A method for preparing 5-ethoxymethylfurfural directly from glucose

Abstract

The present application relates to a method for preparing 5-ethoxymethylfurfural directly using glucose, and belongs to the technical field of high-value utilization of biomass sugar. Glucose is added to a cosolvent to prepare a reaction substrate solution; the cosolvent is composed of ethanol and 1,4-dioxane; a zeolite molecular sieve mixed catalyst is added to the reaction substrate solution to stir and catalyze the reaction to obtain 5-ethoxymethylfurfural; the abundant strong acid sites and Lewis acid sites in the Hbeta zeolite molecular sieve in the zeolite molecular sieve mixed catalyst promote the dehydration of the intermediate product ethyl glucoside (EG) and the etherification reaction of 5-hydroxymethylfurfural (HMF), respectively; the large pore structure and abundant acid sites of the USY zeolite molecular sieve improve the reaction efficiency of glucose isomerization and fructose dehydration, respectively; the ethanol-1,4-dioxane cosolvent helps the etherification reaction of the intermediate product 5-hydroxymethylfurfural and inhibits the side reaction of 5-ethoxymethylfurfural; therefore, the present application can obtain 5-ethoxymethylfurfural with high yield.

Description

Technical Field

[0001] This invention relates to a method for directly preparing 5-ethoxymethylfurfural from glucose, belonging to the field of high-value utilization technology of biomass sugars. Background Technology

[0002] Cellulose is the main component of lignocellulosic biomass, accounting for approximately 30%–50%. Among the many furan-based platform molecules derived from cellulose sugars, 5-ethoxymethylfurfural (5-HMF) is considered an ideal biofuel alternative or diesel additive. This is because 5-HMF possesses environmentally friendly properties; it has high oxidative stability, reducing the generation of soot, sulfur oxides, and nitrogen oxides in vehicle exhaust; furthermore, 5-HMF exhibits good chemical reactivity and excellent flowability at room temperature; its energy density is as high as 30.3 MJ / L. –1 This is similar to standard gasoline (31.1 MJ / L) –1 It is comparable to, and far exceeds, bioethanol (23.5 MJ / L). –1 Given its abundance and cost-effectiveness, glucose, as the most abundant cellulose hexose, is considered one of the most suitable feedstocks for high-value biomass applications. The one-pot synthesis of 5-ethoxymethylfurfural from glucose eliminates the need for intermediate separation and processing, thereby reducing catalyst and solvent consumption, minimizing chemical waste generation, and thus improving the sustainability of 5-ethoxymethylfurfural production.

[0003] However, the production of 5-ethoxymethylfurfural from glucose with a stable hexa-pyranoside structure is challenging because the conversion process involves key reaction steps such as glucose isomerization, fructose dehydration, and 5-hydroxymethylfurfural etherification, all of which are essential for the efficient generation of 5-ethoxymethylfurfural. Therefore, the cascade reaction for the synthesis of 5-ethoxymethylfurfural from glucose requires the synergistic effect of various types of catalysts. For example, although using… Acids act as catalysts, favoring the dehydration of fructose but also increasing the likelihood of glucose being converted to ethyl glucoside in ethanol. This is primarily due to the absence of Lewis acids, which hinders the isomerization of glucose. Furthermore, a weak Lewis acid can impede the etherification of 5-hydroxymethylfurfural, leading to a significant difference between the production and consumption rates, increasing the possibility of side reactions. However, an excess of Lewis acid can cause 5-hydroxymethylfurfural to further convert into byproducts such as ethyl levulinate. In addition, the effects of glucose glycosylation, polymerization of intermediate furan products, and the acetal reaction of the product on the production of 5-ethoxymethylfurfural must be considered. Numerous studies have demonstrated that the conversion of glucose to 5-ethoxymethylfurfural can be achieved in a single step through the rational combination of various catalysts. However, these reactions often suffer from bottlenecks such as low 5-ethoxymethylfurfural yield, long reaction times, and cumbersome procedures. Summary of the Invention

