One-pot synthesis of 2,5-hexanedione from catalytic conversion of biomass

Abstract

The present invention discloses a two-phase solvent system for converting biomass to prepare 2,5-hexanedione, and a one-pot synthesis for catalytically converting biomass to prepare 2,5-hexanedione using the two-phase solvent system. The method includes catalytically reacting a biomass feedstock with a hydrogenation catalyst to obtain 2,5-hexanedione in a heterogeneous system formed of an organic solvent, an inorganic salt and water, using hydrogen as a hydrogen source, and the hydrogenation catalyst includes a hydrogenation active component and a support, the support being selected from one or more of hydrophobic activated carbon and graphene. According to the method of the present invention, efficient conversion of biomass can be achieved without the involvement of an acid catalyst, and the selectivity of the product 2,5-hexanedione is very high.

Description

Detailed Description of the Invention

[0001] [Technical field] The present invention relates to the field of catalytic chemistry, and in particular to a method for the catalytic conversion of biomass to prepare 2,5-hexanedione.

[0002] [Background technology] In recent years, with the rapid consumption of fossil resources worldwide, the preparation of platform compounds and biofuels from biomass has become a hot topic in current research. Among the numerous platform compounds prepared from biomass, 2,5-hexanedione (HDO) has a wide range of potential applications. HDO is widely used in medicines, photographic reagents, pharmaceutical intermediates, electroplating and paint sprays, etc., and can be upgraded by chemical means to prepare a variety of chemical materials and fuels.

[0003] There are many methods for synthesizing 2,5-hexanedione. The traditional method is the Na / Et 2 Starting from ethyl acetoacetate under the action of O, 2This synthesis method involves coupling with 2,5-hexanedione and then decarboxylation under alkaline conditions. However, this method is expensive and unsafe to operate, leading to a high price for 2,5-hexanedione. Current research has focused on starting from biomass, since biomass is the only renewable organic carbon source. For example, the platform compound 5-hydroxymethylfurfural prepared from biomass is hydrolyzed and hydrogenated to prepare 2,5-hexanedione (Green Chemistry. 2016, 18, 3075-3081; Green Chemistry. 2016, 18, 2956-2960; ChemSusChem 2014, 7, 96-100; CN105693486A), and 2,5-dimethylfuran is hydrolyzed to prepare 2,5-hexanedione (CN105348056A; CN101423467B). However, the raw materials 5-hydroxymethylfurfural and 2,5-dimethylfuran used in the above preparation methods are expensive, making the preparation of 2,5-hexanedione high cost and low economic merit.

[0004] Jerome's research group (ChemSusChem 2014,7,96-100) used Pd / C as a hydrogenation catalyst and high-pressure CO as an acid catalyst. 2reported the catalytic preparation of 2,5-hexanedione from fructose in one step using , but the yield of 2,5-hexanedione was only 28%, and the raw material was limited to fructose. Later, Essayem's research group (Applied Catalysis A: General, 2015, 504, 664-671) reported the preparation of 2,5-hexanedione from cellulose using ZrW as a catalyst, but the yield of 2,5-hexanedione was only 24.5% at best, which is relatively low. CN109896938A discloses that the yield of 2,5-hexanedione can reach 65% by using virgin biomass as a raw material and liquid acid and supported precious metals as catalysts. However, in the above reaction, the use of liquid acid as a catalyst causes a certain degree of equipment corrosion, and the liquid acid used causes environmental pollution and high processing costs, which are major problems in industrial practical application. Therefore, there is a need for an efficient and green method for the efficient one-pot catalytic conversion of biomass to prepare 2,5-hexanedione.

[0005] Summary of the Invention The technical problem that the present invention aims to solve is the problem existing in the prior art, such as low catalytic efficiency or environmental pollution caused by liquid acid, therefore, the present invention provides a one-pot method for catalytically converting biomass to prepare 2,5-hexanedione, which can achieve efficient conversion of biomass without the involvement of acid catalyst and has a very high selectivity for the product 2,5-hexanedione.

[0006] In order to solve the above technical problems, the present invention provides a two-phase solvent system for converting biomass to prepare 2,5-hexanedione, the two-phase solvent system containing an organic solvent phase and an aqueous solution phase, the aqueous solution phase containing an anion selected from Group VIIA elements, the aqueous solution phase having a pH in the range of about 6.5 to about 8.5, preferably 7 to 8, and containing a hydrophobic hydrogenation catalyst for preparing 2,5-hexanedione from biomass.

[0007] The organic solvent phase and the aqueous solution phase form a two-phase solvent system. As an example, in one embodiment, the organic solvent phase can have a density lower than that of the aqueous solution phase, about 0.8 Kg / m 3 ~Approx. 0.95Kg / m 3 The range is.

[0008] In one embodiment, the aqueous phase further contains a cation derived from an element of Group IA that is equimolar to the anion derived from the element of Group VIIA and that is capable of forming an inorganic salt with the anion derived from the element of Group VIIA.

[0009] The elements of Group VIIA are halogen elements and the elements of Group IA are alkali metal elements, therefore the inorganic salts formed from their anions and cations are typically neutral and can exhibit a pH of about 7.

[0010] In one embodiment, the inorganic salt is a chloride or bromide. For example, the inorganic salt may be LiCl, NaCl, KCl, LiBr, NaBr, or KBr.

