CN111348988B - Method for preparing coniferyl alcohol, sinapyl alcohol and derivatives thereof from lignocellulose - Google Patents
Method for preparing coniferyl alcohol, sinapyl alcohol and derivatives thereof from lignocellulose Download PDFInfo
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Abstract
The invention relates to a method for preparing coniferyl alcohol, sinapyl alcohol and derivatives thereof by using lignocellulose as a raw material, which comprises the following steps: adding a lignocellulose raw material, a catalyst and a reaction solvent into a high-pressure reaction kettle, introducing hydrogen, heating to the reaction temperature, and stirring for reaction; naturally cooling to room temperature after the reaction is finished, decompressing to normal pressure, and filtering to obtain solid residues and liquid products; spin-drying the obtained liquid product, dissolving with dichloromethane, and extracting to obtain lignin oil product containing coniferyl alcohol, sinapyl alcohol and their derivatives; separating the obtained lignin oil product with chromatographic column to obtain coniferyl alcohol, sinapyl alcohol and their derivatives. The one-pot method converts the lignin into coniferyl alcohol, sinapyl alcohol and derivatives thereof with high yield and high selectivity, can efficiently prepare and separate the coniferyl alcohol, the sinapyl alcohol and the derivatives thereof, and realizes the resource utilization and high-value utilization of the lignin.
Description
Technical Field
The invention relates to a method for preparing coniferyl alcohol, sinapyl alcohol and derivatives thereof by taking lignocellulose as a raw material, belonging to the technical field of biochemical engineering.
Background
Coniferyl alcohol, also known as 4-hydroxy-3-methoxycinnamyl alcohol, belongs to a phenol compound and is present in coniferous wood and broad-leaved wood. Coniferyl alcohol is not only one of the building monomers of plant cell walls, but is also widely used in other respects, for example, coniferyl alcohol is an important intermediate in the synthesis of certain natural products such as silybin (silymarin), an anti-hepatitis drug. The current synthesis method of coniferyl alcohol mainly comprises two methods: 1) The coniferous acid is used as a raw material, acyl chloride is prepared, and esterification and reduction are carried out to obtain coniferous alcohol. 2) Coniferous acid is used as a raw material, and coniferous alcohol is obtained by esterification, acetylation and reduction. Both of these methods require low temperature reduction with lithium aluminum hydroxide, but the yields are relatively low and the operation is complicated. Therefore, the price of coniferyl alcohol in the market is quite expensive (11320 yuan/g, data from sigma-aldrich).
Sinapyl alcohol is a phenolic compound, and is widely present in hardwood. Sinapyl alcohol is also one of the monomers constituting plant cell wall and is also the intermediate of important chemical material, such as synthetic engineering fiber monomer. But also is an excellent anti-inflammatory and anti-infective drug. The price of coniferyl alcohol on the market is also quite expensive (18850 yuan/g, data from sigma-aldrich).
Coniferyl alcohol and sinapyl alcohol are originally present in plant cell walls and are the basic building blocks of lignin. Lignin is a complex network composed of aromatic compounds, including three types: guaiacyl (type G), syringyl (type S) and p-hydroxyphenyl lignin (type H). These three types are derived from three core monolignols: coniferyl alcohol, sinapyl alcohol and p-coumaryl alcohol. The composition of lignin varies from plant species to plant species: in the coniferous wood, lignin is mainly derived from coniferyl alcohol; the lignin of the broad-leaved wood mainly comprises coniferyl alcohol and sinapyl alcohol; the lignin in herbs is rich in coniferyl alcohol, sinapyl alcohol and p-coumaryl alcohol.
Although the study of lignin has been continued for over a century, the mechanism of lignin monomer biosynthesis is still uncertain, and in lignin biosynthesis, many enzymes play a key role, and under the action of various enzymes, coniferyl alcohol and sinapyl alcohol in lignocellulose undergo polymerization to form lignin under the action of enzymes and free radicals (see fig. 1).
