Method for preparing HMF through catalytic conversion

Abstract

The invention belongs to the technical field of compound preparation, and particularly discloses a method for preparing HMF through catalytic conversion. According to the method, starch-based non-grain biomass is used as a raw material, and the HMF is prepared through catalytic conversion in a reaction solvent of water / an organic solvent under the action of a combined catalyst. The starch-based non-grain biomass is used as the raw material, the raw material cost is low, the economic benefit is high, and the HMF can be obtained at high yield.

Description

Technical Field

[0001] The invention belongs to the technical field of compound preparation, and particularly relates to a method for preparing HMF through catalytic conversion. Background Art

[0002] Biomass energy is a renewable new energy source that is expected to replace fossil energy. Among them, carbohydrates show broad application prospects. For example, 5-hydroxymethylfurfural (HMF) prepared by dehydration of hexose is a bio-based precursor of many industrially valuable chemicals, especially its oxidation product FDCA can be used as a polymer monomer to produce environmentally friendly PEF plastics with strong barrier properties.

[0003] At present, the main way to produce HMF from carbohydrates in industry is to use fructose as raw material and dehydrate it. The raw material is expensive and the production cost is high. In the process of preparing HMF from relatively cheap glucose, since Bronsted acid is not easy to catalyze the conversion of glucose into HMF, it is inevitable to first isomerize it into fructose, which leads to a low yield of HMF produced from glucose.

[0004] Therefore, providing a method for efficiently preparing HMF from biomass raw materials with greater commercial value is a prerequisite for the widespread commercial use of its derived downstream products, which is expected to reduce the cost of industrial production and enhance the competitiveness of HMF downstream products. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing HMF by catalytic conversion, using starch-based non-food biomass as raw material, the raw material is cheap and widely available, and the HMF product can be prepared efficiently, with low raw material cost and high economic benefit.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions.

[0007] The present invention provides a method for preparing HMF by catalytic conversion, which uses starch-based non-food biomass as raw material, and catalytic conversion is performed in a water / organic solvent reaction solvent under the action of a combined catalyst to prepare HMF;

[0008] Wherein, the starch-based non-food biomass is selected from any one or more of cassava dry powder, cassava starch, konjac dry powder, grass jelly, and kudzu vine.

[0009] As an embodiment of the present invention, the starch-based non-food biomass is selected from any one or more of cassava dry powder, cassava starch, and konjac dry powder.

[0010] Preferably, the starch-based non-food biomass is cassava powder or cassava starch.

[0011] As an embodiment of the present invention, the starch-based non-food biomass is used as a reaction raw material after being pretreated; preferably, the pretreatment is a gelatinization treatment.

[0012] Further preferably, the gelatinization process comprises:

[0013] The starch-based non-food biomass is stirred and mixed with water to prepare a raw material liquid;

[0014] The raw material liquid is kept at 75-85° C. for 0.5-2 hours to obtain a raw material gelatinized material;

[0015] The raw material gelatinized material is used to prepare HMF.

[0016] As an embodiment of the present invention, when preparing the raw material liquid, the starch-based non-food biomass and water are mixed at a mass ratio of water: starch-based non-food biomass = (0.5-10):1, preferably at a mass ratio of water: starch-based non-food biomass = (2-6):1, and more preferably at a mass ratio of water: starch-based non-food biomass = (2-3):1.

[0017] As an embodiment of the present invention, the catalytic conversion reaction is carried out in a closed reactor, and the reaction temperature is controlled at 130° C. to 150° C., preferably at 140° C.; and / or,

[0018] The reaction time is 30 to 120 min, preferably 50 to 80 min, and more preferably 60 min.

[0019] As an embodiment of the present invention, the organic solvent is selected from one or more of tetrahydrofuran, MIBK (methyl isobutyl ketone), and DMSO (dimethyl sulfoxide).

[0020] Preferably, the organic solvent is tetrahydrofuran.

[0021] As an embodiment of the present invention, in the water / organic solvent reaction solvent, the mass ratio of water to organic solvent is 1:(2-5).

[0022] As an embodiment of the present invention, the amount of the organic solvent used is 10 to 15 times the equivalent amount of glucose in the raw material. Preferably, the amount of the organic solvent used is 13 to 15 times the equivalent amount of glucose in the raw gelatinized material.

[0023] As an embodiment of the present invention, the combined catalyst includes Bronsted acid and Lewis acid; wherein the Bronsted acid is selected from any one or more of phosphoric acid, sulfuric acid, and p-toluenesulfonic acid, and the Lewis acid is selected from any one or more of aluminum chloride, hydrated aluminum chloride, chromium chloride, and ferric chloride.