[0011] In the field, in the existing one-step process of catalytically converting biomass to 2,5-hexanedione, a liquid acid or acid salt is usually added to the reaction system to play a catalytic role together with the supported precious metal. That is, in the known conventional process, an acidic reaction environment is usually maintained. The present inventors, without being limited by known theories, have intensively studied and found that by introducing halogen anions into the reaction system and maintaining them at a constant concentration, and starting the reaction from a nearly neutral pH, it is possible to show excellent reactivity together with the supported precious metal.

[0012] A one-pot method for catalytically converting biomass to prepare 2,5-hexanedione includes catalytically reacting a biomass feedstock with a hydrogenation catalyst in a heterogeneous system formed from an organic solvent, an inorganic salt, and water, using hydrogen gas as a hydrogen source, to obtain 2,5-hexanedione, the hydrogenation catalyst including a hydrogenation active component and a support, the support being selected from one or more of hydrophobic activated carbon and graphene.

[0013] According to the invention, the organic solvent is selected from tetrahydrofuran, toluene, methyl isobutyl ketone, 1,4-dioxane, gamma-valerolactone, chloroform, 1,2-dichloroethane, and mixtures thereof.

[0014] According to the invention, the anions and cations in the inorganic salt are derived from elements of Group VIIA and Group IA, respectively, the elements of Group VIIA being selected from at least one of Cl and Br, and the elements of Group IA being selected from at least one of Li, Na, and K.

[0015] According to the present invention, the ratio of the weight of the organic solvent to the total weight of the inorganic salt and water is in the range of 2 to 16, preferably 3 to 10, and / or the ratio of the weight of the inorganic salt to the weight of water is 0.10 to 0.70, for example, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, and any range between two of them, preferably 0.20 to 0.70, more preferably 0.40 to 0.70, but not limited thereto. In the present invention, the weight ratio of the inorganic salt to water is 0.40 or more, and the effect of improving the selectivity of the product 2,5-hexanedione in the presence of the hydrophobic catalyst of the present invention is more remarkable.

[0016] According to the present invention, the weight ratio of the organic solvent to the biomass feedstock is in the range of 5-60, preferably 15-40.

[0017] According to the present invention, the hydrogenation active component is selected from one or more of ruthenium, platinum and palladium, preferably platinum and / or palladium, and is present in an amount ranging from 0.5% to 10%, preferably from 2% to 6%, in atomic terms, based on the weight of the hydrogenation catalyst on a dry basis.

[0018] According to the present invention, the support is present in an amount ranging from 90% to 99.5%, preferably from 94% to 98%, based on the weight of the hydrogenation catalyst on a dry basis.

[0019] According to the present invention, the contact angle between the hydrogenation catalyst and water is greater than 50°, preferably in the range of 55° to 90°, and more preferably in the range of 60° to 90°, examples of which include, but are not limited to, 55°, 60°, 65°, 70°, 75°, 80°, 85° and 90°.

[0020] According to the present invention, the biomass feedstock is one or more of cellulose, glucose, fructose, sucrose, inulin, starch, corn straw, corn cob, sugarcane bagasse, and the like.

[0021] According to the present invention, the hydrogen pressure in the reaction system is in the range of 0.2 MPa to 6 MPa, preferably 0.5 MPa to 3 MPa.

[0022] According to the present invention, the weight ratio of biomass feedstock to hydrogenation catalyst is (8-0.5):1, preferably (4-1):1, and / or the reaction temperature is in the range of 160°C-240°C, preferably 180°C-220°C, and / or the reaction time is in the range of 2 hours-16 hours, preferably 4 hours-12 hours.

[0023] According to the present invention, the carrier can be a hydrophobic carrier, which is prepared by using a high-temperature calcination process, specifically including calcining activated carbon and / or graphene at high temperature using an inert gas as a carrier gas to produce a hydrophobic carrier. In this process, the high-temperature calcination conditions are a calcination temperature of 400°C to 900°C and a calcination time of 3 hours to 12 hours.

[0024] According to the present invention, the hydrogenation catalyst can be prepared by an impregnation process (preferably an equal volume impregnation process), specifically, the process includes impregnating a carrier with an aqueous solution containing a hydrogenation active metal, followed by drying, calcination and reduction to produce a hydrogenation catalyst, and the aqueous solution containing a hydrogenation active metal can be blended with a soluble metal compound such as a nitrate, a chloride, an acetate and chloroplatinic acid. In the present invention, the impregnation conditions are not particularly limited. For example, the impregnation can be performed at room temperature for 1 hour to 10 hours. The drying can be performed by a conventional method, preferably, the drying temperature is in the range of 40°C to 90°C, and the drying time is in the range of 4 hours to 12 hours. The calcination can be performed by a conventional method, preferably, the calcination temperature is in the range of 300°C to 550°C, and the calcination time is in the range of 3 hours to 8 hours. The reduction can be performed using hydrogen gas, and the reduction conditions are preferably, the reduction temperature is in the range of 300°C to 450°C, and the reduction time is in the range of 3 hours to 6 hours.

[0025] According to the present invention, the reaction product is centrifuged to produce a 2,5-hexanedione-containing organic phase, which contains mainly 2,5-hexanedione and an organic solvent, which can then be separated by conventional methods such as rectification to produce 2,5-hexanedione.

