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

Abstract

The application discloses a kind of heteroatom doped carbon material supported metal oxide catalysts, for catalytic oxidation 5-hydroxymethylfurfural preparation 2,5-furan dimethylaldehyde.The catalyst is heteroatom doped carbon material as carrier, by post-loading metal precursor, after high-temperature calcination obtains heteroatom doped carbon material supported metal oxide catalyst.The catalyst can efficiently catalyze 5-hydroxymethylfurfural preparation 2,5-furan dimethylaldehyde, with high oxidation efficiency, high selectivity, active component is not easy to lose, easy to separate and recover and the like advantage, has broad application prospect.

Description

TECHNICAL FIELD

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

[0002] With the continuous consumption of fossil resources such as petroleum and the continuous growth of greenhouse effect, it is of great significance to develop and utilize renewable and abundant biomass resources for preparing bulk and fine chemicals in response to the shortage of petroleum resources. 5-hydroxymethylfurfural (HMF) is one of the important platform compounds in bio-refining, and its downstream products are widely used. Many chemicals can be produced based on HMF, and 2,5-furandicarboxaldehyde (DFF) is one of the important oxidation products of 5-hydroxymethylfurfural. DFF can undergo various chemical reactions such as hydrogenation, oxidation, polymerization, and hydrolysis to synthesize many useful chemicals, which are widely used in biological medicines, antifungal agents, dyes, and new biomass-based resins, and have important social and economic significance.

[0003] DFF is mainly obtained by oxidation of HMF. The traditional method is to use stoichiometric manganese dioxide, chromium trioxide, sodium hypochlorite and other chemical oxidants for oxidation, but these methods have problems of low product yield, high price, and corrosion, which are not suitable for large-scale industrial production. In recent years, using 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 and molecular oxygen as oxidant, a homogeneous VOSO4 / Cu(NO3)2 catalyst is used in acetonitrile solvent, and the highest HMF conversion rate and DFF selectivity of 99% can be obtained (Appl. Catal. A, 2014, 482, 231-236). However, the homogeneous catalytic system brings difficulties to the recovery of the catalyst and the separation of the product. Therefore, it is of great significance to develop a new technology for oxidizing HMF to prepare DFF, which has the advantages of recyclable catalyst, easy product separation, mild reaction conditions, and high product yield. SUMMARY

[0004] In order to solve the problems of further improving the stability and recycling of the existing reported catalysts, the purpose of the present application is to provide a catalyst and a method for catalyzing HMF oxidation to prepare DFF. The method is a new oxidation technology for oxidizing HMF to prepare DFF with recyclable catalyst, easy product separation, mild reaction conditions, and high product yield, using molecular oxygen or air as oxidant to catalyze HMF oxidation to prepare DFF. The method has broad application prospects.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a preparation method of a selective oxidation catalyst, which comprises:

[0006] S1, stirring the aqueous solution containing a heteroatom source and the carbon material in ethanol at room temperature, drying and then calcining under an inert atmosphere to obtain a heteroatom-doped carbon material.

[0007] S2, mixing the heteroatom-doped carbon material with a metal precursor, and then calcining under an inert atmosphere to obtain the metal oxide catalyst supported by the heteroatom-doped carbon material.

[0008] Optionally, the specific surface area of the carbon material in step S1 is 200-2500 m 2 / g, preferably 800-1800 m 2 / g, the carbon material includes at least one of carbon black, activated carbon, carbon fiber, and the heteroatom includes at least one of nitrogen, phosphorus and boron. The high specific surface area of the carbon material as a carrier of the catalyst can effectively increase the contact area of the active component and the reactant, and improve the selectivity or conversion rate of the reaction. The introduction of the heteroatom into the carbon material can increase the defects or electron cloud density of the carbon material surface, thereby facilitating the adsorption of the active component or the reaction substrate of the catalyst.

[0009] Optionally, the heteroatom source in step S1 can be at least one of urea, melamine, dicyandiamide, boric acid and diammonium hydrogen phosphate.

