Method for preparing xylose by using palm shells as raw materials
Through steam explosion pretreatment and enzymatic lysis steps, the problem of hard texture of palm shells resulting in poor hydrolysis effect is solved, significantly improving the yield and purity of xylose, and achieving efficient utilization of palm shells.
Patent Information
- Application Number
- CN202411720373.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-28
- Publication Date
- 2025-03-04
AI Technical Summary
The prior art is difficult to effectively use palm shells to prepare xylose, mainly because the palm shells are hard, resulting in poor hydrolysis effect and low xylose yield.
The palm shell cell wall was broken through steam explosion pretreatment, and dilute acid soaking made the hemicellulose and lignin easier to detach. Then, enzymatically dissolved using cellulase and pectin enzyme to further release the hemicellulose. Then, acid hydrolysis, alkali salting, activated carbon decolorization, ion exchange desalination and chromatography separation were carried out to obtain high-purity xylose.
Through steam explosion pretreatment and enzymatic lysis steps, the hydrolysis effect and xylose yield of palm shells are significantly improved, the influence of impurities is reduced, and the purity and crystallization effect of xylose are improved.
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of palm shell recycling, and in particular relates to a method for preparing xylose by using palm shell as raw material. Background Art
[0002] Palms are widely distributed in Southeast Asia and other places, and are rich in resources. In the process of palm oil extraction, the kernel is first extracted from the pulp, and then the shell of the kernel is cut off. The cut part is the palm shell. The palm shell itself is not valuable and has long been a kind of pollution. Although the hemicellulose of palm shell contains xylan, which can produce xylose, the palm shell is difficult to further develop due to its hard texture.
[0003] In recent years, with the growing global environmental awareness, the application of palm shells has gradually attracted attention from all parties, and the palm shell industry has developed rapidly. Palms are generally discarded or burned, which not only causes huge waste of resources, but also causes serious environmental pollution. Therefore, it is of positive significance to use palm shells to prepare xylose and carry out the comprehensive utilization of palm shells.
[0004] Xylose is a pentose that exists in plant hemicellulose in a condensed state in nature. Xylose is the most stable of all functional sugars. In addition to being used as a raw material for the production of xylitol, xylose itself does not increase blood sugar levels and can demonstrate its superior functions in the proliferation of bifidobacteria. Summary of the invention
[0005] The object of the present invention is to provide a method for preparing xylose using palm shell as raw material, so as to solve the problems existing in the prior art.
[0006] The technical solution adopted by the present invention to solve its technical problem is:
[0007] A method for preparing xylose using palm shell as raw material comprises the following steps:
[0008] (1) Pretreatment: crushing and steam explosion pretreatment of the air-dried palm shell raw material to obtain palm shell steam explosion residue;
[0009] (2) Enzymatic hydrolysis: The steam explosion residue is mixed with the composite enzyme solution, stirred, kept warm, enzymatically hydrolyzed, and filtered to obtain the enzymatic hydrolysis residue.
[0010] (3) hydrolysis: the enzymatic residue is hydrolyzed with acid to obtain a hydrolyzate;
[0011] (4) Salting out: adding alkali to the hydrolyzate to precipitate the protein, and filtering to obtain the salting out solution;
[0012] (5) Purification: The salting liquid is decolorized by activated carbon and desalted by ion exchange to obtain a purified liquid;
[0013] (6) Purification: The purified liquid is subjected to chromatographic separation to obtain xylose solution and miscellaneous sugar solution;
[0014] (7) Crystallization: The xylose solution is concentrated, crystallized, centrifuged and dried to obtain the xylose product.
[0015] Furthermore, the specific method of pretreatment in step (1) is to crush the palm shell to less than 5 mm by a crusher, put the crushed palm shell into a 0.1-0.3% acid solution and soak it for 30 minutes, then put it into a steam explosion equipment, control the pressure at 2.0-2.2MPa, the steam explosion time is 20-50s, and obtain the steam explosion slag after instantaneous spraying.
[0016] Furthermore, the specific method of enzymolysis in step (2) is as follows: put the steam explosion slag into an enzymolysis tank, add pure water until it covers the steam explosion slag, stir and heat to 50°C, adjust the pH to 5.5, add a composite enzyme according to 4-6% of the mass of the steam explosion slag, stir and enzymolyze for 2-3 hours, and filter after the enzymolysis is completed to obtain the enzymolysis solution and enzymolysis slag.