[0026] Thus, the present invention provides the following exemplary embodiments: 1. A one-pot process for preparing 2,5-hexanedione by catalytic conversion of biomass, comprising: contacting a biomass feedstock with a hydrogenation catalyst in a heterogeneous system formed of an organic solvent, an inorganic salt and water, using hydrogen gas as a hydrogen source, to obtain 2,5-hexanedione; the hydrogenation catalyst comprises a hydrogenation active component and a support, and the support is selected from one or more of hydrophobic activated carbon and graphene.

[0027] 2. The method according to exemplary embodiment 1, wherein the organic solvent is selected from tetrahydrofuran, toluene, methyl isobutyl ketone, 1,4-dioxane, γ-valerolactone, chloroform, 1,2-dichloroethane, and mixtures thereof.

[0028] 3. The method according to exemplary embodiment 1 or 2, characterized in that the anions and cations in the inorganic salt are derived from elements of group VIIA and group IA, respectively, the elements of group VIIA being selected from at least one of Cl and Br, and the elements of group IA being selected from at least one of Li, Na, and K.

[0029] 4. The method according to exemplary embodiment 3, characterized in that the ratio of the weight of the organic solvent to the total weight of the inorganic salt and water is in the range of 2 to 16, preferably 3 to 10, and / or the weight ratio of the inorganic salt to water is in the range of 0.10 to 0.70, preferably 0.20 to 0.70, and further preferably 0.40 to 0.70.

[0030] 5. The method according to any one of exemplary embodiments 1 to 4, characterized in that the weight ratio of organic solvent to biomass feedstock is in the range of 5 to 60, preferably 15 to 40.

[0031] 6. A process characterized in that the hydrogenation active component is selected from one or more of ruthenium, platinum and palladium, preferably platinum and / or palladium, The method according to exemplary embodiment 1, wherein the hydrogenation active component is present in an amount ranging from 0.5% to 10%, preferably from 2% to 6%, in atomic terms, based on the weight of the hydrogenation catalyst.

[0032] 7. The method according to exemplary embodiment 1 or 6, characterized in that the contact angle between the hydrogenation catalyst and water is greater than 50°, preferably in the range of 55° to 90°.

[0033] 8. The method of exemplary embodiment 1, wherein the biomass feedstock is one or more of cellulose, glucose, fructose, sucrose, inulin, starch, corn straw, corn cob, and sugarcane bagasse.

[0034] 9. The method according to exemplary embodiment 1, wherein the hydrogen pressure in the reaction system is in the range of 0.2 MPa to 6 MPa, preferably 0.5 MPa to 3 MPa.

[0035] 10. The method according to any one of exemplary embodiments 1 to 9, characterized in that the weight ratio of biomass feedstock to hydrogenation catalyst is (8-0.5):1, preferably (4-1):1, and / or the reaction temperature is in the range of 160°C to 240°C, preferably 180°C to 220°C, and / or the reaction time is in the range of 2 hours to 16 hours, preferably 4 hours to 12 hours.

[0036] Compared with the prior art, the beneficial effects of the present invention include: In the present invention, cheap and widely available virgin biomass is used as the raw material. No acid catalyst is used in the reaction process, which avoids acid-related problems such as equipment corrosion, environmental pollution, and high processing costs. The process is simple and can convert biomass efficiently. The prepared 2,5-hexanedione product has very high selectivity, and the reaction system has excellent cycle stability, which is expected to have good industrial application.

[0037] Description of the drawings FIG. 1 is a diagram showing the results of measurement of the contact angle between the hydrogenation catalyst obtained in Example 1 and water; FIG. 2 is a diagram showing the results of measuring the contact angle between the hydrogenation catalyst obtained in Comparative Example 1 and water.

[0038] Detailed Description In this specification, unless otherwise specified, all technical features and preferred features mentioned in this specification with respect to the various aspects, various series and / or various embodiments can be combined with each other to form new technical solutions.

[0039] In this specification, unless otherwise specified, the specific steps, specific values, and specific materials described in the examples can be combined with other features in other parts of this specification. For example, if the "Summary of the Invention" or "Detailed Description" of this specification states that the reaction temperature is in the range of 10°C to 100°C, and the specific reaction temperature disclosed in the examples is 20°C, this specification can be considered to specifically disclose the range of 10°C to 20°C or the range of 20°C to 100°C, and this range can be combined with other features in other parts of this specification to form a new technical solution.

[0040] As used herein, unless otherwise specified, terms such as "comprising," "including," "containing," "having," and the like are in an open-ended manner, but it is also to be understood that these terms also disclose general descriptions in a closed-ended manner. For example, "comprising" indicates that other elements not listed may be inclusive, but also explicitly discloses the inclusion of only the listed elements.

[0041] In this specification, unless otherwise specified, the specific steps, specific values, and specific materials described in the examples can be combined with other features in other parts of this specification. For example, if the "Summary of the Invention" or "Detailed Description" of this specification states that the reaction temperature is in the range of 10°C to 100°C, and the specific reaction temperature disclosed in the examples is 20°C, this specification can be considered to specifically disclose the range of 10°C to 20°C or the range of 20°C to 100°C, and this range can be combined with other features in other parts of this specification to form a new technical solution.

