Method for extracting high-purity cellulose from corn cob residues

Abstract

The invention relates to the technical field of biomass resource utilization, in particular to a method for extracting high-purity cellulose from corn cob residues. According to the method, the corn cob residues are treated to obtain high-purity cellulose, in the process, the corn cob residues are impregnated through ionic liquid, in the method, the ionic liquid is [DMEA] [COOH] and / or [DMEA] Cl which has a good dissolution effect on lignin, and in the impregnation process, the ionic liquid is immersed into a cellulose and lignin cross-linked space structure, so that the high-purity cellulose is obtained. At the moment, the cross-linked space structure of the cellulose and the lignin is destroyed in a steam explosion mode, then the reaction is continued, a large amount of lignin can be dissolved in the ionic liquid, and residual hemicellulose in the corn cob residues is degraded, so that the residual cellulose is high-purity cellulose, and the high-purity cellulose is used for preparing glucose through enzymolysis; the method not only can reduce the use amount of cellulase and contribute to reducing the cost, but also can obtain high-purity glucose which is convenient to use in production.

Description

Technical Field

[0001] The invention relates to the technical field of biomass resource utilization, and in particular to a method for extracting high-purity cellulose from xylose residue. Background Art

[0002] Xylose residue is the leftover material after xylose products are made from agricultural waste such as corn cobs, bagasse, and bamboo. Its main components are cellulose and lignin. Its main use is to replace part of the coal for biomass power generation. Another part is bought by farmers for edible fungus cultivation. Its utilization value is relatively low. Solving the high added value utilization of xylose residue is an urgent issue that all companies need to solve.

[0003] The traditional method for treating xylose residue is alkali dissolution. Through alkali dissolution treatment, the lignin in the xylose residue can be dissolved, and the remaining components mainly contain cellulose, thereby achieving the separation of lignin and cellulose; in the subsequent treatment, lignin products and cellulose glucose can be obtained, realizing the comprehensive utilization of xylose residue.

[0004] However, the existing alkaline dissolution process has a poor dissolution effect on lignin, and is unable to dissolve residual hemicellulose, which in turn leads to a low cellulose content in the cellulose component. Since lignin also consumes cellulase, this leads to an increase in the amount of cellulase used in the enzymatic hydrolysis stage of the cellulose component, which increases production costs and also leads to a decrease in product purity. Therefore, a process that can more effectively separate lignin and residual hemicellulose in xylose residue to obtain high-purity cellulose is a technical problem that needs to be solved. Summary of the invention

[0005] The purpose of the present invention is to provide a method for extracting high-purity cellulose from xylose residues, so as to solve the problem that when the existing method treats xylose residues, the obtained cellulose content is low, which brings inconvenience to subsequent utilization.

[0006] To achieve the above object, the present invention adopts the following technical scheme: a method for extracting high-purity cellulose from xylose residue, comprising the following steps:

[0007] S1, crushing the xylose residue to obtain xylose residue powder, and storing the obtained xylose residue powder for standby use;

[0008] S2, adding the xylose residue powder obtained in S1 into a reactor, and adding an ionic liquid into the reactor to perform an impregnation treatment on the xylose residue powder;

[0009] The ionic liquid is [DMEA][COOH] and / or [DMEA]Cl;

[0010] S3, performing steam explosion treatment on the xylose residue powder after the impregnation in S2, and adding ionic liquid into the reactor after the steam explosion treatment to continue the reaction;

[0011] S4. After the reaction is completed, the liquid material in the reactor is discharged and washed with water to obtain high-purity cellulose.

[0012] Furthermore, in the above S1, the xylose residue is dried and then crushed, the moisture content after drying is 5-10%, and the particle size after crushing is 1-3 mm.

[0013] Furthermore, in the S2, the solid-to-liquid ratio of the xylose residue powder to the added amount of the ionic liquid is 1:1-2.