[0004] To address the problems of low yield, long reaction time, and cumbersome steps in the production of 5-ethoxymethylfurfural from glucose in existing technologies, this invention proposes a method for directly preparing 5-ethoxymethylfurfural from glucose. Using glucose as the reaction substrate, a co-solution system of ethanol / 1,4-dioxane is employed as the reaction medium, and a combination of Hβ zeolite molecular sieves and USY zeolite molecular sieves is used as a synergistic catalyst to catalyze the direct conversion of glucose to 5-ethoxymethylfurfural, achieving a yield as high as 60.2%. The combination of Hβ and USY zeolite molecular sieves as a synergistic catalyst, working in conjunction with the ethanol / 1,4-dioxane co-solution system, stabilizes the product 5-ethoxymethylfurfural at high temperatures, effectively suppressing side reactions and significantly improving the yield of the target product. This results in fewer byproducts, easier handling, less environmental pollution, and easier catalyst recovery, significantly reducing the production cost of 5-ethoxymethylfurfural and improving economic efficiency.

[0005] A method for directly preparing 5-ethoxymethylfurfural from glucose, the specific steps of which are as follows:

[0006] (1) Glucose is added to a co-solvent to prepare a reaction substrate solution; the co-solvent is composed of ethanol and 1,4-dioxane;

[0007] (2) Add the zeolite molecular sieve mixed catalyst to the reaction substrate solution and stir to catalyze the reaction to obtain 5-ethoxymethylfurfural; the zeolite molecular sieve mixed catalyst is composed of Hβ zeolite molecular sieve and USY zeolite molecular sieve.

[0008] By volume fraction, ethanol accounts for 10-90% of the co-solvent in step (1).

[0009] Preferably, the concentration of the reaction substrate solution in step (1) is 0.05 to 0.25 mol / L.

[0010] By mass percentage, Hβ zeolite molecular sieve accounts for 10-90% of the zeolite molecular sieve mixed catalyst in step (2).

[0011] Preferably, in step (2), the mass ratio of the zeolite molecular sieve mixed catalyst to glucose in the reaction substrate solution is 1:1 to 1:5.

[0012] Preferably, the temperature of the catalytic reaction in step (2) is 160-200°C and the time is 30-90 min.

[0013] The mechanism for the preparation of 5-ethoxymethylfurfural from glucose is described in [link to relevant documentation]. Figure 1 In the initial stage of the reaction, a portion of glucose is rapidly etherified into stable ethyl glucoside under the action of an acid catalyst. The etherified form of glucose cannot be converted into fructose, nor can it form a ketose form through intramolecular hydrogen transfer. Therefore, all transformations from glucose isomerization to fructose must begin with non-etherified glucose, maintaining equilibrium with the etherified form. The abundant strong acid in the Hβ catalyst facilitates the dehydration of ethyl glucoside to 5-ethoxymethylfurfural, thereby increasing the yield of 5-ethoxymethylfurfural. In the critical glucose isomerization step, the large-pore USY zeolite molecular sieve provides a suitable reaction space for the formation of the glucose isomerization transition state, thus promoting the glucose isomerization reaction. In the 5-hydroxymethylfurfural etherification step, ethanol molecules, acting as electrophiles, are preferentially protonated in the pores of the Hβ catalyst, further increasing the rate of the 5-hydroxymethylfurfural etherification reaction.

[0014] The beneficial effects of this invention are:

[0015] (1) The abundant strong acid sites and Lewis acid sites in the Hβ zeolite molecular sieve of the zeolite molecular sieve mixed catalyst of this invention promote the dehydration of the intermediate product ethyl glucoside (EG) and the etherification reaction of 5-hydroxymethylfurfural (HMF), respectively. The macroporous structure and abundant... The acid sites, respectively, improved the reaction efficiency of glucose isomerization and fructose dehydration;

[0016] (2) The multifunctional synergistic catalytic system composed of Hβ zeolite molecular sieve and USY zeolite molecular sieve constructed in the present invention under a high temperature environment can ensure the effective progress of glucose isomerization, ethyl glucoside dehydration and subsequent reactions, and achieve highly selective synthesis of 5-ethoxymethylfurfural.

