CN109174153B

CN109174153B - Nitrogen-doped carbon material catalyst and application thereof in catalyzing 5-hydroxymethylfurfural to prepare 2, 5-diformylfuran through oxidation

Info

Publication number: CN109174153B
Application number: CN201811058859.2A
Authority: CN
Inventors: 张泽会; 袁紫亮; 刘冰; 池泉
Original assignee: South Central University for Nationalities
Current assignee: South Central Minzu University
Priority date: 2018-09-11
Filing date: 2018-09-11
Publication date: 2021-08-03
Anticipated expiration: 2038-09-11
Also published as: CN109174153A

Abstract

The invention relates to the technical field of catalyzing 5-hydroxymethylfurfural to oxidize and prepare 2, 5-diformylfuran, in particular to a C-N material catalyst with an effective component of a nitrogen-doped carbon material and application thereof in catalyzing 5-hydroxymethylfurfural to oxidize and prepare 2, 5-diformylfuran, wherein the catalyst is prepared by the following method: adding chitosan into urea solution, adding acetic acid after chitosan is completely dispersed to obtain uniform semitransparent paste, drying, and calcining at 500-1200 ℃. The preparation method of the catalyst is particularly simple and easy to operate, and can be used for preparing 2, 5-Diformylfuran (DFF) by catalytic oxidation. The method for preparing the 2, 5-diformylfuran by catalytic oxidation by using the catalyst has the advantages of mild reaction conditions, quick reaction and relatively high yield.

Description

Nitrogen-doped carbon material catalyst and application thereof in catalyzing 5-hydroxymethylfurfural to prepare 2, 5-diformylfuran through oxidation

Technical Field

The invention relates to the technical field of catalyzing 5-hydroxymethylfurfural to oxidize and prepare 2, 5-diformylfuran, and in particular relates to a nitrogen-doped carbon catalyst and application thereof in catalyzing 5-Hydroxymethylfurfural (HMF) to oxidize and prepare 2, 5-Diformylfuran (DFF).

Background

2,5-diformylfuran (English: 2, 5-Diformylfuran) is also called 2, 5-furandicarboxaldehyde, 2, 5-glyoxalfuran, abbreviated as: DFF, molecular formula: c₆H₄O₃Molecular weight: 124.09, CAS number: 823-82-5. 2,5-Diformylfuran (DFF) is one of the most important bio-based material intermediates, which, as a product of selective oxidation of hydroxyl groups in HMF, can provide the most versatile intermediate for the synthesis of a large number of furan-containing functional polymers, poly-Schiff bases, drugs, antifungal agents and organic conductors.

In the early days, including NaOCl, BaMnO₄Or pyridinium chlorochromate ionsStoichiometric oxidants and the like are used to oxidize 5-Hydroxymethylfurfural (HMF) to 2,5-Diformylfuran (DFF), however, these methods are uneconomical and unsustainable for the synthesis of DFF, as a large amount of waste is released. Catalytic oxidation of HMF with molecular oxygen represents a green process, where H₂O is the only other product than DFF. Homogeneous and heterogeneous catalysts have been studied for the oxidation of HMF, in order to overcome the drawbacks of homogeneous catalysts with respect to catalyst recycling, the catalytic oxidation of HMF is mainly carried out in the presence of heterogeneous catalysts; heterogeneous catalysts, comprising primarily vanadium, ruthenium and manganese catalysts, have been reported for the oxidation of HMF to DFF. However, the use of metal catalysts can result in increased costs and metal contamination in the final product, particularly for pharmaceutical agents. For example, Riisager and co-workers report that over 60% of the total activity of the catalyst is a catalytic species from V ₂O₅H-ZSM-5 and V₂O₅The result of dissolution in the/H-mordenite catalyst. Most of the methods for preparing 2, 5-diformylfuran disclosed in the prior art use noble metal catalysts and still require high oxygen pressure, so that the catalyst price is very expensive for preparing industrial catalysts, and the requirements on industrial reaction kettles are more strict under the oxygen pressure of lectures, so that the prior catalysts are not beneficial to large-scale industrial production for preparing 2, 5-diformylfuran. Therefore, it is highly desirable to develop a metal-free catalyst (or metal-free catalytic system) that efficiently oxidizes HMF to DFF.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a C-N material catalyst with an active ingredient of a nitrogen-doped carbon material and application thereof in catalyzing 5-Hydroxymethylfurfural (HMF) to prepare 2, 5-Diformylfuran (DFF), wherein the catalyst is a metal-free catalyst, the preparation method is simple and easy to operate, and the catalyst can be used for catalyzing 5-Hydroxymethylfurfural (HMF) to prepare 2, 5-Diformylfuran (DFF) through oxidation.

