CN109627347B - Pretreatment method of cellulose - Google Patents

Pretreatment method of cellulose Download PDF

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CN109627347B
CN109627347B CN201811520323.8A CN201811520323A CN109627347B CN 109627347 B CN109627347 B CN 109627347B CN 201811520323 A CN201811520323 A CN 201811520323A CN 109627347 B CN109627347 B CN 109627347B
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cellulose
ethyl
hydrothermal reaction
drying
pretreating
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CN109627347A (en
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罗琼林
曾瞬钦
周嘉斌
苏胜培
胡扬剑
欧阳跃军
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Huaihua University
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
    • C08B15/00—Preparation of other cellulose derivatives or modified cellulose, e.g. complexes

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Abstract

The invention discloses a pretreatment method of cellulose, which comprises the following steps: mixing cellulose with 1-ethyl-3-methylimidazole acetateHeating and stirring at 70-90 ℃ to at least partially dissolve the cellulose in the 1-ethyl-3-methylimidazole acetate; adding distilled water and stirring to separate out the cellulose; washing and drying the precipitated cellulose; mixing the dried cellulose with Fe3+Mixing the aqueous solutions, and carrying out hydrothermal reaction at 110-150 ℃; cooling the product of the hydrothermal reaction to separate out the cellulose; and separating and drying the precipitated cellulose to obtain pretreated cellulose.