[0017] (3) The present invention introduces a low-polarity aprotic organic solvent 1,4-dioxane to form an ethanol-1,4-dioxane cosolvent, which helps the etherification reaction of the intermediate product 5-hydroxymethylfurfural and inhibits the condensation reaction of 5-ethoxymethylfurfural, thereby effectively promoting the selective conversion of glucose to 5-ethoxymethylfurfural.

[0018] (4) The multifunctional synergistic catalytic system composed of Hβ zeolite molecular sieve and USY zeolite molecular sieve, together with the catalytic reaction system composed of ethanol-1,4-dioxane cosolvent composed of low polarity aprotic organic solvent 1,4-dioxane, can enhance the selective synthesis of glucose directly converted into 5-ethoxymethylfurfural, and the yield of 5-ethoxymethylfurfural can reach as high as 60.2%. Attached Figure Description

[0019] Figure 1 This is a diagram illustrating the reaction mechanism of the present invention.

[0020] Figure 2 The following are characterization diagrams of the catalyst in Example 1: a is the XRD pattern, b is the FT-IR pattern, c is the NH3-TPD pattern, and d is the Py-FTIR pattern.

[0021] Figure 3 The diagram shows the catalyst structure of Example 1. a represents the pore diameter and pore volume of Hβ zeolite molecular sieve, b represents the pore diameter and pore volume of USY zeolite molecular sieve, c represents the pore size distribution of Hβ zeolite molecular sieve, d represents the pore size distribution of USY zeolite molecular sieve, e represents the molecular structure of chain glucose, f represents the molecular structure of glucose isomerization transition state, and g represents the molecular structure of chain fructose.

[0022] Figure 4 The high-resolution electrospray mass spectra of the reaction solutions in different solvent systems of Comparative Example 3 and Example 1 are shown. a is the stability of 5-ethoxymethylfurfural in ethanol or 1,4-dioxane; b is the ESI-MS spectrum of 5-ethoxymethylfurfural in ethanol after reaction; c is the ESI-MS spectrum of 5-ethoxymethylfurfural in 1,4-dioxane after reaction; d is the free Gibbs energy of 5-ethoxymethylfurfural acetal produced by 5-ethoxymethylfurfural in ethanol; e is the free Gibbs energy of 5-ethoxymethylfurfural acetal produced by 5-ethoxymethylfurfural in the ethanol / 1,4-dioxane mixture.

[0023] Figure 5 The images show the molecular sieve characterizations after the reaction in different solvent systems for Comparative Example 3 and Example 1. a is the XRD pattern and b is the FT-IR pattern. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0025] Example 1: A method for directly preparing 5-ethoxymethylfurfural from glucose (see Example 2) Figure 1 The specific steps are as follows:

[0026] (1) Glucose is added to a co-solvent to prepare a reaction substrate solution; the co-solvent is composed of ethanol and 1,4-dioxane, and the ethanol accounts for 50% by volume fraction; the concentration of the reaction substrate solution is 0.05 mol / L;

[0027] (2) The zeolite molecular sieve mixed catalyst was added to the reaction substrate solution, and the reaction was stirred at 180℃ for 60 min to obtain 5-ethoxymethylfurfural; the zeolite molecular sieve mixed catalyst was composed of Hβ zeolite molecular sieve and USY zeolite molecular sieve; by mass percentage, Hβ zeolite molecular sieve accounted for 50% of the zeolite molecular sieve mixed catalyst; the mass ratio of the zeolite molecular sieve mixed catalyst to glucose in the reaction substrate solution was 1:1;

