JP7416177B2 - Alcohol manufacturing method - Google Patents

Description

The present invention relates to a method for producing alcohol from biomass raw materials. Specifically, when producing alcohol from biomass raw materials, by passing through an acetal intermediate having a furan skeleton, side reactions are suppressed and the desired purpose is achieved. The present invention relates to a method for producing alcohol which can be obtained in high yield and has excellent long-term operational stability.

In recent years, it has become necessary to take measures to deal with the global environmental burden of fossil fuel depletion and an increase in atmospheric carbon dioxide. In response to such social demands, attention has been paid to the development of processes for producing various useful chemicals from biomass raw materials grown in the current atmospheric global environment, and efforts are being made vigorously. The method of utilizing biomass raw materials as starting materials for chemical raw materials is based on the fact that, for example, the production of plant raw materials can be dispersed and diversified in various places, so the supply of raw materials is extremely stable, and it is possible to use biomass raw materials in the global environment of the atmosphere. In order to achieve this goal, the material balance of carbon dioxide absorption and emission is relatively balanced, so it has the advantage of potentially realizing a recycling-oriented society, including recycling, which cannot be expected from fossil resource raw materials. It has extremely high industrial utility value.

Until now, technologies that require biomass raw materials from chemical raw materials include methods that use biomass raw materials themselves as raw materials for general _- purpose resins, and methods that use biomass raw materials as raw materials for monomers that are raw materials for resins, as technologies that greatly contribute to reducing CO2 emissions. Various guidance methods have been proposed. Furthermore, there is active development of methods for inducing high-performance chemicals from biomass raw materials by utilizing the structure of the biomass raw materials (Non-Patent Document 1).

As reactions for inducing useful chemicals from biomass raw materials, biological conversion methods using fermentation of biomass raw materials, chemical conversion methods represented by catalytic reactions, conversion methods using electrochemical methods, etc. have been developed. . However, the reality is that many of the technologies for replacing chemicals derived from these biomass raw materials with chemicals derived from fossil resources or for applying them to general-purpose materials have not yet reached the point of generalization or widespread use. be. The biggest reason for this is that compared to raw materials derived from fossil resources, biomass raw materials and the raw materials derived from them generally contain many impurities such as nitrogen-containing compounds, sulfur-containing compounds, and metal salts that are unique to biomass raw materials. Another reason is that because it has many reactive functional groups such as hydroxyl groups and carbonyl groups, it tends to cause side reactions during production. In other words, in processes that use biomass raw materials as starting materials, a process for removing these impurities and byproducts is essential, which not only complicates the manufacturing process and increases manufacturing costs, but also increases energy consumption during manufacturing. There are many issues in terms of economic efficiency and environmental impact.

Therefore, in the derivatization reaction from biomass raw materials that is the subject of the present invention, it is required to design an efficient conversion reaction process. The method is attracting attention. For example, as such an efficient conversion technique, a technique for converting monosaccharides and sugar alcohols from cellulose using a catalytic reaction has been proposed in Patent Documents 1 to 3 and the like.

On the other hand, among the series of catalytic reactions that derive useful chemicals from biomass raw materials, processes involving compounds with furan rings are particularly important from the viewpoints of functionality, diversity of uses, environmental impact, and economic efficiency. proposed as a process. For example, furandimethanol, which is one of the targets of the present invention, is generally produced by the following reaction.

As a specific production method, for example, Patent Document 4 proposes a method of producing hydroxymethylfurfural (HMF) from monosaccharides such as glucose and fructose in the presence of hydrous niobic acid. Further, regarding a method of producing flange methanol by catalytic hydrogenation of HMF, a method of producing it at room temperature of about 30 to 35° C. is proposed in Patent Documents 5 and 6. On the other hand, Patent Document 7 proposes a method for producing 1,2,6-hexanetriol and 1,6-hexanediol from HMF by catalytic hydrogenation.

However, in the reaction of producing alcohol from the above-mentioned biomass resources via HMF, HMF having reactive functional groups such as aldehyde groups and hydroxyl groups becomes an intermediate, and the thermal stability of this reactive intermediate is poor. Due to this, HMF polymerization and ring-opening reactions proceed, and especially in processes that require reactions at high temperatures, the reaction yield decreases due to the formation of oligomers such as humins, polymers, and levulinic acid. In addition, by-product oligomers and polymers adhere to the interior of the reactor and piping, causing a decrease in the heat conduction efficiency of the reactor and clogging of the piping, making stable long-term operation difficult. In addition, these by-products are generally colored substances and are mixed into the product, causing coloration of the product.Furthermore, the mixing of these by-products into the product impairs the durability and stability of the product, causing the product to deteriorate. There is also the issue that it may lead to the formation of foreign matter inside. In particular, in industrial manufacturing processes, long-term stable operation of the manufacturing process is an important issue in process design, but this essential issue has not yet been resolved in chemical manufacturing processes that utilize biomass raw materials. is the reality. Therefore, in manufacturing processes that require biomass raw materials as raw materials, it is important to design not only efficient conversion reaction processes that improve reaction yields, but also reaction processes that improve the thermal stability of reaction intermediates and reaction stability. has become an issue.

International publication WO2011/036955 Patent No. 5894387 Patent No. 5823756 Japanese Patent Application Publication No. 2009-215172 Japanese Patent Application Publication No. 2015-48349 Japanese Patent Application Publication No. 2015-229657 JP 2015-3308 Publication

Green Chemistry 15 (2013) 1740-1763 Journal of Catalysis 265 (2009) 109-116

The present invention has been made in view of the above-mentioned problems, and it is possible to suppress side reactions and obtain the desired alcohol in high yield when producing alcohol from biomass raw materials, and to achieve long-term operational stability. The purpose of the present invention is to provide an excellent method for producing alcohol.

As a result of intensive studies to solve the above problems, the present inventors discovered that the above problems could be solved by passing through an acetal intermediate having a furan skeleton when producing alcohol from biomass raw materials, and the present invention. I was able to complete it.
That is, the gist of the present invention resides in the following [1] to [9].

[1] A method for producing alcohol from biomass raw materials, which is characterized in that the alcohol is produced via an acetal intermediate having a furan skeleton.

[2] The method for producing alcohol according to [1], wherein the alcohol is produced by hydrogenating the acetal intermediate using hydrogen gas.

[3] The method for producing alcohol according to [1] or [2], wherein the acetal intermediate is produced using a mixed solvent of water and an organic solvent.

[4] The method for producing alcohol according to any one of [1] to [3], wherein the acetal intermediate is a cyclic acetal.

[5] The method for producing alcohol according to [4], wherein the cyclic acetal is a 6-membered cyclic acetal.

[6] The method for producing alcohol according to any one of [1] to [5], wherein the biomass raw material is a saccharide raw material.

[7] The method for producing alcohol according to any one of [1] to [6], wherein the alcohol is furandimethanol or tetrahydrofurandimethanol.

[8] A compound represented by the following formula (1).

(In the formula, R ¹ is a hydrogen atom, -CH ₂ OH, -CH ₂ OR ² or -CH ₂ O(C=O)R ² , and R ² is an alkyl group having 1 to 6 carbon atoms. group or an aryl group having 6 to 12 carbon atoms which may have an alkyl substituent.)

[9] A method for producing alcohol, which comprises producing alcohol from the compound according to [8].

According to the production method of the present invention, when producing alcohol from biomass raw materials, by passing through the acetal intermediate, the thermal stability of the reaction intermediate is improved, and the polymerization and ring-opening reactions of the reaction intermediate are carried out. It is possible to suppress side reactions and improve the yield of the desired alcohol. In addition, by suppressing side reactions, it is possible to prevent operational problems such as deterioration of product quality due to contamination of by-products, blockage of pipes due to by-product polymers, and decrease in heat transfer efficiency, making continuous alcohol production stable and efficient. can be done. Furthermore, it is possible to suppress the coloring and generation of foreign substances in products derived from the produced alcohol as a raw material.

3 is a graph showing the results of Experimental Example 1.

Embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist.
In addition, in the present invention, "equivalent" means molar equivalent.

The method for producing alcohol of the present invention is characterized in that the method for producing alcohol from biomass raw materials involves passing through an acetal intermediate having a furan skeleton.

In the following, the present invention will be explained mainly by exemplifying the case where tetrahydrofurandimethanol is produced as an alcohol according to the present invention (reaction formula (A) below). The present invention is not limited to the production method, and can be effectively applied to, for example, the production of alcohols such as tetrahydrofurfuryl alcohol, furandimethanol, and furfuryl alcohol.

