JP6425936B2 - Process for producing 5-hydroxymethylfurfural - Google Patents

Description

  The present invention relates to a process for producing 5-hydroxymethylfurfural, and more particularly to a process for producing 5-hydroxymethylfurfural using cellulose as a raw material.

5-hydroxymethylfurfural (hereinafter sometimes referred to as "HMF") is a raw material for various useful chemicals such as resin materials, fuels, chemicals, surfactants, cosmetics etc. It is a body. The following are examples of methods of converting this HMF into useful chemicals, and methods of making effective use of the product obtained by the conversion.
It can be converted to furandicarboxylic acid by the oxidation reaction, and this product is expected as a substitute for terephthalic acid. Also, according to the hydrogenation reaction, it is converted to dimethyl furan, and its use as a fuel additive is expected. Furthermore, levulinic acid is produced by the hydrolysis reaction, and it can be expected to be widely used as a raw material of γ-valerolactone.

  This HMF can be produced by hydrolyzing and dehydrating sugars under various conditions, but in recent years, waste biomass such as waste wood has attracted attention as a chemical raw material resource as a substitute for petroleum, Various methods for synthesizing HMF using cellulose as a raw material have been proposed.

  For example, in Patent Document 1, in the method for producing lactic acid and 5-hydroxymethylfurfural and furfural from cellulose, a process of flowing water containing cellulose into a route, and the water in a state where a base is added to the water. In the lactic acid production process in which the temperature is 150 ° C. or more and less than 400 ° C., and the pressure is 5 MPa or more, and before or after the lactic acid production process, the water is added with the acid added to the water. It is described that lactic acid and 5-hydroxymethylfurfural and furfural are produced by 5-hydroxymethylfurfural and furfural manufacturing steps in which the temperature is 250 ° C. or more and less than 400 ° C. and the pressure is 10 MPa or more. However, it is necessary to impose a high pressure condition of 5 MPa pressure, and it is expected that equipment and maintenance for safely performing the high pressure reaction will be costly.

  Moreover, in Patent Document 2, in the method of producing 5-hydroxymethylfurfural from cellulose, the reaction temperature is 200 ° C. or more and less than 400 ° C., and the pressure is 10 MPa or more and 40 MPa or less. The selective decomposition of cellulose directly to 5-hydroxymethylfurfural and the use of scandium triflate, montmorillonite, platinum-loaded alumina as the catalyst are described. However, in this method, it is necessary to maintain water under high pressure conditions of 10 MPa to 40 MPa, and it is expected that equipment cost and maintenance cost will be large for safe reaction. Further, as the acid, inorganic acids such as sulfuric acid, nitric acid and phosphoric acid, and organic acids such as formic acid and acetic acid are mentioned, and it is necessary to use as an additive other than water. In addition, it is expected that maintenance costs such as equipment corrosion will be expensive.

Further, in Patent Document 3, a hexose is contacted with water in a subcritical or supercritical state in the presence of a heterogeneous zirconium phosphate catalyst to obtain 5-hydroxymethylfurfural, and a cellulose or a cellulose-containing material In the presence of a heterogeneous zirconium phosphate catalyst, it is described that it is decomposed into a hexose by contacting with water in a subcritical or supercritical state, and furthermore, 5-hydroxymethylfurfural is obtained from the obtained hexose .
However, when the reaction starting material is cellulose or a cellulose-containing material, when it is brought into contact with water in the subcritical or supercritical state, decomposition proceeds to form monosaccharides and disaccharides. There is a statement that the presence of a zirconium phosphate catalyst in the reaction system does not disturb the decomposition reaction of cellulose, but there is no specific description of the decomposition of cellulose. In addition, in this method, it is necessary to carry out the reaction under subcritical conditions or supercritical conditions, and it is expected that equipment for safely carrying out the reaction under high temperature and high pressure conditions and maintenance thereof are expensive. .

  Further, Patent Document 4 describes that hydroxymethyl furfural is obtained by mixing cellulose in acidic electrolyzed water and stirring the obtained mixture under the condition of the maximum temperature of 210 ° C. and the saturated vapor pressure. It is done. However, the use of acidic electrolyzed water as a solvent rather than ordinary water is expected to lead to high cost.