[0028] The catalyst characterization diagram for this embodiment is shown below. Figure 2 a is the XRD pattern, b is the FT-IR pattern, c is the NH3-TPD pattern, and d is the Py-FTIR pattern; from Figure 2 It was found that the XRD patterns and Fourier transform infrared spectra of the two mixed zeolite molecular sieves did not show any new characteristic diffraction peaks, indicating that their crystal structures remained stable and no new functional groups appeared. It can be inferred that the two catalysts did not undergo chemical interactions after mixing, maintaining their respective catalytic selectivity. NH3-TPD characterization of the zeolite molecular sieves revealed that the abundant strong acid content in the Hβ zeolite molecular sieve was related to the conversion activity of ethyl glucoside; Py-FTIR spectroscopy quantified the activity of the catalyst... The number of acid and Lewis acid sites, Hβ zeolite molecular sieve and USY zeolite molecular sieve in The differences in the sites of acid and Lewis acid are significant. In Hβ zeolite molecular sieves, The presence of Lewis acid sites is relatively balanced, but the number of Lewis acid sites in USY zeolite molecular sieves is significantly less than that in Hβ zeolite molecular sieves. The abundance of Lewis acid sites in Hβ may be the main reason for the formation of ethyl levulinate, as excess Lewis acid sites easily lead to further hydration of the intermediate 5-hydroxymethylfurfural, thus generating the byproduct ethyl levulinate. Py-FTIR analysis of the mixed zeolite molecular sieves shows that... The ratio of acid to Lewis acid sites is more reasonable, changing from 1.07 for Hβ and 7.81 for USY to 3.68. Compared with Hβ zeolite molecular sieves, the combination of Hβ and USY catalysts effectively improves... The concentration of Lewis acid in the mixed catalyst increases the ability to produce 5-hydroxymethylfurfural (5-HMF) from defructose, while USY overcomes the drawback of excessive Lewis acid in Hβ, minimizing the production of furfural and ethyl levulinate. Compared to the USY zeolite molecular sieve, the appropriate increase in Lewis acid in the mixed catalyst improves the etherification efficiency of 5-HMF.

[0029] The catalyst structure diagram of this embodiment is shown below. Figure 3 a represents the pore diameter and pore volume of Hβ zeolite molecular sieve, b represents the pore diameter and pore volume of USY zeolite molecular sieve, c represents the pore size distribution of Hβ zeolite molecular sieve, d represents the pore size distribution of USY zeolite molecular sieve, e represents the molecular structure of chain glucose, f represents the molecular structure of glucose isomerization transition state, and g represents the molecular structure of chain fructose; from Figure 3 It is known that the pore size of zeolite molecular sieves directly affects the selectivity of glucose isomerization, as larger pores are more conducive to the formation of the transition state. Furthermore, larger pores also facilitate the diffusion of cyclic fructose molecules formed after the reaction within the zeolite molecular sieve, thereby improving the availability of active sites. Therefore, the pore structure of Hβ and USY was further observed using Multiwfn software, and their pore size and volume were calculated using Bondi van der Waals diameters. Simultaneously, the zeolite molecular sieves were characterized by adsorption isotherms (Saito-Foley method) under 87 K argon conditions to obtain the true micropore sizes of the two zeolite molecular sieves. The advantage of the Saito-Foley method is that it can better reflect the pore structure and adsorption characteristics of zeolite molecular sieves and is applicable to different types of zeolite molecular sieves. The characterized effective micropore size distribution is consistent with the calculated results. The calculation results from Multiwfn software show that the diameter of the transition state structure for glucose isomerization to fructose is... The large pore size of USY zeolite molecular sieve is The macropore size of Hβ zeolite molecular sieve is Furthermore, the macropore volume of USY is significantly larger than that of Hβ zeolite molecular sieves. Therefore, USY provides a larger reaction space for glucose isomerization, which is more conducive to the formation of transition states. This is also an important reason why the glucose isomerization reaction is easier to carry out in USY zeolite molecular sieves, which have relatively fewer Lewis sites.

[0030] Analysis using high-performance liquid chromatography (HPLC) showed that the yield of the target product 5-ethoxymethylfurfural in this embodiment was 60.2%.

[0031] Comparative Example 1: The only difference between this comparative example and Example 1 is that only Hβ zeolite molecular sieve is used as the catalyst;

[0032] Analysis by high-performance liquid chromatography (HPLC) showed that the yield of the target product 5-ethoxymethylfurfural in this comparative example was 37.9%.