Recently, studies on catalytic degradation of lignin to obtain phenolic compounds from wood flour as a raw material have been reported, for example, depolymerization of birch wood flour with Ru/C as a catalyst at 250 ℃ under a hydrogen pressure of 3MPa to a monomer yield of 50% containing mainly 4-propylguaiacol and 4-propylsyringol (Energy environ. Sci.,8, 1748-1763). Adding a certain amount of Zn into Pd/C as a catalyst, and carrying out hydrogenolysis on poplar wood powder at 225 ℃ and under the hydrogen pressure of 3MPa to obtain the 54% lignin monomer yield (Green chem.,2015, 17, 1492-1499) mainly comprising 2, 6-dimethoxy-4-propyl phenol and 2-methoxy-4-propyl-phenol. However, these studies have been conducted with noble metals as catalysts, which are relatively expensive. Meanwhile, the obtained product is complex and is not beneficial to separation and utilization.
Disclosure of Invention
In view of the above, the main object of the present invention is to provide a method for preparing coniferyl alcohol, sinapyl alcohol and derivatives thereof from lignocellulose, which comprises depolymerizing lignocellulose by using a low-cost metal molybdenum dioxide catalyst to efficiently depolymerize lignin directly into aromatic compounds such as coniferyl alcohol, sinapyl alcohol and derivatives thereof.
In order to achieve the above object, the present invention provides a method for preparing coniferyl alcohol, sinapyl alcohol and derivatives thereof by using lignocellulose as a raw material, comprising the following steps:
1) Adding a lignocellulose raw material, a catalyst and a reaction solvent into a high-pressure reaction kettle, introducing hydrogen, heating to the reaction temperature, and stirring for reaction;
2) Naturally cooling to room temperature after the reaction is finished, releasing pressure to normal pressure, and filtering the reaction product obtained in the step 1) to obtain solid residue and a liquid product;
3) Spin-drying the liquid product obtained in step 2), and then extracting for 3-4 times to obtain a lignin oil product containing coniferyl alcohol, sinapyl alcohol and derivatives thereof;
4) Separating the lignin oil product obtained in the step 3) by a chromatographic column to respectively obtain coniferyl alcohol, sinapyl alcohol and derivatives thereof;
5) Screening the solid residue obtained in the step 2) by using a sieve to recover the catalyst.
Further, in the step 1), the mass ratio of the lignocellulose raw material, the catalyst and the reaction solvent is 1: (0.05 to 20): (1-50); the pressure of the hydrogen is 0-8.0 MPa, the reaction temperature is 140-280 ℃, the reaction time is 0.5-12 hours, and the stirring speed is 500-1000 r/min.
Further, wherein in step 1), the lignocellulosic raw material comprises softwood wood flour and hardwood wood flour; the coniferous material is selected from pine, cypress or cedar; the hardwood is selected from eucalyptus, poplar or birch.
Further, in step 1), the reaction solvent is at least one of methanol, ethanol, isopropanol or water, and the solid-to-liquid ratio is 1:10 to 100; the methanol or ethanol is commercially available analytical grade.
Further, in the step 2), the reaction product obtained in the step 1) is centrifuged at 3000-5000 rmp for 10-40 minutes or is filtered through an organic filter membrane.
Further, in the step 3), the liquid product obtained in the step 2) is evaporated by a rotary evaporator under the condition of 0.05atm and 45-65 ℃ to recover the alcohol solvent.
Further, in step 3), the extractant used for the extraction is dichloromethane or ethyl acetate.
Further, in the step 4), the lignin oil product obtained in the step 3) is subjected to qualitative and quantitative analysis and determination by adopting gas chromatography and gas chromatography-mass spectrometry.
