Method for producing 5-hydroxymethylfurfural

Abstract

The present invention addresses the problem of providing conditions that enable industrial production in a method for producing 5-hydroxymethylfurfural from an aqueous solution of a saccharide such as glucose. The method comprises a step for heating an aqueous saccharide solution containing dimethyl sulfoxide and / or a polar protic organic solvent in the presence of a compound or the like in which a sulfonic acid group and a titanium oxide are covalently bonded, or a step for heating the aqueous saccharide solution by irradiating the aqueous saccharide solution with microwaves in the presence of a compound or the like in which a sulfonic acid group and a titanium oxide are covalently bonded.

Description

Technical Field

[0001] This invention relates to a compound useful as a catalyst for converting sugars such as glucose or fructose into 5-hydroxymethylfurfural (hereinafter sometimes referred to as "HMF" in this specification).

[0002] Furthermore, a method for producing HMF from aqueous solutions of sugars such as glucose and fructose using the aforementioned compound as a catalyst is provided. Background Technology

[0003] HMF is an important intermediate in the synthesis of chemicals from glucose, but its synthetic pathway is very complex. Glucose, as the starting material, undergoes skeletal isomerization in the presence of an acid catalyst to convert to fructose. The resulting fructose is then converted to HMF through a dehydration reaction in the presence of an acid catalyst. However, HMF is further hydrolyzed stepwise by the acid catalyst within the reaction system, transforming into organic acids (formic acid, levulinic acid, etc.). Therefore, a novel catalyst with high selectivity for the production of HMF is needed.

[0004] It is known that titanium phosphate oxide, in which phosphate residues are covalently bonded to the surface of amorphous aqueous titanium oxide, is obtained by treating amorphous aqueous titanium oxide with phosphoric acid. A solid Lewis acid containing this titanium phosphate oxide is then used as a catalyst for converting glucose or fructose into HMF (see Patent Document 1). Specifically, 0.05 g of the aforementioned titanium phosphate oxide is added to a glucose solution containing 0.2 mL of distilled water and 1.8 mL of tetrahydrofuran (THF) and 0.02 g (0.11 mmol) of D-glucose. The reaction is carried out at 20°C for 2 hours, yielding HMF with a conversion rate of 98% and a yield of 81.2%.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2012-108472 Summary of the Invention

[0008] However, using large amounts of THF as a solvent presents problems in industry, and the amount of organic solvent used should be minimized.

[0009] The objective of this invention is to provide conditions for industrial production of HMF in a method for manufacturing HMF from sugars such as glucose and fructose.

[0010] In order to solve the above-mentioned problems, the inventors conducted in-depth research and discovered a novel catalyst that can effectively convert sugars such as glucose and fructose. They found that using a mixed solvent of water and dimethyl sulfoxide and / or a polar protic organic solvent as the reaction solvent for the conversion of sugars such as glucose and fructose into HMF, and further carrying out the conversion of sugars such as glucose and fructose into HMF under microwave irradiation, can solve the above-mentioned problems and thus complete the present invention.

[0011] That is, the present invention relates to a compound formed by covalent bonding of a sulfonic acid group and a titanium oxide.

[0012] The preferred BET specific surface area of ​​the above compound is 200 m². 2 / g or more.

[0013] The preferred BET specific surface area of ​​the above compound is 300 m². 2 / g or less.

[0014] The above-mentioned compounds are preferably solid Lewis acids.

[0015] The above-mentioned compounds are preferably compounds that catalyze chemical reactions in aqueous solutions.

[0016] The above chemical reaction is preferably a dehydration reaction of sugars, and more preferably a reaction in which sugars produce 5-hydroxymethylfurfural.

[0017] Furthermore, the preferred sugars are glucose and / or fructose.

[0018] The present invention also relates to a method for manufacturing 5-hydroxymethylfurfural, comprising a step of heating an aqueous solution of sugars in the presence of the above-mentioned compound.

[0019] In addition, the present invention relates to a method A for manufacturing 5-hydroxymethylfurfural, comprising a step of heating an aqueous sugar solution A containing dimethyl sulfoxide (hereinafter sometimes referred to as "DMSO") and / or a polar protic organic solvent in the presence of the above-mentioned compound or in the presence of a compound formed by the covalent bonding of a phosphonoyl group with a titanium oxide.

[0020] In addition, the present invention relates to a method B for manufacturing 5-hydroxymethylfurfural, which includes a step of heating an aqueous sugar solution B by irradiation with microwaves in the presence of the above-mentioned compound or in the presence of a compound formed by covalent bonding of a phosphonoyl group and a titanium oxide.

[0021] The aforementioned aqueous solution B of sugars is preferably an aqueous solution containing dimethyl sulfoxide and / or a polar protic organic solvent.

[0022] The above-mentioned polar protic organic solvent is preferably an alcohol with 1 to 6 carbon atoms, and is further preferably an alcohol with 3 to 5 carbon atoms.

[0023] The sugars mentioned above are preferably glucose and / or fructose.

[0024] The compounds formed by the covalent bonding of the above phosphonoyl group with titanium oxide are preferably solid Lewis acids.

[0025] In addition, the present invention relates to a method for manufacturing the above-mentioned compound by treating titanium oxide with sulfuric acid.