[0024] Preferably, the combined catalyst is a mixture of phosphoric acid and aluminum chloride or a mixture of phosphoric acid and aluminum chlorohydrate.

[0025] Further preferably, the combined catalyst is a mixture of phosphoric acid and aluminum chlorohexahydrate, wherein aluminum chlorohexahydrate and phosphoric acid are mixed in a mass ratio of (2-10):1, preferably in a mass ratio of (6-10):1, and further preferably in a mass ratio of 8:1.

[0026] As an embodiment of the present invention, the combined catalyst is used in an amount of 30-70% of the equivalent amount of glucose in the raw material.

[0027] The method for preparing HMF by catalytic conversion provided by the present invention is to prepare HMF with starch-based non-grain biomass as raw material. In recent years, the state has called for promoting the non-grain bio-based material industry to accelerate innovation and development and break through the key technology of efficient utilization of non-grain biomass. Starch-based non-grain biomass is one of the raw materials with the most cost advantages at present. For example, cassava, as a cheap non-grain crop, contains high starch, water, and a small amount of sucrose, and is a very potential raw material for HMF production. The main components of cassava derivatives such as cassava and cassava powder are also starch. Raw materials such as konjac, grass jelly, and kudzu also have very high starch content. The characteristics of this type of starch-based non-grain biomass raw material used in the present invention are that it can slowly hydrolyze glucose. Compared with the same equivalent of glucose, in the reaction process of catalytic conversion to prepare HMF, the starch-based non-grain biomass raw material has the advantages of low instantaneous glucose concentration and low reaction intensity, so it can improve the yield of HMF, and can also reduce the generation of other impurities of glucose under the action of acid, avoiding unnecessary consumption. At the same time, the sucrose contained in raw materials such as cassava can also be converted into HMF, which also improves the yield of HMF to a certain extent.

[0028] The present invention has the following advantages:

[0029] (1) The use of cheap starch-based non-food biomass raw materials to prepare 5-hydroxymethylfurfural (HMF) not only avoids the problem of industrial production "competing with people for food", but also greatly reduces the reaction cost compared to the fructose production system, potentially improving the competitiveness of downstream derivative bio-based products.

[0030] (2) Using cassava-based products as raw materials, compared with the same amount of pure glucose, has the characteristic of low instantaneous glucose concentration in the reaction, which avoids carbonization due to high concentration. At the same time, adding pulping, cooking and gelatinization steps in the pretreatment can destroy the branched starch molecules in the crystallization area of ​​cassava-based starch, thereby improving the degree of starch hydrolysis reaction and increasing the HMF yield.

[0031] (3) The amount of Lewis acid and Bronsted acid co-catalyst used in the conversion is small, and there is a synergistic effect under appropriate mass ratio conditions, which can efficiently convert the pretreated raw materials into HMF.

[0032] (4) The reaction conditions of the present invention are relatively mild, no pressure is required, and it is easy to scale up production. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described in detail below. It should be understood by those skilled in the art that the specific implementation is only to help understand the present invention and should not be regarded as a specific limitation of the present invention.

[0034] It should be noted that, unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art, and the raw materials used are all commercially available conventional products.

[0035] The following is a detailed explanation through examples.

[0036] First, starch-based non-food biomass is processed to prepare raw materials for producing HMF. The specific processing method is as follows.

[0037] Take cassava dry powder, or grind cassava dry powder to make cassava dry powder; stir and beat the cassava dry powder with water, the mass ratio of water to cassava dry powder is 3:1, and the obtained beating liquid is the cassava dry powder raw material liquid. The dry basis sugar content (glucose) of the cassava dry powder is 100.8%.

[0038] Take cassava starch, stir and beat the cassava starch with water, the mass ratio of water to cassava starch is 3:1, and the obtained beating liquid is the cassava starch raw material liquid. The sugar content (glucose) of the cassava starch on a dry basis is 102%.

[0039] Take konjac powder, stir and beat the konjac powder with water, the mass ratio of water to konjac powder is 2:1, and the obtained beating liquid is the konjac powder raw material liquid. The konjac powder has a dry basis sugar content (glucose) of 80%.

[0040] The cassava dry powder raw material liquid, cassava starch raw material liquid and konjac dry powder raw material liquid were kept warm at 80° C. for 1 hour to obtain cassava dry powder gelatinized material, cassava starch gelatinized material and konjac dry powder gelatinized material, respectively.

[0041] After gelatinization, the color of the konjac powder raw material liquid becomes darker and the fluidity decreases; the color of the cassava powder raw material liquid and the cassava starch raw material liquid becomes transparent and turns into a gel state, similar to jelly.