[0042] In the present invention, the reaction product 2,5-hexanedione (HDO) is qualitatively analyzed by gas chromatography-mass spectrometry (GC-MS), and the yield of the product 2,5-hexanedione is analyzed by gas chromatography (GC). The gas chromatograph mass spectrometer is Agilent 7890A from Agilent, USA, and the chromatography column is HP-INNOWax capillary column (30 m, 0.53 mm), the gas chromatograph is Agilent 7890B, the detector is a flame ionization detector (FID), and the chromatography column is HP-INNOWax capillary column (30 m, 0.53 mm).

[0043] In the present invention, the calculation formula for the yield of the product 2,5-hexanedione is as follows: Yield% of product 2,5-hexanedione = (molar amount of 2,5-hexanedione produced in the reaction) / (molar amount of hexose units in the reactants) × 100%, where hexose units are C 6 H 10 O 5 It is.

[0044] In the present invention, the contact angle is measured using a measuring instrument model DSA100 manufactured by KRUSS, Germany. A tangent line from the intersection of the gas phase, the liquid phase, and the solid phase to the gas-liquid interface is plotted. The angle θ between the tangent line and the solid-liquid boundary passing through the three-phase contact point is the contact angle of the liquid on the solid surface. When the gas is air, the solid is a hydrogenation catalyst, and the liquid is water, the measured contact angle is the contact angle between the hydrogenation catalyst and water. A larger contact angle means a higher relative hydrophobicity of the hydrogenation catalyst.

[0045] In order to facilitate understanding of the present invention, the following examples are listed, but these examples are only used to aid in understanding the present invention and should not be considered as specific limitations of the present invention.

[0046] Example 1 First, 5 g of graphene sample was treated in an oven at 90 °C for 4 hours and then transferred to a high-temperature tube furnace. Nitrogen gas was introduced as a carrier gas, and the volumetric space velocity of the gas was set to 2 h -1 The temperature was increased to 750°C at a rate of 5°C and held for 8 hours to produce hydrophobic graphene (represented by Gr).

[0047] Preparation of catalyst 3% Pd / Gr: Palladium nitrate was impregnated into the above hydrophobic graphene by equal volume impregnation method. The impregnated amount was calculated according to the weight ratio of precious metal Pd:Gr of 3:100. The impregnated graphene was treated in an oven at 90 °C for 8 h and then transferred to a high-temperature tube furnace. Nitrogen gas was introduced as a carrier gas, and the volumetric space velocity of the gas was set to 2 h -1 The temperature was raised to 500°C at a rate of 10°C, held for 4 hours, and then lowered to room temperature to produce PdO / Gr. The carrier gas was switched to hydrogen gas, and the volumetric space velocity of the gas was set to 2h -1 The temperature was raised to 400°C at a rate of 10°C and held for 4 hours. After that, the carrier gas was switched back to nitrogen gas, and the temperature was lowered to room temperature to produce 3% Pd / Gr. Subsequent measurements showed that the contact angle between the catalyst and water was 64°, as shown in Figure 1, indicating that the catalyst has relatively good hydrophobicity.

[0048] Example 2 First, 5 g of activated carbon sample was treated in an oven at 90 °C for 4 hours and then transferred to a high-temperature tubular furnace. Nitrogen gas was introduced as a carrier gas, and the volumetric space velocity of the gas was set to 2 h -1 The temperature was raised to 700°C at a rate of 5°C and held for 8 hours to produce hydrophobic activated carbon (represented by C).

[0049] Preparation of catalyst 3% Pd / C: Palladium nitrate was impregnated into the above hydrophobic activated carbon by equal volume impregnation method. The impregnated amount was calculated according to the weight ratio of precious metal Pd:C of 3:100. The impregnated activated carbon was treated in an oven at 80 °C for 6 hours and then transferred to a high-temperature tubular furnace. Nitrogen gas was introduced as a carrier gas, and the volumetric space velocity of the gas was set at 2 h -1 The temperature was raised to 450°C at a rate of 10°C, held for 4 hours, and then lowered to room temperature to produce PdO / C. The carrier gas was switched to hydrogen gas, and the volumetric space velocity of the gas was set to 2h -1 The temperature was raised to 400°C at a rate of 10°C and held at that temperature for 4 hours. After that, the carrier gas was switched back to nitrogen gas, and the temperature was lowered to room temperature to produce 3% Pd / C. Subsequent measurements showed that the contact angle between the catalyst and water was 57°, which is similar to the contact angle in Figure 1 and indicates that the catalyst has relatively good hydrophobicity.

[0050] Example 3 First, 5 g of graphene sample was treated in an oven at 90 °C for 4 hours and then transferred to a high-temperature tube furnace. Helium gas was introduced as a carrier gas, and the volumetric space velocity of the gas was set to 2 h -1 The temperature was increased to 800°C at a rate of 5°C and held for 8 hours to produce hydrophobic graphene.