[0026] The compounds and manufacturing methods of the present invention can significantly reduce the amount of organic solvents used, and are therefore suitable for industrial production of HMF. Detailed Implementation

[0027] The compounds of this invention are compounds formed by covalent bonding of a sulfonic acid group (-SO3H) with a titanium oxide. The titanium oxide is not particularly limited, but examples include crystalline titanium oxides such as rutile, anatase, and brookite; amorphous titanium oxides; hydrous titanium oxides such as orthotitanic acid and metatitanic acid; titanium hydroxide; composite oxides of titanium and dissimilar metals such as lithium titanate, barium titanate, and strontium titanate; and hydrolysis products of titanium oxide precursors. One type can be used alone, or two or more types can be used in combination.

[0028] The aforementioned titanium oxides may be doped with metallic elements (excluding titanium, the same applies below), or they may be undoped, or they may be coated with compounds containing metallic elements, or they may be uncoated. Examples of such metallic elements include aluminum, gallium, indium, thallium, magnesium, manganese, calcium, niobium, tantalum, zirconium, silicon, zinc, cerium, iron, tungsten, molybdenum, and vanadium.

[0029] When the titanium oxide is doped with a metal element, the doping rate of the metal element relative to the molar number of titanium atoms is preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 1 mol% or less, and particularly preferably 0.5 mol% or less.

[0030] The aforementioned titanium oxides can be obtained, for example, by hydrolyzing titanium oxide precursors.

[0031] Examples of titanium oxide precursors include inorganic titanium compounds such as titanium hydroxide, titanic acid, titanium trichloride, titanium tetrachloride, titanium tetrabromide, titanium sulfate, and titanium oxysulfate; titanium alkoxide compounds such as tetraisopropoxy titanium, tetra-n-butoxy titanium, tetra(2-ethylhexyloxy) titanium, and tetrastearoxy titanium; titanium acylate compounds; titanium chelate compounds such as diisopropoxybis(acetylacetone) titanium, isopropoxy(2-ethyl-1,3-hexanediol) titanium, and hydroxybis(lactic acid) titanium; organic acid titanium compounds such as titanium oxalate and titanium tetraacetate; and water-soluble titanium complexes. Preferably, the titanium oxide precursor is selected from at least one of titanium chloride, titanium oxalate, titanium sulfate, and titanium alkoxide.

[0032] The number of carbon atoms constituting the alkoxy group in the above-mentioned titanium alkoxide is preferably 1 to 6, more preferably 2 to 4. The alkoxy group can be any of the following: linear, branched, or cyclic.

[0033] The hydrolysis reaction of the above-mentioned titanium oxide precursor can be carried out by reacting the above-mentioned titanium oxide precursor with water in the presence of an acid catalyst or a base catalyst as needed.

[0034] The preferred temperature for the above hydrolysis reaction is 10–100°C, and more preferably 20–50°C.

[0035] The time required for the above hydrolysis reaction can be appropriately set according to the reaction temperature, reaction scale, etc., preferably 0.5 hours to 48 hours, more preferably 10 hours to 24 hours.

[0036] The above hydrolysis reaction can be repeated multiple times. Examples of acids used in the above hydrolysis reaction include hydrochloric acid, sulfuric acid, and nitric acid. Examples of bases used in the above hydrolysis reaction include ammonia, sodium hydroxide, and potassium hydroxide.

[0037] The mixing ratio of the above-mentioned titanium oxide precursor to the above-mentioned acid catalyst or the above-mentioned base catalyst is not particularly limited, but is generally preferred in the range of 1:0.1 to 1:10 in molar ratio, and more preferably in the range of 1:1 to 1:5.

[0038] Furthermore, for the above-mentioned hydrolysis reaction, the initial concentration of the titanium oxide precursor in the entire reaction mixture, including water, is preferably in the range of 1 to 50% by mass, and more preferably in the range of 10 to 20% by mass.

[0039] The hydrolysis products of the above-mentioned titanium oxide precursors are preferably amorphous hydrous titanium oxides.

[0040] Whether the aforementioned amorphous hydrated titanium oxide contains water molecules can be confirmed by surface measurement using an infrared spectrophotometer or by weight reduction caused by heating and dehydration under vacuum. Furthermore, its amorphous nature can be investigated using X-ray diffraction.

[0041] It should be noted that the term "amorphous" in this invention refers to amorphous portions that can be confirmed by X-ray diffraction, including not only cases where the entire amorphous hydrated titanium oxide is amorphous, but also cases where a portion is amorphous. Specifically, the amorphous pattern confirmed by X-ray diffraction refers to a wide wavy pattern that does not exhibit a clearly defined crystalline diffraction pattern.

[0042] The compounds of the present invention are compounds formed by covalent bonding of the above-mentioned sulfonic acid groups with titanium oxide. These compounds can be obtained, for example, by treating the above-mentioned titanium oxide with sulfuric acid.

[0043] Specifically, the above-mentioned sulfuric acid treatment can be carried out by immersing the titanium oxide in an aqueous sulfuric acid solution (e.g., a 0.5-2M aqueous sulfuric acid solution) and stirring.

[0044] The preferred temperature for the sulfuric acid treatment is in the range of 10°C to 100°C, and more preferably in the range of 20°C to 40°C.

[0045] The sulfuric acid treatment time is the time required to generate the desired compound. It is appropriately selected based on the treatment temperature and other conditions, preferably in the range of 1 hour to 96 hours, and more preferably in the range of 24 hours to 72 hours.