For example, when producing tetrahydrofurfuryl alcohol, in the production of tetrahydrofurandimethanol described below, a biomass raw material containing a saccharide unit having 6 carbon atoms as a main component, or carbon produced from a biomass raw material through a saccharification process is used. Tetrahydrofurfuryl can be produced by changing a raw material containing a saccharide with a carbon number of 6 (hereinafter, "a raw material containing a saccharide" is referred to as a "saccharide raw material") to a biomass raw material or a saccharide raw material containing a saccharide unit with a carbon number of 5. Alcohol can be produced (reaction formula (B) below). Moreover, tetrahydrofurfuryl alcohol can also be produced from a saccharide having 6 carbon atoms by appropriately changing the catalyst and/or solvent used. In addition, when producing furan dimethanol and furyl alcohol as alcohols, in the production of tetrahydrofuran dimethanol described below, by appropriately selecting the catalyst to be used and the reaction conditions to be applied, furan dimethanol (the following reaction formula (C )), furfuryl alcohol (reaction formula (D) below) can be produced.

[mechanism]
The present inventors have discovered that in the conventional method of producing alcohol via an aldehyde intermediate having a furan skeleton produced by a dehydration reaction from a biomass raw material and/or a saccharide raw material derived from a biomass raw material, the aldehyde intermediate is It has been found that the various problems described above occur due to poor thermal stability. Therefore, the present inventors have made repeated studies to solve these problems, and have investigated furfural (hereinafter abbreviated as "FRL") and hydroxymethylfurfural (hereinafter abbreviated as "HMF") produced by dehydration reactions. An acetal intermediate with high thermal stability is obtained by immediately acetalizing the aldehyde intermediate by reaction with an alcohol, more preferably a diol, particularly preferably simultaneously with the formation of a furan skeleton by a dehydration reaction, It has been found that the various problems described above can be solved by subsequently producing various alcohols by hydrogenation of the intermediate.

The following explanation will be given using an example in which the aldehyde having a furan skeleton is HMF and a cyclic acetal is formed as a preferred embodiment (reaction formula (E) below). In order to cyclic acetalize HMF produced by the dehydration reaction, a diol may be present in the reaction system. The diol used is preferably 1,3-propanediol (1,3-PD) or ethylene glycol (EG), and is a 6-membered diol because the thermal stability of the acetal formed is significantly improved. Particularly preferred is 1,3-propanediol (1,3-PD) which can form a cyclic acetal.

Specifically, by allowing 1,3-propanediol (1,3-PD) or ethylene glycol (EG) to exist in the dehydration reaction system, HMF generated in the dehydration reaction is , immediately reacts with 1,3-propanediol (1,3-PD) or ethylene glycol (EG) to form a 1,3-propanediol acetal of HMF (hereinafter abbreviated as "PD-HMF") or HMF. is converted into ethylene glycol acetal (hereinafter abbreviated as "EG-HMF").

On the other hand, the alcohol used may be monoalcohols described below such as methanol (MeOH), ethanol (EtOH), propanol (PrOH), butanol (BuOH), or may have an alkyl substituent having 1 to 6 carbon atoms. Phenol etc. may also be used (reaction formula (F) below). In this case as well, specifically, monoalcohol (ROH (R is an alkyl group having 1 to 6 carbon atoms or an alkyl substituent having 1 to 6 carbon atoms) is added to the dehydration reaction system as shown in the reaction formula below. ) represents a phenyl group that may be present, as shown in reaction formula (F) below, HMF generated in the dehydration reaction immediately reacts with monoalcohol (ROH) to form HMF. It is converted into a monoalcohol acetal (hereinafter abbreviated as "R-HMF").

As shown in Experimental Example 1 below, these acetalized products, especially cyclic acetals such as PD-HMF and EG-HMF, have superior thermal stability compared to HMF, so it is difficult to proceed via such acetal intermediates. By that,
(1) Formation of oligomers and polymers due to HMF polymerization is suppressed.
(2) From (1) above, the reaction yield can be maintained high.
(3) According to (1) above, dirt caused by by-products is less likely to adhere to the inside of the reactor and piping, and stable production can be achieved by preventing problems such as a decrease in thermal conductivity and clogging of the piping. In addition, high-quality products can be obtained by preventing coloring and foreign matter caused by by-products.
This effect is produced.

In addition, in order to acetalize furfural, it is necessary to add alcohol to the reaction system as described above.On the other hand, when producing alcohol by hydrogenating an acetal intermediate, alcohol is added as a sub-agent as shown below. live. In the process of the present invention, the alcohol by-produced in this step is usually recovered using a technique such as distillation, and reused as an acetalizing agent in the acetalizing step. Of course, the by-product alcohol may be disposed of as is if the economic efficiency of the manufacturing process is maintained.

In this way, the process of adding and recovering components to be removed in a subsequent process in the previous process, such as adding alcohol to acetalize and then dealcoholizing, is not something that those skilled in the art would normally do. The alcohol production method of the present invention, in which furfural is acetalized by intentionally adding alcohol to the reaction system, cannot be easily imagined from conventional synthesis methods. When using biomass raw materials or their derivatives with the above characteristics as raw materials, how to stabilize reaction intermediates and suppress the production of byproducts derived from biomass raw materials is particularly important in designing the entire process. It is. By employing the method of the present invention, the above-mentioned various problems specific to production processes using biomass raw materials or derivatives thereof as raw materials can be solved.

In the case of HMF, the cyclic acetal in the present invention has a hydroxyl group of carboxylic acid anhydride ((R ² CO) ₂ O (R ² is an alkyl group having 1 to 6 carbon atoms or an alkyl substituent). A cyclic acetal derived from an ester group by reaction with an aryl group having 6 to 12 carbon atoms (R ² OH (R ² is an aryl group having 1 to 6 carbon atoms) or a hydroxyl group derived from an alcohol It represents an alkyl group or an aryl group having 6 to 12 carbon atoms which may have an alkyl substituent.

Hereinafter, preferred embodiments of the present invention will be explained in detail.

[Biomass raw material]
In the present invention, biomass raw materials are those in which sunlight energy is converted and stored in the form of starch, cellulose, hemicellulose, etc. through the photosynthetic action of plants, the bodies of animals that grow by eating plants, and the bodies of animals that grow by eating plants. Includes products made by processing animal bodies. Examples of biomass raw materials include wood, rice straw, rice husk, rice bran, old rice, corn, sugar cane, cassava, sago palm, cardoon, switchgrass, pine wood, poplar wood, maple wood, okara, corn cob, corn stover, and corn fiber. , tapioca, bagasse, vegetable oil residue, potatoes, buckwheat, soybeans, waste paper, paper manufacturing residue, marine product residue, livestock excrement, sewage sludge, food waste, etc. Among these, wood, rice straw, rice husk, rice bran, old rice, corn, sugar cane, cassava, sago palm, cardoon, switchgrass, pine wood, poplar wood, maple wood, bean curd, corn cob, corn stover, corn fiber, tapioca, bagasse, Preferably, plant resources such as vegetable oil residue, potatoes, buckwheat, soybeans, waste paper, and paper residues are used, and more preferably wood, rice straw, rice husk, old rice, corn, sugar cane, cassava, sago palm, cardoon, switchgrass, pine wood, and poplar. wood, maple wood, corn cob, corn stover, corn fiber, bagasse, potato, oil and fat, waste paper, paper residue, most preferably corn, sugar cane, cassava, sago palm, bagasse, cardoon, switch grass, pine wood, poplar wood, These are maple wood, corn cob, corn stover, and corn fiber.

In the present invention, these biomass raw materials are directly induced into FRL and HMF using, for example, known methods such as those described in Green Chemistry 16 (2014) 4816-4838 and its cited documents, and then the FRL The method of deriving acetal by reacting HMF with alcohol is a preferred embodiment because it does not require a saccharification step from the biomass raw material and the number of reaction steps to reach the final target product is reduced. Alternatively, the biomass raw material and alcohol may be made to coexist, and the method may be used to directly induce the acetal form of FRL or HMF. The latter method, in which the biomass raw material and alcohol are allowed to coexist and directly obtain acetal, is preferable in that the number of reaction steps is small and the reaction process is efficient.

[Saccharification]
In the present invention, in addition to the method of directly deriving FRL, HMF, and their acetal forms from the biomass raw material described above, for example, the biomass raw material can be treated with acids, alkalis, etc., or biologically with microorganisms. Through known pretreatment and saccharification processes such as chemical and physical treatments, polysaccharides contained in biomass raw materials are decomposed (saccharified) into their constituent units, saccharides, to form oligosaccharides, disaccharides, and monosaccharides. A method can also be suitably used in which a sugar solution containing FRL is obtained, FRL and HMF are obtained from the sugar solution, and as described above, they are reacted with a diol to induce their acetal forms. By using this method, it is possible to avoid a decrease in the reaction yield of the acetalization reaction and the purity of the produced acetal product due to foreign substances and impurities contained in the biomass raw material.

The method for saccharifying the biomass raw material is not particularly limited, and for example, known methods such as those described in Green Chemisry 16 (2014) 4816-4838 and the cited documents thereof can be used.