The catalyst is used for preparing 2, 5-diformylfuran by catalytic oxidation of 5-hydroxymethylfurfural, and has mild reaction conditions and relatively high yield.

In order to achieve the purpose, the invention adopts the following technical scheme:

a catalyst with nitrogen-doped carbon material as an active ingredient is prepared by the following method:

1) adding chitosan into urea aqueous solution under stirring (preferably vigorous stirring), adding acetic acid after chitosan is completely dispersed, stirring (preferably vigorous stirring) to obtain uniform semitransparent paste, drying, and uniformly grinding to obtain a composite material precursor;

2) in N₂Calcining the composite material precursor obtained in the step (1) at 500-1200 ℃ for 3-8h under the atmosphere, taking out the product after the product is cooled, and grinding the product into powder to obtain the catalyst with the effective component of the nitrogen-doped carbon material.

Further, the adding amount ratio of the urea (the urea in the urea aqueous solution), the chitosan and the acetic acid is 10-15g:1g: 300-.

Further, the specific conditions of the calcination in the step 2) are as follows: in N₂Heating from room temperature to 500-1200 ℃ at the heating rate of 3 ℃/min under the atmosphere, and then preserving the heat for 3-8h, preferably: in N₂Heating from room temperature to 800-950 ℃ at the heating rate of 3 ℃/min under the atmosphere, and then preserving the heat for 5 h.

Further, the temperature for drying in the step 1) is 70 ℃.

The invention also provides application of the catalyst with the nitrogen-doped carbon material as the effective component in catalyzing 5-hydroxymethylfurfural to oxidize and prepare 2, 5-diformylfuran.

The application comprises the following steps:

the catalyst, the solvent, the 5-hydroxymethylfurfural and the nitric acid are mixed according to the proportion (5-30) mg: 10mL of: 0.5 mmol: (0-0.6) mmol is added into a reaction vessel, 1bar-20bar of oxidizing gas is filled after sealing, the temperature is raised to 60-120 ℃, the temperature is kept, the stirring is carried out for 1-24h, and the 2, 5-diformylfuran is obtained.

Further, the concentration of the nitric acid is 65-68 wt%.

Preferably, the application comprises the following steps:

the catalyst, the solvent, the 5-hydroxymethylfurfural and the nitric acid are mixed according to the proportion (20-30) mg: 10mL of: 0.5 mmol: (0.4-0.6) mmol is added into a reaction vessel, after sealing, oxidizing gas of 10-20 bar is filled, the temperature is raised to 120 ℃, the temperature is kept, and the mixture is stirred and reacted for 4-14h, so as to obtain the 2, 5-diformylfuran.

Further, the oxidizing gas is oxygen.

Further, the solvent is at least one of 1, 4-dioxane, dimethyl sulfoxide, acetonitrile, ethyl acetate, toluene, hexane, water and tetrahydrofuran.

Further, the solvent is 1, 4-dioxane or acetonitrile, preferably acetonitrile.

Compared with the prior art, the invention has the following advantages and effects:

1. the invention prepares a novel catalyst on the basis of the composite material precursor of chitosan, formic acid and urea, the catalyst is a C-N material color metal-free catalyst with the effective component of nitrogen-doped carbon material, and the preparation method of the novel catalyst is very simple and can be obtained on the basis of the composite material precursor only by calcining.

2. Compared with the existing method, the method for preparing the 2, 5-Diformylfuran (DFF) by catalyzing the aerobic oxidation of the 5-Hydroxymethylfurfural (HMF) by using the prepared novel catalyst has the advantages that the reaction temperature and the reaction pressure are greatly reduced, the reaction conditions are mild, the preparation cost of the 2, 5-Diformylfuran (DFF) is greatly reduced, and the yield of the product 2, 5-Diformylfuran (DFF) is kept consistent compared with the existing metal catalysts such as Co, Pd, Au and the like.

3. The catalyst prepared by the method has good stability, can be recycled for more than 16 times, and has good industrial application prospect.

Drawings

FIG. 1 is a transmission electron microscope photograph and a scanning electron microscope photograph of examples 1 to 3 in which the effective components of the nitrogen-doped carbon skeleton catalyst, NC-650, NC-800 and NC-950 are respectively the transmission electron microscope photographs of FIG. 1a, FIG. 1c, FIG. 1e, NC-650, NC-800 and NC-950 are respectively the scanning electron microscope photographs of FIG. 1b, FIG. 1d and FIG. 1 f.