[0046] The above-mentioned titanium oxides treated with sulfuric acid can be dried by heating as needed. The heating temperature is not particularly limited, but a temperature sufficient to remove adhering water is preferred, preferably 100°C or higher. Furthermore, in the case of vacuum heating and drying, the temperature can be adjusted appropriately according to the degree of vacuum.

[0047] In FT-IR spectra, the above-mentioned titanium oxides without sulfuric acid treatment showed a value at 1180 cm⁻¹. －1 There are no peaks nearby, while the solid Lewis acid of this invention has a peak at 1180 cm⁻¹. －1 The presence of a stretching vibration signal (peak) from the S-O bond nearby indicates that the sulfonic acid group is covalently bonded to the hydroxyl group (Ti-OH) on the surface of the above-mentioned titanium oxide framework, forming the chemical structure Ti-O-SO2(OH).

[0048] Furthermore, the aforementioned compounds are preferably compounds that function as solid Lewis acids.

[0049] The compounds of the present invention can also be bonded to functional groups other than sulfonic acid groups. However, the sulfonic acid group is preferred as the functional group with the highest molar fraction among the functional groups covalently bonded to the above-mentioned titanium oxide, and the number of sulfonic acid groups in the total number of functional groups covalently bonded to the above-mentioned titanium oxide is preferably 60% or more in molar fraction, more preferably 80% or more, further preferably 95% or more, and particularly preferably 99% or more.

[0050] It should be noted that when the above-mentioned titanium oxide is bonded to both the sulfonic acid group and the phosphonoyl group, the titanium oxide is not titanium phosphate oxide, but is treated as a compound of the present invention.

[0051] The titanium oxides in the above compounds may be doped with a metal element or not, and may be coated with a compound containing a metal element or not. Examples of such metal elements include aluminum, gallium, indium, thallium, magnesium, manganese, calcium, niobium, tantalum, zirconium, silicon, zinc, cerium, iron, tungsten, molybdenum, and vanadium.

[0052] When the above-mentioned titanium oxide is doped with the above-mentioned metal element, the doping rate of the metal element relative to the titanium atoms is preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 1 mol% or less.

[0053] The BET specific surface area of ​​the compounds of the present invention is not particularly limited, but is preferably 100 m² for more efficient chemical reactions described later. 2 / g or more, more preferably 200m 2 / g or more. The inventors speculate that this is because the BET specific surface area is made 100m². 2 / g or more, which sufficiently increases the number of active sites that can come into contact with the objects that promote the chemical reactions described later (such as sugars like glucose and fructose).

[0054] From the viewpoint of superior durability (performance stability) when using catalysts for the chemical reactions described later, the BET specific surface area of ​​the compounds of the present invention is preferably 400 m². 2 / g or less, more preferably 300m 2 / g or less. The inventors speculate that this is because the BET specific surface area is made 400m². 2 With a particle size of less than / g, the catalyst of the present invention maintains a suitable pore size range, and substances generated or introduced into the pores can be released from the pores, thus easily maintaining the activity of the catalyst.

[0055] The BET specific surface area mentioned above was determined by adsorption-desorption isotherms based on nitrogen adsorption-desorption at -196°C, after nitrogen gas was adsorbed onto the surface of the target material (e.g., the compounds of the present invention) at liquid nitrogen temperature. The sample was treated at 150°C under vacuum for 3 hours prior to measurement. The analytical conditions are as follows.

[0056] [Measurement conditions]

[0057] Measurement Apparatus: High-speed specific surface area / porosity distribution measurement device BELSORP-mini2 (manufactured by MicrotracBEL)

[0058] Adsorbed gas: Nitrogen 99.99995% by volume

[0059] Adsorption temperature: Liquid nitrogen temperature (-196℃)

[0060] The compounds of the present invention can be used as catalysts for various chemical reactions. Since the catalytic activity of the compounds of the present invention is not deactivated in the presence of water molecules, they are particularly suitable as catalysts for promoting various chemical reactions in aqueous solutions. Examples of these various chemical reactions include dehydration reactions, allylation reactions, aldol condensation reactions, Michael addition reactions, alkylation reactions, isomerization reactions, and hydrolysis reactions. Among these, skeleton isomerization reactions of carbohydrates and dehydration reactions of carbohydrates are preferred examples. More specifically, reactions that generate HMF from carbohydrates are examples.

[0061] The aforementioned sugars can be D-forms, L-forms, or mixtures thereof. In the aforementioned mixtures, the content of D-forms relative to the total mass of D-forms and L-forms is preferably 20% by mass or more and less than 100% by mass, more preferably 90% by mass or more and less than 100% by mass, even more preferably 99% by mass or more and less than 100% by mass, and particularly preferably 99.9% by mass or more and less than 100% by mass.

[0062] Examples of the aforementioned sugars include allose, talose, gulose, glucose, adroose, mannose, galactose, idole, allulose, fructose, sorbitose, and tagatose, with glucose and fructose being preferred. These sugars can be used individually or in combination of two or more.

[0063] When using the compounds of the present invention as catalysts for various chemical reactions, the form of the compounds of the present invention is not limited, but is preferably particulate.

[0064] When the chemical reaction using the compound of the present invention is carried out intermittently, the particle size obtained by measuring the compound of the present invention using X-ray analysis (XRD) or small-angle X-ray scattering (SAXS) is preferably in the range of 1 nm to 250 nm, more preferably in the range of 3 to 50 nm, and even more preferably in the range of 5 to 10 nm.