[0051] Preparation of catalyst 5% Pt / Gr: Chloroplatinic acid was impregnated into the above hydrophobic graphene by equal volume impregnation method. The impregnated amount was calculated according to the weight ratio of precious metal Pt:Gr of 5:100. The impregnated graphene was treated in an oven at 70 °C for 8 h and then transferred to a high-temperature tube furnace. Nitrogen gas was introduced as a carrier gas, and the volumetric space velocity of the gas was set to 2 h -1The temperature was raised to 500°C at a rate of 10°C, held for 4 hours, and then lowered to room temperature to produce PtO / Gr. The carrier gas was switched to hydrogen gas, and the volumetric space velocity of the gas was set to 2h -1 The temperature was raised to 350°C at a rate of 10°C and held for 5 hours. After that, the carrier gas was switched back to nitrogen gas, and the temperature was lowered to room temperature to produce 5% Pt / Gr. Subsequent measurements showed that the contact angle was 76°, which is similar to the contact angle in Figure 1 and indicates relatively good hydrophobicity.

[0052] Example 4 Glucose was used as a biomass feedstock. The weight ratio of glucose to the 3% Pd / Gr catalyst of Example 1 was 2:1, the weight ratio of organic solvent to glucose was 20:1, the weight ratio of organic solvent to NaCl and water was 8, and the weight ratio of NaCl to water was 0.50. 0.5 g of the catalyst 3% Pd / Gr of Example 1, 2.5 g of NaCl and water (weight ratio of NaCl to water was 0.50), 1.0 g of glucose, and 20 g of tetrahydrofuran as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held at this temperature for 8 hours, after which it was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was more than 99%, and the yield of 2,5-hexanedione was 62%.

[0053] Example 5 Glucose was used as a biomass feedstock. The weight ratio of glucose to the 3% Pd / C catalyst of Example 2 was 2:1, the weight ratio of organic solvent to glucose was 15:1, the weight ratio of organic solvent to NaCl and water was 6, and the weight ratio of NaCl to water was 0.42. 0.5 g of the catalyst 3% Pd / C of Example 2, 2.5 g of NaCl and water (weight ratio of NaCl to water was 0.42), 1.0 g of glucose, and 15 g of tetrahydrofuran as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held at this temperature for 8 hours, after which it was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was more than 99%, and the yield of 2,5-hexanedione was 58%.

[0054] Example 6 Glucose was used as a biomass feedstock. The weight ratio of glucose to the 5% Pt / Gr catalyst of Example 3 was 2:1, the weight ratio of organic solvent to glucose was 20:1, the weight ratio of organic solvent to NaCl and water was 8, and the weight ratio of NaCl to water was 0.25. 0.5 g of the catalyst 5% Pt / Gr of Example 3, 2.5 g of NaCl and water (weight ratio of NaCl to water was 0.25), 1.0 g of glucose, and 20 g of toluene as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held at this temperature for 8 hours, after which it was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was more than 99%, and the yield of 2,5-hexanedione was 52%.

[0055] Example 7 Glucose was used as a biomass feedstock. The weight ratio of glucose to the 3% Pd / C catalyst of Example 2 was 2:1, the weight ratio of organic solvent to glucose was 35:1, the weight ratio of organic solvent to NaCl and water was 5, and the weight ratio of NaCl to water was 0.28. 0.5 g of the catalyst 3% Pd / C of Example 2, 7.0 g of NaCl and water (weight ratio of NaCl to water was 0.28), 1.0 g of glucose, and 35 g of toluene as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held at this temperature for 8 hours, after which it was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was more than 99%, and the yield of 2,5-hexanedione was 48%.

[0056] Example 8 Glucose was used as a biomass feedstock. The weight ratio of glucose to the 5% Pt / Gr catalyst of Example 3 was 2:1, the weight ratio of organic solvent to glucose was 40:1, the weight ratio of organic solvent to NaCl and water was 7, and the weight ratio of NaCl to water was 0.26. 0.5 g of the 5% Pt / Gr catalyst of Example 3, 5.7 g of NaCl and water (weight ratio of NaCl to water was 0.26), 1.0 g of glucose, and 40 g of methyl isobutyl ketone as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held at this temperature for 8 hours, after which it was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was more than 99%, and the yield of 2,5-hexanedione was 55%.

[0057] Example 9 Glucose was used as a biomass feedstock. The weight ratio of glucose to the 3% Pd / Gr catalyst of Example 1 was 2:1, the weight ratio of organic solvent to glucose was 18:1, the weight ratio of organic solvent to KCl and water was 4, and the weight ratio of KCl to water was 0.55. 0.5 g of the 3% Pd / Gr catalyst of Example 1, 4.5 g of KCl and water (weight ratio of KCl to water was 0.55), 1.0 g of glucose, and 18 g of methyl isobutyl ketone as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held at this temperature for 8 hours, after which it was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was more than 99%, and the yield of 2,5-hexanedione was 62%.

[0058] Example 10 Glucose was used as a biomass feedstock. The weight ratio of glucose to the 5% Pt / Gr catalyst of Example 3 was 2:1, the weight ratio of organic solvent to glucose was 18:1, the weight ratio of organic solvent to KBr and water was 8, and the weight ratio of KBr to water was 0.24. 0.5 g of the 5% Pt / Gr catalyst of Example 3, 2.3 g of KBr and water (the weight ratio of KBr to water was 0.24), 1.0 g of glucose, and 18 g of 1,4-dioxane as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held at this temperature for 8 hours, after which it was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was more than 99%, and the yield of 2,5-hexanedione was 54%.