Description

Pretreatment method of cellulose
Technical Field
The invention relates to the field of green energy-saving chemical materials, in particular to a pretreatment method of cellulose.
Background
With the consumption of natural fossil energy and the increasing demand for energy by human beings, environmental problems and energy crisis are becoming more and more serious. Finding renewable resources to replace fossil resources is one of the important approaches to solving the above-mentioned problems. Lignocellulose in biomass resources rapidly rises as the best alternative resource with the advantages of wide sources, low price, renewability and the like. Lignocellulose is mainly composed of cellulose, hemicellulose and lignin. The lignocellulose is pretreated to obtain cellulose, and the cellulose is further hydrolyzed to obtain monosaccharide which is easy to use. The fuel ethanol production by utilizing the lignocellulose raw material comprises the following three processes: pretreatment, hydrolysis and ethanol fermentation.
The pretreatment aims to reduce the loss of reducing sugar, avoid the generation of inhibitors for inhibiting subsequent fermentation, reduce the pollution to the environment, reduce the production cost and improve the enzymolysis saccharification efficiency of the lignocellulose raw material, thereby obtaining higher fuel yield. The traditional pretreatment methods comprise biological pretreatment, acid pretreatment, alkali pretreatment, hydrothermal pretreatment and the like, and the cellulose hydrolysis efficiency is improved by eliminating or weakening the wrapping and covering of hemicellulose and lignin on cellulose in the structure and improving the direct contact area of cellulose and cellulose. However, these pretreatment methods still have to be improved in the effect of improving the efficiency of cellulase hydrolysis.
Disclosure of Invention
Therefore, a pretreatment method for cellulose is needed, which is beneficial to improving the enzymolysis efficiency of cellulose.
A method of pretreating cellulose comprising the steps of:
s10, heating and stirring cellulose and 1-ethyl-3-methylimidazole acetate at 70-90 ℃ to at least partially dissolve the cellulose in the 1-ethyl-3-methylimidazole acetate;
s20, adding distilled water and stirring to separate out the cellulose;
s30, washing and drying the precipitated cellulose;
s40, mixing the dried cellulose with Fe3+Mixing the aqueous solutions, and carrying out hydrothermal reaction at 110-150 ℃;
s50, cooling the product of the hydrothermal reaction to precipitate the cellulose; and
s60, separating and drying the precipitated cellulose to obtain the pretreated cellulose.
In one embodiment, the cellulose is selected from at least one of pure cellulose and cellulose-containing biomass.
In one embodiment, the mass ratio of the cellulose to the 1-ethyl-3-methylimidazolium acetate is less than or equal to 1: 9.
in one embodiment, step S10 is preceded by the step of mixing the cellulose with the 1-ethyl-3-methylimidazolium acetate at 20 ℃ to 30 ℃ to swell the cellulose.
In one embodiment, the drying temperature of step S30 is 25 ℃ to 100 ℃.
In one embodiment, the aqueous solution contains Fe3+The concentration of (B) is 0.05mol/L to 0.15 mol/L.
In one embodiment, the mass ratio of the dried cellulose to the aqueous solution is 1: (8-20).
In one embodiment, the pressure of the hydrothermal reaction is less than or equal to 0.2MPa, and the holding time of the hydrothermal reaction is 20min to 60 min.
In one embodiment, in step S50, the cooling is performed by cooling the product to 20-30 ℃ within 2-5 min.
In one embodiment, the drying temperature of step S60 is 50 ℃ to 80 ℃.
The invention treats cellulose or biomass containing cellulose by using ionic liquid 1-ethyl-3-methylimidazole acetate to dissolve cellulose at least partially, separates out the dissolved cellulose by using distilled water, washes and dries to remove 1-ethyl-3-methylimidazole acetate, and then reacts with the biomass containing Fe3+The aqueous solution is subjected to hydrothermal reaction to completely dissolve cellulose, and the cellulose is crystallized and precipitated again through cooling to obtain pretreated cellulose.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the method for pretreating cellulose of the present invention is further described in detail by examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The embodiment of the invention provides a pretreatment method of cellulose, which comprises the following steps:
s10, heating and stirring cellulose and 1-ethyl-3-methylimidazole acetate at 70-90 ℃ to at least partially dissolve the cellulose in the 1-ethyl-3-methylimidazole acetate;
s20, adding distilled water and stirring to separate out the cellulose;
s30, washing and drying the precipitated cellulose;
s40, mixing the dried cellulose with Fe3+Mixing the aqueous solutions, and carrying out hydrothermal reaction at 110-150 ℃;
s50, cooling the product of the hydrothermal reaction to precipitate the cellulose; and
s60, separating and drying the precipitated cellulose to obtain the pretreated cellulose.
According to the embodiment of the invention, cellulose or biomass containing cellulose is treated by ionic liquid 1-ethyl-3-methylimidazole acetate to at least partially dissolve the cellulose, the dissolved cellulose is separated out by treatment of distilled water, the 1-ethyl-3-methylimidazole acetate is removed by washing and drying, and then the ionic liquid and the Fe-containing biomass are mixed3+The aqueous solution is subjected to hydrothermal reaction to completely dissolve cellulose, and the cellulose is crystallized and precipitated again through cooling to obtain pretreated cellulose.
In step S10, the cellulose may be selected from at least one of pure cellulose and cellulose-containing biomass. In one embodiment, the biomass may include natural biomass material rich in cellulose, such as wood powder, straw, leaves, cotton, and the like. The biomass contains hemicellulose and lignin in addition to cellulose. In biomass, hemicellulose and lignin are covalently bound to surround cellulose, which is detrimental to subsequent enzymatic hydrolysis of cellulose. Dissolving cellulose by adding ionic liquid, separating the cellulose, hemicellulose and lignin, loosening the biomass, and destroying the crystalline structure of cellulose. Many types of ionic liquids are used, and through repeated comparison and selection, the solubility of 1-ethyl-3-methylimidazolium acetate to cellulose is relatively good, but only part of cellulose may be dissolved to obtain a solid-liquid mixture.
In one embodiment, the mass ratio of the cellulose to the 1-ethyl-3-methylimidazolium acetate is less than or equal to 1: and 9, the mass percentage of the 1-ethyl-3-methylimidazole acetate in the mixture of the cellulose and the 1-ethyl-3-methylimidazole acetate is over 90 percent, so that the cellulose can be fully soaked in the 1-ethyl-3-methylimidazole acetate.
Before the step S10, it is preferable to further include a step of mixing the cellulose with the 1-ethyl-3-methylimidazolium acetate at 20 to 30 ℃ to swell the cellulose. The swelling time may be 20min to 60 min. Soaking cellulose in 1-ethyl-3-methylimidazole acetate at normal temperature in advance to fully swell the cellulose, so that more 1-ethyl-3-methylimidazole acetate enters the interior of cellulose molecules, and the cellulose is favorably and quickly dissolved in the subsequent heating and stirring process.
In step S10, the heating temperature is preferably 80 ℃. The stirring time is preferably 20min to 60 min. The cellulose macromolecular chain segment motion is enhanced along with the continuous entering of the 1-ethyl-3-methylimidazole acetate into the interior of the cellulose molecules, the whole cellulose macromolecules move through the coordinated motion of the macromolecular chain segments, and the cellulose gradually enters the 1-ethyl-3-methylimidazole acetate, so that a thermodynamically stable homogeneous system is formed. In this temperature range, the cellulose molecules move faster and the dissolution efficiency is higher. The stirring speed can be 80 r/min-200 r/min.