[0065] When a chemical reaction using the compounds of the present invention is carried out in a flow manner, the lower limit of the volume average particle size of the compounds of the present invention can be appropriately selected according to the chemical reaction. From the viewpoint of reducing the back pressure of the column packed with catalyst particles, the lower limit of the volume average particle size of the compounds of the present invention is preferably 1 μm or more, more preferably 5 μm or more, further preferably 10 μm or more, even more preferably 20 μm or more, particularly preferably 30 μm or more, and most preferably 40 μm or more.

[0066] There is no particular limitation on the upper limit of the volume average particle size, which can be appropriately selected according to the chemistry. From the viewpoint of increasing the surface area per unit volume, the upper limit of the volume average particle size is preferably 500 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less. When the chemical reaction of the compound of the present invention is carried out in a flow reaction, the compound of the present invention can be granulated into particles with the required volume average particle size by granulation methods such as extrusion molding and rotary granulation, where the above-mentioned chemical reaction is carried out in a batch manner.

[0067] The production of HMF according to the present invention includes a step of heating an aqueous sugar solution in the presence of the compound of the present invention. Hereinafter, the above-mentioned aqueous sugar solution will also be referred to as the "reaction solution of the present invention", and the mixture in which the compound of the present invention is added to the reaction solution of the present invention will also be referred to as the "mixture of the present invention".

[0068] The above-mentioned HMF manufacturing method can be carried out in either batch or flow mode.

[0069] When the above-described HMF manufacturing method is carried out intermittently, the concentration of sugars in the mixture of this invention is not particularly limited. Relative to the volume of the mixture of this invention, it is preferably in the range of 0.01 to 90 wt / v, more preferably in the range of 1.0 to 85 wt / v, even more preferably in the range of 2.0 to 80 wt / v, and particularly preferably in the range of 3.0 to 70 wt / v.

[0070] When the above-described method for manufacturing HMF is carried out in a flow manner, the concentration of sugars in the reaction solution is preferably in the range of 0.5% to 50% by mass, more preferably in the range of 1% to 40% by mass, and even more preferably in the range of 5% to 30% by mass.

[0071] When the above-described HMF manufacturing method is carried out intermittently, the concentration of the above-described compounds in the mixture of this invention is not particularly limited, but is preferably in the range of 0.05 to 300% by mass relative to the above-described sugars, and more preferably in the range of 1 to 200% by mass.

[0072] When the above-described HMF manufacturing method is carried out in a batch or flow manner, the reaction temperature (i.e., the temperature at which the reaction solution of this invention comes into contact with the above-described compound; the same applies hereinafter in this specification) is preferably in the range of 80 to 180°C, and more preferably in the range of 100 to 170°C.

[0073] When the above-described method for producing HMF is carried out in an intermittent manner, the reaction time is the time during which the conversion rate of glucose or fructose, the yield of HMF, etc., show the desired values. The reaction time is appropriately selected according to conditions such as reaction temperature, preferably in the range of 10 minutes to 24 hours, and more preferably in the range of 2 hours to 6 hours.

[0074] When the above-described HMF manufacturing method is carried out in a flow manner, the reaction time is preferably in the range of 1 minute to 2 hours, and more preferably in the range of 5 minutes to 30 minutes.

[0075] It should be noted that when implementing the above-mentioned HMF manufacturing method, whether using a batch or flow method, a method that can carry out the reaction under high temperature and high pressure can be appropriately adopted.

[0076] Furthermore, the method A for manufacturing HMF of the present invention includes a step of heating an aqueous sugar solution A containing dimethyl sulfoxide and / or a polar protic organic solvent in the presence of the compound of the present invention or a compound formed by covalently bonding a phosphonoyl group (-PO3H2) with a titanium oxide (hereinafter sometimes referred to as "titanium phosphate oxide" in the specification). Hereinafter, the compound of the present invention and titanium phosphate oxide will be collectively referred to as "specific compounds" in this specification.

[0077] Hereinafter, the aqueous sugar solution A containing dimethyl sulfoxide and / or a polar protic organic solvent in the HMF manufacturing method A of the present invention will also be referred to as a "specific reaction solution," and the mixture in which a specific compound has been added to the specific reaction solution will also be referred to as a "specific mixture." It should be noted that, in this specification, the specific reaction solution and the specific mixture can be separated into an aqueous phase and an oil phase. The HMF manufacturing method described above can be carried out in either a batch or flow-type manner.

[0078] It should be noted that the above-mentioned titanium phosphate oxide can be manufactured by using phosphoric acid instead of sulfuric acid in the method for manufacturing the compound of the present invention.

[0079] Furthermore, the aforementioned titanium phosphate oxide also possesses the same properties as the compounds of the present invention, and its details are the same as those described above regarding the compounds of the present invention.

[0080] Whether the phosphonoyl group in the above-mentioned titanium phosphate compound is covalently bonded to the titanium oxide can be confirmed by the information recorded in International Publication No. 2012 / 108472.

[0081] When the above-described HMF manufacturing method A is carried out intermittently, the concentration of dimethyl sulfoxide in the above-described specific mixture is preferably in the range of 0.1 to 1.0 M, more preferably in the range of 0.2 to 0.8 M, even more preferably in the range of 0.3 to 0.7 M, and particularly preferably in the range of 0.4 to 0.6 M.

