CN114044917B - Method for pretreating cellulose by using 4-butyl-3-methylimidazole hydrogen sulfate-ethanol binary system - Google Patents
Method for pretreating cellulose by using 4-butyl-3-methylimidazole hydrogen sulfate-ethanol binary system Download PDFInfo
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Abstract
The invention discloses a method for pretreating cellulose by a 4-butyl-3-methylimidazole bisulfate-ethanol binary system, which comprises the following steps: adding a certain amount of 4-butyl-3-methylimidazolium hydrogen sulfate ([ BMIM ]]HSO 4 ) Mixing with Ethanol (ET) at a certain proportion to obtain [ BMIM ]]HSO 4 ET solution, then microcrystalline cellulose is added to the prepared [ BMIM ]]HSO 4 In the ET solution, solid-liquid separation is carried out after stirring and heating treatment, filter cakes are washed by ethanol and then dried in vacuum, the treated cellulose can be obtained, the obtained filtrate can be directly recycled without any treatment, the pyrolysis temperature of the cellulose treated by the method is obviously reduced, the energy consumption is saved, the method takes the mixed solution of the imidazolyl ionic liquid and the ethanol as a solvent medium for pretreating the cellulose, the source is wide, the price is low, the method is green and environment-friendly, and compared with the method taking pure ionic liquid as the solvent medium, the method greatly reduces the process cost.
Description
Technical Field
The invention relates to the field of cellulose pretreatment, in particular to a method for pretreating cellulose by a 4-butyl-3-methylimidazole hydrogen sulfate-ethanol binary system.
Background
Due to the fact that environmental pollution is serious day by day, fossil fuels are exhausted day by day, energy requirements are increased day by day, and countries in the world have a plurality of policies and laws and regulations related to environmental management, so that consumption of fossil energy is reduced, and renewable new energy is researched, developed, popularized and applied continuously. Compared with other renewable new energy sources (mainly providing electric power, power and the like), the biomass is the only renewable new energy source capable of providing carbon-based chemicals and carbon-based materials essential for social development, and has the characteristics of greenness, low carbon, cleanness, renewability and the like. The efficient and clean technology for converting lignocellulose biomass into chemicals and carbon-based materials is vigorously developed, and the method has important significance for replacing part of fossil energy consumption, promoting energy conservation and emission reduction and optimizing a new energy structure. The technology for preparing fuel oil or chemicals by biomass cracking and the biomass gasification power generation technology are two kinds of biomass resource thermochemical conversion utilization technologies developed at present.
Cellulose is an important component of biomass, is a polysaccharide which is most widely distributed and contained in nature and accounts for more than 50% of the carbon content in plants. High value-added chemicals such as furan, furan aldehydes, cyclopentanone, and the like can be provided by pyrolysis techniques. Generally, because the cellulose is regularly arranged, the thermal stability is good, the pyrolysis temperature is between 300 ℃ and 400 ℃, the energy consumption required by pyrolysis is high, and the types of pyrolysis products are complicated. Suitable pretreatment may increase the selectivity of the pyrolysis product or reduce the temperature required for pyrolysis.
The ionic liquid is a novel green organic solvent, rapidly draws attention of scholars due to the advantages of extremely low vapor pressure, good thermal stability, nonflammability, easy recovery, adjustable structural properties and the like, and is applied to the pyrolysis process of cellulose to change the pyrolysis path and pyrolysis products of the cellulose. Jiang et al used 1-butyl-3-methylimidazolium chloride pure ionic liquid to dip and treat cellulose at 110 ℃, and then washed by water to remove the ionic liquid, so as to obtain pretreated cellulose. Under different heating rates, the cellulose main weight loss temperature after pretreatment is reduced by 8-12 ℃ compared with the primary weight loss temperature of the original cellulose. The pure ionic liquid can be used for reducing the pyrolysis temperature of the cellulose. However, since the ionic liquid is expensive, the ionic liquid needs to be washed and removed by water after use, which causes the problems of water resource consumption and possible pollution; if the ionic liquid is recycled, the washing liquid needs to be purified and separated, so that the treatment technology cost is increased, and the pretreatment process is increased. Huang et al, which utilize a plurality of pure ionic liquids to mix with cellulose respectively to prepare ionic liquid-cellulose mixtures, have found that mixed pyrolysis can lower the pyrolysis temperature, and there are also problems of ionic liquid recovery and product washing in the later period.