FIG. 2 is an X-ray diffraction pattern (XRD pattern) of nitrogen-doped carbon skeleton catalyst as an active ingredient in examples 1 to 3.

FIG. 3 is an X photoelectron spectroscopy (XPS spectrum) N1 s spectrum of the NC-650 catalyst of example 3.

FIG. 4 is an X photoelectron spectroscopy (XPS spectrum) N1 s spectrum of the NC-800 catalyst of example 2.

FIG. 5 is an X photoelectron spectrum (XPS spectrum) N1 s spectrum of the NC-950 catalyst of example 1.

FIG. 6 is a C1 s spectrum of an X photoelectron spectrum of the NC-950 catalyst of example 1 after fitting.

FIG. 7 shows Raman spectra (Ramman spectra) of nitrogen-doped carbon skeleton catalysts as the active ingredient in examples 1 to 3.

FIG. 8 shows N as an active ingredient of nitrogen-doped carbon skeleton catalyst in examples 1 to 3₂Adsorption-desorption (fig. 8-1) and pore size distribution (fig. 8-2).

Fig. 9 is a graph plotting the effect of reaction temperature on conversion and product selectivity of HMF oxidation.

FIG. 10 is O₂Graph of the effect of pressure on conversion and product selectivity of HMF oxidation.

FIG. 11 is a graph of the effect of catalyst loading on HMF conversion and product selectivity.

Detailed Description

The technical solutions of the present invention are described in detail below with reference to specific examples and drawings of the specification, but the following examples are not intended to limit the scope of the present invention.

The chitosan (degree of deacetylation. gtoreq.95%, viscosity 100-.

Example 1

A C-N material catalyst with nitrogen-doped carbon skeleton material as an active ingredient is prepared by the following method:

1) urea (12g) was dissolved in 10mL H₂O, then slowly adding chitosan (1g) to the urea solution with vigorous stirringAfter chitosan was completely dispersed, acetic acid (500. mu.L) was rapidly added and vigorously stirred for 30min to obtain a uniform translucent paste. After drying the resulting translucent paste at 70 ℃ overnight, a single white solid was obtained, which was thoroughly ground to a powder to give a composite precursor.

2) In N₂Placing the composite material precursor obtained in the step 1) into a furnace for calcination under the atmosphere: firstly, heating a furnace from room temperature to a calcination temperature of 950 ℃ at a heating rate of 3 ℃/min, then keeping the temperature at 950 ℃ for 5h, finally cooling a sample to room temperature, taking out the sample, and grinding the sample into fine powder to obtain the C-N material catalyst with the effective component of the nitrogen-doped carbon framework material, wherein the prepared catalyst is abbreviated as NC-950.

Example 2

The same operation and procedure as in example 1 were carried out except that the calcination temperature was changed to 800 ℃ to obtain a C — N material catalyst having an active ingredient of nitrogen-doped carbon skeleton material: NC-800.

Example 3

In the same manner as in example 1, the calcination temperature was changed to 650 ℃ by changing the calcination temperature alone, and a C — N material catalyst having an active ingredient of a nitrogen-doped carbon skeleton material was obtained: NC-650.

The C — N material catalysts prepared in examples 1 to 3, the active ingredients of which are nitrogen-doped carbon framework materials, were scanned by a Transmission Electron Microscope (TEM), and the obtained TEM and sem images are shown in fig. 1, and it can be found from fig. 1 that:

the morphology of the prepared NC-X (X denotes calcination temperature) catalyst sample is greatly affected by the pyrolysis temperature. Severe agglomeration of the nitrogen-doped carbon layer was observed in both TEM and SEM images of the NC-650 catalyst (fig. 1a and b). By increasing the pyrolysis temperature to 800 ℃, as can be seen from the SEM and TEM images, a thin carbon layer was obtained (fig. 1c and d). The pyrolysis temperature was further increased to 950 ℃, thin carbon destruction was clearly observed in TEM and SEM images of the NC-950 catalyst, and a large number of pores were clearly observed (fig. 1e and f). These results show that high pyrolysis temperatures can destroy the structure of the NC-X catalyst samples prepared.