[0017] Furthermore, the complex enzyme is composed of cellulase, pectinase and cysteine in a mass ratio of 4:1:0.5.
[0018] Furthermore, the specific method of hydrolysis in step (3) is to put the enzymatic hydrolysis residue into a hydrolysis kettle, add an acid solution with a mass concentration of 1.0-2.0% until the enzymatic hydrolysis residue is submerged, hydrolyze at 110-120° C. for 60-150 minutes, and filter to obtain a hydrolyzate.
[0019] Furthermore, the specific method of salting out in step (4) is to add alkaline solution to the hydrolyzate to adjust the pH to 5, and filter to obtain the salting out solution.
[0020] Furthermore, the specific method of purification in step (5) is to heat the salting-out liquid to 60-75° C., add powdered activated carbon to the salting-out liquid according to 5-7% of the dry matter, keep the temperature for 30-60 min, filter to obtain a decolorized liquid, pass the decolorized liquid through an ultrafiltration membrane, collect the permeate, and perform membrane concentration on the permeate to a refractive index of 15-25% to obtain a membrane concentrated liquid, and perform cation exchange on the membrane concentrated liquid to obtain a relatively pure purified liquid.
[0021] Furthermore, the specific method of purification in step (6) is to first evaporate and concentrate the purified liquid to a refractive index of 40-50%, and then separate the xylose solution and the miscellaneous sugar solution by a chromatographic separation device, wherein the xylose purity in the xylose solution is above 85%.
[0022] The present invention has the following beneficial effects:
[0023] 1. The present invention breaks the hard palm shell cell wall through steam explosion pretreatment, and makes hemicellulose and lignin separate better during steam explosion through dilute acid soaking, thereby releasing more hemicellulose and obtaining a better hydrolysis effect.
[0024] 2. The cellulase and pectinase continue to destroy the cell wall structure of palm meal, thereby continuing to release hemicellulose and further increasing the xylose yield.
[0025] 3. After hydrolysis, add alkali for salting out to precipitate impurities such as peptides and proteins in the hydrolyzate, thereby reducing their impact on subsequent production.
[0026] 4. Through membrane filtration after decolorization, the residual protein, colloid, pigment and other impurities are further removed, thereby reducing the viscosity of the sugar solution and making crystallization easier. While the membrane concentrates the sugar solution, it further removes impurity ions such as acid radicals, calcium and magnesium, reduces the ion exchange load, and improves work efficiency. DETAILED DESCRIPTION
[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0028] Embodiment 1:
[0029] A method for preparing xylose using palm shell as raw material comprises the following steps:
[0030] (1) Pretreatment: The palm shell raw material is crushed and steam-exploded to obtain palm shell steam-exploded residue.
[0031] The palm shell is crushed to less than 5mm by a crusher, and the crushed palm shell is put into a 0.1% sulfuric acid solution and soaked for 30 minutes, and then put into the steam explosion equipment, the pressure is controlled at 2.0MPa, the steam explosion time is 50s, and the steam explosion residue is obtained after instantaneous spraying. The texture of palm shell is hard, and it is difficult for hydrogen ions to enter the cell wall to hydrolyze its hemicellulose during direct hydrolysis.
[0032] Steam explosion is a technology that pre-treats biomass through an explosion process based on the principle of steam ejection. The essence of the technology is to instantly release the steam molecules that have penetrated into the plant tissue, convert the internal energy of the steam into mechanical energy and act on the cell layers of the biomass tissue, thereby destroying the cell wall and achieving the purpose of easier hydrolysis. Soaking in an olefinic acid solution before steam explosion is a means to promote this process. The dilute acid can remove part of the hemicellulose from the cell wall, interrupting the interaction between hemicellulose and lignin, thereby increasing the yield of xylose.
[0033] (2) Enzymatic hydrolysis: The steam explosion residue is mixed with the composite enzyme solution, stirred, kept warm, enzymatically hydrolyzed, and filtered to obtain the enzymatic hydrolysis residue.