The invention uses the mixed solution of the ionic liquid 4-butyl-3-methylimidazole bisulfate and the ethanol as a pretreatment solvent, stirs the pretreated cellulose for a certain time at a certain temperature, and carries out solid-liquid separation on the pretreated cellulose and the ionic liquid-ethanol solvent through filtration, the pyrolysis temperature of the obtained pretreated cellulose is obviously reduced, and the ionic liquid-ethanol solvent can be reused.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method for pretreating cellulose by a 4-butyl-3-methylimidazole bisulfate-ethanol binary system, which mainly comprises the following steps: mixing a certain amount of 4-butyl-3-methylimidazole bisulfate with ethanol in proportion to form a cellulose pretreatment solution, then adding microcrystalline cellulose into the prepared cellulose pretreatment solution, stirring, heating and soaking, then carrying out solid-liquid separation, directly recycling filtrate without any treatment, washing filter cakes with ethanol, and then carrying out vacuum drying to obtain the treated cellulose.
In order to realize the technical effects, the following technical scheme is adopted:
a method for pretreating cellulose by a 4-butyl-3-methylimidazole bisulfate-ethanol binary system comprises the following steps:
step S1: mixing 4-butyl-3-methylimidazole hydrogen sulfate with ethanol in proportion, and stirring uniformly to form uniform [ BMIM ]]HSO 4 -ET mixed solution;
step S2: weighing microcrystalline cellulose, placing the microcrystalline cellulose in a hydrothermal reaction kettle, and adding the prepared BMIM]HSO 4 -ET solution;
and step S3: heating for a certain time under the condition of stirring, and then cooling;
and step S4: taking out the treated solid-liquid mixture, and performing solid-liquid separation to obtain filter cake and filtrate (BMIM)]HSO 4 ET Mixed solution, recyclable instead of [ BMIM ] in step S1]HSO 4 -ET mixed solution;
step S5: washing the filter cake with ethanol;
step S6: drying the washed filter cake at a certain temperature to obtain a product, namely the treated cellulose.
Further, the mass ratio of the 4-butyl-3-methylimidazole hydrogen sulfate to the ethanol in the step S1 is in a range of 0.1-60.
Further, in the step S1, the mass ratio of 4-butyl-3-methylimidazole hydrogen sulfate to ethanol is preferably 1.
Further, in the step S2, the mass ratio of the microcrystalline cellulose to the 4-butyl-3-methylimidazole bisulfate-ethanol binary system is within a range from 1.
Further, the mass ratio of the microcrystalline cellulose to the 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system in the step S2 is preferably 1.
Further, the stirring in step S3 is magnetic stirring.
Further, the heating treatment time in the step S3 is 0.5-16 h, and the temperature is cooled to be below 40 ℃.
Further, the solid-liquid separation method in the step S4 is vacuum filtration, and the filtrate can be directly reused without any treatment.
Further, the washing mode of the solid cellulose filter cake in the step S5 is ethanol washing, and the washed liquid is distilled and then the fraction at 78.3 ℃ is collected for reuse.
Further, the drying temperature of the filter cake after washing in the step S6 is 50 ℃, the drying time is 8 hours, and the drying mode is vacuum drying.
The beneficial effects of the invention are as follows:
the invention discloses a method for pretreating cellulose by a 4-butyl-3-methylimidazole bisulfate-ethanol binary system, which mainly comprises the following steps: mixing a certain amount of 4-butyl-3-methylimidazole bisulfate with ethanol in proportion to form a cellulose pretreatment solution, then adding microcrystalline cellulose into the prepared cellulose pretreatment solution, stirring, heating and soaking, then carrying out solid-liquid separation, distilling the filtrate, recycling, washing the filter cake with ethanol, and then carrying out vacuum drying to obtain the treated cellulose.
