Preparation method of selective oxidation catalyst and application of selective oxidation catalyst in synthesis of 2, 5-furandicarboxaldehyde

Abstract

The invention discloses a heteroatom-doped carbon material supported metal oxide catalyst which is used for preparing 2, 5-furandicarboxaldehyde through catalytic oxidation of 5-hydroxymethylfurfural. According to the catalyst, a heteroatom-doped carbon material is used as a carrier, and the heteroatom-doped carbon material loaded metal oxide catalyst is obtained through post-loading of a metal precursor and high-temperature roasting. The catalyst can efficiently catalyze 5-hydroxymethylfurfural to prepare 2, 5-furandicarboxaldehyde, has the advantages of high oxidation efficiency, high selectivity, difficulty in loss of active components, easiness in separation and recovery and the like, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the research field of biomass catalytic synthesis of high value-added products, and specifically relates to a heteroatom-doped carbon material-loaded metal oxide catalyst and a preparation method thereof and application thereof in the preparation of 2,5-furandicarboxaldehyde from 5-hydroxymethylfurfural. Background Art

[0002] With the continuous consumption of fossil resources such as petroleum and the growing greenhouse effect, the development and utilization of renewable and abundant biomass resources for the preparation of bulk and fine chemicals is of great significance for coping with the shortage of petroleum resources and achieving carbon neutrality. 5-Hydroxymethylfurfural (HMF) is one of the important platform compounds in biorefining. Its downstream products are extensive and can be used to produce a variety of chemicals. Among them, 2,5-furandicarboxaldehyde (DFF) is one of the important oxidation products of 5-hydroxymethylfurfural. It can undergo a variety of chemical reactions, such as hydrogenation, oxidation, polymerization, hydrolysis, etc., to synthesize many useful chemicals. It is widely used in biomedicine, antifungal agents, dyes, biomass-based new resins, etc., and has important social and economic significance.

[0003] DFF is mainly obtained by oxidation of HMF. The traditional method is to use chemical oxidants such as stoichiometric manganese dioxide, chromium trioxide, sodium hypochlorite, etc. for oxidation. However, these methods have the problems of low product yield, high price, and corrosiveness, and are not suitable for large-scale industrial production. In recent years, the use of cheap and green molecular oxygen O2 to oxidize HMF to prepare DFF is a promising method. For example, under mild conditions, using HMF as raw material, molecular oxygen as oxidant, and a homogeneous VOSO4 / Cu(NO3)2 catalyst in acetonitrile solvent, a maximum HMF conversion rate of 99% and a DFF selectivity of 99% can be obtained (Appl. Catal. A, 2014, 482, 231-236). However, the homogeneous catalytic system brings difficulties to catalyst recovery and product separation. Therefore, it is of great significance to develop a new technology for oxidizing HMF to prepare DFF with a recyclable catalyst, easy product separation, mild reaction conditions, and high product yield. Summary of the invention

[0004] In order to solve the problems that the stability and recycling of the catalyst reported in the prior art need to be further improved, the purpose of the present invention is to provide a catalyst and a method for catalyzing the oxidation of HMF to prepare DFF, which is a new oxidation technology for oxidizing HMF to prepare DFF with a recyclable catalyst, easy separation of products, mild reaction conditions and high product yield, and molecular oxygen or air is used as an oxidant to catalyze the oxidation of HMF to prepare DFF. The method has broad application prospects.

[0005] To achieve the above object, the first aspect of the present invention provides a method for preparing a selective oxidation catalyst, the method comprising: S1. Stirring an aqueous solution containing a heteroatom source and a carbon material in ethanol at room temperature, drying and then calcining in an inert atmosphere to obtain a heteroatom-doped carbon material.

[0006] S2. Mixing the heteroatom-doped carbon material with a metal precursor, and then calcining the mixture under an inert atmosphere to obtain the heteroatom-doped carbon material-supported metal oxide catalyst.

[0007] Optionally, in step S1, the specific surface area of ​​the carbon material is 200-2500 m 2 / g, preferably 800-1800 m 2 / g, the carbon material includes at least one of carbon black, activated carbon, and carbon fiber, and the heteroatom includes at least one of nitrogen, phosphorus, and boron. Carbon materials with high specific surface area as catalyst carriers can effectively increase the contact area between active components and reactants, and improve the selectivity or conversion rate of the reaction. Introducing heteroatoms into carbon materials can increase the defects or electron cloud density on the surface of carbon materials, which is beneficial to the adsorption of active components of the catalyst or reaction substrates.