[0059] Example 11 Glucose was used as a biomass feedstock. The weight ratio of glucose to the 3% Pd / Gr catalyst of Example 1 was 2:1, the weight ratio of organic solvent to glucose was 25:1, the weight ratio of organic solvent to NaCl and water was 5, and the weight ratio of NaCl to water was 0.20. 0.5 g of the 3% Pd / Gr catalyst of Example 1, 5.0 g of NaCl and water (weight ratio of NaCl to water was 0.20), 1.0 g of glucose, and 25 g of 1,4-dioxane as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held at this temperature for 8 hours, after which it was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was more than 99%, and the yield of 2,5-hexanedione was 48%.

[0060] Example 12 Glucose was used as a biomass feedstock. The weight ratio of glucose to the 3% Pd / C catalyst of Example 2 was 2:1, the weight ratio of the organic solvent to glucose was 25:1, the weight ratio of the organic solvent to concentrated saline consisting of NaCl and water was 8, and the weight ratio of NaCl to water was 0.25. 0.5 g of the catalyst 3% Pd / C of Example 2, 3.1 g of NaCl and water (weight ratio of NaCl to water was 0.25), 1.0 g of glucose, and 25 g of γ-valerolactone as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, the reaction system was heated to 200°C, and kept at this temperature for 8 hours, then cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was more than 99%, and the yield of 2,5-hexanedione was 49%.

[0061] Example 13 Glucose was used as a biomass feedstock. The weight ratio of glucose to the 5% Pt / Gr catalyst of Example 3 was 2:1, the weight ratio of organic solvent to glucose was 20:1, the weight ratio of organic solvent to NaCl and water was 8, and the weight ratio of NaCl to water was 0.28. 0.5 g of the 5% Pt / Gr catalyst of Example 3, 2.5 g of NaCl and water (weight ratio of NaCl to water was 0.28), 1.0 g of glucose, and 20 g of chloroform as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held at this temperature for 8 hours, after which it was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was more than 99%, and the yield of 2,5-hexanedione was 53%.

[0062] Example 14 Glucose was used as a biomass feedstock. The weight ratio of glucose to the 3% Pd / C catalyst of Example 2 was 2:1, the weight ratio of organic solvent to glucose was 20:1, the weight ratio of organic solvent to NaCl and water was 8, and the weight ratio of NaCl to water was 0.30. 0.5 g of the catalyst 3% Pd / C of Example 2, 2.5 g of NaCl and water (weight ratio of NaCl to water was 0.30), 1.0 g of glucose, and 20 g of 1,2-dichloroethane as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held at this temperature for 8 hours, after which it was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was more than 99%, and the yield of 2,5-hexanedione was 52%.

[0063] Example 15 Glucose was used as a biomass feedstock. The weight ratio of glucose to the 3% Pd / C catalyst of Example 2 was 2:1, the weight ratio of organic solvent to glucose was 20:1, the weight ratio of organic solvent to NaCl and water was 8, and the weight ratio of NaCl to water was 0.55. 0.5 g of the catalyst 3% Pd / C of Example 2, 2.5 g of NaCl and water (weight ratio of NaCl to water was 0.55), 1.0 g of glucose, and 20 g of 1,2-dichloroethane as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held at this temperature for 8 hours, after which it was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was more than 99%, and the yield of 2,5-hexanedione was 61%.

[0064] In order to more intuitively explain the reaction conditions and results of Examples 4 to 15 described above, various parameters and results are shown in Table 1.

[0065] [Table 1]

[0066] [Examples 16 to 24] Into a high-pressure magnetically stirred batch reactor, the catalyst 3% Pd / Gr of Example 1, 4.0 g of NaCl and water (weight ratio of NaCl to water is 0.30), 1.0 g of glucose, and 30 g of tetrahydrofuran as an organic solvent were separately added. Hydrogen gas at a constant pressure was introduced, and the reaction system was heated to a constant temperature and maintained for a certain period of time. After the reaction was completed, the reaction system was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The yield of 2,5-hexanedione was calculated, and the results are shown in Table 2.

[0067] [Table 2]

[0068] [Examples 25 to 32] In a high-pressure magnetically stirred batch reactor, 0.5 g of the catalyst 3% Pd / C of Example 2, 4.0 g of NaCl and water (weight ratio of NaCl to water is 0.30), 0.5 g of different raw materials, and 20 g of tetrahydrofuran as an organic solvent were separately added. Hydrogen gas was introduced until the hydrogen pressure reached 1.5 MPa, and the reaction system was heated to 200°C and kept at this temperature for 8 hours. After the reaction was completed, the reaction system was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The yield of 2,5-hexanedione was calculated and the results are shown in Table 3.

[0069] [Table 3]

[0070] Example 33 A cycle stability test was carried out, and the operation procedure was as follows. The upper layer tetrahydrofuran solvent organic phase material of the reaction solution in Example 4 was directly separated and the yield of 2,5-hexanedione was analyzed. The remaining material in the lower layer was retained. Then, 1.0 g of glucose as a reaction substrate and 20 g of tetrahydrofuran solvent were fed into the reactor and involved in a new reaction. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200 ° C and held at this temperature for 8 hours. Then, the reaction system was cooled to room temperature and centrifuged to obtain a 2,5-hexanedione-containing organic phase, which was subjected to gas chromatography analysis. The yield of 2,5-hexanedione was calculated, and the cycle results are shown in Table 4. As a result, even when the cycle operation reached the fifth cycle, the yield of 2,5-hexanedione hardly changed, indicating that the cycle stability of the reaction system was good.