(1) The method comprises the steps of taking a mixed solution of 4-butyl-3-methylimidazole bisulfate and ethanol as a pretreatment solvent, stirring and soaking cellulose for a certain time at a certain temperature, filtering to carry out solid-liquid separation on the pretreated cellulose and an ionic liquid-ethanol solvent, wherein the pyrolysis temperature of the obtained pretreated cellulose is obviously reduced, and the ionic liquid-ethanol solvent can be reused without treatment;
(2) Compared with the pure ionic liquid as the solvent medium, the mixed solution of the imidazole ionic liquid 4-butyl-3-methylimidazole bisulfate and the ethanol is used as the solvent medium for pretreating cellulose, so that the viscosity of the solvent is reduced, the stirring is easy, the cellulose and the solvent can be fully contacted and mixed, and the uniformity of cellulose pretreatment can be effectively improved;
(3) The mixed solution of the imidazolyl ionic liquid 4-butyl-3-methylimidazole bisulfate and the ethanol is used as a solvent medium for pretreating cellulose, the ethanol is a volatile colorless transparent low-toxicity organic solvent, and can be prepared by fermenting biomass, so that the preparation method is wide in source, low in cost and environment-friendly. Compared with the pure ionic liquid as a solvent medium, the method greatly reduces the process cost.
(4) The preparation method takes the mixed solution of the imidazolyl ionic liquid 4-butyl-3-methylimidazole hydrogen sulfate and ethanol as a solvent medium for pretreating cellulose, the cellulose is pretreated, the pretreated cellulose can be completely separated from the solvent medium and products through filtration, the product separation is simple, and the equipment requirement is low;
(5) The preparation method takes the mixed solution of the imidazolyl ionic liquid 4-butyl-3-methylimidazole hydrogen sulfate and ethanol as a solvent medium for pretreating cellulose, the cellulose is pretreated, the pretreated cellulose can be completely separated from a product through filtration, the obtained solvent can be recycled, further processing is not needed, the operation is simple, and the process requirement is low;
(6) The preparation method comprises the steps of using a mixed solution of imidazole-based ionic liquid 4-butyl-3-methylimidazole bisulfate and ethanol as a solvent medium for pretreating cellulose, pretreating the cellulose, and adjusting the pyrolysis starting temperature of the cellulose obtained by pretreatment by adjusting the mixing ratio of the imidazole-based ionic liquid and the ethanol.
Drawings
FIG. 1 is a flow chart of cellulose processing in an embodiment of the present invention;
FIG. 2 is a graph comparing infrared analysis of pretreated cellulose with different contents of 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system in accordance with the present invention;
FIG. 3 is a comparative graph of Raman analysis of pretreated cellulose with different contents of 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system in accordance with the present invention;
FIG. 4 is a comparative graph of X-ray diffraction analysis of pretreated cellulose with different contents of 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system in accordance with the present invention;
FIG. 5 is a comparative graph of laser particle size analysis of pretreated cellulose with different contents of 4-butyl-3-methylimidazolium bisulfate-ethanol binary system in examples of the present invention;
FIG. 6 is a comparison graph of the morphology of a scanning electron microscope of pretreated cellulose with different contents of 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system in the embodiment of the present invention;
FIG. 7 is a graph comparing the thermogravimetric curves of pretreated cellulose with different contents of 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system in the examples of the present invention;
FIG. 8 is a graph comparing the thermogravimetric curves of pretreated cellulose with different contents of 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system in the examples of the present invention;
FIG. 9 is a comparison graph of the thermal weight loss curves of the 4-butyl-3-methylimidazole bisulfate-ethanol binary mixed solvent recycled cellulose in the example of the invention.