[0008] Optionally, in step S1, the heteroatom source may be at least one of urea, melamine, dicyandiamide, boric acid, and diammonium hydrogen phosphate.

[0009] Optionally, in step S1, the mass ratio of the heteroatom source to the carbon material is about 1:4 to 1:7; the calcination conditions are: the calcination temperature is 600 to 800 o C, calcination time 3 to 5 h.

[0010] Optionally, in step S2, the metal precursor comes from both a metal vanadium oxide precursor and a metal copper oxide precursor, wherein the metal vanadium oxide precursor may be ammonium metavanadate or ammonium polyvanadate, and the metal copper oxide precursor may be any one of copper nitrate, copper acetate, and cuprous chloride.

[0011] Optionally, in step S2, the mass ratio of the metal vanadium oxide precursor to the heteroatom-doped carbon material is 1:8 to 1:20, and the mass ratio of the metal copper oxide precursor to the heteroatom-doped carbon material is 1:4 to 1:8; the calcination temperature is 500 to 800 o C, calcination time 3 to 5 h.

[0012] In the present application, the inert atmosphere includes nitrogen atmosphere and other inert gas atmospheres.

[0013] The second aspect of the present invention provides a method for preparing 2,5-furandicarboxaldehyde, the preparation method comprising: SS1. Dissolve 5-hydroxymethylfurfural in an organic solvent to obtain a mixed solution.

[0014] SS2. Add the heteroatom-doped carbon material-supported metal oxide catalyst into the above mixed solution, and carry out oxidation reaction in a reactor.

[0015] Optionally, in step SS1, the organic solvent is selected from one or more of acetonitrile, toluene, dioxane, N,N-dimethylformamide, and acetone; the mass ratio of the organic solvent to 5-hydroxymethylfurfural is 10-20:1, preferably 10:1; and the amount of the catalyst in step SS2 is 1-50% of the amount of 5-hydroxymethylfurfural.

[0016] Optionally, the conditions for the oxidation reaction in step SS2 include: a reaction temperature of 80 to 120 o C; reaction time is 10 to 18 h; reaction oxygen pressure is 0.1-2.0 MPa.

[0017] Through the above technical solution, the present invention has the following beneficial effects: (1) The present invention uses carbon-containing materials as catalyst carriers, which can effectively increase the contact area between the active components and the reactants while stabilizing the vanadium copper oxide, thereby improving the selectivity and conversion rate of the reaction. The introduction of heteroatoms into carbon materials can increase the defects or electron cloud density on the surface of the carbon materials, which is beneficial to the adsorption of the active components or reaction substrates of the catalyst. Therefore, the use of this catalyst can promote the catalytic conversion of high-concentration reactants to obtain highly selective target products. By optimizing the conditions, the catalyst has higher catalytic performance, which not only overcomes the need for precious metals in the oxidation of HMF to prepare DFF, but also reduces the requirements for equipment technology in this reaction, laying the foundation for the industrialization of DFF.

[0018] (2) The catalyst preparation process of the present invention is simple and easy to obtain, the catalyst is easy to separate and recover, and has good stability in recycling. In addition, oxygen is used as the oxygen source, which optimizes the environment and has little pollution. It is green and environmentally friendly and has broad industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the XPS spectrum of the nitrogen element in the nitrogen-doped carbon support of Example 1.

[0020] Figure 2 This is the XPS spectrum of the boron element in the boron-doped carbon support of Example 2. DETAILED DESCRIPTION

[0021] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0022] The calculation methods of conversion rate and selectivity in the examples of this application are as follows: ; ; Example 1 This example is used to illustrate the preparation of the nitrogen-doped carbon material of the present invention.

[0023] 1.5 g of Cabot carbon black was stirred evenly in 40 mL of 1 wt% urea solution and 10 mL of ethanol, stirred at room temperature for 3 h, dried at 80 °C overnight, and put into a tube furnace after grinding. Under nitrogen protection, the tube furnace was heated to 800 °C at a heating rate of 2 °C / min and kept at a constant temperature for 3 h to obtain a nitrogen-doped carbon material.

[0024] XPS analysis results showed that the nitrogen mass fraction was 0.44%; the oxygen mass fraction of XPS analysis was 3.14%; Figure 1 This is the XPS spectrum of the nitrogen-doped carbon material of Example 1.