[0082] When the above-described HMF manufacturing method A is carried out in a flow manner, the concentration of dimethyl sulfoxide in the specific reaction solution is preferably in the range of 0.1 to 1.0 M, more preferably in the range of 0.2 to 0.8 M, even more preferably in the range of 0.3 to 0.7 M, and particularly preferably in the range of 0.4 to 0.6 M.

[0083] When the above-described HMF manufacturing method A is carried out intermittently, the content of the polar protic organic solvent in the above-described specific mixture is preferably in the range of 20 to 200 vol% relative to the total volume of the above-described specific mixture, more preferably in the range of 50 to 150 vol%, further preferably in the range of 70 to 130 vol%, and particularly preferably in the range of 80 to 120 vol%.

[0084] When the above-described HMF manufacturing method A is carried out in a flow manner, the content of the above-described polar protic organic solvent in the above-described specific reaction solution is preferably in the range of 20 to 200 vol% relative to the total volume of the above-described specific reaction solution, more preferably in the range of 50 to 150 vol%, further preferably in the range of 70 to 130 vol%, and particularly preferably in the range of 80 to 120 vol%.

[0085] Examples of polar protic organic solvents included in the aforementioned specific reaction solutions or mixtures include alcohols, aliphatic amines, alicyclic amines, amides, and carboxylic acids. One or more of these solvents may be used alone or in combination.

[0086] The aforementioned polar protic organic solvents are preferably alcohols with 1 to 6 carbon atoms. Examples of alcohols with 1 to 6 carbon atoms include methanol, ethanol, n-propanol, isopropanol, cyclopropanol, n-butanol, isobutanol, sec-butanol, cyclobutanol, n-pentanol, isopentanol, sec-pentanol, neopentanol, cyclopentanol, n-hexanol, isohexanol, sec-hexanol, 2,2-dimethyl-1-butanol, and cyclohexanol. Alcohols with 3 to 5 carbon atoms are preferred. They can be used alone or in combination of two or more.

[0087] Dimethyl sulfoxide and the aforementioned polar protic organic solvents can be used individually, but it is more preferable to use them in combination.

[0088] The specific mixture or reaction solution described above may or may not contain any components other than water, sugars, the compounds of the present invention, the aforementioned titanium phosphate oxide, dimethyl sulfoxide, and the aforementioned polar protic organic solvents (hereinafter also referred to as "other components"). The content of other components relative to the total mass of the specific mixture or reaction solution is preferably 0 to 200% by mass, more preferably 0 to 20% by mass, further preferably 0 to 5% by mass, and particularly preferably 0 to 1% by mass.

[0089] When the HMF manufacturing method A described above is carried out intermittently, the concentration of sugars in the specific mixture is not particularly limited. Relative to the volume of the specific mixture, it is preferably in the range of 0.01 to 90 wt / v, more preferably in the range of 1.0 to 85 wt / v, even more preferably in the range of 2.0 to 80 wt / v, and particularly preferably in the range of 3.0 to 70 wt / v.

[0090] When the above-described HMF manufacturing method A is carried out in a flow manner, the concentration of sugars in the specific reaction solution is preferably in the range of 0.5 to 50% by mass, more preferably in the range of 1 to 40% by mass, and even more preferably in the range of 5 to 30% by mass.

[0091] When the HMF manufacturing method A described above is carried out intermittently, the concentration of the specific compound in the specific mixture described above is not particularly limited, but is preferably in the range of 0.05 to 300% by mass relative to the sugars described above, and more preferably in the range of 1 to 200% by mass. It should be noted that the specific compound described above is a single compound of the present invention, a single titanium phosphate oxide described above, or a mixture of the compound of the present invention and the titanium phosphate oxide described above in an appropriate proportion.

[0092] When the above-described HMF manufacturing method A is carried out in an intermittent or flow manner, the reaction temperature is preferably in the range of 80 to 180°C, and more preferably in the range of 100 to 170°C.

[0093] When the above-described HMF manufacturing method A is carried out in an intermittent manner, the reaction time is the time during which the sugar conversion rate, HMF yield, etc., show the desired values. The reaction time is appropriately selected according to conditions such as reaction temperature, preferably in the range of 10 minutes to 24 hours, and more preferably in the range of 2 hours to 6 hours.

[0094] Furthermore, when the above-mentioned HMF manufacturing method A is carried out in a flow manner, the reaction time is preferably in the range of 1 minute to 2 hours, and more preferably in the range of 5 minutes to 30 minutes.

[0095] It should be noted that when implementing the above-mentioned HMF manufacturing method A, whether using a batch or a flow method, the reaction vessel can be a vessel capable of carrying out the reaction under appropriate high temperature and high pressure.

[0096] In addition, the HMF manufacturing method B of the present invention includes a step of heating the aqueous sugar solution B by irradiation with microwaves in the presence of the compound of the present invention or the above-mentioned titanium phosphate oxide.

[0097] Examples of chemical reaction apparatuses that carry out chemical reactions by irradiating the aforementioned microwaves include those disclosed in Japanese Patent Application Publication Nos. 2011-235262, 2011-235263, and 2011-240213.

[0098] The frequency of the microwaves used for irradiation can be arbitrarily set according to the set reaction temperature and reaction time. Specifically, it is preferably in the range of 300MHz to 300GHz, more preferably in the range of 900MHz to 50GHz, and more specifically, examples include 2.45GHz, 5.8GHz, 24GHz, and 913MHz. In addition, heating can be achieved by irradiating with microwaves of two or more frequencies.

