Catalyst for preparing 5-hydroxymethylfurfural through sugar conversion as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for preparing 5-hydroxymethylfurfural through sugar conversion and a preparation method and application thereof.The preparation process of the catalyst comprises the steps that hydrochloric acid or metal chloride is prepared into an aqueous solution with the concentration being 10-25 wt%, nitrogen-containing organic matter is added, the mixture is stirred for 0.5-3 h at the temperature of 20-50 DEG C, the organic matter and water are evaporated through reduced pressure distillation, and the catalyst is obtained; according to the present invention, the residual crystalline solid is collected so as to obtain the catalyst, the catalyst is used for preparing 5-hydroxymethylfurfural through sugar conversion, and compared with other homogeneous catalysts, the developed catalyst has advantages of low equipment corrosion, high reaction activity and high HMF selectivity.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and particularly relates to a catalyst for preparing 5-hydroxymethylfurfural by sugar conversion, and a preparation method and application thereof. Background Art

[0002] 5-Hydroxymethylfurfural (HMF) is a platform compound that can be prepared by dehydrating monosaccharides. Various compounds with broad application prospects can be obtained through different reaction pathways. For example, HMF can be used to prepare 2,5-furandicarboxylic acid through oxidation reaction. 2,5-furandicarboxylic acid can be used as a monomer for synthesizing polyesters and can also be used to prepare bio-based surfactants. HMF can also be hydrogenated to obtain 2,5-dimethylfuran. 2,5-dimethylfuran has the advantages of high energy density, high boiling point and incompatibility with water, and can be used as a liquid fuel.

[0003] There have been many reports on the preparation of HMF. The catalysts that can be used to catalyze the conversion of sugars to produce HMF mainly include inorganic acids, metal chlorides, metal oxides, and ion exchange resins. Various catalysts and corresponding solvent systems together construct an efficient HMF preparation system. Lewis acids such as metal chlorides not only have a good effect on the dehydration of fructose to produce HMF, but also have a good effect on the isomerization of glucose and the one-pot production of HMF. Metal oxides and ion exchange resin catalysts also show superior new energy in the conversion process of fructose and glucose. At the same time, heterogeneous catalysts also have the advantages of easy separation and recycling.

[0004] At present, inorganic acid catalysts such as hydrochloric acid and sulfuric acid have poor selectivity for HMF. In addition to dehydrating fructose, they can also catalyze other side reactions, such as the hydrolysis of HMF to produce levulinic acid and formic acid. At the same time, hydrochloric acid is highly corrosive and easy to volatilize, and its application conditions are poor. Lewis acids such as metal chlorides are less corrosive to equipment than inorganic acids, but metal ions are difficult to separate after the reaction, which will affect the subsequent purification of HMF and further application. Heterogeneous catalysts are affected by the mass transfer process, and there are problems of low conversion efficiency or poor HMF selectivity. Summary of the invention

[0005] In view of the above problems, the object of the present invention is to provide a catalyst for preparing 5-hydroxymethylfurfural by sugar conversion, and a preparation method and application thereof.

[0006] The specific technical solutions are as follows:

[0007] A method for preparing a catalyst for preparing 5-hydroxymethylfurfural by sugar conversion comprises the following steps: preparing hydrochloric acid or metal chloride into an aqueous solution with a concentration of 10-25wt%, adding nitrogen-containing organic matter, stirring at 20-50 DEG C for 0.5-3h, evaporating the organic matter and water by reduced pressure distillation, and collecting the remaining crystalline solid to obtain the catalyst.

[0008] Furthermore, the metal chloride is aluminum chloride, vanadium chloride, tin chloride, chromium chloride, lithium chloride or zinc chloride.

[0009] Furthermore, the nitrogen-containing organic compound is s-triazine, ethylenediamine, n-butylamine, N,N-dimethylformamide or N,N-dimethylacetamide.

[0010] Furthermore, the mass ratio of the nitrogen-containing organic matter to the hydrochloric acid or metal chloride aqueous solution is 0.1-1:1.5.

[0011] Furthermore, the conditions for reduced pressure distillation are: pressure of -0.08 to -0.1 MPa, and distillation temperature of 20 to 100°C.

[0012] A catalyst prepared by the preparation method and used for preparing 5-hydroxymethylfurfural by sugar conversion.