[0014] Furthermore, in S2, when the ionic liquid is [DMEA][COOH] and [DMEA]Cl,

[0015] The ratio of [DMEA][COOH] to [DMEA]Cl is 1:1.

[0016] Furthermore, in the S2, the immersion treatment temperature is 120-180°C, the time is 2-4 hours, and the stirring intensity is 80-120 r / min.

[0017] Furthermore, in the above-mentioned S3, the pressure of the steam explosion is 2-4 MPa, and the processing time is 1-2 min.

[0018] Furthermore, in S3, after the ionic liquid is added, the solid-liquid ratio of the xylose residue powder to the total amount of the ionic liquid in the reactor is 1:5-10.

[0019] Furthermore, in the S3, after the ionic liquid is added, the reaction is continued for 2 to 4 hours at 120 to 180° C. and a stirring intensity of 80 to 120 r / min.

[0020] Furthermore, in S4, water is used to wash the cellulose obtained in the reactor, the solid-liquid ratio of added water to xylose residue powder is 1:3-5, the number of washings is 1-3 times, the stirring intensity during the washing process is 60-120 r / min, and the time for a single washing is 15-30 min.

[0021] Furthermore, in the above-mentioned S4, the purity of the obtained high-purity cellulose can reach above 99%.

[0022] Beneficial effects of the present invention:

[0023] 1. It can remove lignin and residual hemicellulose in xylose residue at the same time, so that the purity of the obtained cellulose is higher, reaching more than 99%;

[0024] 2. Use ionic liquid to treat xylose residue. In the process, ionic liquid is a "green solvent", which is safer and more environmentally friendly. At the same time, it can also be recovered and recycled through reduced pressure distillation and other methods, and lignin can be recovered for easy use in production;

[0025] 3. In the subsequent processing process, due to the high purity of cellulose, the amount of cellulase used can be effectively reduced, thereby reducing production costs, and high-purity cellulose glucose can be obtained, thereby increasing the value of the product. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0027] Example 1

[0028] The xylose residue was dried and crushed for later use. After testing, the average particle size of the obtained xylose residue powder was 2.3 mm, the moisture content was 8.7%, and the dry weight was 91.3 kg; the cellulose content of the dry material was 69.47%, the lignin content was 18.62%, the hemicellulose content was 4.61%, and the remainder was ash.

[0029] Add 150L of ionic liquid to the reactor (in the technical solution of the present invention, the solid-liquid ratio is the ratio of solid mass to liquid volume). At this time, the material is in an infiltrated state. In this embodiment, the ionic liquid is [DMEA][COOH] (DMEA is N,N-dimethylethanolamine, the same below). Under mechanical stirring conditions of 100r / min, 100kg of the above-mentioned xylose residue is added to the reactor, the temperature is raised to 150°C, and the immersion treatment is carried out for 3h.

[0030] After the impregnation treatment is completed, the material is subjected to steam explosion treatment. The processing pressure during the process is 3MPa and the processing time is 90s. After the treatment is completed, the pressure is instantly lost to normal pressure after the pressure is maintained, and the steam explosion is completed.

[0031] After the steam explosion was completed, 500 L of ionic liquid was added to the reactor, the stirring intensity was 100 r / min, and the reaction was continued at 150° C. for 3 h.

[0032] After the reaction is completed, the liquid material in the reactor is discharged, and the remaining cellulose material in the reactor is washed with clean water (preferably pure water). The single washing water volume is 400L, the washing time is 20min, and the washing is performed twice. The stirring intensity during the washing process is 80r / min.

[0033] After cleaning, the cellulose in the reactor was taken out, dried and measured, and the mass of the obtained cellulose was 63.8 kg. The cellulose in the reactor was tested, and the purity of the obtained cellulose was 98.57%, and the yield was over 99%.

[0034] Example 2

[0035] Take the same batch of materials as in Example 1.

[0036] In this embodiment, the immersion treatment temperature is 180° C., the mechanical stirring intensity is 120 r / min, and the treatment time is 4 h.