[0025] Example 2 This example is used to illustrate the preparation of the boron-doped carbon material of the present invention.

[0026] The difference from Example 1 is that 1.8 g of activated carbon is uniformly stirred in 40 mL of 3 wt% boric acid solution and 10 mL of ethanol, and calcined at 600° C. for 3 h to finally obtain a boron-doped carbon material.

[0027] XPS analysis results show that the mass fraction of boron is 0.88%; the mass fraction of oxygen analyzed by XPS is 4.84%; Figure 2 This is the XPS spectrum of the boron-doped carbon support of Example 2.

[0028] Example 3 This example is used to illustrate the preparation of the phosphorus-doped carbon material of the present invention.

[0029] The difference from Example 1 is that 1.5 g of carbon fiber is evenly stirred in 40 mL of 10 wt% diammonium hydrogen phosphate solution and 10 mL of ethanol, and calcined at 800° C. for 3 h to finally obtain a phosphorus-doped carbon material.

[0030] Example 4 This example is used to illustrate the preparation of the nitrogen-doped carbon material-supported metal oxide catalyst of the present invention.

[0031] Take 1 g of the nitrogen-doped carbon material obtained in Example 1, add 0.096 g of ammonium metavanadate, 0.18 g of copper nitrate trihydrate and 30 mL of deionized water, stir and evaporate at 90°C for 3 h, dry in an oven at 80°C overnight, grind and calcine at 800°C for 3 h in a nitrogen atmosphere to obtain a nitrogen-doped carbon material-loaded vanadium copper oxide catalyst, recorded as catalyst A.

[0032] Example 5 The difference from Example 4 is that: 1.5 g of the boron-doped carbon material obtained in Example 2 is used as a carrier, and 0.15 g of ammonium metavanadate and 0.32 g of copper acetate monohydrate are added to obtain a boron-doped carbon material-supported vanadium copper oxide catalyst, which is recorded as Catalyst B.

[0033] Example 6 The difference from Example 5 is that 1.2 g of the phosphorus-doped carbon material obtained in Example 3 is used as a carrier, and 0.12 g of ammonium metavanadate and 0.25 g of copper acetate monohydrate are added to obtain a phosphorus-doped carbon material-supported vanadium copper oxide catalyst, which is recorded as Catalyst C.

[0034] Example 7 The difference from Example 5 is that 1.2 g of the phosphorus-doped carbon material obtained in Example 3 is used as a carrier, and 0.12 g of ammonium metavanadate, 0.25 g of copper acetate monohydrate, and 0.1 g of cuprous chloride are added to obtain a phosphorus-doped carbon material-loaded vanadium copper oxide catalyst, which is recorded as Catalyst D.

[0035] Example 8 This example is used to illustrate the method for preparing 2,5-furandicarboxaldehyde of the present invention.

[0036] 0.252 g (2 mmol) of 5-hydroxymethylfurfural, 80 mg of catalyst A obtained in Example 4, and 10 mL of acetonitrile were added to a stainless steel autoclave, and 1.0 MPa of oxygen was introduced. The reaction was carried out at 120°C for 10 hours under stirring conditions of 500 rpm. After the reaction was completed, the reaction was cooled to room temperature with an ice bath, and the catalyst was removed by filtration. The reaction solution was filtered with a 0.22 μm organic filter head, and 0.5 mL of internal standard mesitylene was added. The conversion rate of 5-hydroxymethylfurfural and the gas phase yield of 2,5-furandicarboxaldehyde were determined by gas-liquid chromatography. The catalytic reaction results are listed in Table 1.

[0037] Example 9 The difference from Example 8 is that the catalyst used is the catalyst B obtained in Example 5, and the amount of the catalyst used is 70 mg. The catalytic reaction results are listed in Table 1.

[0038] Example 10 The difference from Example 8 is that the catalyst used is the catalyst C obtained in Example 6, and the amount of the catalyst used is 85 mg. The catalytic reaction results are listed in Table 1.

[0039] Embodiment 11 The difference from Example 8 is that the catalyst is the catalyst D obtained in Example 7, and the amount of the catalyst is 50 mg. The catalytic reaction results are listed in Table 1.

[0040] Comparative Example 1 The difference from Example 4 is that the carrier is Cabot carbon black that has not been doped with heteroatoms, and the catalyst is denoted as E. Using catalyst E, 2,5-furandicarboxaldehyde was prepared according to the method of Example 8, and the catalytic reaction results are listed in Table 1.