Further, in step 4), the specific operation of the chromatographic column separation is as follows: A. sampling: dissolving a sample in an organic solvent, taking 0.05-0.1 mL of the sample by using a capillary tube, and putting the sample into a centrifugal tube, wherein the label is used as a reference; B. column assembling: sequentially adding cotton and a silica gel solvent into a chromatographic column, and then compacting the silica gel by using an air pump; C. sample adding: adding a sample dissolved by an organic solvent into a chromatographic column, repeatedly washing a sample bottle 3 times by using the organic solvent, and transferring the washed liquid into the column; D. column passing: adding a developing agent along the inner wall of the column by a dropper until the top of the column is 5-10 cm; the pre-column solvent is connected with a conical flask, then the developing solvent washed off by a test tube is connected, and whether the sample flows out of the test tube or not is continuously checked. When a sample wash out is detected, the sample is collected and its structure is determined by GC-MS. The following samples were then taken in succession. The separated samples and the original sample were run on the same silica gel plate and each separated sample was determined. The coniferyl alcohol, sinapyl alcohol and their derivatives separated are identified by nuclear magnetic analysis.
Further wherein the organic solvent is selected from ethyl acetate, dichloromethane, tetrahydrofuran or dioxane.
Further, in the step 5), the size of the sieve is 300 meshes.
Compared with the prior art, the invention has the beneficial effects that:
the one-pot method of the invention converts the lignin into coniferyl alcohol, sinapyl alcohol and derivatives thereof with high yield and high selectivity, can efficiently prepare and separate the coniferyl alcohol, the sinapyl alcohol and the derivatives thereof, and realizes the resource utilization and high-value utilization of the lignin.
1. The method has high selectivity and good separation yield when the lignocellulose components are depolymerized and separated, and coniferyl alcohol, sinapyl alcohol monomers and derivatives thereof can be directly obtained through column chromatography separation; meanwhile, the catalytic degradation conversion rate of the lignin is high, the reaction condition is mild, the additional value is high, and the method has a good industrial application prospect.
2. The lignocellulose raw material used by the invention is the most abundant renewable resource in nature, and has wide source and low cost.
3. The metal molybdenum dioxide catalyst of the invention adopts abundant reserves in nature and low price as an active center, and the preparation method is simple.
Drawings
FIG. 1 is a diagram of the formation of lignin building blocks;
FIG. 2 is a graph of the products of wood powder degradation reaction of birch;
FIG. 3 shows MoO under different solvent conditions 2 GC spectrogram of hydrogenolysis products of birch wood powder subjected to catalytic depolymerization;
FIG. 4 is a GC spectrum of birch wood flour in methanol solvent with different catalysts and without catalyst;
FIG. 5 is a nuclear magnetic hydrogen spectrum of coniferyl alcohol;
FIG. 6 is a nuclear magnetic hydrogen spectrum of sinapyl alcohol;
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
Example 1
Birch wood powder was crushed to 20 to 60 mesh, and after extraction with toluene and ethanol (2, 1,vWood flour 1g, moO 2 Adding C and methanol into a high-pressure Parr reaction kettle according to the mass ratio of 1.05. The liquid product is extracted by 30mL of dichloromethane, is dried by a rotary evaporator under the condition of 0.05atm and 45 ℃, is dissolved and filtered by dichloromethane containing 0.1mg/mL of n-tetradecane internal standard, and then enters a GC (gas chromatograph), and is qualitatively and quantitatively analyzed by a GC-MS (gas chromatograph-mass spectrometer) (the product is shown in figure 2), and the yield of the lignin monomer and the selectivity of coniferyl alcohol, sinapyl alcohol and derivatives thereof are calculated by the following formulas. Then separating directly degraded lignin oil product (i.e. the liquid product obtained by filtering) by column chromatography, respectively separating coniferyl alcohol (figure 5), sinapyl alcohol (figure 6) and their derivatives, and calculating the total separation yield of the three. The analysis results are shown in FIG. 1, the yield of lignin monomer reaches 45.2%, the selectivity (sinapyl alcohol, coniferyl alcohol and derivatives thereof) reaches 92%, and the separation yield (coniferyl alcohol, sinapyl alcohol and derivatives thereof) reaches 18%. As shown in table 1.