FIG. 10 is a comparison graph of the thermal weight loss curves of the 4-butyl-3-methylimidazole bisulfate-ethanol binary mixed solvent recycled cellulose in the example of the invention.
Detailed Description
The invention will be further described with reference to the accompanying drawings, without limiting the scope of the invention to the following:
example 1 (mass concentration of 4-butyl-3-methylimidazole hydrogensulfate is 0.1%):
as shown in figure 1, the method for pretreating cellulose by using a 4-butyl-3-methylimidazole hydrogen sulfate-ethanol binary system comprises the following steps:
step S1: mixing 4-butyl-3-methylimidazole bisulfate with ethanol in proportion, and stirring uniformly to form uniform [ BMIM ]]HSO 4 -ET mixed solution;
step S2: weighing microcrystalline cellulose, placing the microcrystalline cellulose in a hydrothermal reaction kettle, and adding the prepared [ BMIM ] according to the mass ratio of the microcrystalline cellulose to the 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system of 1]HSO 4 -ET solution;
and step S3: heating for 5h under stirring, and cooling to 25 deg.C;
and step S4: taking out the treated solid-liquid mixture, and performing solid-liquid separation to obtain filter cake and filtrate, wherein the filtrate is [ BMIM ]]HSO 4 ET Mixed solution, recyclable alternative to [ BMIM ] in step S1]HSO 4 -ET mixed solution;
step S5: washing the filter cake with ethanol;
step S6: and drying the washed filter cake for 8h at 50 ℃ to obtain a product, namely the treated cellulose 1.
Example 2 (mass concentration of 4-butyl-3-methylimidazole hydrogensulfate 1%):
as shown in figure 1, the method for pretreating cellulose by using a 4-butyl-3-methylimidazole hydrogen sulfate-ethanol binary system comprises the following steps:
step S1: mixing 4-butyl-3-methylimidazole bisulfate with ethanol in proportion, and stirring uniformly to form uniform [ BMIM ]]HSO 4 -ET mixed solution;
step S2: weighing microcrystalline cellulose, placing the microcrystalline cellulose in a hydrothermal reaction kettle, and adding the prepared [ BMIM ] according to the mass ratio of the microcrystalline cellulose to the 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system of 1]HSO 4 -ET solution;
and step S3: heating for 5h under stirring, and cooling to 25 deg.C;
and step S4: taking out the treated solid-liquid mixture, and performing solid-liquid separation to obtain filter cake and filtrate, wherein the filtrate is [ BMIM ]]HSO 4 ET Mixed solution, recyclable instead of [ BMIM ] in step S1]HSO 4 -ET mixed solution;
step S5: washing the filter cake with ethanol;
step S6: and drying the washed filter cake for 8 hours at 50 ℃ to obtain a product, namely the treated cellulose 2.
Example 3 (5% by mass of 4-butyl-3-methylimidazole hydrogensulfate):
as shown in figure 1, the method for pretreating cellulose by using a 4-butyl-3-methylimidazole hydrogen sulfate-ethanol binary system comprises the following steps:
step S1: mixing 4-butyl-3-methylimidazole bisulfate with ethanol in proportion, and stirring uniformly to form uniform [ BMIM ]]HSO 4 -ET mixed solution;
step S2: balanceMeasuring microcrystalline cellulose, placing the microcrystalline cellulose in a hydrothermal reaction kettle, and adding the prepared [ BMIM ] according to the mass ratio of the microcrystalline cellulose to the 4-butyl-3-methylimidazole hydrogen sulfate-ethanol binary system of 1]HSO 4 -ET solution;
and step S3: heating for 5h under stirring, and cooling to 25 deg.C;
and step S4: taking out the treated solid-liquid mixture, and performing solid-liquid separation to obtain filter cake and filtrate (BMIM)]HSO 4 ET Mixed solution, recyclable instead of [ BMIM ] in step S1]HSO 4 -ET mixed solution;
step S5: washing the filter cake with ethanol;
step S6: and drying the washed filter cake for 8 hours at 50 ℃ to obtain a product, namely the treated cellulose 3.