The process is not particularly limited, but usually includes a micronization process by pretreatment such as chipping, shaving, or grinding the biomass raw material. If necessary, a pulverizing step using a grinder or a mill is further included. The biomass raw material that has been refined in this way undergoes further pretreatment and saccharification steps to produce sugar solution.Specific methods include acid treatment with strong acids such as sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid, and alkaline treatment. , chemical methods such as ammonia freeze-steam explosion method, solvent extraction, subcritical fluid treatment, supercritical fluid treatment, oxidizing agent treatment, physical methods such as pulverization, steam explosion method, microwave treatment, electron beam irradiation, etc. Biological treatments such as hydrolysis by microorganisms or enzyme treatments, or a combination thereof may be used.

Saccharides derived from the above biomass raw materials usually include hexoses such as glucose, mannose, galactose, fructose, sorbose, and tagatose, pentoses such as arabinose, xylose, ribose, xylulose, and ribulose, pentosan, xylan, saccharose, starch, Disaccharides, oligosaccharides, and polysaccharides such as cellulose are used, and among these, glucose, fructose, and xylose are preferred. Among these, fructose and xylose are particularly preferred because of their high reaction yields. On the other hand, cellulose and hemicellulose are preferred as saccharides derived from plant resources in a broader sense.

The sugar solution obtained by saccharification of biomass raw materials is usually an aqueous solution of sugars, and may contain other components in addition to water and sugars. Other components are not particularly limited, but may include, for example, by-products other than sugars produced when sugars are obtained from biomass raw materials and impurities contained in sugar raw materials. Specifically, such impurities include carbonyl compounds other than sugars, alcohol compounds such as aliphatic conjugated alcohols, phenol compounds derived from lignin, alkali metal compounds, alkaline earth metal compounds, nitrogen compounds, sulfur compounds, Examples include inorganic compounds such as halogen compounds and sulfate ions.

The total concentration of sugars contained in the sugar solution in the present invention (hereinafter referred to as "sugar concentration") varies greatly depending on the origin of the sugar solution, the type of sugar contained, etc., and is not particularly limited, but the lower limit is usually The content is 1% by mass or more, preferably 3% by mass or more, more preferably 5% by mass or more, while the upper limit is usually preferably 60% by mass or less, more preferably 50% by mass or less. This sugar solution may be subjected to the next step as it is, and if necessary, a method of distilling off water under reduced pressure, a method of distilling water off by heating, or a method of distilling off water by heating, or nano A concentrated sugar solution with concentrated sugar components may be obtained using a method of filtering through a filtration membrane and/or a reverse osmosis membrane, and then subjected to the next step. In particular, the method of concentrating the sugar solution is preferable in that the productivity of the entire process is improved in the subsequent dehydration reaction and acetalization reaction.

In addition, as another method, a method of separating monosaccharides such as glucose, fructose, and xylose from a sugar solution using a known method and subjecting the separated monosaccharides to the next process reduces the amount of impurities in the raw materials. This is the most preferable embodiment in that stable long-term operation is possible because it is possible to improve the reaction yield of the subsequent reaction step and to reduce the amount of variation between lots. These monosaccharides are currently available on an industrial scale. In the present invention, isolated monosaccharides may be additionally added in order to obtain a sugar solution with a high content of sugar components.

[Dehydration/acetalization]
In the production of alcohol via an acetal intermediate in the present invention, there is a method of directly producing an acetal intermediate from a biomass raw material, or a method of first deriving a saccharide raw material from a biomass raw material through a saccharification process, and then producing an acetal intermediate from the saccharide raw material. A manufacturing method is used.

In addition, in these methods, in order to produce an acetal intermediate from a biomass raw material and/or a saccharide raw material, there are a step of producing FRL and/or HMF from a biomass raw material and/or a saccharide raw material, and a step of producing FRL and/or HMF from a biomass raw material and/or a saccharide raw material. It may be carried out through two steps, including the step of producing an acetal (hereinafter, this method is referred to as a "two-step method"), and FRL and/or HMF produced from biomass raw materials and/or saccharide raw materials are immediately converted into acetals. It may be carried out in one step so as to convert into a compound (hereinafter, this method will be referred to as a "one-step method"). That is, in the presence of the acetalizing alcohol described below, FRL and/or HMF, which have low thermal stability, are immediately converted into acetal forms of FRL and/or HMF, so they are generated from biomass raw materials and saccharide raw materials through a dehydration reaction. By allowing an acetalizing alcohol to exist in the FRL and/or HMF production reaction system, an acetal intermediate with high thermal stability can be formed in the same reaction system. This not only improves the reaction yield of intermediates, but also reduces the production of colored and polymerized by-products, which is an industrially advantageous method that suppresses the contamination of these products. It becomes a manufacturing process. In particular, the effects of the present invention become remarkable by employing a production process that involves an HMF acetal intermediate.

In addition, when producing an acetal intermediate by a two-step method, once produced FRL and/or HMF is isolated and/or purified (hereinafter referred to as "isolation/purification"), and the acetal is produced in a separate reaction vessel. The acetalization may be carried out in the same reaction vessel without isolation/purification of FRL and/or HMF.

The production of FRL or HMF from biomass raw materials and/or saccharide raw materials, as well as its acetal form, is preferably carried out in a solvent in the presence of a catalyst. The catalyst may be any catalyst as long as it can produce FRL or HMF, or even its acetal form, from biomass raw materials or saccharide raw materials, and is not particularly limited, but typically includes hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, and boric acid. inorganic acids and their metal salts such as alkali metals or alkaline earth metals, sulfonic acids such as p-toluenesulfonic acid and their metal salts such as alkali metals or alkaline earth metals, amberlyst, amberlite, diamond Acidic cation exchange resin such as ion, zeolite, Al ₂ O ₃ , TiO ₂ , ZrO ₂ , SiO ₂ -Al ₂ O ₃ , SiO ₂ -MgO, SiO ₂ -TiO ₂ , Nb ₂ O ₅ , YNbO ₄ , SnO ₂ , In ₂ O ₃ , Ga ₂ O ₃ , WO ₃ , MoO ₃ , Ta ₂ O ₅ , CeO ₂ , Nb ₂ O ₅ -WO ₃ , Nb ₂ O ₅ -MoO ₃ , TiO ₂ -WO ₃ , TiO ₂ - Metal oxides and metal composite oxides such as MoO ₃ , SiO ₂ -Nb ₂ O ₅ , SiO ₂ -Ta ₂ O ₅ , SiO ₂ -ZrO ₂ , clay, sulfuric acid immobilized catalysts such as sulfated ZrO ₂ , phosphorus Examples include phosphoric acid fixed catalysts such as acid-treated titania and niobia, and heteropolyacids.

Also, aliphatic monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, and caproic acid, oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, aconitic acid, and itaconic acid. , aliphatic dicarboxylic acids such as oxaloacetic acid, fumaric acid, maleic acid, cyclopentanedicarboxylic acid, cyclohexanedicarboxylic acid, aliphatic tricarboxylic acids such as cyclohexanetricarboxylic acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, trimesic acid, Aromatic carboxylic acids such as trimellitic acid, hemimellitic acid, merophanic acid, prenitic acid, pyromellitic acid, benzenepentacarboxylic acid, mellitic acid, organic acids such as hydroxycarboxylic acids such as lactic acid, malic acid, citric acid, tartaric acid, etc. Salts of alkali metals, alkaline earth metals, etc. that are obtained by neutralizing at least a portion of these organic acids can also be used as catalysts.

In the present invention, among the above-mentioned catalysts, it is preferable to carry out the reaction in a heterogeneous system using a solid catalyst insoluble in the reaction solvent, since the continuous flow reaction is easy and the reaction selectivity is high. Specifically, among the above catalysts, acidic cation exchange resins such as Amberlyst, Amberlite, and Diaion, zeolite, Nb ₂ O ₅ , YNbO ₄ , Ta ₂ O ₅ , Nb ₂ O ₅ -WO ₃ , Metal oxides and metal composite oxides such as Nb ₂ O ₅ -MoO ₃ , TiO ₂ -WO ₃ , TiO ₂ -MoO ₃ , SiO ₂ -Nb ₂ O ₅ , SiO ₂ -Ta ₂ O ₅ , clay, sulfated Sulfuric acid immobilized catalysts such as ZrO ₂ and phosphoric acid immobilized catalysts such as titania and niobia treated with phosphoric acid are preferred. Among them, zeolite, Nb ₂ O ₅ , Nb ₂ O ₅ -WO ₃ , and Nb ₂ O ₅ -MoO ₃ are more preferable in that they selectively allow only the acetalization reaction of HMF to proceed, and in particular zeolite, Nb ₂ O ₅ is preferred.

These catalysts may be used alone or in combination of two or more. When using two or more types of catalysts, the combination is not particularly limited, and it may be one in which each metal has catalytic activity (cocatalyst) or one that improves the catalytic activity of one or more metals (cocatalyst). You can.

When these catalysts are soluble in a solvent, the lower limit is usually 0.001% by mass or more, preferably 0.005% by mass or more, and more preferably 0. .01% by mass or more, more preferably 0.05% by mass or more, while the upper limit is 50% by mass or less, preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less. It is. On the other hand, this does not apply when a continuous reaction is carried out using a solid catalyst insoluble in the reaction solvent, for example, in a fixed bed reactor or a suspended bed reactor.