[0010] Optionally, the mass ratio of the heteroatom source to the carbon material in step S1 is about 1:4-1:7, and the calcination conditions are as follows: calcination temperature 600-800 o C, and calcination time 3-5 h.

[0011] Optionally, the metal precursor in step S2 is derived from both a metal vanadium oxide precursor and a metal copper oxide precursor, wherein the metal vanadium oxide precursor can be ammonium metavanadate or ammonium polyvanadate, and the metal copper oxide precursor can be any one of copper nitrate, copper acetate and cuprous chloride.

[0012] Optionally, 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, and the calcination time is 3-5 h.

[0013] In this application, the inert atmosphere includes a nitrogen atmosphere and other inert gas atmospheres.

[0014] The second aspect of the present application provides a preparation method of 2,5-furandicarboxaldehyde, which comprises:

[0015] SS1, dissolving 5-hydroxymethylfurfural in an organic solvent to obtain a mixed solution.

[0016] SS2, the metal oxide catalyst loaded on the heteroatom-doped carbon material is added to the mixed solution, and an oxidation reaction is carried out in a reaction kettle.

[0017] 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 used in step SS2 is 1-50% of the amount of 5-hydroxymethylfurfural.

[0018] Optionally, in step SS2, the conditions of the oxidation reaction include: the reaction temperature is 80-120 o C; the reaction time is 10-18 h; and the reaction oxygen pressure is 0.1-2.0 MPa.

[0019] Through the above technical solution, the present application has the following beneficial effects:

[0020] (1) The present application uses carbon-containing material as a catalyst carrier, which can effectively increase the contact area of the active component and the reactant while stabilizing vanadium copper oxide, thereby improving the selectivity and conversion rate of the reaction. The introduction of heteroatoms into the carbon material can increase the defects or electron cloud density on the surface of the carbon material, thereby facilitating the adsorption of the active component or the reaction substrate of the catalyst. Therefore, using the catalyst can promote the catalytic conversion of high-concentration reactants to obtain high-selectivity target products. Through condition optimization, the catalyst has high catalytic performance, which not only overcomes the demand for noble metals in the preparation of DFF from HMF, but also reduces the technical requirements of the equipment for the reaction, laying a foundation for the industrialization of DFF.

[0021] (2) The present application has simple catalyst preparation process, easy catalyst separation and recovery, good recycling stability, uses oxygen as the oxygen source, has little environmental pollution, is green and environmentally friendly, and has broad industrial application prospects. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is an XPS spectrum of nitrogen elements in the nitrogen-doped carbon carrier of Example 1.

[0023] Figure 2 is an XPS spectrum of boron elements in the boron-doped carbon carrier of Example 2. DETAILED DESCRIPTION

[0024] The present application will be described in detail below with reference to the examples, but the present application is not limited to these examples.

[0025] The conversion rate and selectivity calculation method in the examples of the present application is as follows:

[0026] ; ;

[0027] Example 1

[0028] This example is used to illustrate the preparation of the nitrogen-doped carbon material of the present application.

[0029] 1.5 g of Cabot black carbon was stirred uniformly 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 then ground and placed in a tube furnace. The tube furnace was heated to 800°C at a heating rate of 2°C / min under nitrogen protection, and held at this temperature for 3 h to obtain the nitrogen-doped carbon material.

[0030] XPS analysis showed that the nitrogen mass fraction was 0.44%; the oxygen mass fraction analyzed by XPS was 3.14%; Figure 1 XPS spectrum of the nitrogen-doped carbon material of Example 1.

[0031] Example 2

[0032] This example is used to illustrate the preparation of the boron-doped carbon material of the present application.

[0033] The difference from Example 1 is that 1.8 g of activated carbon was stirred uniformly in 40 mL of 3 wt% boric acid solution and 10 mL of ethanol, and then calcined at 600°C for 3 h to finally obtain the boron-doped carbon material.

[0034] XPS analysis showed that the boron mass fraction was 0.88%; the oxygen mass fraction analyzed by XPS was 4.84%; Figure 2 XPS spectrum of the boron-doped carbon support of Example 2.