[0033] Comparative Example 2: The only difference between this comparative example and Example 1 is that only USY zeolite molecular sieve is used as the catalyst;

[0034] Analysis by high-performance liquid chromatography (HPLC) showed that the yield of the target product 5-ethoxymethylfurfural in this comparative example was 41.4%.

[0035] Comparative Example 3: The only difference between this comparative example and Example 1 is that only ethanol is used as the solvent;

[0036] The electrospray mass spectra of the reaction in different solvent systems of the comparative example and Example 1 are shown below. Figure 4 a) Stability of 5-ethoxymethylfurfural in ethanol or 1,4-dioxane; b) ESI-MS spectrum of 5-ethoxymethylfurfural in ethanol after reaction; c) ESI-MS spectrum of 5-ethoxymethylfurfural in 1,4-dioxane after reaction; d) Free Gibbs energy of 5-ethoxymethylfurfural acetal formation from ethanol; e) Free Gibbs energy of 5-ethoxymethylfurfural acetal formation from ethanol / 1,4-dioxane mixture. Figure 4 It was found that the retention rate of 5-ethoxymethylfurfural in the ethanol system was almost 35% lower than that in the 1,4-dioxane solvent, further confirming that 5-ethoxymethylfurfural has poor stability in the ethanol environment and is prone to condensation polymerization to form humic substances. ESI-MS results in both solvent systems showed that a large amount of acetal byproducts were generated in the ethanol system, which is consistent with the Fukui function calculations mentioned above. Furthermore, the Gibbs free energy of 5-ethoxymethylfurfural forming acetal byproducts in different solvent systems also confirms the above conclusions.

[0037] Characterization diagrams of the molecular sieves after reaction in different solvent systems for the comparative example and Example 1 are shown below. Figure 5 a is the XRD pattern, b is the FT-IR pattern, from Figure 5 It can be seen that the characteristic peaks of the catalyst crystals after reaction in the 1,4-dioxane co-solvent system are better preserved than those of the catalyst in the ethanol system. This may be attributed to the protective effect of 1,4-dioxane on the catalyst and the reduction of humic substance production during the reaction, thereby reducing the adhesion of humic substances to the catalyst surface. Another possibility is that ethanol is a proton-based organic solvent. Proton-based organic solvents have a greater impact on the crystal structure of zeolite molecular sieve catalysts. According to the FT-IR spectra, the mixed catalysts after reaction retain their unique functional group diffraction peaks, proving that the functional group structure of the catalysts after reaction is not destroyed. Compared to the 1,4-dioxane co-solvent system, the catalysts in the ethanol system show peaks at 814, 1398, 1465, and 1521 cm⁻¹. –1Distinct characteristic peaks were detected in the wavenumber infrared spectrum. These characteristic peaks mainly correspond to the CH and C=C bonds of alkanes and aromatic humic substances, which is presumably due to the formation of humic substances.

[0038] Analysis by high-performance liquid chromatography (HPLC) showed that the yield of the target product 5-ethoxymethylfurfural in this comparative example was 35.5%.

[0039] Example 2: A method for directly preparing 5-ethoxymethylfurfural from glucose (see Example 2) Figure 1 The specific steps are as follows:

[0040] (1) Glucose is added to a co-solvent to prepare a reaction substrate solution; the co-solvent is composed of ethanol and 1,4-dioxane, and the ethanol accounts for 90% of the co-solvent by volume fraction; the concentration of the reaction substrate solution is 0.05 mol / L;

[0041] (2) The zeolite molecular sieve mixed catalyst was added to the reaction substrate solution, and the reaction was stirred at 180℃ for 60 min to obtain 5-ethoxymethylfurfural; the zeolite molecular sieve mixed catalyst was composed of Hβ zeolite molecular sieve and USY zeolite molecular sieve; by mass percentage, Hβ zeolite molecular sieve accounted for 50% of the zeolite molecular sieve mixed catalyst; the mass ratio of the zeolite molecular sieve mixed catalyst to glucose in the reaction substrate solution was 1:1;

[0042] Analysis using high-performance liquid chromatography (HPLC) showed that the yield of the target product 5-ethoxymethylfurfural in this embodiment was 53.2%.