TABLE 1 MoO in methanol solvent 2 Hydrogenation results of C catalyzed birch wood flour
| Substrate | Catalyst and process for preparing same | Solvent(s) | Monomer yield (wt%) | Selectivity (wt%) | Separation ofYield (wt%) |
| Birch wood powder | MoO 2 /C | Methanol | 45.2 | 92％ | 18 |
The monomer yield, selectivity of coniferyl alcohol and sinapyl alcohol and the separation yield of coniferyl alcohol, sinapyl alcohol and derivatives thereof are calculated by the following formulas:
w (the content of lignin in wood flour) represents the mass of lignin in wood flour, w (total amount of monomers) represents the mass of lignin monomers, w (amount of coniferyl alcohol monomers) represents the mass of coniferyl alcohol monomers, w (amount of sinapyl alcohol monomers) represents the mass of sinapyl alcohol monomers, and w (total mass separated) represents the total mass of coniferyl alcohol, sinapyl alcohol and derivatives thereof separated by column chromatography.
Example 2
As in example 1, only the reaction solvent of the step was replaced with ethanol, isopropanol or water. The monomer yield, selectivity and separation yield are shown in Table 2,FIG. 3 is a schematic view; TABLE 2 MoO in different solvents 2 And C, catalyzing the hydrogenation result of birch wood powder. From the data in table 2 and fig. 3, it can be seen that the yield of catalytic degradation lignin monomer and the selectivity and separation yield of coniferyl alcohol, sinapyl alcohol and their derivatives are high in the organic solvent system, and lignin cannot be degraded well in the water-solvent system.
TABLE 2 MoO in different solvents 2 Hydrogenation result of C catalytic birch wood powder
| Solvent(s) | Monomer yield (wt%) | Selectivity (wt%) | Isolation yield (wt%) |
| Ethanol | 43.6 | 92 | 18 |
| Isopropanol (I-propanol) | 37.8 | 91 | 16 |
| Water (W) | 9.3 | - | - |
Example 3
As in example 1, the catalyst was only recycled, i.e., the catalyst collected after the last reaction was activated at high temperature and used. The yield, selectivity and separation yield of lignin monomers are shown in Table 3, and Table 3 shows MoO in different solvents 2 And C, catalyzing the hydrogenation result of birch wood powder. As can be seen from the data in Table 3, moO 2 After five times of circulation, the yield of the catalyst/C catalyst for catalyzing and degrading the lignin monomer can still reach 43.6%, and the selectivity can still reach over 90%. Thus showing that the catalyst has higher stability.
TABLE 3 MoO in different solvents 2 Hydrogenation result of C catalytic birch wood powder
Example 4
In the same manner as in example 1, the amount of birch wood powder was 10g, which was 10 times larger than the original 1g, and birch wood powder and MoO 2 The mass ratio of/C and methanol was the same as in example 1 and was 1. The monomer yield, selectivity and separation yield are shown in Table 4, table 4 is MoO 2 C, catalyzing the reaction result of hydrogenation and amplification of birch wood powder. As can be seen from the data in Table 4, comparative analysis of a large number of experiments with ten fold expansion of the substrate amount gives experimental results similar to those of example 1.