As the solvent, water or an organic solvent is usually used, but it may be preferable to use a mixed solvent of water and an organic solvent. From the perspective of cost advantage, it is preferable to use a single solvent as the reaction solvent, and from the perspective of improving the yield of the acetal intermediate, it is preferable to use a mixed solvent of water and an organic solvent as the reaction solvent. There is. Depending on the selection of organic solvent, the reaction can be carried out in a homogeneous mixed solvent, but since it suppresses the polymerization and decomposition reactions of the generated FRL and HMF or their acetal forms, and improves the yield of acetal forms, the aqueous layer In some cases, it is preferable to use an organic solvent that forms a two-layer system consisting of an organic layer and an organic layer. That is, by using this method, it is possible to perform a continuous extraction reaction in which the generated FRL, HMF, or their acetal form is extracted into an organic solvent, and after the reaction, the reaction solution is separated into two layers to separate the products. It can be efficiently separated from the organic solvent layer.

The organic solvent to be used is not particularly limited as long as it does not inhibit the produced FRL, HMF, and their acetalization reaction, but examples include diethyl ether, tetrahydrofuran (THF), tetrahydropyran, and dipropyl. Ether, diisopropyl ether, methyl-tert-butyl ether, butyl ether, pentyl ether, hexyl ether, octyl ether, nonyl ether, decyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, etc. with 4 carbon atoms ~20 ethers; 2-butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyclohexanone, 4-methyl-2-pentanone, 2-heptanone, 5-methyl-2-hexanone, 2, 4-dimethylpentanone, 5-nonanone, 4-decanone, 5-decanone, 2-undecanone, 4-undecanone, 3-dodecanone, 2-tridecanone, 2-tetradecanone, 4-tetradecanone, 2-pentadecanone, 3-pentadecanone, Ketones having 4 to 20 carbon atoms such as 7-pentadecanone, 2-hexadecanone, 3-hexadecanone, 4-hexadecanone, 6-hexadecanone, 2-heptadecanone, 4-heptadecanone, 9-heptadecanone, 3-octadecanone, acetophenone; ethyl acetate , esters such as propyl acetate, butyl acetate; saturated aliphatic hydrocarbon compounds having 3 to 12 carbon atoms such as pentane, hexane, cyclohexane, heptane, octane, nonane, decane, dodecane, isododecane; toluene, xylene, trimethylbenzene , 1,2,3,4-tetrahydronaphthalene, 1-methylnaphthalene; lactones such as γ-butyrolactone, γ-valerolactone; dichloromethane, chloroform, dichloroethane, tetrachloroethane, hexachloroethane, etc. Halogenated hydrocarbons; Others: dimethylacetamide, N,N-dimethylformamide, N-methylmorpholine, N-methyl-2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoric triamide, tetra Examples include methylurea, dimethyl sulfoxide, sulfolane, isosorbide, isosorbide dimethyl ether, propylene carbonate, and mixtures thereof. Other examples include pyrrolidinium salts such as 1-butyl-1-methylpyrrolidinium bromide; piperidinium salts such as 1-butyl-1-methylpiperidinium triflate; pyridinium salts such as 1-butylpyridinium tetrafluoroborate; 1- Ionicity such as imidazolium salts such as ethyl-3-methylimidazolium chloride; ammonium salts such as tetrabutylammonium chloride; phosphonium salts such as tetrabutylphosphonium bromide; sulfonium salts such as triethylsulfonium bis(trifluoromethanesulfonyl)imide; A liquid may also be used.

Among these, the organic solvent is preferably selected from at least one of the group consisting of ethers, ketones, esters, alcohols, phenols, lactones, aromatic hydrocarbons, halogenated hydrocarbons, and saturated aliphatic hydrocarbons. . Among these, it is preferable to select at least one from the group consisting of ethers, ketones, esters, lactones, aromatic hydrocarbons, and saturated aliphatic hydrocarbons because of their low environmental impact.

In addition, when carrying out the reaction in a two-layer system, the extraction efficiency of the acetal is high, and the amount of organic solvents dissolved in water is small. Benzene, 1,2,3,4-tetrahydronaphthalene, 1-methylnaphthalene, cyclohexane, and isododecane are preferred, and among these, methyl ethyl ketone, methyl isobutyl ketone, butylphenol, cyclohexanone, and toluene are particularly preferred. It is preferable to use only one type of these organic solvents in consideration of recovery and reuse of the solvent, but two or more types may be used.

In the present invention, alcohol is used as a reaction reagent as an acetalizing agent, but the reason is that alcohol itself can be used as a reaction solvent, and the subsequent recovery of the reaction solvent and complications in the purification process can be avoided. One of the preferred embodiments is a method in which alcohol is used as both a reaction solvent and an acetalizing agent. Specifically, such alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, and 1-propanol. Pentanol, 2-pentanol, 3-pentanol, 3-methyl-1-butanol, 2,2-dimethyl-1-propanol, 1-hexanol, 2-hexanol, 3-hexanol, 2-methyl-1-pene Tanol, 1-heptanol, 2-heptanol, 1-octanol, 2-octanol, 3-octanol, 2-ethyl-1-hexanol, 1-nonanol, 1-decanol, 1-undecyl alcohol, 1-lauryl alcohol, 1 -Tridecyl alcohol, 1-tetradecanol, 1-pentadecyl alcohol, 1-hexadecanol, cis-9-hexadecen-1-ol, 1-heptadecanol, 1-octadecanol, 16-methylheptadecene Monoalcohols with 1 to 20 carbon atoms such as -1-ol, nonadecyl alcohol, arachidyl alcohol; ethylene glycol, propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,3-butane Diol, 1,3-pentanediol, 1-phenyl-1,3-propanediol, 2-phenyl-1,3-propanediol, 1,2-propanediol, 1,2-butanediol, 1,2-pentane Diols having as a substituent an alkyl group having 1 to 6 carbon atoms such as diol, 1-phenyl-ethylene glycol, or an aryl group having 6 to 12 carbon atoms which may have an alkyl substituent; phenol, methylphenol, Examples include phenols having 6 to 12 carbon atoms such as ethylphenol, propylphenol, and butylphenol.

In the present invention, when using a mixed solvent of water and an organic solvent, the amount of the organic solvent used is not particularly limited as long as it does not impair the spirit of the present invention, but it is preferably 10 to 5000% by mass based on water. , particularly preferably 10 to 1000% by mass. If the amount of the organic solvent used is too small than the above range, polymerization or decomposition reactions of FRL, HMF, or their acetals to be produced tend to occur, and the yield of the acetal intermediate tends to decrease accordingly. If the amount is too large, it will be necessary to remove a large amount of organic solvent when recovering the acetal intermediate produced, which will not only reduce recovery efficiency and complicate the process, but also increase the size of the reaction equipment, which is economically disadvantageous. There is a tendency to

Therefore, when using a sugar solution as a saccharide raw material, it is preferable to add an organic solvent or water and an organic solvent to the water in the sugar solution so that the amount falls within the above range.

Specifically, the alcohol added to acetalize HMF (hereinafter sometimes referred to as "alcohol for acetalization") includes monoalcohols, diols, and phenols listed as reaction solvents. Illustrated. Among them, diols are preferred because the acetal of HMF produced has a cyclic acetal structure, the acetal has high thermal stability, side reactions such as polymerization and ring-opening reactions are suppressed, and coloring is less likely to occur. . When producing such a cyclic acetal intermediate of HMF with high thermal stability, the diol to be added (hereinafter sometimes referred to as "diol for cyclic acetalization") is selected depending on the type of cyclic acetal intermediate to be produced. A diol capable of forming a 6-membered cyclic acetal is used in the production of PD-HMF, and a diol capable of forming an acetal with a 5-membered ring skeleton is used in the production of EG-HMF. Among these, since the acetal intermediate is preferably a 6-membered cyclic acetal, the diol used is also preferably a diol that can form a 6-membered cyclic acetal. Specifically, typical examples include 1,3-propanediol for the production of PD-HMF, and ethylene glycol for the production of EG-HMF, but are not limited to these in any way. 2-methyl-1,3-propanediol, neopentyl glycol, 1,3-propanediol having as a substituent an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms which may have an alkyl substituent Butanediol, 1,3-pentanediol, 1-phenyl-1,3-propanediol, 2-phenyl-1,3-propanediol, 1,2-propanediol, 1,2-butanediol, 1,2- It may also be pentanediol or 1-phenyl-ethylene glycol. Catechol is also preferably used. Although it is possible to use two or more types of these diols for cyclic acetalization, one type is usually used. In the present invention, the above-mentioned diol is used as a cyclic acetalizing agent as a reaction reagent, but the diol can also be used as the above-mentioned organic solvent, which reduces the complexity of subsequent reaction solvent recovery and purification steps. The method of using a diol as both a solvent and an acetalizing agent is one of the preferred embodiments because it can avoid this.