Also, in Patent Document 5, a method for converting lignocellulosic materials (cellulose, hemicellulose and lignin) of wood and agricultural waste into value-added materials by one-step hydrolysis using solid heterogeneous acid catalysts Have been proposed, and in the examples of the document also those using only water as solvent are described.
However, for analysis of the reaction mixture, it was analyzed by HPLC (high performance liquid chromatograph), and calibration of all compounds (xylose, arabinose, glucose, 5-hydroxymethylfurfural and furaldehyde) was performed prior to analysis. Although described, for products other than xylose, it is only described that a 40% furfural yield was observed, and there is no specific description for HMF.

In addition, in Non-Patent Document 1, a reaction system obtained by dissolving a catalyst metal component of CuCl ₂ and CrCl ₂ in 1-ethyl-3-methylimidazolium chloride is effective for conversion of cellulose, and the yield of HMF is It is stated that 55.4 ± 4.0%.
However, chromium, which is a harmful metal, is used as a catalyst, which is expected to cause problems in safety during production, and to require a great deal of cost for treating the catalyst after use, treating waste liquid, and the like.

Further, in Non-Patent Document 2, microwave treatment of cellulose and glucose in the presence of an ionic liquid is an effective method for obtaining HMF, and chromium trichloride hexahydrate is used as a catalyst. Is stated to be effective.
However, in this method, it is expected that the cost of treating chromium, which is also a harmful metal, is high.

Japanese Patent Application Publication No. 2005-232116 Unexamined-Japanese-Patent No. 2007-145736 JP 2007-196174 A JP, 2011-115061, A JP, 2013-517792, A

Applied Catalysis A: General, 361, Issues 1-2, pages 117-122 Tetrahedron Letters Vol. 50, (2009) 5403-5405.

As described above, in the production of HMF, it is possible to produce sugars such as glucose from cellulose using an acid catalyst etc. and produce HMF from the obtained sugars such as glucose, but it is possible to produce cellulose or cellulose-containing It is preferable to synthesize HMF by one pot (one step) reaction using a substance as a raw material.
However, there are few methods for producing HMF directly from cellulose in one step, and most of them use harmful chromium catalysts or expensive ionic liquids, if any.
In addition, based on the concept of green chemistry, the catalyst is required to be free of harmful metal elements. Furthermore, the solvent is preferably water from the viewpoint of post-treatment and cost.

  The present invention has been made in view of the present situation, and provides a method for synthesizing HMF by one-pot (one-step) reaction using cellulose or a cellulose-containing substance as a raw material without using a harmful catalyst or an organic solvent. The purpose is to

  As a result of intensive studies to achieve the above object, the present inventors have used calcium phosphate as a catalyst, preferably, a raw material cellulose and / or a cellulose-containing substance alone or in combination with the catalyst. The catalyst and the cellulose or cellulose-containing material of the raw material are reduced after the crystallinity of the cellulose-containing raw material is reduced or a physically strong contact state is established by grinding and mixing in a ball mill or an automatic mortar. It has been found that the reaction of the desired product to HMF proceeds effectively by sealing and heating the mixture in the autoclave together with the water solvent.

The present invention has been completed based on these findings, and according to the present invention, the following inventions are provided.
[1] Using a cellulose and / or a cellulose-containing substance as a reaction raw material, heat treatment is carried out in a catalyst comprising Ca ₃ (PO ₄ ) ₂ and a water solvent to obtain 5-hydroxymethylfurfural. Process for the preparation of hydroxymethylfurfural.
[2] The method for producing 5-hydroxymethylfurfural according to [1], wherein the reaction raw material alone or the catalyst is mixed with the catalyst before pulverization and grinding.
[3] The method for producing 5-hydroxymethylfurfural according to [2], wherein the pretreatment is ball milling.
[4] The method for producing 5-hydroxymethylfurfural according to any one of [1] to [3], wherein the heat treatment is performed in an inert gas.
[5] The method for producing 5-hydroxymethylfurfural according to any one of [1] to [4], wherein the heat treatment is performed at 180 to 220 ° C.