[0042] Examples 1-6

[0043] The following Examples 1 to 6 use the above-prepared cassava powder raw material liquid and cassava powder gelatinized material as reaction raw materials to carry out catalytic conversion to prepare HMF, and the specific steps are as follows:

[0044] Take cassava dry powder raw material liquid or cassava dry powder gelatinized material, add it into the reactor together with water / organic solvent reaction solvent and combined catalyst aqueous solution, close the reactor and heat and stir to react, the stirring speed is controlled at 500 rpm, the reaction temperature is 140°C, and the reaction time is 1h.

[0045] The combined catalyst aqueous solution is obtained by mixing the combined catalyst with water. The amount of water added to the combined catalyst is shown in Table 1.

[0046] The materials after the reaction of Examples 1-6 were filtered and then detected and analyzed using an Agilent 1260 high performance liquid chromatograph, a PL Hi-Plex H column (300×7.7 mm, 8 μm), with a flow rate of 0.6 mL / min, a 5 mM H2SO4 solution as the mobile phase, a detector temperature of 60°C, and external standard method quantification, and the HMF yield was calculated.

[0047]

[0048] The yields of HMF in the following table are all calculated based on the glucose equivalent of the reaction raw material.

[0049] The reaction materials, reaction conditions and test results in Examples 1-6 are specifically shown in Table 1.

[0050] Table 1

[0051]

[0052]

[0053] It can be seen from the results of Examples 1-6 in Table 1 that when the mass ratio of water to THF (tetrahydrofuran) in the reaction solvent is 1:5, the yield of HMF is the highest.

[0054] It can also be seen that, when other conditions are the same and the composition of the combined catalyst is different, when the mass ratio of aluminum chloride hexahydrate to phosphoric acid in the combined catalyst is 8:1 (0.8 g / 0.1 g), the yield of HMF is the highest.

[0055] The structure of starch granules includes a crystalline region and an amorphous region. The crystalline region is mainly formed by amylopectin molecules in a double helix structure, and the structure is relatively dense. It can also be seen from the results in Table 1 that the amylopectin molecules in the starch crystalline region can be effectively destroyed by steaming and gelatinization, thereby improving the degree of starch hydrolysis reaction. Example 6 uses cassava dry powder gelatinized material as a raw material to prepare HMF, which significantly improves the yield of HMF.

[0056] Examples 7-10

[0057] The following Examples 7-10 use the cassava starch raw material liquid and cassava starch gelatinized material prepared above as reaction raw materials, and carry out catalytic conversion to prepare HMF, and the specific steps are as follows:

[0058] Take cassava starch raw material liquid or cassava starch gelatinized material, add it into the reactor together with water / organic solvent reaction solvent and combined catalyst aqueous solution, close the reactor and heat and stir to react, the stirring speed is controlled at 500 rpm, the reaction temperature is 140°C, and the reaction time is 1h.

[0059] The materials after the reaction of Examples 7-10 were filtered and then detected and analyzed using an Agilent 1260 high performance liquid chromatograph, a PL Hi-Plex H column (300×7.7 mm, 8 μm), a flow rate of 0.6 mL / min, a 5 mM H2SO4 solution as the mobile phase, a detector temperature of 60°C, and external standard method quantification, and the HMF yield was calculated.

[0060] The reaction conditions and test results in Examples 7-10 are specifically shown in Table 2.

[0061] Table 2

[0062]

[0063] From the results of Examples 7-10 in Table 2, it can be seen that when the mass ratio of water to THF (tetrahydrofuran) in the reaction solvent is 1:5, the yield of HMF is the highest. It can also be seen that the yield of HMF prepared by cooking and gelatinizing cassava starch gelatinized material is significantly improved.

[0064] Examples 11-13

[0065] The following Examples 11-13 respectively use pure glucose, konjac powder raw material liquid and prepared konjac powder gelatinized material as reaction raw materials, and carry out catalytic conversion to prepare HMF, and the specific steps are as follows:

[0066] Pure glucose, konjac powder raw material liquid, and konjac powder gelatinized material were taken separately, and added into the reactor together with water / organic solvent reaction solvent and combined catalyst aqueous solution. The reactor was closed and heated and stirred for reaction. The stirring speed was controlled at 500 rpm, the reaction temperature was 140°C, and the reaction time was 1h.

[0067] The materials after the reaction of Examples 11-13 were filtered and then detected and analyzed using an Agilent 1260 high performance liquid chromatograph, a PL Hi-Plex H column (300×7.7 mm, 8 μm), a flow rate of 0.6 mL / min, a 5 mM H2SO4 solution as the mobile phase, a detector temperature of 60°C, and external standard method quantification, and the HMF yield was calculated.