[0034] Take 10 kg of steam explosion slag and put it into an enzymolysis tank (the enzymolysis tank is sterilized in advance), add pure water until it covers the steam explosion slag, stir and heat to 50°C, adjust the pH to 5.5, add 0.2 kg of composite enzyme according to 4% of the mass of the steam explosion slag (the composite enzyme is composed of cellulase, pectinase, and cysteine in a mass ratio of 4:1:0.5), stir and enzymolyze for 3 hours, and filter after the enzymolysis is completed to obtain the enzymolysis solution and enzymolysis slag.
[0035] The cellulase and pectinase continue to destroy the cell wall structure of palm meal, thereby releasing hemicellulose and further improving the xylose yield. Cysteine plays a role in promoting enzyme reactions.
[0036] (3) Hydrolysis: The enzymatic residue is hydrolyzed with acid to obtain a hydrolyzate.
[0037] 8.9 kg of enzymatic residue was put into the hydrolysis kettle, 1.0% dilute sulfuric acid solution was added until the residue was covered, hydrolyzed at 120°C for 150 min, and the hydrolyzate was obtained by filtering (to ensure the xylose yield, the hydrolyzed residue can be washed twice and the washing liquid can be added to the hydrolyzate).
[0038] (4) Salting out: Add alkali to the hydrolyzate to precipitate the protein, and filter to obtain the salting out solution.
[0039] Add alkali solution to the hydrolyzate, adjust the pH to 5, and filter to obtain the salting-out solution. The hydrolyzate contains enzymatic peptides and added enzyme proteins. These substances are impurities and usually have electrical properties. When decolorizing, more activated carbon adsorption is required, and the activated carbon will become sticky and difficult to filter. Its charged nature causes the ion exchange resin to reduce the exchange capacity of acid and alkali, so it needs to be removed in advance. By increasing the pH of the hydrolyzate, the peptides and enzymes are precipitated, thereby reducing their impact on subsequent production.
[0040] (5) Purification: The salting liquid is decolorized by activated carbon and desalted by ion exchange to obtain a purified liquid.
[0041] The refractive index of the salting-out liquid is 4.2%. The temperature of the salting-out liquid is raised to 75°C. 2.1 g of activated carbon is added to every 1 kg of the salting-out liquid. The temperature is kept for 60 min. The decolorized liquid is filtered to obtain the decolorized liquid. The decolorized liquid is passed through an ultrafiltration membrane. The permeate is collected and concentrated by membrane to a refractive index of 15% to obtain a membrane concentrated liquid. The membrane concentrated liquid is subjected to cation and anion exchange to obtain a relatively pure purified liquid.
[0042] (6) Purification: The purified liquid is subjected to chromatographic separation to obtain xylose solution and miscellaneous sugar solution.
[0043] The purified liquid is first evaporated and concentrated to a refractive index of 40%, and then separated by a chromatographic separation device to obtain a xylose solution and a miscellaneous sugar solution. The xylose purity in the xylose solution is 88.6%.
[0044] (7) Crystallization: The xylose solution is concentrated, crystallized, centrifuged and dried to obtain the xylose product.
[0045] Embodiment 2:
[0046] (1) Pretreatment: The palm shell raw material is crushed and steam-exploded to obtain palm shell steam-exploded residue.
[0047] The air-dried palm shell is crushed to less than 5 mm by a crusher, and the crushed palm shell is immersed in a 0.3% acid solution for 30 minutes, and then put into a steam explosion device, the pressure is controlled at 2.2 MPa, the steam explosion time is 20 seconds, and the steam explosion slag is obtained after instantaneous spraying.
[0048] (2) Enzymatic hydrolysis: The steam explosion residue is mixed with the composite enzyme solution, stirred, kept warm, enzymatically hydrolyzed, and filtered to obtain the enzymatic hydrolysis residue.
[0049] Take 10 kg of steam explosion slag and put it into an enzymolysis tank (the enzymolysis tank is sterilized in advance), add pure water until it covers the steam explosion slag, stir and heat to 50°C, adjust the pH to 5.5, add 0.3 kg of composite enzyme according to 6% of the mass of the steam explosion slag (the composite enzyme is composed of cellulase, pectinase, and cysteine in a mass ratio of 4:1:0.5), stir and enzymolyze for 2 hours, and filter after the enzymolysis is completed to obtain the enzymolysis solution and enzymolysis slag.
[0050] (3) Hydrolysis: The enzymatic residue is hydrolyzed with acid to obtain a hydrolyzate.