[0037] The pressure of steam explosion treatment is 4MPa and the treatment time is 2min.

[0038] After the steam explosion was completed, the reaction was continued for 4 hours at 180°C and 120 r / min stirring intensity.

[0039] After the reaction is completed, clean water is used for three times, with a single washing water volume of 500 L and a washing time of 30 min. The stirring intensity during the washing process is 120 r / min.

[0040] The rest is the same as in Example 1.

[0041] The mass of the obtained cellulose was 63.5 kg. The cellulose in the reactor was tested and the purity of the obtained cellulose was 99.11%, and the yield was over 99%.

[0042] Example 3

[0043] Take the same batch of materials as in Example 1.

[0044] In this embodiment, the ionic liquid is [DMEA]Cl, and other conditions are the same as those in Embodiment 1.

[0045] The mass of the obtained cellulose is 63.5 kg, the purity is 98.95%, and the yield is over 99%.

[0046] Example 4

[0047] Take the same batch of materials as in Example 1.

[0048] In this embodiment, the immersion treatment temperature is 180° C., the mechanical stirring intensity is 120 r / min, and the treatment time is 4 h.

[0049] The pressure of steam explosion treatment is 4MPa and the treatment time is 2min.

[0050] After the steam explosion was completed, the reaction was continued for 4 hours at 180°C and 120 r / min stirring intensity.

[0051] After the reaction is completed, clean water is used for three times, with a single washing water volume of 500 L and a washing time of 30 min. The stirring intensity during the washing process is 120 r / min.

[0052] The rest is the same as in Example 3.

[0053] The mass of the obtained cellulose was 63.5 kg. The cellulose in the reactor was tested and the purity of the obtained cellulose was 99.17%, and the yield was over 99%.

[0054] Example 5

[0055] Take the same batch of materials as in Example 1.

[0056] In this embodiment, the ionic liquids selected are [DMEA][COOH] and [DMEA]Cl, the ratio of [DMEA][COOH] to [DMEA]Cl is 1:1, and the rest is the same as in Embodiment 1.

[0057] The mass of the obtained cellulose was 63.4 kg, the purity was 99.26%, and the yield was over 99%.

[0058] Comparative Example 1

[0059] Take the same batch of materials as in Example 1.

[0060] In this comparative example, the amount of ionic liquid added is 300 L, and the rest is the same as in Example 5.

[0061] When the amount of ionic liquid was 300 L, the ionic liquid was excessive, and the material was immersed in the ionic liquid, which affected the subsequent steam explosion process. Finally, the remaining material in the reactor was 83.1 kg after drying, and the cellulose content was only 76.33%.

[0062] It can be seen that steam explosion is crucial to the removal of lignin and hemicellulose in xylose residue.

[0063] Comparative Example 2

[0064] Take the same batch of materials as in Example 1.

[0065] In this comparative example, the amount of ionic liquid added is 80 L, and the rest is the same as in Example 5.

[0066] When the amount of the ionic liquid was 80 L, the amount of the ionic liquid was insufficient, and finally, the remaining material in the reactor was 74.7 kg after drying, wherein the cellulose content was 84.91%.

[0067] It can be seen that when the amount of ionic liquid is insufficient, the impregnation treatment is incomplete and the ionic liquid cannot fully enter the cross-linked spatial structure of cellulose, hemicellulose and lignin, thereby affecting the effect of subsequent steam explosion.

[0068] Comparative Example 3

[0069] Take the same batch of materials as in Example 1.

[0070] In this comparative example, the step of adding ionic liquid to continue the reaction after the steam explosion was omitted, and the rest was the same as in Example 5.

[0071] Finally, the remaining material in the reactor after drying was 76.5 kg, wherein the cellulose content was 82.91%.