[0071] [Table 4]

[0072] Comparative Example 1 This example was carried out with reference to Example 12, except for the preparation of catalyst 3% Pd / DC: palladium nitrate was impregnated onto the untreated activated carbon (represented as DC) of Example 2 by equal volume impregnation method. The impregnated amount was calculated according to the weight ratio of precious metal Pd:DC of 3:100. The impregnated activated carbon was treated in an oven at 80°C for 6 hours, and then transferred to a high-temperature tube furnace. Nitrogen gas was introduced as a carrier gas, and the volumetric space velocity of the gas was 2 h -1 The temperature was raised to 450°C at a rate of 10°C, held for 4 hours, and then cooled to room temperature. The carrier gas was switched to hydrogen gas, and the volumetric space velocity of the gas was set to 2h -1 The temperature was increased to 400°C at a rate of 10°C and held for 4 hours. The carrier gas was then switched back to nitrogen gas and the temperature was decreased to room temperature to produce 3% Pd / DC. Subsequent measurements showed that the contact angle was about 28°, as shown in Figure 2, indicating that the material was relatively poorly hydrophobic.

[0073] Glucose was used as a biomass feedstock. The weight ratio of glucose to the 3% Pd / DC catalyst of Comparative Example 1 was 2:1, the weight ratio of organic solvent to glucose was 25:1, the weight ratio of organic solvent to NaCl and water was 8, and the weight ratio of NaCl to water was 0.25. 0.5 g of the catalyst 3% Pd / DC of Comparative Example 1, 3.1 g of NaCl and water (weight ratio of NaCl to water was 0.25), 1.0 g of glucose, and 25 g of γ-valerolactone as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held for 8 hours, then cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion rate of glucose was more than 99%, and the yield of 2,5-hexanedione was 25%.

[0074] Comparative Example 2 Glucose was used as a biomass feedstock. The weight ratio of glucose to the 3% Pd / Gr catalyst of Example 1 was 2:1, the weight ratio of the organic solvent to glucose was 20:1, the aqueous phase was deionized water, and the weight ratio of the organic solvent to the deionized water was 8. 0.5 g of the catalyst 3% Pd / Gr of Example 1, 2.5 g of deionized water, 1.0 g of glucose, and 20 g of tetrahydrofuran as an organic solvent were separately added to a high-pressure magnetic stirring batch reactor. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, the reaction system was heated to 200°C, and kept at this temperature for 8 hours, then cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion rate of glucose was 68%, and the yield of 2,5-hexanedione was 5%.

[0075] Comparative Example 3 In this example, the weight ratio of glucose to the 3% Pd / Gr catalyst in Example 1 was 2:1, the weight ratio of the organic solvent to glucose was 20:1, and the weight ratio of the organic solvent Na 2 SO 4 and a weight ratio of 8 to water, Na 2 SO 4 The procedure was carried out with reference to Example 4, except that the weight ratio of 3% Pd / Gr of the catalyst of Example 1 and 2.5 g of Na were added to a high-pressure magnetically stirred batch reactor. 2 SO 4 and water (Na 2 SO 4 The weight ratio of glucose to water was 0.50), 1.0 g of glucose, and 20 g of tetrahydrofuran as an organic solvent were added separately. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held at this temperature for 8 hours, after which it was cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was over 99%, and the yield of 2,5-hexanedione was 4%.

[0076] Comparative Example 4 In this example, the weight ratio of glucose to the 3% Pd / Gr catalyst in Example 1 was 2:1, the weight ratio of the organic solvent to glucose was 20:1, and the organic solvent was CaCl 2 and a weight ratio of 8 to water, CaCl 2 The procedure was carried out with reference to Example 4, except that the weight ratio of 3% Pd / Gr of the catalyst of Example 1 and 2.5 g of CaCl were added to a high-pressure magnetically stirred batch reactor. 2 and water (CaCl 2 The weight ratio of glucose to water was 0.50), 1.0 g of glucose, and 20 g of tetrahydrofuran as an organic solvent were added separately. Hydrogen gas was introduced until the hydrogen pressure reached 2 MPa, and the reaction system was heated to 200°C and held at this temperature for 8 hours. It was then cooled to room temperature and centrifuged to obtain an organic phase containing 2,5-hexanedione, which was subjected to gas chromatography analysis. The calculated conversion of glucose was over 99%, and the yield of 2,5-hexanedione was 27%.

[0077] Although the specific embodiments of the present invention have been described in detail above, the present invention is not limited thereto. Within the scope of the technical idea of ​​the present invention, many simple modifications can be made to the technical solutions of the present invention, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the disclosure of the present invention, and all should be regarded as belonging to the protection scope of the present invention. [Brief description of the drawings]

[0078] [Figure 1] FIG. 2 is a graph showing the results of measuring the contact angle between the hydrogenation catalyst obtained in Example 1 and water. [Diagram 2] FIG. 2 is a graph showing the results of measuring the contact angle between the hydrogenation catalyst obtained in Comparative Example 1 and water.