[0051] 9.1 kg of enzymatic residue was put into the hydrolysis kettle, and 2.0% dilute sulfuric acid solution was added until the residue was covered. The mixture was hydrolyzed at 110°C for 60 min and the hydrolyzate was obtained by filtering (to ensure the xylose yield, the hydrolyzed residue was washed twice and the washing liquid was added to the hydrolyzate).
[0052] (4) Salting out: Add alkali solution to the hydrolyzate, adjust the pH to 5, precipitate the protein, and filter to obtain the salting out solution.
[0053] (5) Purification: The salting liquid is decolorized by activated carbon and desalted by ion exchange to obtain a purified liquid.
[0054] The refractive index of the salting-out liquid is 4.6%. The temperature of the salting-out liquid is raised to 60°C. 3.2g of activated carbon is added to every 1kg of the salting-out liquid. The temperature is kept for 30min. The decolorized liquid is filtered to obtain the decolorized liquid. The decolorized liquid is passed through an ultrafiltration membrane. The permeate is collected and concentrated by membrane to a refractive index of 25% to obtain a membrane concentrated liquid. The membrane concentrated liquid is subjected to cation and anion exchange to obtain a relatively pure purified liquid.
[0055] (6) Purification: The purified liquid is subjected to chromatographic separation to obtain xylose solution and miscellaneous sugar solution.
[0056] The purified liquid is first evaporated and concentrated to a refractive index of 50%, and then separated by a chromatographic separation device to obtain a xylose solution and a miscellaneous sugar solution. The xylose purity in the xylose solution is 87.8%.
[0057] (7) Crystallization: The xylose solution is concentrated, crystallized, centrifuged and dried to obtain the xylose product.
[0058] Embodiment 3:
[0059] (1) Pretreatment: The palm shell raw material is crushed and steam-exploded to obtain palm shell steam-exploded residue.
[0060] The air-dried palm shell is crushed to less than 5 mm by a crusher, and the crushed palm shell is immersed in a 0.3% acid solution for 30 minutes, and then put into a steam explosion device, the pressure is controlled at 2.1 MPa, the steam explosion time is 49 seconds, and the steam explosion slag is obtained after instantaneous spraying.
[0061] (2) Enzymatic hydrolysis: The steam explosion residue is mixed with the composite enzyme solution, stirred, kept warm, enzymatically hydrolyzed, and filtered to obtain the enzymatic hydrolysis residue.
[0062] Take 10 kg of steam explosion slag and put it into an enzymolysis tank (the enzymolysis tank is sterilized in advance), add pure water until it covers the steam explosion slag, stir and heat to 50°C, adjust the pH to 5.5, add 0.25 kg of composite enzyme according to 5% of the mass of the steam explosion slag (the composite enzyme is composed of cellulase, pectinase, and cysteine in a mass ratio of 4:1:0.5), stir and enzymolyze for 2.5 hours, and after the enzymolysis is completed, filter to obtain the enzymolysis solution and enzymolysis slag.
[0063] (3) Hydrolysis: The enzymatic residue is hydrolyzed with acid to obtain a hydrolyzate.
[0064] 8.7 kg of enzymatic residue was put into the hydrolysis kettle, 1.5% dilute sulfuric acid solution was added until the residue was covered, hydrolyzed at 115°C for 90 min, and the hydrolyzate was obtained by filtering (to ensure the xylose yield, the hydrolyzed residue can be washed twice and the washing liquid can be added to the hydrolyzate).
[0065] (4) Salting out: Add alkali solution to the hydrolyzate, adjust the pH to 5, precipitate the protein, and filter to obtain the salting out solution.
[0066] (5) Purification: The salting liquid is decolorized by activated carbon and desalted by ion exchange to obtain a purified liquid.
[0067] The refractive index of the salting-out liquid is 4.4%. The temperature of the salting-out liquid is raised to 70°C. 2.6g of activated carbon is added to every 1kg of the salting-out liquid. The temperature is kept for 50min. The decolorized liquid is filtered to obtain the decolorized liquid. The decolorized liquid is passed through an ultrafiltration membrane. The permeate is collected and concentrated by membrane to a refractive index of 20% to obtain a membrane concentrated liquid. The membrane concentrated liquid is subjected to cation and anion exchange to obtain a relatively pure purified liquid.
[0068] (6) Purification: The purified liquid is subjected to chromatographic separation to obtain xylose solution and miscellaneous sugar solution.