Example 4 (mass concentration of 4-butyl-3-methylimidazole hydrogensulfate 10%):
as shown in figure 1, the method for pretreating cellulose by using a 4-butyl-3-methylimidazole hydrogen sulfate-ethanol binary system comprises the following steps:
step S1: mixing 4-butyl-3-methylimidazole hydrogen sulfate with ethanol in proportion, and stirring uniformly to form uniform [ BMIM ]]HSO 4 -ET mixed solution;
step S2: weighing microcrystalline cellulose, placing the microcrystalline cellulose in a hydrothermal reaction kettle, and adding the prepared [ BMIM ] according to the mass ratio of the microcrystalline cellulose to the 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system of 1]HSO 4 -ET solution;
and step S3: heating for 5h under stirring, and cooling to 25 deg.C;
and step S4: taking out the treated solid-liquid mixture, and performing solid-liquid separation to obtain filter cake and filtrate, wherein the filtrate is [ BMIM ]]HSO 4 ET Mixed solution, recyclable instead of [ BMIM ] in step S1]HSO 4 -ET mixed solution;
step S5: washing the filter cake with ethanol;
step S6: and drying the washed filter cake for 8 hours at 50 ℃ to obtain a product, namely the treated cellulose 4.
Example 5 (mass concentration of 4-butyl-3-methylimidazole hydrogensulfate is 20%):
as shown in figure 1, the method for pretreating cellulose by using a 4-butyl-3-methylimidazole hydrogen sulfate-ethanol binary system comprises the following steps:
step S1: mixing 4-butyl-3-methylimidazole hydrogen sulfate with ethanol in proportion, and stirring uniformly to form uniform [ BMIM ]]HSO 4 -ET mixed solution;
step S2: weighing microcrystalline cellulose, placing the microcrystalline cellulose in a hydrothermal reaction kettle, and adding the prepared [ BMIM ] according to the mass ratio of the microcrystalline cellulose to a 4-butyl-3-methylimidazole hydrogen sulfate-ethanol binary system of 1]HSO 4 -ET solution;
and step S3: heating for 5h under stirring, and cooling to 25 deg.C;
and step S4: taking out the treated solid-liquid mixture, and performing solid-liquid separation to obtain filter cake and filtrate, wherein the filtrate is [ BMIM ]]HSO 4 ET Mixed solution, recyclable instead of [ BMIM ] in step S1]HSO 4 -ET mixed solution;
step S5: washing the filter cake with ethanol;
step S6: and drying the washed filter cake for 8h at 50 ℃ to obtain a product, namely the treated cellulose 5.
Example 6 (mass concentration of 4-butyl-3-methylimidazole hydrogensulfate 40%):
as shown in figure 1, the method for pretreating the cellulose by using the binary system of 4-butyl-3-methylimidazole bisulfate and ethanol comprises the following steps:
step S1: mixing 4-butyl-3-methylimidazole bisulfate with ethanol in proportion, and stirring uniformly to form uniform [ BMIM ]]HSO 4 -ET mixed solution;
step S2: weighing microcrystalline cellulose, placing the microcrystalline cellulose in a hydrothermal reaction kettle, and adding the prepared [ BMIM ] into the hydrothermal reaction kettle according to the mass ratio of the microcrystalline cellulose to the 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system of 1]HSO 4 -ET solution;
and step S3: heating for 5h under stirring, and cooling to 25 deg.C;
and step S4: taking out the solid-liquid mixture after the treatment,performing solid-liquid separation to obtain filter cake and filtrate (BMIM)]HSO 4 ET Mixed solution, recyclable instead of [ BMIM ] in step S1]HSO 4 -ET mixed solution;
step S5: washing the filter cake with ethanol;
step S6: and drying the washed filter cake for 8h at 50 ℃ to obtain a product, namely the treated cellulose 6.