[0099] The microwave irradiation output can be arbitrarily determined according to the type and scale of the reaction. Furthermore, the microwave irradiation method can be multimode or single-mode. Additionally, the microwave irradiation can be performed continuously or intermittently (discontinuously).

[0100] The microwave irradiation time is preferably 10-100% of the total reaction time, more preferably 50-100%, and even more preferably 80-100%.

[0101] Furthermore, in the above-described method B for manufacturing HMF, the reaction time is preferably in the range of 1 minute to 2 hours, and more preferably in the range of 5 minutes to 30 minutes.

[0102] It should be noted that in the above-mentioned method B for manufacturing HMF, the reaction vessel can be a vessel capable of carrying out the reaction under appropriate high temperature and high pressure.

[0103] The output of the microwaves described above can be adjusted appropriately to achieve the desired reaction temperature. Furthermore, in method B for manufacturing HMF described above, the heat source for the reaction can be microwaves alone, or it can be combined with other heat sources.

[0104] In the above-mentioned method B for manufacturing HMF, the above-mentioned aqueous sugar solution B preferably contains dimethyl sulfoxide and / or a polar protic organic solvent.

[0105] It should be noted that the amounts of dimethyl sulfoxide and the aforementioned polar protic organic solvents used, and the specific examples of the aforementioned polar protic organic solvents, are as described above.

[0106] In addition, the above-mentioned HMF manufacturing method B can be carried out in either batch or flow mode.

[0107] In the above-described methods B for manufacturing HMFs, the sugars used are as described above, with glucose and fructose being preferred examples. One type may be used alone, or two or more may be used in combination.

[0108] In the method for producing HMF of the present invention, and in methods A and B of the present invention, glucose undergoes skeletal isomerization with the compound of the present invention to become fructose, which is further converted into HMF through a stepwise dehydration reaction. Since the compound of the present invention does not deactivate in aqueous solvents and thus functions, it can be used as a catalyst for chemical reactions in aqueous solutions.

[0109] It is speculated that the compounds of the present invention increase the Brønsted acid effect by giving the above-mentioned titanium oxides a sulfonic acid group, and can promote the dehydration reaction even without the use of DMSO or the above-mentioned polar protic organic solvents, thus becoming compounds with good reactivity.

[0110] Furthermore, it is speculated that in the HMF manufacturing method of the present invention and in HMF manufacturing methods A and B of the present invention, by using DMSO and the above-mentioned polar protic organic solvent, the activation energy of the dehydration reaction can be reduced, thereby making the reaction easier to carry out.

[0111] The present invention will now be described in more detail with reference to embodiments, but the scope of the invention is not limited to the embodiments.

[0112] (High-performance liquid chromatography (HPLC) determination method)

[0113] Analysis was performed using a photodiode array (PDA; 254nm, 283nm) and a refractive index (RI) detector under the following conditions.

[0114] HPLC; LC-2000 (Jasco)

[0115] Aminex HPX-87H column (7.8mm diameter × 300mm, Bio-Rad Laboratories Inc. Co. Ltd.)

[0116] Eluent (a 100-fold dilution of 0.5 mmol / L M H₂SO₄ and 0.5 mol / L sulfuric acid (1N) reagent solution (Kanto Chemical Cat. No. 37880-08))

[0117] Flow rate (0.5 mL / min)

[0118] Column temperature (308K)

[0119] The sample was diluted with water and injected into 10 μL for measurement. The retention time of HMF was 41.7 minutes. Quantification was performed using the calibration curve method.

[0120] Unless otherwise specified, all treatments and procedures in the following experiments were carried out at 25°C.

[0121] Example 1

[0122] 36 g of anatase titanium oxide (product name: ST-01, manufactured by Ishihara Kogyo Co., Ltd., X-ray particle size: 7 nm) was added to 1800 ml of 1M sulfuric acid aqueous solution and stirred for 48 hours. The reaction solution was filtered, and the residue was washed with distilled water until the pH of the filtrate was 3-4. The resulting white solid was dried at 120°C for 16 hours to obtain 32 g of a compound covalently bonded to sulfonic acid groups and titanium oxide as a white solid (the pH mentioned above is the pH at 25°C). The BET surface area of ​​the obtained compound was measured and found to be 280 m². 2 / g.

[0123] FT-IR spectra were measured, and the results confirmed that the above-mentioned titanium oxides without sulfuric acid treatment exhibited a fluorescence intensity at 1180 cm⁻¹. －1 There are no peaks nearby, while the compound of this invention has a peak at 1180 cm⁻¹. －1 The presence of a stretching vibration signal (peak) from the S-O bond nearby indicates that the sulfonic acid group is covalently bonded to the hydroxyl group (Ti-OH) on the surface of the above-mentioned titanium oxide framework, forming the chemical structure Ti-O-SO2(OH).

[0124] [Reference Example]

[0125] Add 18 ml of nitric acid (specific gravity 1.38) and 36 g of anatase titanium oxide (product name: ST-01, manufactured by Ishihara Kogyo Co., Ltd., X-ray particle size: 7 nm) to 1800 ml of 1M phosphoric acid aqueous solution, and stir for 48 hours. Filter the reaction solution and wash the residue with distilled water until the pH of the filtrate is 3-4. Dry the resulting white solid at 120°C for 16 hours to obtain 32 g of a solid Lewis acid covalently bonded to phosphonyl groups and titanium oxide. Measure the BET surface area of ​​the obtained solid Lewis acid; the result is 290 m². 2 / g.

