7-29 concentrated solution;

[0062] Figure 3 It is a schematic diagram of the concentration treatment result in Experiment 2 of the present invention. From left to right are the M7-29 original solution, the M7-6 clear solution, and the M7-6 concentrated solution. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0063] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0064] As Figure 1 shown, in some embodiments of the present invention, a xylose purification process is disclosed, including the following steps:

[0065] Step 1: The xylose hydrolysis solution storage tank is connected to the pretreatment device, and then connected to the tubular ultrafiltration membrane system. After filtration, a clear solution ① and a concentrated solution ① are obtained; Step 2: The above clear solution ① is decolorized by the spiral wound ultrafiltration membrane decolorization system, and after filtration, a clear solution ② and a concentrated solution ② are obtained; Step 3: The above clear solution ② is passed through a cationic hardness removal resin device to remove hardness ions such as calcium ions and magnesium ions in the solution, and an effluent ③ is obtained;

[0066] Step 4: Concentrate and deacidify the above-mentioned effluent ③ through a high-pressure nanofiltration membrane concentration and deacidification system to obtain a clear liquid ④ and a concentrated liquid ④;

[0067] Step 5: Concentrate the above-mentioned clear liquid ④ through a high-acid-resistant RO membrane concentration system to obtain a clear liquid ⑤ and a concentrated liquid ⑤;

[0068] Step 6: Further adsorb the cations in the solution with the above-mentioned concentrated liquid ④ through a cation exchange resin device, and exchange out hydrogen ions to obtain an effluent ⑥;

[0069] Step 7: Further adsorb the anions in the solution with the above-mentioned effluent ⑥ through an anion exchange resin device, and exchange out hydroxide ions to obtain an effluent ⑦;

[0070] Step 8: After the above-mentioned effluent ⑦ is processed by an evaporation, crystallization and drying system, xylose products and a small amount of mother liquor after crystallization are obtained.

[0071] In the embodiment of the present application, the pretreatment device is a rotary drum filter, which is used for preliminary filtration of the storage liquid in the xylose hydrolysis storage tank.

[0072] In the process method of the present application, ultrafiltration decolorization and purification can replace activated carbon, high-pressure nanofiltration can concentrate the xylose solution and remove sulfuric acid, greatly extend the regeneration cycle of the anion exchange resin, and at the same time, sulfuric acid is recovered through membrane concentration technology and returned to the previous acid hydrolysis process, and the produced water is returned to the production line as dialysis water or production water for recycling. At the same time, through membrane technology, the feed amount of the evaporator can be reduced, the evaporation amount can be reduced, the investment in the evaporator can be reduced, the energy consumption can be reduced, and the production efficiency can be improved.

[0073] In some other embodiments of the present invention, a device for purifying xylose from xylose hydrolysis solution is disclosed, including a xylose hydrolysis solution storage tank 001, a tubular ultrafiltration membrane system 002, a spiral ultrafiltration membrane decolorization system 003, a cation hardness removal resin device 004, a high-pressure nanofiltration membrane concentration and deacidification system 005, a high-acid-resistant RO membrane concentration system 006, a cation exchange resin device 007, an anion exchange resin device 008, and an evaporation, crystallization and drying system 009.

[0074] The xylose hydrolysis solution storage tank 001 is connected to the tubular ultrafiltration membrane system 002, and a clear liquid ① and a concentrated liquid ① are obtained after filtration;

[0075] Further, the clear liquid outlet of the tubular ultrafiltration membrane system 002 is connected to the raw water tank of the spiral ultrafiltration membrane decolorization system 003. The concentrated liquid outlet of the tubular ultrafiltration membrane system 002 is connected to the inlet of the sewage treatment station pipeline;

[0076] Further, the clear liquid tank of the spiral ultrafiltration membrane decolorization system 003 is connected to the raw water tank of the cation hardness removal resin device 004; the concentrated liquid outlet of the spiral ultrafiltration membrane decolorization system 003 is connected to the inlet of the sewage treatment station pipeline;