Example 7 (mass concentration of 4-butyl-3-methylimidazole hydrogensulfate 60%):
as shown in figure 1, the method for pretreating the cellulose by using the binary system of 4-butyl-3-methylimidazole bisulfate and ethanol comprises the following steps:
step S1: mixing 4-butyl-3-methylimidazole bisulfate with ethanol in proportion, and stirring uniformly to form uniform [ BMIM ]]HSO 4 -ET mixed solution;
step S2: weighing microcrystalline cellulose, placing the microcrystalline cellulose in a hydrothermal reaction kettle, and adding the prepared [ BMIM ] according to the mass ratio of the microcrystalline cellulose to the 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system of 1]HSO 4 -ET solution;
and step S3: heating for 5h under stirring, and cooling to 25 deg.C;
and step S4: taking out the treated solid-liquid mixture, and performing solid-liquid separation to obtain filter cake and filtrate, wherein the filtrate is [ BMIM ]]HSO 4 ET Mixed solution, recyclable instead of [ BMIM ] in step S1]HSO 4 -ET mixed solution;
step S5: washing the filter cake with ethanol;
step S6: and drying the washed filter cake for 8h at 50 ℃ to obtain a product, namely the treated cellulose 7.
Comparative example 1:
in comparative example 1, untreated microcrystalline cellulose was used.
Comparative example 2:
comparative example 2 is microcrystalline cellulose treated with ethanol alone.
Comparative example 3:
comparative example 3 is microcrystalline cellulose treated with 4-butyl-3-methylimidazolium hydrogen sulfate alone.
Thermogravimetric and structural characterization of the treated cellulose obtained in examples 1-7 and comparative examples 1-3 were carried out:
and (3) characterization results:
characterized by a thermogravimetric analyzer, the infrared spectrum, the Raman spectrogram, the X-ray diffraction spectrogram, the particle size analysis result and the scanning electron microscope topography of the microcrystalline cellulose treated by the binary system with different 4-butyl-3-methylimidazole hydrogen sulfate contents at 140 ℃ are shown in figures 2, 3, 4, 5 and 6, the results show that the chemical structure of the pretreated cellulose has no obvious difference, but the crystal structure is damaged, the microcrystalline cellulose is gradually converted into amorphous cellulose along with the increase of the 4-butyl-3-methylimidazole hydrogen sulfate content, and the particle size of the cellulose is continuously reduced. The thermogravimetric curves and the thermogravimetric curves of the microcrystalline cellulose treated by the binary systems with different 4-butyl-3-methylimidazole hydrogen sulfate contents are shown in fig. 7 and fig. 8, so that the initial pyrolysis temperature of the cellulose pretreated by the binary system of 4-butyl-3-methylimidazole hydrogen sulfate-ethanol is continuously reduced along with the increase of the concentration of the 4-butyl-3-methylimidazole hydrogen sulfate compared with the untreated cellulose.
The method for pretreating cellulose by using the 4-butyl-3-methylimidazole hydrogen sulfate-ethanol binary system has repeatability verification
The thermogravimetric curves and the thermogravimetric curves of the microcrystalline cellulose subjected to 10 times of repeated treatments by using a binary system of 4-butyl-3-methylimidazole hydrogensulfate-ethanol at a concentration of 1% of 4-butyl-3-methylimidazole hydrogensulfate are shown in fig. 9 and 10. Therefore, the 4-butyl-3-methylimidazole bisulfate-ethanol binary mixed solvent used in the invention has good recycling performance.
The invention discloses a method for pretreating cellulose by a 4-butyl-3-methylimidazole bisulfate-ethanol binary system, which comprises the following steps: adding a certain amount of 4-butyl-3-methylimidazolium hydrogen sulfate [ BMIM ]]HSO 4 Mixing with ethanol ET proportionally to obtain BMIM]HSO 4 ET solution, then microcrystalline celluloseVitamin is added into prepared BMIM]HSO 4 In the ET solution, solid-liquid separation is carried out after stirring and heating treatment, the obtained filtrate can be directly recycled without any treatment, the filter cake is washed by ethanol and then dried in vacuum, and the treated cellulose can be obtained.