TABLE 4 MoO 2 Reaction result of hydrogenation amplification of C catalytic birch wood powder
Example 5
In the same way as in example 1, only birch wood flour was replaced with other lignocellulosic raw materials, table 5 is MoO 2 the/C catalyzes the hydrogenation result of different raw materials. As can be seen from the data in Table 5, hardwood species such as eucalyptus and poplar all have high monomer yields and selectivity and isolation yields for coniferyl alcohol, sinapyl alcohol and their derivatives, while coniferous species such as pine, cypress, and cedar have relatively low results。
TABLE 5 MoO 2 C catalysis of hydrogenation results of different feedstocks
Control test: the procedure of example 1 was the same, except that no catalyst was added during the reaction, and a blank comparative reaction was carried out, and the monomer yield, the selectivity (sum of sinapyl alcohol and coniferyl alcohol and derivatives thereof) and the separation yield (sum of sinapyl alcohol and coniferyl alcohol and derivatives thereof) were as shown in table 6, and table 6 is the hydrogenation result of birch wood flour without catalyst in methanol solvent. As can be seen from the data in Table 6, in the absence of catalyst, the yield of monolignol is very low, the target products coniferyl alcohol, sinapyl alcohol and their derivatives are not produced, and the products are analyzed as shown in FIG. 4.
TABLE 6 hydrogenation results of birch wood flour without catalyst in methanol solvent
While the invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A method for preparing coniferyl alcohol, sinapyl alcohol and derivatives thereof by using lignocellulose as a raw material is characterized by comprising the following steps:
1) Adding a lignocellulose raw material, a catalyst and a reaction solvent into a high-pressure reaction kettle, introducing hydrogen, heating to the reaction temperature, and stirring for reaction;
2) Naturally cooling to room temperature after the reaction is finished, decompressing to normal pressure, and filtering the reaction product obtained in the step 1) to obtain solid residue and a liquid product;
3) Spin-drying the liquid product obtained in step 2), and then extracting for 3-4 times to obtain a lignin oil product containing coniferyl alcohol, sinapyl alcohol and derivatives thereof;
4) Separating the lignin oil product obtained in the step 3) by a chromatographic column to respectively obtain coniferyl alcohol, sinapyl alcohol and derivatives thereof;
5) Screening and recovering the catalyst by using a screen for the solid residue obtained in the step 2);
the catalyst is MoO 2 /C。
2. The method according to claim 1, wherein in step 1), the mass ratio of the lignocellulosic feedstock, catalyst and reaction solvent is 1: (0.05 to 20): (1 to 50); the pressure of the hydrogen is 0 to 8.0MPa, the reaction temperature is 140 to 280 ℃, the reaction time is 0.5 to 12 hours, and the stirring speed is 500 to 1000 revolutions per minute.
3. The method of claim 1, wherein in step 1), the lignocellulosic feedstock comprises softwood wood flour and hardwood wood flour.
4. The method of claim 3, wherein in step 1), the coniferous wood is selected from pine, cypress or cedar; the hardwood is selected from eucalyptus, poplar or birch.
5. The method according to claim 1, wherein in step 1), the reaction solvent is at least one of methanol, ethanol, isopropanol or water, and the solid-to-liquid ratio is 1:10 to 100; the methanol or ethanol is commercially available analytically pure.
6. The method according to claim 1, wherein in step 2), the reaction product obtained in step 1) is centrifuged at 3000 to 5000 rpm for 10 to 50 minutes or is filtered through an organic filter.
7. The method as claimed in claim 1, wherein in the step 3), the rotary drying is performed by evaporating the liquid product obtained in the step 2) to dryness by using a rotary evaporator under the condition of 0.05atm and 45-65 ℃ so as to recover the alcohol solvent.
8. The method of claim 1, wherein in step 3), the extractant used in the extraction is dichloromethane or ethyl acetate.
9. The method of claim 1, wherein in step 4), the lignin oil product obtained in step 3) is qualitatively and quantitatively analyzed and determined using gas chromatography and gas chromatography-mass spectrometry.
10. The method of claim 1, wherein in step 5), the size of the screen is 300 mesh.
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| CN104276930A (en) * | 2013-07-08 | 2015-01-14 | 中国科学院大连化学物理研究所 | Method for preparation of phenolic compound by direct hydrogenolysis of lignin |
| CN106442794B (en) * | 2016-10-21 | 2018-12-18 | 安徽农业大学 | A kind of method of gas chromatography mass spectrometry separation detection coniferyl alcohol and sinapinic alcohol |
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