[0043] Example 3: A method for directly preparing 5-ethoxymethylfurfural from glucose (see Example 4) Figure 1 The specific steps are as follows:

[0044] (1) Glucose is added to a co-solvent to prepare a reaction substrate solution; the co-solvent is composed of ethanol and 1,4-dioxane, and the ethanol accounts for 10% by volume fraction; the concentration of the reaction substrate solution is 0.05 mol / L;

[0045] (2) The zeolite molecular sieve mixed catalyst was added to the reaction substrate solution, and the reaction was stirred at 180℃ for 60 min to obtain 5-ethoxymethylfurfural; the zeolite molecular sieve mixed catalyst was composed of Hβ zeolite molecular sieve and USY zeolite molecular sieve; by mass percentage, Hβ zeolite molecular sieve accounted for 50% of the zeolite molecular sieve mixed catalyst; the mass ratio of the zeolite molecular sieve mixed catalyst to glucose in the reaction substrate solution was 1:1;

[0046] Analysis by high-performance liquid chromatography (HPLC) showed that the yield of the target product 5-ethoxymethylfurfural in this embodiment was 46.7%.

[0047] Example 4: A method for directly preparing 5-ethoxymethylfurfural from glucose (see Example 4) Figure 1 The specific steps are as follows:

[0048] (1) Glucose is added to a co-solvent to prepare a reaction substrate solution; the co-solvent is composed of ethanol and 1,4-dioxane, and the ethanol accounts for 50% by volume fraction; the concentration of the reaction substrate solution is 0.25 mol / L;

[0049] (2) The zeolite molecular sieve mixed catalyst was added to the reaction substrate solution, and the reaction was stirred at 180℃ for 60 min to obtain 5-ethoxymethylfurfural; the zeolite molecular sieve mixed catalyst was composed of Hβ zeolite molecular sieve and USY zeolite molecular sieve; by mass percentage, Hβ zeolite molecular sieve accounted for 50% of the zeolite molecular sieve mixed catalyst; the mass ratio of the zeolite molecular sieve mixed catalyst to glucose in the reaction substrate solution was 1:2.5;

[0050] Analysis using high-performance liquid chromatography (HPLC) showed that the yield of the target product 5-ethoxymethylfurfural in this embodiment was 43.7%.

[0051] Example 5: A method for directly preparing 5-ethoxymethylfurfural from glucose (see Example 5) Figure 1 The specific steps are as follows:

[0052] (1) Glucose is added to a co-solvent to prepare a reaction substrate solution; the co-solvent is composed of ethanol and 1,4-dioxane, and the ethanol accounts for 50% by volume fraction; the concentration of the reaction substrate solution is 0.05 mol / L;

[0053] (2) The zeolite molecular sieve mixed catalyst was added to the reaction substrate solution, and the reaction was stirred at 160℃ for 60 min to obtain 5-ethoxymethylfurfural; the zeolite molecular sieve mixed catalyst was composed of Hβ zeolite molecular sieve and USY zeolite molecular sieve; by mass percentage, Hβ zeolite molecular sieve accounted for 50% of the zeolite molecular sieve mixed catalyst; the mass ratio of the zeolite molecular sieve mixed catalyst to glucose in the reaction substrate solution was 1:1;

[0054] Analysis by high-performance liquid chromatography (HPLC) showed that the yield of the target product 5-ethoxymethylfurfural in this embodiment was 45.1%.

[0055] Example 6: A method for directly preparing 5-ethoxymethylfurfural from glucose (see Example 6) Figure 1 The specific steps are as follows:

[0056] (1) Glucose is added to a co-solvent to prepare a reaction substrate solution; the co-solvent is composed of ethanol and 1,4-dioxane, and the ethanol accounts for 50% by volume fraction; the concentration of the reaction substrate solution is 0.05 mol / L;

[0057] (2) The zeolite molecular sieve mixed catalyst was added to the reaction substrate solution, and the reaction was stirred at 200℃ for 60 min to obtain 5-ethoxymethylfurfural; the zeolite molecular sieve mixed catalyst was composed of Hβ zeolite molecular sieve and USY zeolite molecular sieve; by mass percentage, Hβ zeolite molecular sieve accounted for 50% of the zeolite molecular sieve mixed catalyst; the mass ratio of the zeolite molecular sieve mixed catalyst to glucose in the reaction substrate solution was 1:1;

[0058] Analysis using high-performance liquid chromatography (HPLC) showed that the yield of the target product, 5-ethoxymethylfurfural, in this embodiment was 51.4%.