[0013] The invention discloses an application of a catalyst for preparing 5-hydroxymethylfurfural by sugar conversion, comprising the following steps: adding the catalyst and sugar into a reaction solvent, reacting at 90-150°C for 0.5-10 hours, and preparing 5-hydroxymethylfurfural.

[0014] Furthermore, the carbohydrate is fructose, glucose, sucrose, maltose, cellobiose, dextrin, starch or inulin, and the mass ratio of the catalyst to the carbohydrate is 0.1-10:100.

[0015] Furthermore, the reaction solvent is an organic solvent, a mixed system of an organic solvent and water, or an ionic liquid system; the organic solvent is tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, acetone, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethanol dimethyl ether, or isopropanol; and the ionic liquid is an imidazole ionic liquid or a choline ionic liquid.

[0016] The beneficial effects of the present invention are:

[0017] Compared with other homogeneous catalysts, the present invention introduces acidic substances and alkaline substances to synthesize the catalyst, which has the advantages of low corrosion to equipment, high reaction activity and high HMF selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the NMR data of the catalyst prepared in Example 6. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited thereto.

[0020] Example 1

[0021] Concentrated hydrochloric acid (36.5wt%) was diluted with water to 6mol / L, ethylenediamine was slowly added, and the amount of ethylenediamine added was 10% of the mass of the hydrochloric acid aqueous solution, stirred at 25°C for 1 hour, transferred to a rotary evaporator, and rotary evaporated at 70°C with a pressure of -0.09MPa. After no liquid remained, white crystals were collected and transferred to a centrifuge tube. The obtained crystals were a solid mixture containing ethylenediamine hydrochloride, which was used as a catalyst.

[0022] Mix fructose and water in a ratio of 1:1, add 2 times the volume of dimethyl sulfoxide, add a catalyst of 10% of the mass of fructose, add sodium chloride of 0.5 times the mass of fructose, and convert at 140°C for 1h, with a reaction pressure of 0.8MPa. Then quench the reactor to quench the reaction. Take 1g of the sample and dilute it to 100ml, and analyze it by high performance liquid chromatography, with a column of 87H, a mobile phase of 5mmol / L sulfuric acid aqueous solution, a column oven temperature of 50°C, a visual detector, and a detector temperature of 50°C. The molar yield of HMF is 65%. Calculate the HMF yield according to the following formula:

[0023] HMF yield = (the amount of HMF produced by the reaction / the amount of sugar added to the reaction solution) × 100%.

[0024] Embodiment 2-6

[0025] The operation process is the same as in Example 1, the operating conditions are shown in Table 1, and other conditions are the same.

[0026] Table 1 Summary of reaction conditions and results of Examples 2-6

[0027]

[0028] from Figure 1 It can be proved that the catalyst synthesized by the present invention is neither the nitrogen-containing compound itself nor hydrochloric acid, but a new substance with a complex structure formed by the two.

[0029] By comparing Examples 1 to 6, it can be found that the catalyst prepared by the method provided by the present invention has a higher selectivity for HMF, and the performance of the catalyst obtained by treating different amine compounds with hydrochloric acid is higher than the performance of fructose conversion catalyzed by hydrochloric acid under the same conditions. By comparing Example 1 and Example 3, it can be found that the catalyst prepared by increasing the amount of ethylenediamine has a higher HMF selectivity, among which the catalyst prepared in Example 5 can catalyze fructose to obtain a 75% HMF yield.

[0030] Example 7

[0031] Aluminum chloride hexahydrate was diluted with water to 2 mol / L, s-triazine was slowly added, and the amount of s-triazine added was 2 / 3 of the mass of the aluminum chloride aqueous solution, stirred at 25°C for 1 hour, transferred to a rotary evaporator, and rotary evaporated at 90°C with a pressure of -0.1MPa. After no liquid remained, white crystals were collected and transferred to a centrifuge tube. A solid mixture was obtained.

[0032] Glucose and butyltrimethylimidazole chloride (BMIMCl) were stirred at a mass ratio of 1:2 at 100 degrees Celsius for 1 hour to obtain a slightly yellow transparent solution. The prepared catalyst solid was added to the solution, with a mass of 10% of the mass of glucose, and converted at 110°C for 1 hour. The reactor was then quenched to quench the reaction. 1g of the sample was diluted to 100ml and analyzed by high performance liquid chromatography. The column was 87H, the mobile phase was 5mmol / L sulfuric acid aqueous solution, the column oven temperature was 50°C, the detector was an inspection detector, the detector temperature was 50°C, and the HMF molar yield was 60%.