Claims

1. A two-phase solvent system for converting biomass to prepare 2,5-hexanedione, comprising a high pressure magnetically stirred batch reactor containing an organic solvent phase and an aqueous solution phase; The aqueous solution phase contains an anion selected from the group VIIA elements, and the pH of the aqueous solution phase is in the range of 6.5 to 8.5 at room temperature of 25° C.; the organic solvent phase contains a hydrophobic hydrogenation catalyst for the preparation of 2,5-hexanedione from biomass; A two-phase solvent system, wherein the aqueous solution phase further contains a cation derived from an element of Group IA in an equimolar amount with the anion derived from an element of Group VIIA and capable of forming an inorganic salt with the anion derived from an element of Group VIIA.

2. The two-phase solvent system according to claim 1, characterized in that the pH of the aqueous solution phase is in the range of 7 to 8 under room temperature conditions of 25°C.

3. 2. The two-phase solvent system of claim 1, wherein the Group VIIA elements are selected from at least one of Cl and Br and / or the Group IA elements are selected from at least one of Li, Na and K.

4. 2. The two-phase solvent system of claim 1, wherein the hydrophobic hydrogenation catalyst comprises a hydrogenation active component and a support, the support being selected from one or more of hydrophobic activated carbon and graphene.

5. The two-phase solvent system according to any one of claims 1 to 4, characterized in that the organic solvent of the organic solvent phase is selected from tetrahydrofuran, toluene, methyl isobutyl ketone, 1,4-dioxane, γ-valerolactone, chloroform, 1,2-dichloroethane, and mixtures thereof.

6. 6. The two-phase solvent system of claim 5, wherein the anion from a Group VIIA element and the cation from a Group IA element are added by adding an inorganic salt containing the anion and the cation, and wherein the ratio of the weight of the organic solvent in the organic solvent phase to the combined weight of the inorganic salt and water in the aqueous solution phase is in the range of 2 to 16 and / or the weight ratio of inorganic salt to water is 0.10 to 0.

70.

7. 6. The two-phase solvent system of claim 5, wherein the ratio of the weight of the organic solvent in the organic solvent phase to the combined weight of the inorganic salt and water in the aqueous solution phase is in the range of 3 to 10 and / or the weight ratio of inorganic salt to water is 0.40 to 0.

70.

8. 5. The two-phase solvent system of claim 4, wherein the hydrogenation active component is selected from one or more of ruthenium, platinum and palladium.

9. 5. The two-phase solvent system of claim 4, wherein the hydrogenation active component is present in an amount ranging from 0.5% to 10% by weight, in atomic terms, based on the weight of the hydrophobic hydrogenation catalyst on a dry basis.

10. 5. The two-phase solvent system of claim 4, wherein the hydrogenation active component is present in an amount ranging from 2% by weight to 6% by weight, in atomic terms, based on the weight of the hydrophobic hydrogenation catalyst on a dry basis.

11. The two-phase solvent system according to any one of claims 1 and 8 to 10, characterized in that the contact angle between the hydrophobic hydrogenation catalyst and water is greater than 50°.

12. The two-phase solvent system according to any one of claims 1 and 8 to 10, characterized in that the contact angle between the hydrophobic hydrogenation catalyst and water is in the range of 60° to 90°.

13. A two-phase solvent system characterized in that the organic solvent phase has a density lower than the density of the aqueous solution phase, for example, the organic solvent phase has a density of 0.8 Kg / m ３ ~0.95kg / m ３ The two-phase solvent system according to any one of claims 1 to 4, having a density in the range of

14. A one-pot process for catalytically converting biomass to prepare 2,5-hexanedione, comprising the steps of contacting a biomass feedstock with a hydrophobic hydrogenation catalyst using hydrogen gas as a hydrogen source in a two-phase solvent system as described in claim 1 to obtain 2,5-hexanedione.

15. 15. The method of claim 14, wherein no acid is added to the two-phase solvent system during the method.

16. 15. The method of claim 14, wherein no acid salt is added to the two-phase solvent system during the method.

17. 15. The method of claim 14, wherein the weight ratio of the organic solvent to the biomass feedstock is in the range of 5 to 60.

18. 15. The method of claim 14, wherein the weight ratio of the organic solvent to the biomass feedstock is in the range of 15 to 40.

19. 15. The method of claim 14, wherein the biomass feedstock is one or more of cellulose, glucose, fructose, sucrose, inulin, starch, corn straw, corn cob, and sugarcane bagasse.

20. The method according to claim 14, characterized in that in the two-phase solvent system, the hydrogen pressure is in the range of 0.2 MPa to 6 MPa.

21. The method according to claim 14, characterized in that in the two-phase solvent system, the hydrogen pressure is in the range of 0.5 MPa to 3 MPa.

22. 21. The method according to any one of claims 14 to 20, characterized in that the weight ratio of the biomass feedstock to the hydrophobic hydrogenation catalyst is (8-0.5):1, and / or the reaction temperature is in the range of 160°C to 240°C, and / or the reaction time is in the range of 2 hours to 16 hours.

23. 21. The method according to any one of claims 14 to 20, characterized in that the weight ratio of the biomass feedstock to the hydrophobic hydrogenation catalyst is (4-1):1, and / or the reaction temperature is in the range of 180°C to 220°C, and / or the reaction time is in the range of 4 hours to 12 hours.

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