[0077] Further, the effluent outlet of the cationic dehardening resin device 004 is connected to the raw water tank of the high-pressure nanofiltration membrane concentration and deacidification system 005. The clear liquid outlet of the high-pressure nanofiltration membrane concentration and deacidification system 005 is connected to the raw water tank of the acid-resistant high-pressure RO membrane concentration system 006. The concentrated liquid outlet of the high-pressure nanofiltration membrane concentration and deacidification system 005 is connected to the raw water tank of the cation exchange resin device 007;

[0078] The clear liquid outlet of the acid-resistant high-pressure RO membrane concentration system 006 is connected to the inlet pipeline of the clear liquid tank of the acid-resistant high-pressure RO membrane concentration system. The concentrated liquid outlet of the acid-resistant high-pressure RO membrane concentration system 006 is connected to the inlet pipeline of the concentrated liquid tank of the acid-resistant high-pressure RO membrane concentration system;

[0079] Further, the effluent outlet of the cation exchange resin device 007 is connected to the inlet pipeline of the raw water tank of the anion exchange resin device 008;

[0080] Further, the effluent outlet of the anion exchange resin device 008 is connected to the inlet pipeline of the raw water tank of the evaporation crystallization and drying system 009. After evaporation, crystallization, centrifugation, and drying in the evaporation crystallization and drying system 009, xylose products are obtained;

[0081] Further, the concentrated solutions of the tubular ultrafiltration membrane system 002 and the spiral ultrafiltration membrane decolorization system 003 are sent to the sewage treatment station for biochemical treatment. The evaporation crystallization mother liquor is an excellent animal feed additive after being dried;

[0082] Among the components of this example, the cut-off molecular weight of the tubular ultrafiltration membrane is 200,000 - 300,000 Dalton, and the purpose is to remove insoluble substances, etc. The cut-off molecular weight of the spiral ultrafiltration membrane is 1,000 - 5,000 Dalton, and the purpose is to remove macromolecular substances such as pigments. The cut-off molecular weight of the high-pressure nanofiltration membrane is 100 - 3,000 Dalton, and the purpose is to concentrate the xylose solution, increase the xylose concentration, and permeate sulfuric acid. The purpose of the acid-resistant high-pressure RO membrane concentration system is to concentrate dilute sulfuric acid, concentrate the dilute sulfuric acid to 5 - 10% and recycle it to the xylose hydrolysis process, and the permeate is recycled as process water such as dialysis water;

[0083] In view of the actual process situation of xylose, the present invention proposes, through long-term experimental research, to integrate membrane filtration technology, membrane purification technology, membrane concentration technology, etc., to solve the problems that have troubled xylose production enterprises, such as using a large amount of sulfuric acid in the production process, using calcium salts to neutralize sulfuric acid, generating a large amount of difficult-to-treat high-salt wastewater from a large amount of acid-base regenerated resin, reducing steam consumption, reducing equipment investment costs, reducing wastewater discharge, etc., and realizing acid recycling and water recycling. The environmental, economic, and social benefits brought are of great significance.

[0084] In some embodiments of the present invention, for the xylose produced by a certain factory, the above-mentioned equipment for purifying xylose from the xylose hydrolysis solution is used to perform the purification process, obtaining Experiment 1 and Experiment 2.

[0085] The specific steps of Experiment 1 include taking 67.6 kg of xylose solution (pH 2.53, conductivity 33050, solid content 5%, density 1.02, calcium ion 16.32 mg / l, magnesium ion 4.39 mg / l, hardness 58.79 mg / l) after passing through the tubular ultrafiltration membrane system 002 and subjecting it to decolorization with M7-29. The M7-29 corresponds to the spiral ultrafiltration membrane decolorization system 003 described in the embodiments of the present application.

[0086] The results after treatment are as Figure 2 shown in Table 1 and Table 2 below.

[0087] Table 1: Decolorization data

[0088]

[0089] Table 2: Weight and sulfate detection data

[0090] Weight kg Sulfate radical mg / l Stock solution 67.6 7551.36 M7-29 clear solution 60.4 6041.08 M7-29 concentrated solution 7.2 8390.4

[0091] The specific steps of Experiment 2 include: after passing 60.2 kg of M7-29 clear liquid (solid content: 2%, conductivity: 34210 us / cm, PH: 2.49) through the cationic hardening removal resin device 004, and then concentrating it with M7-6, obtaining the data shown in Table 3 and Figure 3 the results shown. The M7-6 used here corresponds to the high-pressure nanofiltration membrane concentration and deacidification system 005 in the embodiments of the present application.