[0033] Embodiment 8-15

[0034] The operation process is the same as in Example 7, the operating conditions are shown in Table 2, and other conditions are the same.

[0035] Table 2 Reaction conditions and results summary of Examples 8-15

[0036]

[0037]

[0038] By comparing Example 7 with Example 11, it can be found that under the condition of high concentration glucose conversion in ionic liquid, aluminum chloride hexahydrate has lower HMF selectivity than the catalyst prepared with aluminum chloride hexahydrate in Example 7. Similarly, the catalyst prepared with chromium chloride hexahydrate also has higher HMF selectivity than pure chromium chloride hexahydrate. As shown in Example 12, the catalyst prepared with chromium chloride hexahydrate and s-triazine has higher HMF selectivity, and the HMF yield can reach 65%.

[0039] Comparing Example 14 with Example 15, for sucrose conversion, the catalyst prepared in the manner of Example 14 has higher HMF selectivity than the pure aluminum chloride catalyst. Example 14 also proves that the catalyst prepared in this patent is also suitable for the conversion of polysaccharides.

[0040] The catalyst preparation method developed in the present invention can prepare a catalyst suitable for the conversion of monosaccharides, disaccharides and polysaccharides, which has high activity and HMF selectivity in different solvent systems. Compared with catalysts such as inorganic acids and metal chlorides, the catalyst prepared by the method provided by the present invention has a higher HMF yield. The catalyst preparation method provided by the present invention will help the large-scale production of HMF.

Claims

1. A method for preparing a catalyst for preparing 5-hydroxymethylfurfural by sugar conversion, characterized in that: The method comprises the following steps: preparing hydrochloric acid or metal chloride into a 10-25wt% aqueous solution, adding nitrogen-containing organic matter, stirring at 20-50°C for 0.5-3h, evaporating the organic matter and water by reduced pressure distillation, and collecting the remaining crystalline solid, which is the catalyst.

2. The method for preparing a catalyst for preparing 5-hydroxymethylfurfural by sugar conversion according to claim 1, characterized in that: The metal chloride is aluminum chloride, vanadium chloride, tin chloride, chromium chloride, lithium chloride or zinc chloride.

3. The method for preparing a catalyst for preparing 5-hydroxymethylfurfural by sugar conversion according to claim 1, characterized in that: The nitrogen-containing organic matter is s-triazine, ethylenediamine, n-butylamine, N,N-dimethylformamide or N,N-dimethylacetamide.

4. The method for preparing a catalyst for preparing 5-hydroxymethylfurfural by sugar conversion as claimed in claim 3, characterized in that: The mass ratio of the nitrogen-containing organic matter to the hydrochloric acid or metal chloride aqueous solution is 0.1-1:1.

5.

5. The method for preparing a catalyst for preparing 5-hydroxymethylfurfural by sugar conversion according to claim 1, characterized in that: The conditions for reduced pressure distillation are: pressure of -0.08 to -0.1 MPa, and distillation temperature of 20 to 100°C.

6. A catalyst for preparing 5-hydroxymethylfurfural by converting sugar, prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the catalyst for preparing 5-hydroxymethylfurfural by sugar conversion as claimed in claim 6, characterized in that: The method comprises the following steps: adding a catalyst and sugars into a reaction solvent, reacting at 90-150° C. for 0.5-10 hours, and preparing 5-hydroxymethylfurfural.

8. The use of a catalyst for preparing 5-hydroxymethylfurfural by sugar conversion as claimed in claim 7, characterized in that: The sugar is fructose, glucose, sucrose, maltose, cellobiose, dextrin, starch or inulin, and the mass ratio of the catalyst to the sugar is 0.1-10:

100.

9. The use of a catalyst for preparing 5-hydroxymethylfurfural by sugar conversion as claimed in claim 7, characterized in that: The reaction solvent is an organic solvent, a mixed system of an organic solvent and water or an ionic liquid system; the organic solvent is tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, acetone, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethanol dimethyl ether or isopropanol; and the ionic liquid is an imidazole ionic liquid or a choline ionic liquid.

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