Example 4

The C — N material catalyst prepared in examples 1 to 3, the active ingredient of which is a nitrogen-doped carbon material, was subjected to X-ray diffraction pattern analysis, and the diffraction pattern thereof was analyzed by performing X-ray diffraction test on the material to obtain information such as the structure or morphology of atoms or molecules inside the material, and the XRD pattern of the NC-X catalyst in fig. 2 showed two diffraction peaks at 2 θ ≈ 25 ° and 44 °, having a large width and a low intensity. The strong peak near 2 θ ≈ 25 ° is the (002) plane of graphitic carbon, indicating the presence of graphitic carbon in the NC-X catalyst. The original NC-X catalyst having a graphite structure is advantageous in that it can improve the electrical conductivity and mechanical stability of the matrix. In addition, the weak peak at 2 θ ≈ 44 ° has low intensity, indicating that the catalyst has an in-layer condensation phenomenon and doping of nitrogen atoms in graphite layers. XRD results show that nitrogen-doped carbon materials have been successfully prepared.

Example 5

X photoelectron spectroscopy was performed on the C — N material catalyst prepared in examples 1 to 3, the effective ingredient of which is a nitrogen-doped carbon material, and the valence states of nitrogen and carbon were characterized by XPS technique, and the obtained X photoelectron spectroscopy was as shown in fig. 3 to 6, fig. 3 is an energy spectrum diagram of the NC-650 catalyst of example 3, fig. 4 is an energy spectrum diagram of the NC-800 catalyst of example 2, and fig. 5 is an energy spectrum diagram of the NC-950 catalyst of example 1.

The N1 s spectrum in the NC-X catalyst can be decomposed into three peaks which respectively correspond to pyridine N (N1,397.9-398.0 eV), pyrrole N (N2,399.6-399.8 eV) and graphite N (N3,400.7-400.9 eV). From FIGS. 3 to 5, it can be observed that the relative peak area ratios of pyridine N and graphite N in the NC-X catalyst are affected by the pyrolysis temperature. The relative peak area ratio of pyridine N gradually decreased with increasing pyrolysis temperature, while graphite N increased. The relative peak area of pyrrole N is kept stable and is within the range of 27-28%. Further, the total nitrogen contents determined by XPS for the NC-650 catalyst, the NC-800 catalyst and the NC-950 catalyst were 15.9 at%, 13.0 at% and 8.7 at%, respectively. The decrease in nitrogen content with increasing pyrolysis temperature should be due to the higher pyrolysis temperature severely damaging the nitrogen atoms in the graphitic carbon structure. A C1 s XPS spectrum of the NC-950 catalyst was also fitted (FIG. 6), which is shown at 284.6eOne main peak at V corresponds to sp²-hybrid graphitic carbon (C ═ C) and two additional peaks with small signals of 285.6eV and 286.5eV, which are assigned to C-O/C ═ N and O-C ═ O.

Example 6

The C-N material catalyst which is prepared in the embodiment 1-3 and takes the nitrogen-doped carbon material as the active ingredient is subjected to Raman spectrum analysis, the obtained Raman spectrum is shown in figure 7, and all the NC-X catalysts can be seen to show two peaks, the wave number is 1351-1365 cm ^-11542-1579 cm^-1Within the scope of which are referred to as D-band and G-band, respectively. Intensity ratio of D zone and G zone for NC-650, NC-800 and NC-950 catalysts (I)_D/I_G) 1.3, 1.8 and 2.3 respectively. I is_D/I_GIs inversely proportional to the crystallite structure, indicating that as the pyrolysis temperature is increased, the crystallite structure of the NC-X sample decreases, there are more defect sites, consistent with TEM and SEM results.

FIG. 8 shows N as an active ingredient of nitrogen-doped carbon skeleton catalyst in examples 1 to 3₂Adsorption-desorption (fig. 8-1) and pore size distribution (fig. 8-2). N of NC-X catalyst₂The adsorption-desorption isotherms are similar, and can be classified into a type IV isotherm with a type H4 hysteresis loop and a type I isotherm with equilibrium in the range of 0-0.1P/Po at 0.1-1.0P/Po, indicating that NC-X catalyst samples all have mesoporous and microporous structures; the samples have wide mesopore size distribution, and all the samples have small bulges with the same size at 0.54nm and narrow size distribution; meanwhile, with the rise of the pyrolysis temperature, the volumes of the mesopores and the micropores are greatly increased, the mass transfer is facilitated due to the large specific surface area and the rich pores, and the catalytic reaction is facilitated due to the rich active sites at the edges.

Example 7

The method for preparing 2, 5-Diformylfuran (DFF) by catalyzing 5-Hydroxymethylfurfural (HMF) to be oxidized by using the C-N material catalyst which is prepared by the embodiment and takes a nitrogen-doped carbon material as an active ingredient comprises the following steps:

HMF (63mg, 0.5mmol), NC-950(20mg), 65 wt% HNO₃(0.29mmol) and acetonitrile (10mL) as solvent were added to the autoclave, which was then purged with O₂Purging 5The autoclave was sealed and then charged with 10bar of O at room temperature₂Then, the reaction mixture was heated from room temperature to 100 ℃ and then reacted at 100 ℃ for 1 hour at a mechanical stirring speed of 1000rpm, and after the reaction was completed, the catalyst was collected by centrifugation to obtain 2, 5-Diformylfuran (DFF) with a conversion of 55.5% and a selectivity of 2, 5-diformylfuran of 98.0% and a by-product of 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) with a selectivity of 1.5%.