There is no particular restriction on the amount of biomass raw material and/or saccharide raw material used relative to the reaction solvent, especially when the reaction is carried out in a heterogeneous system.

When the raw material is dissolved in the reaction solvent in a homogeneous system, the lower limit of the concentration of the raw material to the reaction solvent is usually 0.1% by mass or more, preferably 1% by mass or more, and more preferably 5% by mass. The content is more preferably 10% by mass or more, particularly preferably 15% by mass or more. On the other hand, the upper limit is 50% by mass or less, preferably 30% by mass or less, and more preferably 25% by mass or less. When the raw material concentration is above the above lower limit value, the separation efficiency between the acetal intermediate and the solvent tends to be high, and when the raw material concentration is below the above upper limit value, side reactions can be suppressed and the yield of the acetal body becomes high. There is a trend and it is desirable. In addition, when the reaction is carried out in a homogeneous system, the concentration of the raw materials in the reaction solution is the concentration of the solvent used in the reaction (including water in the sugar solution when using a sugar solution) and the catalyst in the case of a two-step method. It is the ratio of the raw material to the total of the raw materials, and in the case of a one-stage method, it is the ratio of the raw material to the total of the above-mentioned diol for acetalization.

In the case of a two-stage method, the reaction temperature of the dehydration reaction to obtain HMF is preferably 100°C or higher, more preferably 120°C or higher, and preferably 250°C or lower, and more preferably 230°C or lower. It is. When the reaction temperature is equal to or higher than the above lower limit, the reaction tends to proceed faster and the productivity of the product improves. It is preferable that the reaction temperature is below the above upper limit because it tends to suppress decomposition and polymerization of the product and reaction intermediates and improve the yield of the product. In the case of a two-stage method, after FRL and HMF are produced by a dehydration reaction, the produced FRL and HMF are isolated/purified, or the above-mentioned alcohol for acetalization is added without isolation/purification. Further dehydration and acetalization may be performed to obtain an acetal form of FRL or HMF. The above-mentioned alcohol for acetalization used in acetalization may be at least the expected production equivalent of FRL or HMF, and is usually added in an amount of 1 to 10 times the expected production amount of FRL or HMF (however, When an alcohol for acetalization is used as a reaction solvent, it is preferable to add the alcohol in the amount of the reaction solvent) and to carry out the reaction at a temperature of 10 to 150°C.

In addition, in the case of a one-stage method, a solvent is added to the monosaccharide or sugar solution so that the monosaccharide concentration in the reaction solution and the amount of organic solvent in the reaction solvent are within the above-mentioned ranges, and the above-mentioned alcohol for acetalization is added. Add 1 to 10 equivalents to the expected production amount of FRL or HMF (however, when using an alcohol for acetalization as a reaction solvent, add the same amount of alcohol as the reaction solvent), and adjust the reaction temperature. The lower limit of is usually 100°C or higher, preferably 120°C or higher, while the upper limit is usually 250°C or lower, preferably 230°C or lower to carry out the dehydration and acetalization reactions.

The reaction solution in which the acetal intermediate has been produced in this way by the two-step method or the one-step method may be directly subjected to the following hydrogenation, or the produced acetal intermediate may be isolated/purified and then hydrogenated. You may also serve it.

[Hydrogenation]
Hydrogenation of the acetal intermediate is preferably carried out in the presence of a catalyst, and the hydrogenation catalyst used in the present invention is not particularly limited, but may include a metal element having catalytic hydrogenation ability (hereinafter referred to as "specific metal component"). (sometimes referred to as ".") as an active ingredient.

Specific metal components include, for example, nickel, cobalt, iron, ruthenium, metal, osmium, palladium, platinum, gold, iridium, copper, zinc, silver, molybdenum, tungsten, chromium, manganese, rhenium, and mixtures thereof. Can be mentioned. Among them, nickel, iron, ruthenium, metal, palladium, platinum, gold, iridium, copper, zinc, molybdenum, chromium, manganese, and rhenium are used because of their high hydrogenation catalytic ability and good reaction selectivity. The solid catalyst is preferably a solid catalyst containing at least one member selected from the group consisting of nickel, ruthenium, metal, palladium, platinum, gold, iridium, copper, zinc, molybdenum, and rhenium. It is a solid catalyst containing.

This specific metal component may be in a metallic state or in a cationic state as long as it exhibits hydrogenation ability. Among these, the metal state is preferable in some cases because it has a stronger hydrogenation ability and is stable in a reducing atmosphere. The specific metal components can be used alone or in combination of two or more in a state contained in the solid catalyst. Furthermore, when two or more specific metal components are used, there are no particular restrictions on their combination, mixing ratio, or form, and they can be used in the form of a mixture of individual metals, an alloy, or an intermetallic compound.

There are no particular limitations on the raw materials for these specific metal components, and those used as raw materials when preparing catalysts by conventionally known methods can be employed. Such raw materials include, for example, hydroxides, oxides, fluorides, chlorides, bromides, iodides, sulfates, nitrates, acetates, ammonium salts, ammine complexes, and carbonyl complexes of the respective metal elements. It will be done. These may be used alone or in combination of two or more.

In the hydrogenation catalyst used in the present invention, a specific metal component can be used alone or in combination with a metal that does not have catalytic hydrogenation ability. Examples include catalysts such as palladium black and platinum black that are composed of fine metal powders of specific metal components, and forming alloys from specific metal components, aluminum, and small amounts of additives, and then forming alloys with aluminum and small amounts of additives. Alternatively, a sponge catalyst prepared by partially leaching can be mentioned.

In addition, in order to further improve the activity, selectivity, and physical properties of the catalyst, we have added lithium, sodium, potassium, rubidium, and cesium as alkali metal elements, magnesium, calcium, strontium, and barium as alkaline earth metal elements, and fluorine as a halogen element. , chlorine, bromine, and iodine, and a compound of one or more elements selected from the group consisting of aluminum, gallium, germanium, silicon, lead, bismuth, tin, tellurium, and antimony as auxiliary additive elements (hereinafter referred to as specific additive components). ) can also be added to the catalyst together with the above-mentioned specific metal components. There are no particular restrictions on the raw materials for these specific additive components, and those used as raw materials for preparing catalysts by conventionally known methods can be employed. Such raw materials include, for example, hydroxides, oxides, fluorides, chlorides, bromides, iodides, sulfates, nitrates, acetates, ammonium salts, and ammine complexes of the respective metal elements. These may be used alone or in combination of two or more. Further, there are no particular limitations on the method of adding the specific additive component and the ratio of the specific additive component and the specific metal component.

In the hydrogenation catalyst used in the present invention, a specific metal component can also be used in combination with a non-metallic substance. Examples of nonmetallic substances include mainly simple elements, carbides, nitrides, oxides, hydroxides, sulfates, carbonates, and phosphates (hereinafter referred to as "specific nonmetallic components"). ). Specific examples thereof include graphite, diamond, activated carbon, silicon carbide, silicon nitride, aluminum nitride, boron nitride, boron oxide, aluminum oxide (alumina), silicon oxide (silica), titanium oxide, zirconium oxide, and Hafnium, lanthanum oxide, cerium oxide, yttrium oxide, niobium oxide, magnesium silicate, calcium silicate, magnesium aluminate, calcium aluminate, zinc oxide, chromium oxide, aluminosilicate, aluminosilicophosphate, aluminophosphate, porophosphate Magnesium phosphate, calcium phosphate, strontium phosphate, hydroxyapatite (calcium hydroxyphosphate), chlorinated apatite, fluorinated apatite, calcium sulfate, barium sulfate, and barium carbonate. The specific nonmetallic components may be used alone or in combination of two or more. There are no particular restrictions on the combination, mixing ratio, or form when two or more types are used in combination, and they can be used in the form of a mixture of individual compounds, a composite compound, or a double salt. From the viewpoint of industrial use, specific nonmetallic components that can be easily obtained at low cost are preferred.

As the hydrogenation catalyst, a specific metal component may be used alone, a specific metal component and a specific non-metal component may be used in combination, and in some cases, a specific additive component may be included in addition to these components.

The method for producing the hydrogenation catalyst is not particularly limited, and conventionally known methods can be used. Examples include a method in which a raw material compound for a specific metal component is impregnated onto a specific non-metal component (support method), a method in which a raw material compound for a specific metal component and a raw material compound for a specific non-metal component are dissolved together in an appropriate solvent. Examples include a method of simultaneously precipitating using an alkali compound or the like (co-precipitation method), and a method of mixing and homogenizing the raw material compound of the specific metal component and the specific non-metal component in an appropriate ratio (kneading method).