[0068] The reaction conditions and test results in Examples 11-13 are specifically shown in Table 3.

[0069] Table 3

[0070]

[0071] From the results of Examples 11-13 in Table 3, it can be seen that the HMF yield of konjac powder is higher than that of pure glucose, and the HMF yield of konjac powder after gelatinization is further improved. However, compared with cassava powder and cassava starch raw materials, the HMF yield is lower when pure glucose or konjac powder is used.

[0072] Examples 14-15

[0073] The following Examples 14-15 respectively use cassava powder gelatinized material as the reaction raw material and carry out catalytic conversion to prepare HMF. The specific steps are as follows:

[0074] Take cassava powder gelatinized material, add it into the reactor together with water / organic solvent reaction solvent and combined catalyst aqueous solution, close the reactor, heat and stir to react, control the stirring speed at 500 rpm, the reaction temperature is shown in Table 4, and the reaction time is 1 h.

[0075] The materials after the reaction of Examples 14-15 were filtered and then detected and analyzed using an Agilent 1260 high performance liquid chromatograph, a PL Hi-Plex H column (300×7.7 mm, 8 μm), a flow rate of 0.6 mL / min, a 5 mM H2SO4 solution as the mobile phase, a detector temperature of 60°C, and external standard method quantification, and the HMF yield was calculated.

[0076] The reaction conditions and test results in Examples 14-15 are specifically shown in Table 4.

[0077] Table 4

[0078]

[0079]

[0080] From the results in Table 4, it can be seen that under the same conditions, when the reaction temperature is 140°C, the yield of HMF is the highest, so the optimal reaction temperature is 140°C.

[0081] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for preparing HMF by catalytic conversion, characterized in that: Using starch-based non-food biomass as raw materials, HMF is produced by catalytic conversion in a water / organic solvent reaction solvent under the action of a combined catalyst; Wherein, the starch-based non-food biomass is selected from any one or more of cassava dry powder, cassava starch, konjac dry powder, grass jelly, and kudzu vine.

2. The method according to claim 1, characterized in that The starch-based non-food biomass is selected from any one or more of cassava dry powder, cassava starch, and konjac dry powder; preferably, the starch-based non-food biomass is cassava dry powder or cassava starch.

3. The method according to claim 1 or 2, characterized in that: The starch-based non-food biomass is used as a reaction raw material after being pretreated; preferably, the pretreatment is gelatinization; Further preferably, the gelatinization process comprises: The starch-based non-food biomass is stirred and mixed with water to prepare a raw material liquid; The raw material liquid is kept at 75-85° C. for 0.5-2 hours to obtain a raw material gelatinized material; The raw material gelatinized material is used to prepare HMF.

4. The method according to claim 3, characterized in that The starch-based non-food biomass and water are mixed at a mass ratio of water: starch-based non-food biomass = (0.5-10):1, preferably at a mass ratio of water: starch-based non-food biomass = (2-6):

1.

5. The method according to any one of claims 1 to 4, characterized in that: The reaction is carried out in a closed reactor, and the reaction temperature is controlled at 130° C. to 150° C., preferably at 140° C.; and / or, The reaction time is 30 to 120 min, preferably 50 to 80 min, and more preferably 60 min.

6. The method according to claim 5, characterized in that The organic solvent is selected from one or more of tetrahydrofuran, MIBK, and DMSO; preferably, the organic solvent is tetrahydrofuran; and / or, In the water / organic solvent reaction solvent, the mass ratio of water to organic solvent is 1:(2-5).

7. The method according to claim 6, characterized in that The amount of the organic solvent used is 10 to 15 times the amount of glucose equivalent in the raw material.

8. The method according to claim 5, characterized in that The combined catalyst comprises a Bronsted acid and a Lewis acid; wherein the Bronsted acid is selected from any one or more of phosphoric acid, sulfuric acid, and p-toluenesulfonic acid, and the Lewis acid is selected from any one or more of aluminum chloride, aluminum chlorohydrate, chromium chloride, and ferric chloride; Preferably, the combined catalyst is a mixture of phosphoric acid and aluminum chloride or a mixture of phosphoric acid and aluminum chlorohydrate.

9. The method according to claim 8, characterized in that The combined catalyst is a mixture of phosphoric acid and aluminum chlorohexahydrate, wherein the aluminum chlorohexahydrate and the phosphoric acid are mixed in a mass ratio of (2-10):1, preferably in a mass ratio of (6-10):1, and more preferably in a mass ratio of 8:

1.

10. The method according to claim 8 or 9, characterized in that: The dosage of the combined catalyst is 30-70% of the equivalent amount of glucose in the raw material.

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