Thus, it will be appreciated by those skilled in the art that while embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications can be made which conform to the principles of the invention, as may be directly determined or derived from the disclosure herein, without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.
Claims (8)
1. A method for pretreating cellulose by using a 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system, which is characterized by comprising the following steps of:
step S1: mixing 4-butyl-3-methylimidazolium hydrogen sulfate [ BMIM ] HSO4 and ethanol ET according to a proportion, and uniformly stirring to form a uniform [ BMIM ] HSO4-ET mixed solution;
step S2: weighing microcrystalline cellulose, placing the microcrystalline cellulose in a hydrothermal reaction kettle, and adding the prepared [ BMIM ] HSO4-ET solution;
and step S3: heating for a certain time under the condition of stirring, and then cooling;
and step S4: taking out the treated solid-liquid mixture, and carrying out solid-liquid separation to obtain a filter cake and a filtrate, wherein the filtrate is a [ BMIM ] HSO4-ET mixed solution and can be recycled to replace the [ BMIM ] HSO4-ET mixed solution in the step S1;
step S5: washing the filter cake with ethanol;
step S6: drying the washed filter cake at a certain temperature to obtain a product, namely the treated cellulose;
the mass ratio range of the 4-butyl-3-methylimidazole hydrogen sulfate to the ethanol in the step S1 is 0.1 to 60 to 40 to 99.9;
the mass ratio range of the microcrystalline cellulose to the 4-butyl-3-methylimidazole hydrogen sulfate-ethanol binary system in the step S2 is 1 to 0.5-1.
2. The method for pretreating cellulose by using a 4-butyl-3-methylimidazole bisulfate-ethanol binary system as claimed in claim 1, wherein the mass ratio of 4-butyl-3-methylimidazole bisulfate to ethanol in step S1 is 1.
3. The method for pretreating cellulose by using a 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system according to claim 1, wherein the mass ratio of the microcrystalline cellulose to the 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system in step S2 is 1.
4. The method for pretreating cellulose by using a 4-butyl-3-methylimidazolium hydrogen sulfate-ethanol binary system according to claim 1, wherein the stirring in the step S3 is magnetic stirring.
5. The method for pretreating cellulose by using the binary system of 4-butyl-3-methylimidazole hydrogensulfate and ethanol as claimed in claim 1, wherein the heating treatment time in the step S3 is 0.5h to 16h, and the cooling is carried out to 40% o C is below.
6. The method for pretreating cellulose by using the binary system of 4-butyl-3-methylimidazole bisulfate-ethanol as claimed in claim 1, wherein the solid-liquid separation method in the step S4 is vacuum filtration, and the filtrate can be directly reused without any treatment.
7. The method for pretreating cellulose by using the binary system of 4-butyl-3-methylimidazolium hydrogen sulfate and ethanol as claimed in claim 1, wherein the solid cellulose filter cake in the step S5 is washed by ethanol, and the 78.3 ℃ fraction is collected after the washed liquid is distilled and reused.
8. The method for pretreating cellulose by using the binary system of 4-butyl-3-methylimidazole bisulfate-ethanol as claimed in claim 1, wherein the drying temperature of the washed filter cake in the step S6 is 50 ℃, the drying time is 8h, and the drying mode is vacuum drying.
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| CA2642866A1 (en) * | 2006-03-08 | 2007-09-13 | Basf Se | Method for breaking down cellulose |
| CN104781466A (en) * | 2012-08-20 | 2015-07-15 | 国际人造丝公司 | Methods for removing hemicellulose |
| CN109627347A (en) * | 2018-12-12 | 2019-04-16 | 怀化学院 | The preprocess method of cellulose |
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| US8790542B2 (en) * | 2009-09-30 | 2014-07-29 | Sandia Corporation | Compositions and methods useful for ionic liquid treatment of biomass |
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