  According to the method of the present invention, by using calcium phosphate which does not harm human body as a catalyst and using only water as a solvent, cellulose or a cellulose-containing material can be used in one pot without using harmful catalyst or organic solvent. HMF can be synthesized by reaction).

Figure showing an outline of the chemical reaction of the present invention

The method for producing 5-hydroxymethylfurfural according to the present invention comprises using cellulose and / or a cellulose-containing substance as a reaction raw material, mixing the reaction raw material with a catalyst comprising calcium phosphate in an aqueous solvent and heating the mixture. It is characterized by
FIG. 1 shows the outline of the chemical reaction of the present invention, and according to the present invention, from cellulose and / or cellulose-containing substances, conventional two-step or multi-steps without the use of harmful catalysts or organic solvents The HMF can be synthesized in a one-pot (one-step) reaction.

  In the present invention, as cellulose or a cellulose-containing substance suitable for use as a raw material, besides purified cellulose provided as a reagent or food additive, waste paper resources such as waste paper and waste cloth, and further thinning materials It is possible to use natural wood and processed products typified by sawdust and the like. In the case of waste, paper contains additives and inks, in the case of cloth, dyes and synthetic fibers, and in natural wood, impurities other than cellulose such as lignin and hemicellulose are contained. It does not adversely affect the use of cellulose-containing materials, and good reaction results can be obtained.

In the present invention, the catalyst used for the one-pot (one-step) reaction is calcium phosphate (chemical formula: Ca ₃ (PO ₄ ) ₂ ), and commercially available reagents and those synthesized by various known methods can be used.

  In the present invention, the cellulose or the cellulose-containing substance is preferably ground alone or mixed with the catalyst before heat treatment, and subjected to grinding and grinding using mechanical mortar or the like as mechanical energy. Later, the reaction is carried out by mixing in an aqueous solvent. By crushing and grinding using a mechanical processor, the crystallinity of the raw material cellulose or the cellulose-containing material is reduced, and the reactivity is greatly enhanced. In order to obtain a rate, it is preferable to carry out the pretreatment operation. The pretreatment time is preferably about 1 hour to 7 days, and more preferably about 24 hours to 72 hours.

In the present invention, the heat treatment is carried out by heating to a reaction temperature of 180 to 220 ° C., preferably about 200 ° C., for 1 to 10 hours, preferably 2 hours. Since this reaction is a multistep sequential reaction, undesirable reactions and phenomena such as decomposition and polymerization of the desired product and deposition on the catalyst surface progress if the time is too long, leading to a decrease in yield. If the reaction time is too short, the reaction rate of the raw material is low and the yield is lowered.
The heat treatment is preferably performed under an inert gas atmosphere such as argon gas to eliminate adverse effects such as oxidation due to the presence of air.
Moreover, although various well-known systems can be applied to heat processing, a batch system (batch system) and a circulation system are mentioned as a representative example. In the case of the batch system, it is preferable to keep the closed state so that the solvent water is in the liquid state at the reaction temperature. In the case of the flow-through type, it is preferable that the internal pressure is adjusted by a mechanism such as a pressure control valve so that water of the solvent can pass through the reactor in a liquid state.

  Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.

Example 1
The reaction raw material, microcrystalline cellulose manufactured by Merck, was ground and rubbed for a total of 48 hours using a ball mill. In this case, the ball mill used was a container of 3 L in volume, in which 1 kg of alumina balls each having a diameter of 2 cm was enclosed in air with cellulose. Thereafter, in order to adjust the water content, drying was carried out in air in a drier at 80 ° C. for 12 hours or more, and then it was stored at room temperature in a desiccator kept dry with silica gel.
0.2 g of the above-stored cellulose, 1.8 g of calcium phosphate (made by Merck) as a catalyst, and 20 mL of distilled water were added to a pressure-resistant glass industrial reaction container (TPR-1 type, internal volume 100 mL). The reaction vessel was sealed, the space was replaced with argon to eliminate the influence of oxygen in air, and the initial pressure was adjusted to 0.4 MPa at room temperature. The reaction was carried out while heating to 200 ° C. using a heater and performing stirring operation at 300 rpm using a stirrer. After 2 hours, the heater was removed and the reaction vessel was immersed in water at room temperature to quench and quench the reaction.