[0041] Table 1. Preparation of 2,5-furandicarboxaldehyde by 5-hydroxymethylfurfural catalyzed by heteroatom-doped carbon material supported metal oxide catalyst

[0042] Comparing the results of Examples 8-11 with those of Comparative Example 1, it can be seen that when 5-hydroxymethylfurfural is used to prepare 2,5-furandicarboxaldehyde, the carbon carrier is treated with heteroatom doping, which can effectively improve the HMF conversion rate and DFF selectivity. The catalyst and its composition have a great influence on the reaction results described in the present invention.

[0043] Example 12 In order to study the stability and recycling performance of the catalyst prepared by the present invention, a recycling reaction was carried out according to the method of Example 11. The catalytic reaction results are listed in Table 2.

[0044] Table 2. Cyclic performance of nitrogen-doped carbon materials supported on metal oxide catalysts

[0045] The above results show that after the catalyst is recycled for 5 times, the conversion rate of 5-hydroxymethylfurfural is above 90%, and the selectivity of 2,5-furandicarboxaldehyde is still basically above 85%, indicating that the stability and recycling performance of the catalyst prepared in the present invention are improved to a certain extent.

[0046] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A heteroatom-doped carbon material-supported metal oxide catalyst for catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxaldehyde, characterized in that: The catalyst uses a heteroatom-doped carbon material as a carrier, and is loaded with a metal precursor, and then calcined at a high temperature to obtain a heteroatom-doped carbon material loaded with a metal oxide catalyst; The heteroatom is selected from at least one of nitrogen, phosphorus and boron; The carbon material is selected from at least one of carbon black, activated carbon and carbon fiber. The metal precursor is selected from both a metal vanadium oxide precursor and a metal copper oxide precursor; The catalyst is prepared according to the following steps: S1, stirring an aqueous solution containing a heteroatom source and a carbon material in ethanol at room temperature, drying and then calcining in an inert atmosphere to obtain a heteroatom-doped carbon material; S2. Mixing the heteroatom-doped carbon material with a metal precursor, and then calcining the mixture under an inert atmosphere to obtain the heteroatom-doped carbon material-supported metal oxide catalyst.

2. The catalyst according to claim 1, characterized in that In step S1, the heteroatom source may be at least one of urea, melamine, dicyandiamide, boric acid, and diamine hydrogen phosphate.

3. The catalyst according to claim 1, characterized in that In step S1, the mass ratio of the heteroatom source to the carbon material is about 1:4 to 1:7; the calcination conditions are: calcination temperature 600 to 800° C., and calcination time 3 to 5 h.

4. The catalyst according to claim 1, characterized in that In step S2, the metal precursor comes from both a metal vanadium oxide precursor and a metal copper oxide precursor, wherein the metal vanadium oxide precursor may be ammonium metavanadate or ammonium polyvanadate, and the metal copper oxide precursor may be copper nitrate or copper acetate.

5. The catalyst according to claim 1, characterized in that In step S2, the mass ratio of the metal vanadium oxide precursor to the heteroatom-doped carbon material is 1:8-1:20, and the mass ratio of the metal copper oxide precursor to the heteroatom-doped carbon material is 1:4-1:8; the calcination temperature is 500-800 o C, calcination time 3 to 5 h.

6. Use of the catalyst according to any one of claims 1 to 5 in the oxidation of 5-hydroxymethylfurfural to produce 2,5-furandicarboxaldehyde.

7. The use according to claim 6, characterized in that The preparation method of 2,5-furandicarboxaldehyde comprises: SS1. Dissolve 5-hydroxymethylfurfural in an organic solvent to obtain a mixed solution. SS2. Add the heteroatom-doped carbon material-supported metal oxide catalyst into the above mixed solution, and carry out oxidation reaction in a reactor.

8. The use according to claim 7, characterized in that In step S1, the organic solvent is selected from one or more of acetonitrile, toluene, dioxane, N,N-dimethylformamide, and acetone, The mass ratio of the organic solvent to 5-hydroxymethylfurfural is 10-20:1, preferably 10:

1.

9. The use according to claim 7, characterized in that The amount of catalyst used in step SS2 is 1-50% of the amount of 5-hydroxymethylfurfural used.

10. The use according to claim 7, characterized in that The conditions for the oxidation reaction in step SS2 include: a reaction temperature of 80 to 120° C.; a reaction time of 10 to 18 h; and a reaction oxygen pressure of 0.1 to 2.0 MPa.

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