In step S20, since cellulose is insoluble in water, cellulose can be precipitated from the solution by adding distilled water. The temperature of the distilled water may be normal temperature, such as 20-30 ℃. The amount of the added distilled water may be large, and preferably, the volume ratio of the distilled water to the 1-ethyl-3-methylimidazole acetate is 1:1 to 4: 1. The homogeneous system of the solution can be destroyed by stirring, so that the cellulose is precipitated.
Through the steps of dissolving and then precipitating in the steps S10 and S20, the crystallinity of the cellulose is favorably reduced, and the enzymolysis efficiency of the pretreated cellulose is improved.
In step S30, the solvent used for the washing may be distilled water, the number of times of the washing may be 3 or more, 1-ethyl-3-methylimidazole acetate on the cellulose is removed by repeating the washing, and water is removed by drying. The drying temperature may be 25 ℃ to 100 ℃. The drying temperature is not suitable to be too high, so that the crystallinity of the cellulose is not improved.
In step S40, Fe is added3+Aqueous solution and fiber ofMixing the cellulose and carrying out hydrothermal reaction to completely dissolve the cellulose. Said Fe-containing3+Fe in an aqueous solution of3+The concentration of (B) may be 0.05mol/L to 0.15 mol/L. The dried cellulose and the Fe-containing3+The mass ratio of the aqueous solution of (a) may be 1: (8-20). Said Fe-containing3+Preferably FeCl3And (3) solution. The cellulose and the aqueous solution can be stirred to form a uniformly mixed solid-liquid mixture, then the solid-liquid mixture is transferred into a hydrothermal reaction kettle, protective gas is introduced into the hydrothermal reaction kettle and the hydrothermal reaction kettle is sealed, and a high-temperature high-pressure environment is generated inside the hydrothermal reaction kettle by heating. The heating temperature is preferably 110-120 ℃, the heat preservation time is preferably 20-60 min, and the pressure in the reaction kettle is preferably less than or equal to 0.2 MPa. By controlling the temperature, pressure and time of the hydrothermal reaction in a lower or shorter range, the dissolution of cellulose can be promoted while the increase of the crystallinity of cellulose during the hydrothermal treatment can be avoided.
The step S50 may include: and immersing the reaction kettle after the hydrothermal reaction in cold water to rapidly cool the reaction kettle, and rapidly crystallizing and separating out the cellulose through rapid cooling. The immersion time in cold water can be 2 min-5 min, so that the temperature of the product is reduced to 20-30 ℃. The cooling time is controlled, so that the crystallinity of the cellulose is favorably reduced, and the hydrolysis efficiency of the cellulose is favorably improved.
In step S60, the product of the hydrothermal reaction may be filtered with suction to separate the precipitated cellulose from the cooled product to obtain a solid phase product, and the solid phase product may be dried in an oven to obtain pretreated cellulose. The drying temperature may be 50 ℃ to 80 ℃. The drying time can be 1-12 h.
Example 1
(1) Cellulose and 1-ethyl-3-methylimidazolium acetate were mixed in a mass ratio of 1:9, and swollen at room temperature for 30 minutes. Then, the mixture was stirred at 80 ℃ for 1 hour to dissolve the cellulose portion to obtain a solid-liquid mixture.
(2) Distilled water was added to the solid-liquid mixture and stirred to precipitate cellulose.
(3) The precipitated cellulose was repeatedly washed and dried in a vacuum oven at 100 ℃.
(4) Mixing the dried cellulose with 0.1mol/L FeCl3The aqueous solution is mixed in a hydrothermal reaction kettle according to the mass ratio of 1:20 to form a cellulose ferric salt solid-liquid mixture, and the hydrothermal reaction is carried out for 60 minutes by heating the reaction kettle to 150 ℃.
(5) And immersing the reaction kettle after the hydrothermal reaction in cold water for 3 minutes to quickly reduce the temperature in the reaction kettle to be lower than 30 ℃ so as to quickly crystallize and separate out cellulose.
(6) And opening the reaction kettle to carry out suction filtration on the cooled product, and then putting the product into a vacuum drying oven to carry out drying at 80 ℃ to obtain the pretreated cellulose.
Example 2
Example 2 is essentially the same as example 1 except that the hydrothermal reaction temperature is 120 ℃.
Example 3
Example 3 is substantially the same as example 1 except that the precipitated cellulose is repeatedly washed in step (3) and dried in a vacuum oven at 130 ℃.
Example 4
Example 4 is substantially the same as example 1 except that the cooling in step (5) is carried out by naturally cooling the reaction vessel after the hydrothermal reaction at room temperature to less than 30 ℃.
Comparative example 1
Comparative example 1 differs from example 1 in that steps (1) to (3) are not included, and only steps (4) to (6) are included.
Comparative example 2
Comparative example 2 is substantially the same as example 1 except that the stirring temperature of step (1) is 130 ℃.
Comparative example 3
The non-pretreated cellulose of step (1) of example 1 was used directly.
Taking the pretreated celluloses of the above examples 1-4 and comparative examples 1-2 and the untreated cellulose of the comparative example 3, respectively, and carrying out enzymolysis hydrolysis reaction under the same conditions, specifically, adding 20U of cellulase per gram of cellulose, and then adding distilled water to carry out hydrolysis reaction at 50 ℃. The yield of reducing sugars was determined by dinitrosalicylic acid colorimetry (DNS method). The results are shown in Table 1.
TABLE 1 reducing sugar yield
Group of Reducing sugar yield (%)
Example 1 94.1
Example 2 90.4
Example 3 92.2
Example 4 91.6
Comparative example 1 85.7
Comparative example 2 88.6
Comparative example 3 82.9
The examples and comparative examples were each tested for reducing sugar yield under the same conditions. As can be seen from Table 1, pretreatmentCan improve the hydrolysis efficiency of the cellulose, and directly adopts Fe3+Compared with the cellulose treatment, the embodiment of the invention adopts 1-ethyl-3-methylimidazolium acetate and Fe3+The hydrolysis efficiency of the cellulose can be obviously improved after the cellulose is treated step by step, probably because the cellulose, the hemicellulose and the lignin can be combined more loosely by dissolving 1-ethyl-3-methylimidazole acetate and then crystallizing and separating out the dissolved cellulose and the dissolved cellulose, and then the combined cellulose, the hemicellulose and the lignin are treated by Fe3+The crystallization is quickly cooled and precipitated after the secondary dissolution is carried out under the hydrothermal condition, so that the crystallinity of the cellulose can be reduced, the reduced crystallinity is beneficial to the efficiency of enzyme hydrolysis, and the yield of reducing sugar is improved. Through hydrolysis experiments, the stirring temperature, the drying temperature and the use of Fe during the dissolution of the 1-ethyl-3-methylimidazole acetate are also found3+The temperature for carrying out the hydrothermal reaction is controlled within a proper range, and the crystallization degree of the cellulose is possibly improved due to the overhigh temperature, so that the subsequent enzyme hydrolysis of the cellulose is not facilitated.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (6)