[0035] Example 3

[0036] This example is used to illustrate the preparation of the phosphorus-doped carbon material of the present application.

[0037] The difference from Example 1 is that 1.5 g of carbon fiber was stirred uniformly in 40 mL of 10 wt% diammonium hydrogen phosphate solution and 10 mL of ethanol, and then calcined at 800°C for 3 h to finally obtain the phosphorus-doped carbon material.

[0038] Example 4

[0039] This example is used to illustrate the preparation of the metal oxide catalyst supported on the nitrogen-doped carbon material of the present application.

[0040] Take the nitrogen-doped carbon material 1 g obtained in Example 1, add 0.096 g ammonium metavanadate, 0.18 g copper nitrate trihydrate and 30 mL deionized water, stir at 90°C for 3 h, oven dry at 80°C overnight, grind and calcine at 800°C for 3 h under nitrogen atmosphere to obtain a nitrogen-doped carbon material supported vanadium copper oxide catalyst, denoted as catalyst A.

[0041] Example 5

[0042] The difference from Example 4 is that the boron-doped carbon material 1.5 g obtained in Example 2 is used as the carrier, and 0.15 g ammonium metavanadate and 0.32 g copper acetate monohydrate are added to obtain a boron-doped carbon material supported vanadium copper oxide catalyst, denoted as catalyst B.

[0043] Example 6

[0044] The difference from Example 5 is that the phosphorus-doped carbon material 1.2 g obtained in Example 3 is used as the carrier, and 0.12 g ammonium metavanadate and 0.25 g copper acetate monohydrate are added to obtain a phosphorus-doped carbon material supported vanadium copper oxide catalyst, denoted as catalyst C.

[0045] Example 7

[0046] The difference from Example 5 is that the phosphorus-doped carbon material 1.2 g obtained in Example 3 is used as the carrier, and 0.12 g ammonium metavanadate, 0.25 g copper acetate monohydrate and 0.1 g cuprous chloride are added to obtain a phosphorus-doped carbon material supported vanadium copper oxide catalyst, denoted as catalyst D.

[0047] Example 8

[0048] This example is used to illustrate the method for preparing 2,5-furandicarboxaldehyde according to the present application.

[0049] Put 0.252 g (2 mmol) 5-hydroxymethylfurfural, 80 mg catalyst A obtained in Example 4, 10 mL acetonitrile into a stainless steel autoclave, introduce 1.0 MPa oxygen, stir at 500 rpm, react at 120°C for 10 hours, after the reaction is completed, cool to room temperature with an ice bath, filter off the catalyst, filter the reaction liquid with a 0.22 μm organic filter, add 0.5 mL internal standard mesitylene, and determine the conversion of 5-hydroxymethylfurfural and the gas phase yield of 2,5-furandicarboxaldehyde by gas chromatography. The results of the catalytic reaction are shown in Table 1.

[0050] Example 9

[0051] The difference from Example 8 is that catalyst B obtained in Example 5 is selected as the catalyst, and the catalyst dosage is 70 mg. The results of the catalytic reaction are shown in Table 1.

[0052] Example 10

[0053] The difference from Example 8 is that the catalyst is catalyst C obtained from Example 6, and the catalyst dosage is 85 mg. The catalytic reaction results are listed in Table 1.

[0054] Example 11

[0055] The difference from Example 8 is that the catalyst is catalyst D obtained from Example 7, and the catalyst dosage is 50 mg. The catalytic reaction results are listed in Table 1.

[0056] Comparative Example 1

[0057] The difference from Example 4 is that the carrier is Cabot carbon black without heteroatom doping treatment, and the catalyst is marked as E. 2,5-furandicarboxaldehyde is prepared according to the method of Example 8 using catalyst E, and the catalytic reaction results are listed in Table 1.