(Product analysis method and analysis results)
The mixture after completion of the reaction in the reaction vessel was separated from the catalyst and the unreacted raw material using a membrane filter (manufactured by Advantec) to obtain a yellow transparent aqueous solution passed through the filter. The aqueous solution was diluted 10 times with distilled water and analyzed with a high performance liquid chromatograph (hereinafter referred to as HPLC) (manufactured by Shimadzu Corporation). A calibration curve was prepared using a commercially available reagent as a standard substance, and the concentration contained in the aqueous solution was calculated by the calibration curve. Unit structure of the cellulose is denoted by C ₆ H ₁₀ O ₅ and _{(C 6 H 10 O 5)} n, a case where it is hydrolyzed to the 100% yield of glucose to all glucose _{(C 6 H 12 O 6)} . For HMF, the concentration of HMF obtained in 100% yield from 100% glucose was calculated to be 100% yield.
As a result of the reaction, a good yield was obtained with a yield of glucose of 9.0% and a yield of HMF of 35.1%. Other byproducts showed minute amounts of fructose close to the lower detection limit, but other minute peaks could not be identified by comparison with the reagents. These are presumed to be dimers other than glucose and HMF monomers, and oligomers having multiple polymerization.

The above experiment was carried out with the reaction temperature conditions changed to 205 ° C. and the other conditions not changed. As a result, HMF yield was 25.0% and glucose was a minute amount close to the lower limit of detection.
Next, the reaction temperature conditions were changed to 195 ° C., and the above experiment was performed without changing the other conditions. As a result, the HMF yield was 25.9%, and the yield of glucose was 12.2%.
Furthermore, when the reaction time was extended to 3 hours at a temperature of 195 ° C., the HMF yield was 26.5% and the yield of glucose was 8.2%.

(Example 2)
In this example, in order to confirm the versatility of the reaction raw material, microcrystalline cellulose made by SERVA is used as a raw material in place of microcrystalline cellulose made by Merck as a raw material, and grinding and rubbing for a total of 48 hours using a ball mill. The treatment was carried out as in the previous example. Thereafter, the same reaction operation as described above was performed, and synthesis of HMF was performed at a reaction temperature of 200 ° C. and a reaction time of 2 hours.
As a result, the HMF yield was 27.0%, and the yield of glucose was 9.4%.
As a result, it became clear that HFF can be synthesized although there is some variation depending on the manufacturer of the raw material cellulose.

(Example 3)
Using the same Merck microcrystalline cellulose as in Example 1 as the reaction raw material, Merck microcrystalline cellulose was subjected to grinding and rubbing treatment in air at room temperature for a total of 10 hours using an automatic mortar. Thereafter, in order to adjust the water content, drying was carried out in air in a drier at 80 ° C. for 12 hours or more, and then it was stored at room temperature in a desiccator kept dry with silica gel.
0.2 g of the above-stored cellulose, 1.8 g of calcium phosphate (made by Merck) as a catalyst, and 30 mL of distilled water were added to a pressure-resistant glass industrial reaction container (TPR-1 type). The reaction vessel was sealed, the space was replaced with argon to eliminate the influence of oxygen in air, and the initial pressure was adjusted to 0.4 MPa at room temperature. The reaction was carried out while heating to 200 ° C. using a heater and stirring at 300 rpm using a stirrer. After 2 hours, the heater was removed and the reaction vessel was immersed in water at room temperature to quench and quench the reaction. The HPLC analysis was performed exactly as in Example 1.
The analysis results of the reaction showed that the yield of glucose was 8.7%, and the yield of HMF was 25.1%. Other byproducts showed minute amounts of fructose close to the lower detection limit, but other minute peaks could not be identified. It is presumed that dimers other than glucose and HMF monomers and oligomers having multiple polymerizations are used.
As a result, as a pretreatment method, it can be said that the ball mill for 48 hours is superior to the automatic mortar treatment for 10 hours.

The above experiment was carried out with the reaction temperature conditions changed to 205 ° C. and the other conditions not changed. As a result, the HMF yield was 21.2%, and the glucose yield was 5.4%.
In addition, the reaction temperature conditions were changed to 195 ° C., and the above experiment was performed without changing the other conditions. As a result, the HMF yield was 18.1% and the glucose yield was 8.5%.