1. A method for pretreating cellulose, comprising the steps of:
s10, mixing cellulose and 1-ethyl-3-methylimidazole acetate in a mass ratio of 1:9 at 20-30 ℃, swelling the cellulose for 20-60 min, heating and stirring at 70-90 ℃ for 20-60 min, and at least partially dissolving the cellulose in the 1-ethyl-3-methylimidazole acetate;
s20, adding distilled water and stirring to separate out the cellulose;
s30, washing and drying the precipitated cellulose;
s40, mixing the dried cellulose with 0.05 mol/L-0.15 mol/L Fe3+The aqueous solution of (1) is mixed according to the mass ratio of (8-20), and hydrothermal reaction is carried out at the temperature of 110-150 ℃;
s50, cooling the product of the hydrothermal reaction to precipitate the cellulose; and
s60, separating and drying the precipitated cellulose to obtain the pretreated cellulose.
2. The method of pretreating cellulose according to claim 1, wherein the cellulose is at least one selected from the group consisting of pure cellulose and cellulose-containing biomass.
3. The method for pretreating cellulose according to claim 1, wherein the drying temperature in step S30 is 25 ℃ to 100 ℃.
4. The method for pretreating cellulose according to claim 1, wherein the pressure of the hydrothermal reaction is less than or equal to 0.2MPa, and the holding time of the hydrothermal reaction is 20-60 min.
5. The method for pretreating cellulose according to claim 1, wherein the cooling step S50 is carried out by cooling the product to 20-30 ℃ within 2-5 min.
6. The method for pretreating cellulose according to claim 1, wherein the drying temperature in step S60 is 50 ℃ to 80 ℃.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102071266A (en) * 2010-12-03 2011-05-25 江南大学 Application of ionic liquid to preparation of reducing sugar by cellulose hydrolysis
CN102491962A (en) * 2011-11-28 2012-06-13 江南大学 Preparation method of 5-hydroxymethylfurfural by cellulose hydrolysis in ionic liquid

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US7939681B2 (en) * 2006-08-07 2011-05-10 Battelle Memorial Institute Methods for conversion of carbohydrates in ionic liquids to value-added chemicals
CN102268827A (en) * 2011-08-26 2011-12-07 重庆恒远晋通科技有限公司 Method for extracting celluloses from tobaccos based on ferric chloride pretreatment

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102071266A (en) * 2010-12-03 2011-05-25 江南大学 Application of ionic liquid to preparation of reducing sugar by cellulose hydrolysis
CN102491962A (en) * 2011-11-28 2012-06-13 江南大学 Preparation method of 5-hydroxymethylfurfural by cellulose hydrolysis in ionic liquid

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
离子液体对锯末中纤维素的溶解及再生研究;陶芙蓉等;《分子催化》;20131015;第27卷(第05期);第420-428页 *

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