[0072] It can be seen that although the steam explosion opens up the intertwined spatial structure of cellulose, lignin and hemicellulose, the subsequent dissolution of lignin by ionic liquid still requires certain conditions, otherwise the lignin and hemicellulose cannot be dissolved well.

[0073] Comparative Example 4

[0074] Take the same batch of materials as in Example 1 and dry them to absolute dryness, and take 100 kg of the materials after drying to absolute dryness.

[0075] The other steps are the same as in Example 5.

[0076] Finally, the remaining material in the reactor after drying was 70.1 kg, in which the cellulose content was 98.34%, and the yield was over 99%.

[0077] It can be seen that the presence of a certain amount of moisture in the material after drying helps to improve the treatment effect, because under the same conditions, the presence of moisture can promote the effect of impregnation treatment.

[0078] Comparative Example 5

[0079] The undried xylose residue of Example 1 was taken and dried to a moisture content of about 20%, and then crushed. During the crushing process, the equipment was blocked due to the high moisture content of the material, which was not conducive to the actual production operation.

[0080] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to those of the present application fall within the protection scope of the present invention.

Claims

1. A method for extracting high-purity cellulose from xylose residue, characterized in that: The following steps are involved: S1, crushing the xylose residue to obtain xylose residue powder, and storing the obtained xylose residue powder for standby use; S2, adding the xylose residue powder obtained in S1 into a reactor, and adding an ionic liquid into the reactor to perform an impregnation treatment on the xylose residue powder; The ionic liquid is [DMEA][COOH] and / or [DMEA]Cl; S3, performing steam explosion treatment on the xylose residue powder after the impregnation in S2, and adding ionic liquid into the reactor after the steam explosion treatment to continue the reaction; S4. After the reaction is completed, the liquid material in the reactor is discharged and washed with water to obtain high-purity cellulose.

2. The method for extracting high-purity cellulose from xylose residue according to claim 1, characterized in that: In the above-mentioned S1, the xylose residue is dried and then crushed, the moisture content after drying is 5-10%, and the particle size after crushing is 1-3 mm.

3. The method for extracting high-purity cellulose from xylose residue according to claim 1, characterized in that: In the S2, the solid-to-liquid ratio of the xylose residue powder to the added amount of the ionic liquid is 1:1-2.

4. The method for extracting high-purity cellulose from xylose residue according to claim 1, characterized in that: In S2, when the ionic liquid is [DMEA][COOH] and [DMEA]Cl, [DMEA][COOH] and The ratio of [DMEA]Cl is 1:

1.

5. The method for extracting high-purity cellulose from xylose residue according to claim 1, characterized in that: In the above-mentioned S2, the immersion treatment temperature is 120-180° C., the time is 2-4 hours, and the stirring intensity is 80-120 r / min.

6. The method for extracting high-purity cellulose from xylose residue according to claim 1, characterized in that: In the above-mentioned S3, the pressure of the steam explosion is 2-4 MPa, and the processing time is 1-2 min.

7. The method for extracting high-purity cellulose from xylose residue according to claim 1, characterized in that: In the S3, after the ionic liquid is added, the solid-liquid ratio of the xylose residue powder to the total amount of the ionic liquid in the reactor is 1:5-10.

8. The method for extracting high-purity cellulose from xylose residue according to claim 1, characterized in that: In the S3, after the ionic liquid is added, the reaction is continued for 2 to 4 hours at 120 to 180° C. and a stirring intensity of 80 to 120 r / min.

9. The method for extracting high-purity cellulose from xylose residue according to claim 1, characterized in that: In the S4, the cellulose obtained in the reactor is washed with water, the solid-liquid ratio of the added water to the xylose residue powder is 1:3-5, the washing is performed 1-3 times, the stirring intensity during the washing process is 60-120 r / min, and the single washing time is 15-30 min.

10. The method for extracting high-purity cellulose from xylose residue according to claim 1, characterized in that: In the above-mentioned S4, the purity of the obtained high-purity cellulose can reach over 99%.