[0126] Example 2

[0127] A 5 ml mixture was prepared using 1.0 g of the compound obtained in Example 1, 0.5 g of D-glucose, and distilled water. This mixture was then placed in a pressure-resistant glass container and sealed. Next, while maintaining the sealed container, the mixture was heated at 120°C for 4 hours with stirring. The resulting reaction solution was quantified using high-performance liquid chromatography (HPLC), confirming the presence of HMF at 94 mM. However, during HPLC quantification, the compound obtained in Example 1 was removed from the reaction solution beforehand by filtration. Therefore, the HMF concentration in the reaction solution was the same as the concentration of HMF in the reaction solution after removing the compound from Example 1, as was also observed in the following experimental examples.

[0128] It should be noted that in the solution described in this embodiment, the amount of the compound obtained in Example 1 is 200% by mass relative to the total mass of D-glucose, and the amount of D-glucose is 10% by mass / volume relative to the volume of the mixed solution described above.

[0129] Example 3

[0130] In Example 2, 2.2 mmol of dimethyl sulfoxide (DMSO) was further added to the mixed solution (equivalent to a DMSO concentration of 0.43 M in the solution with added DMSO). Otherwise, the same procedure as in Example 2 was performed, and it was confirmed that HMF was obtained in the reaction solution at 108 mM.

[0131] Example 4

[0132] 5 ml of n-butanol was further added to the mixed solution in Example 2, and otherwise the same procedure was followed as in Example 2 to obtain HMF at 148 mM.

[0133] It should be noted that the reaction solution is separated into an aqueous phase and an oil phase, but the concentration of HMF obtained in the reaction solution mentioned here is the overall concentration of the reaction solution as a whole separated into aqueous and oil phases (i.e., the average concentration of the aqueous and oil phases). The same applies to the following cases where the reaction solution is separated into aqueous and oil phases.

[0134] Example 5

[0135] The amount of added D-glucose was changed to 1.25 g, but otherwise the same procedure was followed as in Example 4, and HMF was obtained at 271 mM in the reaction solution.

[0136] Example 6

[0137] The added D-glucose was changed to 2.0g, but otherwise the same procedure as in Example 4 was followed to obtain HMF at 382mM.

[0138] Example 7

[0139] 2.2 mmol of dimethyl sulfoxide (DMSO) and 5 ml of n-butanol were further added to the mixed solution in Example 2, and otherwise the same procedure was followed as in Example 2 to obtain HMF at 150.1 mM.

[0140] Example 8

[0141] The amount of added D-glucose was changed to 1.25g, but otherwise the procedure was the same as in Example 7, and HMF was obtained at 285.5mM.

[0142] Example 9

[0143] The added D-glucose was changed to 2.0g, but otherwise the same procedure was followed as in Example 7 to obtain HMF at 390.4mM.

[0144] Example 10

[0145] The compound obtained in Example 1 was packed into a cylindrical pressure-resistant column with an inner diameter of 7.6 mm and a height of 150 mm, and the temperature was maintained at 160 °C. A 25% (w / w) aqueous glucose solution (reaction solution) was passed through the cylindrical pressure-resistant column at a flow rate of 0.5 mL / min for 4 hours. The flow was repeated once. The reaction solution after the flow was quantified by high-performance liquid chromatography, confirming the yield of HMF at 125 mM.

[0146] It should be noted that in this embodiment, the average contact time between the reaction solution and the compound of the present invention was 13.6 minutes.

[0147] Example 11

[0148] A 5 ml mixture was prepared using 1.0 g of the compound obtained in Example 1, 2.0 g of D-glucose, and distilled water. The resulting mixture was placed in a pressure-resistant glass container and sealed. Next, while maintaining the sealed container, the mixture was irradiated with a 2.45 GHz microwave for 10 minutes with stirring. The microwave output was set so that the temperature of the irradiated mixture was 160 °C. The reaction solution was quantified using high-performance liquid chromatography (HPLC), and HMF was obtained at 271 mM in the reaction solution.

[0149] It should be noted that in the mixed solution of this embodiment, the amount of the compound of the present invention is 50% by mass relative to the total mass of D-glucose, and the amount of D-glucose is 40 by mass / volume relative to the total volume of the mixed solution.

[0150] Example 12

[0151] 2.2 mmol of dimethyl sulfoxide (DMSO) (equivalent to a concentration of 0.43 M in the above mixed solution) was further added to the mixed solution in Example 11, otherwise the same procedure was performed as in Example 11 to obtain HMF at 392 mM.

[0152] Example 13

[0153] 5 ml of n-butanol was further added to the mixed solution in Example 11, and otherwise the same procedure was followed as in Example 11 to obtain HMF at 485 mM.

[0154] Example 14

[0155] The added D-glucose was changed to 0.5g, and 5ml of n-butanol was added. Otherwise, the process was the same as in Example 11 to obtain HMF at 170mM.

[0156] Example 15

[0157] The added D-glucose was changed to 1.25g, and 5ml of n-butanol was added. Otherwise, the procedure was the same as in Example 11 to obtain HMF at 322mM.

[0158] Example 16

[0159] Add 1 g of the compound obtained in the reference example, 0.5 g of D-glucose, and distilled water to prepare a 5 mL solution. Further add 5 mL of n-butanol. Place the resulting mixture into a pressure-resistant glass container and seal it. React the mixture at 120 °C for 4 hours while stirring. Quantify the reaction solution using high-performance liquid chromatography (HPLC), and the result is HMF at 148.8 mM.