Depending on the composition of the hydrogenation catalyst or the catalyst preparation method, the specific metal component may be prepared in a cationic state and then subjected to a reduction treatment to be converted into a metallic state. As the reducing method and reducing agent for this purpose, conventionally known ones can be used, and there are no particular limitations. Examples of reducing agents include hydrogen gas, carbon monoxide gas, ammonia, reducing inorganic gases such as hydrazine, phosphine and silane, lower oxygen-containing compounds such as methanol, formaldehyde and formic acid, sodium borohydride and hydride. Examples include hydrides such as lithium aluminum. Among them, hydrogen gas, which does not require separation and purification after reduction treatment, is preferred. By reducing the specific metal component in the cation state in the gas phase or liquid phase where these reducing agents are present, the specific metal component is converted to the low valence metal state. The conditions for the reduction treatment at this time can be set to suitable conditions depending on the type and amount of the specific metal component and reducing agent. This reduction treatment operation may be carried out using a separate catalytic reduction device before the hydrogenation of the acetal intermediate, or it may be carried out before the start of the reaction or simultaneously with the reaction operation in the acetal intermediate hydrogenation reactor. Good too.

Furthermore, there are no particular limitations on the metal content and shape of the hydrogenation catalyst. Its shape may be powder or molded, and there are no particular restrictions on the shape or molding method. For example, spherical products, tablet molded products, extrusion molded products, and shapes obtained by crushing them into appropriate sizes can be appropriately selected and used.

The content of metal in the hydrogenation catalyst is not particularly limited, but is usually 0.1% by mass or more, preferably 0.5% by mass or more, based on the total weight of the catalyst, as a weight percentage in terms of metal. It is 1% by mass or more, and usually 50% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less. By keeping the metal content within the above range, sufficient catalytic activity can be obtained. In the description of the catalyst below, the value described as % by mass indicates the metal content based on the total weight of the catalyst.

The hydrogen source used for hydrogenation is not particularly limited, but it is desirable to use gaseous hydrogen that does not require separation and purification after the reaction is completed.

The hydrogen gas pressure is not particularly limited, but it is usually carried out under hydrogen gas pressurization conditions. The hydrogen gas pressure during the hydrogenation reaction is usually 0.1 MPa or higher, preferably 0.3 MPa or higher, more preferably 0.4 MPa or higher, and usually 15 MPa or lower, preferably 20 MPa or lower, more preferably 5 MPa or lower, and even more preferably It is 3 MPa or less.

In general, increasing the reaction pressure promotes hydrogen supply to the hydrogenation catalyst and improves the reaction rate. On the other hand, in order to carry out the reaction at a high pressure, equipment such as a reactor with specially increased pressure resistance is required, and since the hydrogenation capacity increases, there is a possibility that hydrogenolysis will proceed.

The hydrogen concentration in the hydrogen gas atmosphere is not particularly limited, but is usually 70% by volume or more, preferably 80% by volume or more, more preferably 90% by volume or more, and the upper limit is usually 100% by volume.

The hydrogenation of the acetal intermediate may be carried out in a solvent-free environment using only the acetal as a raw material, or a reaction solvent may be used.

When using a reaction solvent, there are no particular restrictions on its type or concentration as long as it is inactive to hydrogenation reduction. However, if a reaction solvent that interacts more strongly with the specific metal component in the hydrogenation catalyst than acetal does, the reaction rate may be extremely reduced or the reaction may stop. From this point of view, for example, it is preferable not to use compounds containing phosphorus, nitrogen, or sulfur as a reaction solvent, but they may be used in trace amounts that do not significantly affect the reaction rate. Preferred reaction solvents are water, hydrocarbons, esters, ethers, and alcohols, and these may be used alone or in combination of two or more.

Examples of the reaction solvent include water, pentane, hexane, 2,2-dimethylbutane, heptane, 2,2,4-dimethylpentane, octane, octane, nonane and its isomers, dehydrone, and pentade. Hydrocarbons such as cyclohexane, methylcyclohexane, dimethylcyclohexane and its isomers, decalin, toluene, xylene, trimethylbenzene, 1,2,3,4-tetrahydronaphthalene, 1-methylnaphthalene; methyl acetate, ethyl acetate , butyl acetate, methyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, cyclohexyl butyrate, and esters such as methyl valerate and its isomers; dimethyl ether, diethyl ether, dipropyl ether, dipropyl ether, dibutyl ether, methyl Propyl ether, ethyl propyl ether, methyl butyl ether, methyl pentyl ether, ethyl butyl ether, propyl butyl ether, methyl cyclopentyl ether, methyl cyclohexyl ether, ethyl cyclopentyl ether, ethyl cyclohexyl ether, propyl cyclopentyl ether, propyl cyclohexyl ether, butyl cyclopentyl ether, butyl cyclohexyl Ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, tetrahydrofuran, methyltetrahydrofuran, tetrahydropyran, methyltetrahydropyran , 1,4-dioxane, dimethyl-1,4-dioxane, and isomers thereof. In addition, specific alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1- Pentanol, 2-pentanol, 3-pentanol, 3-methyl-1-butanol, 2,2-dimethyl-1-propanol, 1-hexanol, 2-hexanol, 3-hexanol, 2-methyl-1-pene Tanol, 1-heptanol, 2-heptanol, 1-octanol, 2-octanol, 3-octanol, 2-ethyl-1-hexanol, 1-nonanol, 1-decanol, 1-undecyl alcohol, 1-lauryl alcohol, 1 -Tridecyl alcohol, 1-tetradecanol, 1-pentadecyl alcohol, 1-hexadecanol, cis-9-hexadecen-1-ol, 1-heptadecanol, 1-octadecanol, 16-methylheptadecene -1-ol, nonadecyl alcohol, arachidyl alcohol, ethylene glycol, propanediol, 2-methyl-1,3-propanediol, 1,3-butanediol, 1,3-pentanediol, 1-phenyl-1, Examples include 3-propanediol, 2-phenyl-1,3-propanediol, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, and 1-phenyl-ethylene glycol. A plurality of these may be used in combination as a mixed solvent.

The amount of the solvent to be used is not particularly limited since the reaction can be carried out in a solvent-free environment, but the lower limit is usually 1 time or more, preferably 2 times or more, more preferably 2 times or more, based on the mass ratio of the acetal. 3 times or more, more preferably 4 times or more, most preferably 5 times or more, while the upper limit is usually 100 times or less, preferably 50 times or less, more preferably 30 times or less, still more preferably 20 times or less, Most preferably it is 8 times or less. If the amount of solvent used is too large, the reaction vessel becomes too large and the production efficiency decreases, which is not preferable for an economical industrial process. On the other hand, if the amount is too small, the reaction rate tends to decrease and the reaction time tends to become longer, which may be undesirable. However, the acetal intermediate according to the present invention, especially in the case of a cyclic acetal intermediate, has excellent thermal stability and polymerization stability, and even under high concentration conditions, oligomers such as humins, polymers, and by-products such as levulinic acid are unlikely to occur. Due to these characteristics, it is possible to produce alcohol with a lower amount of solvent used, that is, under conditions of higher concentration.

In addition, in the hydrogenation reaction of HMF, the presence of a base improves the stability of the cyclic acetal and suppresses side reactions such as polymerization of reaction intermediates and ring-opening reactions. The reaction may be carried out in the presence of a base because the yield may be improved in some cases. Examples of such bases include inorganic bases such as sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium hydroxide, potassium carbonate, and potassium hydrogen carbonate, and organic bases such as sodium alkoxide, potassium alkoxide, and triethylamine.

The amount of the base used when carrying out the hydrogenation reaction in the presence of a base is not particularly limited, but the lower limit is 0.01 equivalent or more, preferably 0.1 equivalent or more with respect to the HMF cyclic acetal, The upper limit is 5 equivalents or less, preferably 1 equivalent or less, and more preferably 0.5 equivalents or less. By using such an amount, the stability of the cyclic acetal can be improved and side reactions such as polymerization of reaction intermediates and ring-opening reactions can be suppressed, and the yield of the target alcohol can be improved. be able to.

The reaction temperature in the hydrogenation reaction is not particularly limited, but is usually 20°C or higher, preferably 50°C or higher, more preferably 90°C or higher, usually 350°C or lower, preferably 250°C or lower, more preferably 150°C or lower, and Preferably it is 120°C or lower. When the reaction temperature is within the above range, the target alcohol can be obtained in high yield. In particular, in the method using the acetal intermediate of the present invention, the process at high temperature is advantageous because the intermediate has excellent thermal stability.

The reaction time for hydrogenation is not particularly limited as long as the acetal intermediate can be hydrogenated to obtain the desired alcohol. The duration is usually 30 minutes or more, preferably 1 hour or more, more preferably 3 hours or more, and usually 24 hours or less, preferably 12 hours or less, and more preferably 5 hours or less. Note that when the hydrogenation reaction is carried out continuously, the reaction time is not limited to this.

The reaction apparatus used in hydrogenation is also not particularly limited, but usually a high-pressure reactor capable of high-pressure reaction is used. It is also possible to use a continuous reactor, and the reaction can also be carried out by filling the reactor with a catalyst and circulating the raw material liquid and hydrogen gas. In the case of a continuous reactor, a catalyst separation step is not necessary, and a continuous reactor is preferable for mass production.