[0092] Table 3: Concentration data

[0093]

[0094] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0095] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed.

Claims

1. A process for purifying xylose from xylose hydrolysate, characterized in that: The following steps are involved: The xylose hydrolysate is pretreated and then transported to a tubular ultrafiltration membrane for filtration; The clear liquid obtained by filtering with tubular ultrafiltration membrane is filtered and decolorized with spiral ultrafiltration membrane; The clear liquid obtained by decolorization is treated by a cationic hardness-removing resin device for hardness-removal; The effluent after hardness removal is concentrated and deacidified by high-pressure nanofiltration membrane; The clear liquid after deacidification is concentrated by an acid-resistant high-pressure RO membrane; the concentrated liquid after deacidification is treated by a cation exchange resin device, and the resulting effluent is transported to an anion exchange resin device for further adsorption of anions in the solution. The resulting effluent is treated by an evaporation, crystallization and drying system to obtain a xylose product.

2. The process for purifying xylose from xylose hydrolyzate according to claim 1, characterized in that: The clear liquid outputted by the acid-resistant high-pressure RO membrane is returned to the tubular ultrafiltration membrane and / or the rolled ultrafiltration membrane for use as dialysis water.

3. The process for purifying xylose from xylose hydrolyzate according to claim 1, characterized in that: The sulfuric acid recovered by the acid-resistant high-pressure RO membrane is returned to the hydrolysis process in the production of xylose.

4. The process for purifying xylose from xylose hydrolyzate according to claim 1, characterized in that: The molecular weight cutoff of the tubular ultrafiltration membrane is 200,000-300,000 Dalton; the molecular weight cutoff of the spiral ultrafiltration membrane is 1000-5,000 Dalton; and the molecular weight cutoff of the high-pressure nanofiltration membrane is 100-300 Dalton.

5. The process for purifying xylose from xylose hydrolyzate according to claim 1, characterized in that: The concentrated liquid of the tubular ultrafiltration membrane and the rolled ultrafiltration membrane is output to the biochemical system of the sewage station for treatment.

6. A xylose hydrolysate purification device, characterized in that: Including tubular ultrafiltration membrane, spiral ultrafiltration membrane, cationic hardness removal resin device, high-pressure nanofiltration membrane, cationic exchange resin device, anionic exchange resin device and evaporation crystallization device; The output end of the clear liquid filtered by the tubular ultrafiltration membrane is connected to the input end of the rolled ultrafiltration membrane; The clear liquid output end of the rolled ultrafiltration membrane is connected to the input end of the cationic hardness removal resin device; The effluent output end of the cationic hardness removal resin device is connected to the input end of the high-pressure nanofiltration membrane; The clear liquid output end of the high-pressure nanofiltration membrane is connected to the input end of the acid-resistant high-pressure RO membrane; The concentrated liquid output end of the high pressure nanofiltration membrane is connected to the input end of the cation exchange resin device; The effluent output end of the cation exchange resin device is connected to the input end of the anion exchange resin device; The effluent output end of the anion exchange resin device is connected to the input end of the evaporation crystallization drying device.

7. The xylose hydrolyzate purification device according to claim 6, characterized in that: The clear liquid output end of the acid-resistant high-pressure RO membrane is connected to the dialyzed water input end of the tubular ultrafiltration membrane and / or the rolled ultrafiltration membrane.

8. The xylose hydrolyzate purification device according to claim 6, characterized in that: The concentrated liquid output end of the acid-resistant high-pressure RO membrane is connected to the hydrolysis equipment for xylose production.

9. The xylose hydrolyzate purification device according to claim 6, characterized in that: The molecular weight cutoff of the tubular ultrafiltration membrane is 200,000-300,000 Dalton; the molecular weight cutoff of the spiral ultrafiltration membrane is 1000-5,000 Dalton; and the molecular weight cutoff of the high-pressure nanofiltration membrane is 100-300 Dalton.

10. Use of the process for purifying xylose from xylose hydrolysate according to any one of claims 1 to 5, or the equipment for purifying xylose hydrolysate according to any one of claims 6 to 9 in the purification or production of xylose.

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