[0160] Example 17

[0161] 2.2 mmol of dimethyl sulfoxide (DMSO) was further added to the mixed solution in Example 16, otherwise the same procedure was followed as in Example 16 to obtain HMF at 180.9 mM.

[0162] Example 18

[0163] Using the compound obtained in the reference example, HMF was added to a 25% glucose aqueous solution at a concentration of 0.43 M in the overall solution containing DMSO, otherwise the same procedure as in Example 10 was followed to obtain HMF at 151 mM.

[0164] Example 19

[0165] D-fructose was used instead of D-glucose, otherwise the procedure was the same as in Example 2, and HMF was obtained at 154.2 mM.

[0166] <Comparative Example 1>

[0167] Using the compound obtained in the reference example, except as in Example 10, HMF was obtained at 113 mM.

[0168] <Comparative Example 2>

[0169] D-fructose was used instead of D-glucose, and anatase titanium dioxide (product name: ST-01, manufactured by Ishihara Kogyo Co., Ltd., X-ray particle size: 7 nm) was used instead of the compound obtained in Example 1. Otherwise, the same procedure as in Example 2 was followed to obtain HMF at 89.8 mM.

[0170] <Comparative Example 3>

[0171] Anatase titanium dioxide (product name: ST-01, manufactured by Ishihara Kogyo Co., Ltd., X-ray particle size: 7 nm) was used instead of the compound obtained in Example 1. Otherwise, the same procedure as in Example 4 was followed to obtain HMF at 55.3 mM.

[0172] <Comparative Example 4>

[0173] Using tetrahydrofuran instead of n-butanol, heating at 70°C, otherwise the process was the same as in Example 4, to obtain HMF at 0.5 mM.

[0174] Industrial availability

[0175] The method for manufacturing HMF of the present invention is useful for the industrial production of HMF from sugars such as glucose.

Claims

1. A compound formed by the covalent bonding of a sulfonic acid group and a titanium oxide.

2. The compound according to claim 1, wherein, The compound has a BET specific surface area of ​​200 m². 2 / g or more.

3. The compound according to claim 1 or 2, wherein, The compound has a BET specific surface area of ​​300 m². 2 / g or less.

4. The compound according to claim 1 or 2, wherein, The compound is a solid Lewis acid.

5. The compound according to claim 1 or 2, wherein, The compound is a catalytic compound that catalyzes chemical reactions in aqueous solutions.

6. The compound according to claim 5, wherein, The chemical reaction is a dehydration reaction of carbohydrates.

7. The compound according to claim 5, wherein, The chemical reaction is the reaction in which sugars are converted into 5-hydroxymethylfurfural.

8. The compound according to claim 6, wherein, The sugars are glucose and / or fructose.

9. The compound according to claim 7, wherein, The sugars are glucose and / or fructose.

10. A method for producing 5-hydroxymethylfurfural, comprising the step of heating an aqueous solution of sugars in the presence of the compound of claim 1 or 2.

11. A method for producing 5-hydroxymethylfurfural, comprising the step of heating an aqueous solution of a sugar containing dimethyl sulfoxide and / or a polar protic organic solvent in the presence of the compound of claim 1 or 2 or in the presence of a compound formed by covalent bonding of a phosphonoyl group with a titanium oxide.

12. A method for producing 5-hydroxymethylfurfural, comprising the step of heating an aqueous solution of sugar by microwave irradiation in the presence of the compound of claim 1 or 2 or in the presence of a compound formed by covalent bonding of a phosphonoyl group with a titanium oxide.

13. The method for manufacturing 5-hydroxymethylfurfural according to claim 12, wherein, The aqueous solution of the sugar is an aqueous solution containing dimethyl sulfoxide and / or a polar protic organic solvent.

14. The method for manufacturing hydroxymethylfurfural according to claim 11, wherein, The polar protic organic solvent is an alcohol with 1 to 6 carbon atoms.

15. The method for producing hydroxymethylfurfural according to claim 13, wherein, The polar protic organic solvent is an alcohol with 1 to 6 carbon atoms.

16. The method for manufacturing 5-hydroxymethylfurfural according to claim 11, wherein, The polar protic organic solvent is an alcohol with 3 to 5 carbon atoms.

17. The method for manufacturing 5-hydroxymethylfurfural according to claim 13, wherein, The polar protic organic solvent is an alcohol with 3 to 5 carbon atoms.

18. The method for manufacturing 5-hydroxymethylfurfural according to claim 10, wherein, The sugars are glucose and / or fructose.

19. The method for producing 5-hydroxymethylfurfural according to claim 11, wherein, The sugars are glucose and / or fructose.

20. The method for manufacturing 5-hydroxymethylfurfural according to claim 12, wherein, The sugars are glucose and / or fructose.

21. The method for manufacturing 5-hydroxymethylfurfural according to claim 11, wherein, The compound formed by the covalent bonding of the phosphonoyl group and titanium oxide is a solid Lewis acid.

22. The method for manufacturing 5-hydroxymethylfurfural according to claim 12, wherein, The compound formed by the covalent bonding of the phosphonoyl group and titanium oxide is a solid Lewis acid.

23. The method for manufacturing the compound according to claim 1 or 2, wherein, Titanium oxides were treated with sulfuric acid.