[Product recovery method]
The products obtained in each of the above steps may be recovered by isolation and/or purification after the completion of the reaction, or may be used as raw materials for the next step without going through the isolation and/or purification steps. You can.

When using it as a raw material for the next step without isolation/purification, if the reaction is carried out in a batch reaction, the reaction solution after the completion of the reaction may be directly introduced into the reactor for the next step. Alternatively, the product may be extracted from the reaction solution after completion of the reaction using a different organic solvent, and the extracted solution may be introduced into the reactor for the next step. In addition, when the reaction is carried out by a flow reaction, the reaction liquid may be passed as it is to the reactor of the next step under the flow reaction process, and the reaction liquid is brought into contact with a different organic solvent to extract the product. After that, the extract may be introduced into a reactor for the next step.

On the other hand, when isolating/purifying the product obtained in each step, depending on the physical properties of the product, usually a solvent distillation method, a method of extracting with an organic solvent after solvent distillation, a distillation method, The product can be recovered by sublimation, crystallization, or chromatography. Among these, when the product is liquid under the handling temperature conditions, it is preferable to collect the product while purifying it by distillation, and when the product is solid under the handling temperature conditions, it is preferable to use crystallization. A method in which the product is recovered while being purified by a method is preferred. In addition, in this case, a preferred embodiment is a method in which the obtained solid product is purified by washing.

[Cyclic acetal]
A particularly preferable cyclic acetal in the present invention is a 1,3-propanediol acetal of FRL or HMF represented by the following formula (2) (hereinafter sometimes referred to as "cyclic acetal (2)"), as described above. In the dehydration and cyclic acetalization of 1,3-propanediol is used as the diol for cyclic acetalization.

(In the formula, A represents a hydrogen atom or -CH ₂ OH.)

As shown in Experimental Example 1 below, this cyclic acetal has excellent thermal stability and can be used as a raw material for the above-mentioned oxidative esterification to industrially advantageously produce carboxylic esters or carboxylic acids according to the present invention. can be manufactured.

Furthermore, in this cyclic acetal (2), when A is a -CH ₂ OH group, the hydroxyl group is replaced with a carboxylic acid anhydride ((R ² CO) ₂ O (R ² is an alkyl group having 1 to 6 carbon atoms, or represents an aryl group having 6 to 12 carbon atoms which may have an alkyl substituent), or an alcohol (R ² OH (R ² is an aryl group having 1 to 6 carbon atoms)). Represents an alkyl group or an aryl group having 6 to 12 carbon atoms which may have an alkyl substituent. It can be derived into an acetal intermediate with excellent thermal stability. The acetal intermediate represented by the following formula (3) replaces the hydroxyl group of HMF with carboxylic acid anhydride ((R ² CO) ₂ O (R ² is an alkyl group having 1 to 6 carbon atoms or an alkyl substituent) (represents ^an aryl group having 6 to ¹² carbon atoms which may have a It represents an aryl group having 6 to 12 carbon atoms which may have an alkyl substituent.) It may be one derived by converting it into an ether group by reaction with propanediol and then reacting with propanediol.

(In the formula, B is -CH ₂ OR ² or -CH ₂ O(C=O)R ² (R ² is an alkyl group having 1 to 6 carbon atoms, or may have an alkyl substituent. Represents an aryl group having 6 to 12 carbon atoms.)
In addition, when the above R ² is an aryl group having 6 to 12 carbon atoms which may have an alkyl substituent, examples of the alkyl substituent include an alkyl group having 1 to 6 carbon atoms.

That is, in consideration of the above formulas (2) and (3), in the present invention, a compound represented by the following formula (1) is mentioned as a preferable cyclic acetal intermediate.

In formula (1), R ¹ is a hydrogen atom, -CH ₂ OH, -CH ₂ OR ² or -CH ₂ O(C=O)R ² , and R ² has 1 to 6 carbon atoms. represents an alkyl group or an aryl group having 6 to 12 carbon atoms which may have an alkyl substituent. In addition, when R ² has an alkyl substituent, a preferable substituent is an alkyl group having 1 to 6 carbon atoms.

Hereinafter, the present invention will be explained in more detail using experimental examples and examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

[Experimental example 1-1: Evaluation of thermal stability of HMF and HMF acetal]

The thermal stability of HMF (manufactured by Sigma-Aldrich) and two types of HMF acetals (PD-HMF, EG-HMF) obtained by the method described in Experimental Example 7 below was evaluated by the following method. went.
Water contained in the sample was removed by introducing 3 to 4 mg of the sample into a pressure-resistant NMR tube and treating it at room temperature under vacuum evacuation for 2 hours. Thereafter, the tube was placed in an oven, and the temperature was raised from room temperature to 200°C at a rate of 10°C/min and held at 200°C for 2 hours. 1 mL of CDCl ₃ and an internal standard (benzoic acid, 1 mg) were added to the sample after heating, and the residual rate of the sample was analyzed by ¹ H NMR to evaluate thermal stability. The higher the residual rate, the better the thermal stability. The results are shown in Figure 1.

From FIG. 1, it can be seen that HMF acetal has superior thermal stability compared to HMF.

[Experimental example 1-2: Evaluation of thermal stability of FRL and FRL acetal]

The thermal stability of FRL (manufactured by Sigma-Aldrich) and FRL acetal (PD-FRL) obtained by the method described in Experimental Example 7 described below was evaluated by the same method as Experimental Example 1-1. As a result, the residual rate after 2 hours was 12% for FRL, while it was significantly improved to 80% for PD-FRL, indicating that the cyclic acetal has high thermal stability. .

[Experimental Example 1-3: Evaluation of thermal stability of ester and ether of PD-HMF]

The ester form (PD-HMF-acetate) and ether form (PD-HMF-ether) of HMF acetal (PD-HMF) obtained by the method described in Experimental Example 7 described later were treated in the same manner as in Experimental Example 1-1. As a result of evaluating the thermal stability using this method, the residual rate after 2 hours was 76% and 74%, respectively, and it was found that the thermal stability was superior to that of HMF.

[Experimental example 2: Temperature dependence of thermal decomposition of HMF acetal]
In Experimental Example 1, the residual rate of the heated sample was analyzed by ¹ H NMR in the same manner as in Example 1, except that PD-HMF was held at 150°C or 180°C for 2 hours, and the results were used in Experimental Example. The results of heating at 200°C in Example 1 are shown in Table 1 below.

From Table 1, it can be seen that there is no correlation between heating temperature and survival rate. Approximately 50% of the decomposition products of PD-HMF were HMF, which is a hydrolyzate of an acetal form due to water carried in the solvent.

[Experimental Examples 3-1 to 3-8: Yield evaluation of PD-HMF from HMF]
HMF (manufactured by Sigma-Aldrich, 50 mg), 1,3-propanediol (75 μL), and a catalyst were added to 2.5 mL of various solvents and stirred to perform a reaction to obtain PD-HMF. . Note that the catalyst, solvent, reaction temperature, and reaction time are as shown in Table 2. Note that the β-type zeolite used in Experimental Examples 3-4 to 3-7 was calcined at 550° C. for 8 hours in the air before use. Chlorobenzene was added as an internal standard to the solution after the reaction, and the produced PD-HMF was quantified by column gas chromatography ("GC2025" manufactured by Shimadzu Corporation) to determine the yield of PD-HMF. The column used was DB-FFAP (manufactured by Agilent Technologies). The results obtained are shown in Table 2.

[Experimental Example 4: Synthesis I of HMF acetal from monosaccharides derived from biomass raw materials]
An experiment was conducted to synthesize HMF acetal from glucose by changing the amount of catalyst using Nb ₂ O ₅ obtained by calcining hydrated niobic acid ("HY-340" manufactured by CBMM) at 400 ° C. for 4 hours as a catalyst. .

100 mg or 200 mg of Nb ₂ O ₅ and 20 mg of glucose were placed in a pressure-resistant glass container, and 1.8 mL of THF, 0.2 mL of water, and 0.2 mL of 1,3-propanediol were added thereto, and the container was sealed. The glass container was placed in an oil bath preheated to 125° C. and heated for 1 hour while stirring. After heating and stirring for 1 hour, the container was immediately introduced into cold water to stop the reaction, 25 μL of chlorobenzene was added as an internal standard, and the generated HMF and PD-HMF were analyzed by gas chromatography (Shimadzu Corporation: GC- 2025, column: DB-FFAP) to determine the yield relative to glucose, and the results are shown in Table 3.

From Table 3, No. 1 with a catalyst amount of 100 mg. No. 1 was 200 mg. It can be seen that sample No. 2 has a higher yield of PD-HMF.

[Experimental Example 5: Synthesis of HMF acetal from monosaccharides II]
Experiments were conducted to synthesize HMF acetal from glucose using the following catalysts and changing the catalyst.