[0069] The purified liquid is first evaporated and concentrated to a refractive index of 45%, and then separated by a chromatographic separation device to obtain a xylose solution and a miscellaneous sugar solution. The xylose purity in the xylose solution is 86.4%.
[0070] (7) Crystallization: The xylose solution is concentrated, crystallized, centrifuged and dried to obtain the xylose product.
[0071] The above-described embodiments are merely descriptions of preferred implementations of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made by ordinary persons in the art to the technical solution of the present invention should all fall within the scope of protection of the present invention.
[0072] The techniques, shapes, and structural parts not described in detail in the present invention are all well-known techniques.
Claims
1. A method for preparing xylose using palm shell as raw material, characterized in that: The following steps are involved: (1) Pretreatment: crushing and steam explosion pretreatment of the air-dried palm shell raw material to obtain palm shell steam explosion residue; (2) Enzymatic hydrolysis: The steam explosion residue is mixed with the composite enzyme solution, stirred, kept warm, enzymatically hydrolyzed, and filtered to obtain the enzymatic hydrolysis residue. (3) hydrolysis: the enzymatic residue is hydrolyzed with acid to obtain a hydrolyzate; (4) Salting out: adding alkali to the hydrolyzate to precipitate the protein, and filtering to obtain the salting out solution; (5) Purification: The salting liquid is decolorized by activated carbon and desalted by ion exchange to obtain a purified liquid; (6) Purification: The purified liquid is subjected to chromatographic separation to obtain xylose solution and miscellaneous sugar solution; (7) Crystallization: The xylose solution is concentrated, crystallized, centrifuged and dried to obtain the xylose product.
2. The method for preparing xylose from palm shell as raw material according to claim 1, characterized in that: The specific method of the pretreatment in step (1) is to crush the palm shell to less than 5 mm by a crusher, put the crushed palm shell into a 0.1-0.3% acid solution and soak it for 30 minutes, then put it into a steam explosion equipment, control the pressure at 2.0-2.2MPa, the steam explosion time is 20-50s, and obtain the steam explosion slag after instantaneous spraying.
3. The method for preparing xylose from palm shell as raw material according to claim 1, characterized in that: The specific method of enzymolysis in step (2) is as follows: put the steam explosion slag into an enzymolysis tank, add pure water until it covers the steam explosion slag, stir and heat to 50°C, adjust the pH to 5.5, add complex enzyme according to 2-3% of the mass of the steam explosion slag, stir and enzymolyze for 2-3 hours, and filter after the enzymolysis is completed to obtain the enzymolysis solution and enzymolysis slag.
4. The method for preparing xylose from palm shell as raw material according to claim 3, characterized in that: The complex enzyme is composed of cellulase, pectinase and cysteine in a mass ratio of 4:1:0.
5.
5. The method for preparing xylose from palm shell as raw material according to claim 1, characterized in that: The specific method of hydrolysis in step (3) is to put the enzymatic hydrolysis residue into a hydrolysis kettle, add an acid solution with a mass concentration of 1.0-2.0% until the enzymatic hydrolysis residue is submerged, hydrolyze at 110-120° C. for 60-150 minutes, and filter to obtain a hydrolyzate.
6. The method for preparing xylose from palm shell as raw material according to claim 1, characterized in that: The specific method of salting out in step (4) is to add alkali solution to the hydrolyzate to adjust the pH to 5, and filter to obtain the salting out solution.
7. The method for preparing xylose from palm shell as raw material according to claim 1, characterized in that: The specific method of purification in step (5) is to heat the salting-out liquid to 60-75° C., add powdered activated carbon to the salting-out liquid according to 5-7% of the dry matter, keep the temperature for 30-60 minutes, filter to obtain a decolorized liquid, pass the decolorized liquid through an ultrafiltration membrane, collect the permeate, and perform membrane concentration on the permeate to a refractive index of 15-25% to obtain a membrane concentrated liquid, and perform cation and anion exchange on the membrane concentrated liquid to obtain a relatively pure purified liquid.
8. The method for preparing xylose from palm shell as raw material according to claim 1, characterized in that: The specific method of purification in step (6) is to first evaporate and concentrate the purified liquid to a refractive index of 40-50%, and then separate the xylose solution and the miscellaneous sugar solution through a chromatographic separation device, wherein the purity of xylose in the xylose solution is above 85%.