[0059] Example 7: A method for directly preparing 5-ethoxymethylfurfural from glucose (see Example 7) Figure 1 The specific steps are as follows:

[0060] (1) Glucose is added to a co-solvent to prepare a reaction substrate solution; the co-solvent is composed of ethanol and 1,4-dioxane, and the ethanol accounts for 50% by volume fraction; the concentration of the reaction substrate solution is 0.05 mol / L;

[0061] (2) The zeolite molecular sieve mixed catalyst was added to the reaction substrate solution, and the reaction was stirred at 180℃ for 30 min to obtain 5-ethoxymethylfurfural; the zeolite molecular sieve mixed catalyst was composed of Hβ zeolite molecular sieve and USY zeolite molecular sieve; by mass percentage, Hβ zeolite molecular sieve accounted for 50% of the zeolite molecular sieve mixed catalyst; the mass ratio of the zeolite molecular sieve mixed catalyst to glucose in the reaction substrate solution was 1:1;

[0062] Analysis by high-performance liquid chromatography (HPLC) showed that the yield of the target product 5-ethoxymethylfurfural in this embodiment was 48.2%.

[0063] Example 7: A method for directly preparing 5-ethoxymethylfurfural from glucose (see Example 7) Figure 1 The specific steps are as follows:

[0064] (1) Glucose is added to a co-solvent to prepare a reaction substrate solution; the co-solvent is composed of ethanol and 1,4-dioxane, and the ethanol accounts for 50% by volume fraction; the concentration of the reaction substrate solution is 0.05 mol / L;

[0065] (2) The zeolite molecular sieve mixed catalyst was added to the reaction substrate solution, and the reaction was stirred at 180℃ for 90 min to obtain 5-ethoxymethylfurfural; the zeolite molecular sieve mixed catalyst was composed of Hβ zeolite molecular sieve and USY zeolite molecular sieve; by mass percentage, Hβ zeolite molecular sieve accounted for 50% of the zeolite molecular sieve mixed catalyst; the mass ratio of the zeolite molecular sieve mixed catalyst to glucose in the reaction substrate solution was 1:1.

[0066] Analysis by high-performance liquid chromatography (HPLC) showed that the yield of the target product 5-ethoxymethylfurfural in this embodiment was 53.4%.

[0067] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for directly preparing 5-ethoxymethylfurfural from glucose, characterized in that, The specific steps are as follows: (1) Glucose is added to a co-solvent to prepare a reaction substrate solution; the co-solvent is composed of ethanol and 1,4-dioxane; by volume fraction, ethanol accounts for 10-90% in the co-solvent; (2) Add the zeolite molecular sieve mixed catalyst to the reaction substrate solution and stir to catalyze the reaction to obtain 5-ethoxymethylfurfural; the zeolite molecular sieve mixed catalyst is composed of Hβ zeolite molecular sieve and USY zeolite molecular sieve; by mass percentage, Hβ zeolite molecular sieve accounts for 10~90% of the zeolite molecular sieve mixed catalyst.

2. The method for directly preparing 5-ethoxymethylfurfural from glucose according to claim 1, characterized in that: In step (1), the concentration of the reaction substrate solution is 0.05~0.25 mol / L.

3. The method for directly preparing 5-ethoxymethylfurfural from glucose according to claim 1, characterized in that: Step (2) The mass ratio of the zeolite molecular sieve mixed catalyst to glucose in the reaction substrate solution is 1:1 to 1:

5.

4. The method for directly preparing 5-ethoxymethylfurfural from glucose according to claim 1, characterized in that: The temperature of the catalytic reaction in step (2) is 160~200℃ and the time is 30~90min.

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