(Example 4)
Instead of Merck cellulose, microcrystalline cellulose from SERVA was crushed for 10 hours in an automatic mortar and used as a raw material. 1.8 g of a calcium phosphate catalyst was added and dispersed in 30 mL of water, charged in the same reaction vessel as in Example 1, charged with argon, and reacted by heating at 205 ° C. for 2 hours with stirring at 300 rpm. As a result, glucose was obtained at a yield of 5.1%, and HMF was obtained at a yield of 15.1%. In addition, some minor by-product peaks that could not be identified and quantified were detected.
The results of this example show that it is not a phenomenon unique to Merck cellulose but a general reaction result.

(Example 5)
In this example, in order to confirm the versatility of the raw material, the reaction was performed using waste cloth (a shirt, 100% cotton, manufactured by UNIQLO) as the cellulose-containing raw material.
The used cloth was cut into a size of 1 cm × 5 cm, and after removing threads used for sewing, etc., pulverization treatment was performed with a crusher to obtain cotton-like cellulose. The reaction was carried out in water by mixing with the catalyst in the same manner as in Example 1. As a result, 10.4% of HMF was formed. As other by-products, many difficult-to-identify micro peaks were observed, and brown deposits were also observed on the catalyst surface. These are presumed to be dimers other than glucose and HMF monomers, and oligomers having multiple polymerization. The quantitative calculation assumes that the raw material is all cellulose.

Subsequently, the cotton-like cellulose raw material obtained by pulverizing the above-mentioned waste cloth with a grinder was subjected to treatment for a further 48 hours by a ball mill. That is, it is the raw material which performed both a grinder process and a ball mill process. As a result of the ball milling, most of the cotton-like raw material changed from cotton-like to fine powder. Add 0.2 g of calcium phosphate catalyst to 0.2 g of finely powdered ground waste cloth (cellulose-containing raw material), disperse it in 30 mL of water, place in the same reaction vessel as in Example 1, and enclose argon at 200 ° C. The reaction was carried out by heating for 2 hours with stirring at 300 rpm.
As a result, glucose was obtained at a yield of 6.8% and HMF was obtained at a yield of 30.6%. It can be said that the reactivity of the raw materials is enhanced by the effect of the ball milling process, leading to a high yield. In addition, some minor by-product peaks that could not be identified and quantified were detected. These by-products are presumed to be dimers other than glucose and HMF monomers, and oligomers with multiple polymerization. The quantitative calculation assumes that the raw material is all cellulose.
As a result, although the yield slightly decreases compared to microcrystalline cellulose as a reagent, it became clear that HMF can be manufactured from waste cloth, which is one of cellulose-containing wastes, as raw materials, and the versatility of the raw materials could be demonstrated.

(Example 6)
In this example, in order to confirm the versatility of the raw material, the reaction was performed using a copy paper as the cellulose raw material.
As pre-processing, printed copy paper was processed by a grinder. 0.2 g of cotton-like crushed material was used as a raw material, 1.8 g of a catalyst was added, dispersed in 30 mL of water, and reacted at 200 ° C. for 2 hours. The quantification was calculated assuming that all 0.2 g of raw material is cellulose. As a result, an HMF yield of 8.3% was obtained, but not at a significantly high value.
The HMF yield improved to 21.7% when using a raw material that was ball milled for 48 hours to demonstrate the need for mechanical energy such as ball milling. The glucose yield at that time was close to the lower limit of detection, and accurate quantitative analysis could not be performed. In copy paper, various additives are used for quality improvement, so the cellulose content is a value lower than 100%. Therefore, the HMF yield based on cellulose is considered to be higher than the above value.