Examples 8 to 12

In the same manner as in example 7, except for changing the catalyst to be added, 2, 5-Diformylfuran (DFF) and 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) were obtained, as shown in Table 1:

TABLE 1 Effect of different catalysts on HMF Oxidation

Examples 13 to 22

In the same manner as in example 7, the reaction solvent and reaction time were varied to obtain 2, 5-Diformylfuran (DFF) and-hydroxymethyl-2-furancarboxylic acid (HMFCA), as shown in Table 2:

TABLE 2 Effect of different solvents on HMF Oxidation

Examples 23 to 36

The procedure and procedure of example 7 were followed, with a reaction time of 4h and varying the reaction temperature and O, respectively₂2, 5-Diformylfuran (DFF) and 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) were obtained in the same manner, but with different conversions and yields, as shown in FIGS. 9 (Table 3), 10 (Table 4), 11 (Table 5), in which the leftmost column of the results for each example represents the conversion and the other column represents the selectivity for DFF and HMFCA:

TABLE 3 Effect of reaction temperature on HMF Oxidation

TABLE 4O₂Effect of pressure on HMF Oxidation

TABLE 5 results of oxidizing HMF to DFF with varying amounts of NC-950

Examples 37 to 43

The same procedure and procedure as in example 7 was followed, with a reaction time of 4h and with a fixed HMF addition, the HMF/HNO ratio was varied₃2, 5-Diformylfuran (DFF) and 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) were obtained in the same molar ratios, with different conversions and yields, as shown in Table 6:

TABLE 6

Examples 44 to 59

Following the procedure and procedure of example 7, in HMF (0.5mmol), NC-950(20mg), acetonitrile (10mL), 10bar O₂，100℃，0.29mmol 65wt.％HNO₃Reacting for 8 hours; after the reaction, the NC-950 catalyst was collected by centrifugation and washed with distilled water until the pH of the washing solution became 7, and then the washed catalyst was dried under vacuum and used for the next cycle. As shown in table 7, the conversion of HMF was almost quantitative in 16 runs and the selectivity of DFF remained stable above 93.5% over the 16 cycles studied. All results show that the NC-950 catalyst has good repeatability and stability and is resistant to HNO under the above reaction conditions ₃And O₂All exhibit resistance to destructive oxidation.

TABLE 7

Claims

1. The application of the catalyst with the effective component of the nitrogen-doped carbon material in preparing 2, 5-diformylfuran by catalyzing 5-hydroxymethylfurfural oxidation is characterized in that the catalyst is prepared by the following method:

1) adding chitosan into urea aqueous solution under stirring, adding acetic acid after chitosan is completely dispersed, stirring to obtain uniform semitransparent paste, drying and uniformly grinding to obtain a composite material precursor;

the adding amount ratio of the urea, the chitosan and the acetic acid is 10-15g:1g: 300-;

2) in N₂Heating the composite material precursor obtained in the step (1) from room temperature to 500-1200 ℃ at the heating rate of 3 ℃/min under the atmosphere, then preserving heat for 3-8h, taking out the product after the product is cooled, and grinding the product into powder to obtain the catalyst with the effective component of the nitrogen-doped carbon material;

the application comprises the following steps:

the catalyst, the solvent, the 5-hydroxymethylfurfural and the nitric acid are mixed according to the proportion (20-30) mg: 10mL of: 0.5 mmol: (0.4-0.6) mmol is added into a reaction vessel, 10bar-20bar of oxygen is filled after sealing, the temperature is raised to 120 ℃, the temperature is kept, the stirring is carried out for 4-14h, and the 2, 5-diformylfuran is obtained.

2. Use according to claim 1, wherein the temperature of drying in step 1) is 70 ℃.

3. The use according to claim 1, wherein the solvent is at least one of 1, 4-dioxane, dimethylsulfoxide, acetonitrile, ethyl acetate, toluene, hexane, water and tetrahydrofuran.

4. Use according to claim 3, wherein the solvent is 1, 4-dioxane or acetonitrile.

5. Use according to claim 4, wherein the nitric acid has a concentration of 65-68 wt.%.