[0058] Table 1, Heteroatom-doped carbon material supported metal oxide catalyst catalyzing 5-hydroxymethylfurfural to prepare 2,5-furandicarboxaldehyde

[0059]

[0060] Comparing the results of Examples 8-11 with Comparative Example 1, it can be seen that when 5-hydroxymethylfurfural is used to prepare 2,5-furandicarboxaldehyde, the heteroatom doping treatment of the carbon carrier can effectively improve the conversion rate of HMF and the selectivity of DFF, and the catalyst and its composition have a great influence on the reaction results described in the present application.

[0061] Example 12

[0062] In order to study the stability and recycling performance of the catalyst prepared in the present application, a recycling reaction was carried out according to the method of Example 11, and the catalytic reaction results are listed in Table 2.

[0063] Table 2, Recycling performance of nitrogen atom-doped carbon material supported metal oxide catalyst

[0064]

[0065] The above results show that after 5 cycles of the catalyst, the conversion rate of 5-hydroxymethylfurfural is more than 90%, and the selectivity of 2,5-furandicarboxaldehyde is still basically more than 85%, indicating that the stability and recycling performance of the catalyst prepared in the present application have been improved to a certain extent.

[0066] The above merely describes several embodiments of the present application, and does not limit the present application in any form. Although the present application is disclosed with the preferred embodiments, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the disclosed technical contents without departing from the scope of the technical solutions of the present application, and the equivalent embodiments are equivalent to the equivalent embodiments, which are within the scope of the technical solutions.

Claims

1. Use of a heteroatom-doped carbon material supported metal oxide catalyst in the catalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxaldehyde, characterized in that, the heteroatom-doped carbon material supported metal oxide catalyst is prepared by using a heteroatom-doped carbon material as a support, loading a metal precursor thereon, and then calcining at a high temperature to obtain the heteroatom-doped carbon material supported metal oxide catalyst; the heteroatom is at least one selected from nitrogen, phosphorus, and boron; the carbon material is at least one selected from carbon black, activated carbon, and carbon fiber; the metal precursor is from both a metal vanadium oxide precursor and a metal copper oxide precursor; the catalyst is prepared according to the following steps: S1. stirring a water solution containing a heteroatom source and a carbon material in ethanol at room temperature, drying, and then calcining under an inert atmosphere to obtain a heteroatom-doped carbon material; S2. mixing the heteroatom-doped carbon material with a metal precursor, and then calcining under an inert atmosphere to obtain the heteroatom-doped carbon material supported metal oxide catalyst.

2. Use according to claim 1, characterized in that, In step S1, the heteroatom source is at least one selected from urea, melamine, dicyandiamide, boric acid, and hydrogen diammonium phosphate.

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

4. Use according to claim 1, characterized in that, In step S2, the metal precursor is from both a metal vanadium oxide precursor and a metal copper oxide precursor, wherein the metal vanadium oxide precursor is selected from ammonium metavanadate and ammonium polyvanadate, and the metal copper oxide precursor is selected from copper nitrate and copper acetate.

5. The use 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 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°C, and the calcination time is 3 to 5 h.

6. The use according to claim 1, characterized in that, 2. A method for preparing 2,5-furandicarboxaldehyde, comprising: SS1. dissolving 5-hydroxymethylfurfural in an organic solvent to obtain a mixed solution; SS2. adding the heteroatom-doped carbon material supported metal oxide catalyst to the mixed solution, and performing an oxidation reaction in a reaction kettle.

7. Use according to claim 6, characterized in that, In step SS1, the organic solvent is one or more selected from acetonitrile, toluene, dioxane, N,N-dimethylformamide, and acetone, and the mass ratio of the organic solvent to 5-hydroxymethylfurfural is 10-20:

1.

8. Use according to claim 7, characterized in that, The mass ratio of the organic solvent to 5-hydroxymethylfurfural is 10:

1.

9. Use according to claim 6, characterized in that, In step SS2, the catalyst is used in an amount of 1-50% of the amount of 5-hydroxymethylfurfural.

10. Use according to claim 6, characterized in that, In step SS2, the oxidation reaction conditions include a reaction temperature of 80 to 120°C, a reaction time of 10 to 18 h, and an oxygen pressure of 0.1 to 2.0 MPa.

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