(Example 7)
In this example, in order to confirm the versatility of the raw material, the reaction was performed using natural wood as the raw material.
The reaction was carried out using the powdered Akita cedar as a raw material as it was, using a crusher. As a result of measuring the content rate of the sugar component which comprises the wood of a raw material, it is revealed that the glucose derived from cellulose and hemicellulose is 43.9% (weight ratio). The other sugar components are 9.9% xylose, 7.5% galactose, 12.3% mannose, and the component other than the sugar component is lignin.
The amount of the raw material used was 0.456 g, which was calculated based on the sugar content in wood flour and adjusted in weight so that the amount of glucose was 0.2 g. As a result of the reaction, HMF was obtained in 14.3% yield. Glucose was close to the lower detection limit and could not be accurately quantified. The calculation method of the yield at the time of using natural wood as a raw material is as follows. Based on the analysis value, the HMF yield was calculated based on the amount of glucose converted to HMF. Therefore, the above reaction result is 6.3% HMF yield (based on total weight) based on the total weight of wood.
The wood flour crushed by the grinder was further subjected to ball milling for 48 hours and used as a reaction material. As a result, an HMF yield of 35.5% and a glucose yield of 9.3% were obtained. The standard value used to calculate this yield is also based on glucose (content 43.9%).
As a result of this example, it became clear that the wood raw material can also be efficiently converted to HMF, and the versatility of the raw material could be demonstrated.

(Comparative example 1)
The same Merck Microcrystalline Cellulose as used in Example 1 was ball milled for 48 hours, and 0.2 g was used as a reaction raw material. The reaction vessel was dispersed in 30 mL of water without addition of any catalyst, placed in the same reaction vessel as in the example, sealed with argon, and heated at 200 ° C. for 2 hours while stirring at 300 rpm for reaction. As a result, HMF was obtained in 16.7% yield and glucose was obtained in 14.8% yield. In addition, some minor by-product peaks that could not be identified and quantified were detected.
The reaction results show that the reaction is slow without using a catalyst and the HMF yield is small, and the effect of adding the catalyst into the reaction system could be demonstrated.

(Example 8)
In this example, a ball mill process was not performed on microcrystalline cellulose manufactured by Merck, and it was used as a raw material. 1.8 g of the catalyst was added as in Example 1 and dispersed in 30 mL of water, placed in the same reaction vessel as in Example 1, charged with argon, heated at 200 ° C. for 2 hours with stirring at 300 rpm and reacted The
As a result, HMF was obtained in a yield of 12.8%, and glucose was obtained in a yield of 5.8%.

(Example 9)
In Example 1, the inside of the reaction vessel is replaced with argon to eliminate the influence of oxygen in the air, but in this example, air is removed without performing argon replacement in order to clarify the adverse effect of residual air. The reaction was carried out while remaining. The other conditions were the same as in Example 1.
As a result, the HMF yield decreased to 23.1%, and the glucose yield also decreased to 4.9%.
This result shows the adverse effect of air, and the effect of substituting the inside of the reaction vessel with an inert gas such as argon has become clear.

(Comparative example 2)
An experiment was conducted to investigate the effect of the presence or absence of a catalyst on Example 7 using natural wood.
The raw material obtained by subjecting the powder of Akita cedar powder to a ball mill treatment for 48 hours for which excellent reaction results are obtained in Example 7 was used as the raw material of 0.456 g which is the amount of wood such that the amount of glucose is 0.2 g. As a result of carrying out the reaction under the same conditions as in Example 7 using this raw material without adding any catalyst, the HMF yield was 24.2%, and the glucose yield was 11.0%.
As a result, when the catalyst was not used, the HMF yield decreased, and the effect of using the catalyst became clear.

Claims (5)

A 5-hydroxymethyl furfural is obtained by using a cellulose and / or a cellulose-containing substance as a reaction raw material and performing heat treatment in a water solvent and a catalyst comprising Ca ₃ (PO ₄ ) ₂ to obtain 5-hydroxymethylfurfural. How to make furfural.   The method for producing 5-hydroxymethylfurfural according to claim 1, wherein the reaction raw material alone or mixed with the catalyst is subjected to a pulverization / grinding treatment before the heat treatment.   The method for producing 5-hydroxymethylfurfural according to claim 2, wherein the pretreatment is ball milling.   The method for producing 5-hydroxymethylfurfural according to any one of claims 1 to 3, wherein the heat treatment is performed in an inert gas.   The method for producing 5-hydroxymethylfurfural according to any one of claims 1 to 4, wherein the heat treatment is performed at 180 to 220 ° C.

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