Nb ₂ O ₅ : Nb ₂ O ₅ obtained by calcining hydrated niobic acid (“HY-340” manufactured by CBMM) at 400° C. for 4 hours.
H-BEA-25: Acid-type β-zeolite catalyst “H-BEA-25” manufactured by Clariant Catalysts
Amberlyst-15: Strong cation exchange resin “Amberlyst-15” manufactured by Sigma-Aldrich
TiO ₂ : Titanium oxide manufactured by Showa Titanium Co., Ltd. “JRC-TIO-11 (Catalysis Society of Japan, reference catalyst)”

200 mg of the catalyst shown in Table 4 and 20 mg of glucose were placed in a pressure-resistant glass container, and 1.4 mL of THF, 0.6 mL of water, and 0.2 mL of 1,3-propanediol were added thereto, and the container was sealed. The glass container was placed in an oil bath preheated to 125° C. and heated for 1 hour while stirring. After heating and stirring for 1 hour, the reaction was stopped by immediately introducing the container into cold water, and in the same manner as in Experimental Example 4, the produced HMF and PD-HMF were quantified by gas chromatography, and the yield relative to glucose was determined. The results are shown in Table 4.

Table 4 shows that Nb ₂ O ₅ is preferable as the catalyst.

[Experimental Example 6: Synthesis of HMF acetal from monosaccharide III]
Using Nb ₂ O ₅ obtained by calcining hydrated niobic acid ("HY-340" manufactured by CBMM) at 400°C for 4 hours as a catalyst, we conducted an experiment to synthesize HMF acetal by changing the raw material monosaccharide. .

200 mg of Nb ₂ O ₅ and 20 mg of glucose or fructose were placed in a pressure-resistant glass container, and 1.8 mL of THF, 0.2 mL of water, and 0.2 mL of 1,3-propanediol were added thereto, and the container was sealed. The glass container was placed in an oil bath preheated to 125° C. and heated for 2 hours while stirring. After heating and stirring for 2 hours, the reaction was stopped by immediately introducing the container into cold water, and in the same manner as in Experimental Example 4, the produced HMF and PD-HMF were quantified by gas chromatography, and the yield relative to glucose or fructose was determined. The ratio was determined and the results are shown in Table 5.

[Experiment Example 7: Synthesis of other samples]
<Synthesis of HMF acetate>
By adding 1.5 molar equivalents of acetic anhydride and 2 molar equivalents of triethylamine to an acetonitrile solution (0.1 mol/L) in which HMF (manufactured by Sigma-Aldrich) is dissolved, and stirring at room temperature for 1 hour. The hydroxyl group of HMF was converted to acetate. The obtained product was purified by column chromatography to obtain HMF acetate.

<Synthesis of EG-HMF>
HMF acetate obtained by the above method was dissolved in a dichloromethane solution (concentration of HMF acetate: 0.1 mol/L), and a catalytic amount (0.01 equivalent) of indium trifluoromethanesulfonate (In(OTf) ₃ ) was added thereto. By adding excess amounts of trimethyl orthoformate and ethylene glycol and stirring at room temperature, the aldehyde moiety bonded to the furan ring was converted into a cyclic acetal. Finally, the desired ethylene glycol-HMF acetal (EG-HMF) was obtained by reacting the product with sodium carbonate in a methanol solution to decompose the acetate moieties.

<Synthesis of PD-HMF>
HMF acetate obtained by the above method was dissolved in a dichloromethane solution (concentration of HMF acetate: 0.1 mol/L), and a catalytic amount (0.01 equivalent) of indium trifluoromethanesulfonate (In(OTf) ₃ ) was added thereto. By adding an excess amount of trimethyl orthoformate and 1,3-propanediol and stirring at room temperature, the aldehyde moiety bonded to the furan ring was converted to a cyclic acetal. Finally, the desired propanediol-HMF acetal (PD-HMF) was obtained by reacting the product with sodium carbonate in a methanol solution to decompose the acetate moiety.

<Synthesis of PD-HMF-ether>
To a mixed solution of HMF (manufactured by Sigma-Aldrich, 50 mg), methanol (2 mL), and 1,3-propanediol (0.1 mL), 0.01 molar equivalent of In(OTf) ₃ and an excess amount relative to HMF were added. of trimethyl orthoformate was added thereto, and the mixture was stirred at room temperature for 3 hours. The target PD-HMF-ether was obtained by separating the catalyst from the solution after the reaction and further purifying it by column chromatography.

<Synthesis of PD-HMF-acetate>
In a dichloromethane solution in which the HMF acetate obtained by the above method is dissolved (HMF acetate concentration: 0.1 mol/L), 0.01 molar equivalent of In(OTf) ₃ is added in excess to the HMF acetate. of trimethyl orthoformate and 1,3-propanediol were added and the solution was stirred at room temperature for 3 hours. The target PD-HMF-acetate was obtained by separating the catalyst from the solution after the reaction and further purifying it by column chromatography.

<Synthesis of PD-FRL>
Proton type beta zeolite (50 mg), furfural (manufactured by Sigma-Aldrich, 0.1 mmol), and 1,3-propanediol (75 μL) were added to 2 mL of dichloromethane, and the mixture was stirred at room temperature for 3 hours. After separating the solid catalyst by filtration, the target PD-FRL was obtained by purification by column chromatography.

[Example 1: Production of alcohol from biomass raw material via PD-HMF]
30 mg of PD-HMF synthesized based on Experimental Example 7 was dissolved in 3.5 ml of 1,3-propanediol, and hydrogen gas was heated to 8 MPa in an autoclave in the presence of 10 mg of a catalyst in which palladium (2% by mass) was supported on a zirconium oxide support. The hydrogenation reaction was carried out at 230° C. for 3 hours.
After the reaction was completed, the reaction solution was analyzed by gas chromatography (GC-2025, manufactured by Shimadzu Corporation, column: Rxi-35SilMS, manufactured by RESTEK). As a result, tetrahydrofuran-2,5-dimethanol accounted for 80% of the GC area ratio. It was produced with high selectivity, and there was little dirt attached inside the autoclave.

[Comparative Example 1: Production of alcohol from HMF derived from biomass raw material]
In the above alcohol production (Example 1), when the reaction was carried out in the same manner except that HMF (manufactured by Sigma-Aldrich) was used instead of PD-HMF, tetrahydrofuran-2,5-dimethanol was It was produced with a selectivity of 70%, and was characterized by a large number of unknown by-product species in the reaction solution. In addition, the reaction solution was significantly colored, and there was a lot of dirt deposited inside the autoclave.

[Example 2: Production of alcohol from biomass raw material via PD-HMF]
148 mg (0.80 mmol) of PD-HMF synthesized based on Experimental Example 7 was dissolved in 2 mL of water, and hydrogen gas was heated to 5 MPa in a high-pressure reactor in the presence of 50 mg of a catalyst in which gold (1% by mass) was supported on an aluminum oxide support. The hydrogenation reaction was carried out at 140° C. for 4 hours. Note that the pressure at 140°C was 7 MPa.
After the reaction was completed, the reaction solution was analyzed by gas chromatography, and the selectivity of flange methanol was 34%, and the amount of dirt deposited inside the high-pressure reactor was also small.

[Comparative Example 2: Production of alcohol from HMF derived from biomass raw material]
The reaction was carried out in the same manner as in the production of alcohol (Example 2) except that 100 mg (0.80 mmol) of HMF (manufactured by Sigma-Aldrich) was used instead of PD-HMF. As a result, the selectivity of furandimethanol was The reaction solution was colored deep yellow, and was characterized by a large number of unknown by-products in the solution.

The alcohol obtained by the present invention is industrially useful as a raw material alcohol for resins such as polyester resins, and in particular, tetrahydrofurandimethanol can provide resins with excellent heat resistance due to its cyclic skeleton. Its industrial value is extremely high.

Claims (9)

In a method for producing furandimethanol or tetrahydrofurandimethanol from a saccharide raw material derived from a biomass raw material, the first step is to produce hydroxymethylfurfural from the saccharide raw material, and the second step is to produce hydroxymethylfurfural from the hydroxymethylfurfural in the presence of a solid catalyst. A method for producing alcohol, which comprises producing an acetal intermediate of hydroxymethylfurfural, and then hydrogenating the acetal intermediate. The method for producing alcohol according to claim 1, wherein the alcohol is produced by hydrogenating the acetal intermediate using hydrogen gas. The method for producing alcohol according to claim 1 or 2, wherein the acetal intermediate is produced using a mixed solvent of water and an organic solvent. The method for producing alcohol according to any one of claims 1 to 3, wherein the acetal intermediate is a cyclic acetal. The method for producing alcohol according to claim 4, wherein the cyclic acetal is a 6-membered cyclic acetal. The method for producing alcohol according to any one of claims 1 to 5, wherein the hydrogenation is performed at 50°C or higher. 7. The method for producing alcohol according to claim 1, wherein the hydroxymethyl furafur obtained in the first step is purified before the second step. The method for producing alcohol according to any one of claims 1 to 7, wherein the acetal intermediate is represented by any one of the following formulas (1A) to (1D).

The method for producing alcohol according to any one of claims 1 to _{8, wherein the solid catalyst contains zeolite or Nb2O5 .}

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