A method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF

Abstract

The present invention discloses a method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF, which relates to the technical field of DFF preparation, including preparing Ultrathin-C3N4 using melamine as a raw material, loading spinel by a solvothermal method to prepare a photocatalyst; dispersing HMF and the catalyst in a reaction solvent, reacting for a certain period of time under an oxygen atmosphere, xenon lamp illumination and a water cooling device, and obtaining a compound DFF. The selectivity of DFF prepared by the method of the present invention can reach up to 99.23%, and HMF can be reused by separation technology under the condition of incomplete conversion, which effectively avoids the influence of by-products, and does not consume electric heating energy, which is green and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of DFF preparation, in particular to a DFF preparation method based on oxygen photocatalytic selective oxidation of HMF. Background Art

[0002] In recent years, the technology of converting HMF into DFF and its derivatives by oxidation has been continuously expanded, mainly including stoichiometric oxidation, thermal catalysis, electrocatalysis, enzyme catalysis, piezoelectric catalysis, etc., but these processes generally have limitations in practical applications. For example, the oxidant used in the stoichiometric oxidation method is easy to cause environmental pollution; the high temperature and high pressure required by the thermal catalytic method will increase the energy consumption load; the electrocatalytic method requires the use of specific conductive media and special instruments, and aggravates energy consumption; the biocatalytic method requires high costs and the fragility of enzyme catalysts needs to be overcome; the application research of piezoelectric catalysis in biomass production of valuable chemicals is still in its infancy. In order to make the conversion of HMF into DFF reach the practical application level, it is necessary to explore green and economical alternative technologies to enable the conversion of HMF to be carried out in a gentle, efficient and controllable manner.

[0003] Photocatalytic technology has the advantages of environmental sustainability and catalytic economy. It can selectively oxidize or reduce specific biomass derivatives for the production of high-value biomass chemicals and polymer materials. At present, photocatalytic technology has been continuously applied to the photooxidative synthesis of DFF. As the most common photocatalytic semiconductor, carbon nitride g-C3N4 has been proven to be effectively used in the photooxidative preparation of DFF. Its medium band gap is conducive to light absorption, and its conduction band potential (-1.3 eV) is conducive to the activation of molecular oxygen to produce superoxide radicals for the selective conversion of raw material HMF to DFF. At the same time, the valence band potential of 1.4 eV can inhibit the formation of degradable hydroxyl radicals. Due to the insufficient light response of a single semiconductor and the low photocarrier dynamics, many studies have constructed g-C3N4-derived heterojunction photocatalysts to generate superoxide radicals for selective oxidative organic conversion, and spinel has also been proven to enhance the photocatalytic performance of g-C3N4 and promote the catalytic conversion of HMF to DFF. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above and / or existing problems in the existing DFF preparation method based on oxygen photocatalytic selective oxidation of HMF, the present invention is proposed.

[0006] Therefore, the problem to be solved by the present invention is how to provide a method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF, which comprises preparing Ultrathin-C3N4 with melamine as raw material, and loading spinel to obtain a photocatalyst by a solvothermal method; dispersing HMF and the catalyst in a reaction solvent, reacting for a certain period of time under an oxygen atmosphere, xenon lamp illumination and a water cooling device, to obtain a compound DFF.

[0008] As a preferred scheme of the DFF preparation method based on oxygen photocatalytic selective oxidation of HMF described in the present invention, the preparation of Ultrathin-C3N4 using melamine as raw material includes the following steps: calcining melamine at high temperature; after the calcination is completed, modifying it with nitric acid for 4-8h to obtain Ultrathin-C3N4.

[0009] As a preferred embodiment of the DFF preparation method based on oxygen photocatalytic selective oxidation of HMF according to the present invention, the high temperature is 520° C. and the nitric acid concentration is 3M to 5M.

[0010] As a preferred embodiment of the method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF according to the present invention, the concentration of nitric acid is 5 M and the modification treatment time is 8 h.

[0011] As a preferred embodiment of the DFF preparation method based on oxygen photocatalytic selective oxidation of HMF described in the present invention, the solvothermal method refers to using ethylene glycol as solvent, urea as precipitant, solvothermal reaction time of 12h, and solvothermal temperature of 180°C.

[0012] As a preferred embodiment of the method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF according to the present invention, the reaction solvent is any one of acetonitrile, DMF, DCM and EA.

[0013] As a preferred embodiment of the DFF preparation method based on oxygen photocatalytic selective oxidation of HMF according to the present invention, the concentration of HMF is 0.04-0.24 mM, and the amount of catalyst is 2-8 mg / mL.

[0014] As a preferred embodiment of the DFF preparation method based on oxygen photocatalytic selective oxidation of HMF according to the present invention, the HMF concentration is 0.16 mM and the catalyst concentration is 6 mg / mL.

[0015] As a preferred embodiment of the DFF preparation method based on oxygen photocatalytic selective oxidation of HMF described in the present invention, the reaction atmosphere is an oxygen and xenon lamp atmosphere, and the cutoff wavelength is 390-420 nm.

[0016] The beneficial effects of the present invention are as follows: the selectivity of DFF prepared by the method provided by the present invention can reach up to 99.23%, and HMF can be reused through separation technology under the condition of incomplete conversion, which effectively avoids the influence of by-products, does not consume electric heating energy, and is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0018] Figure 1 This is a diagram showing the catalytic reaction effects of different spinel loading ratios in Examples 2 to 6.

[0019] Figure 2 This is a diagram showing the catalytic reaction effects of different spinel loadings in Example 7 and Example 8.

[0020] Figure 3 The catalytic reaction effect diagram of Example 9 and Example 10 under different reaction solvents. DETAILED DESCRIPTION

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0022] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0023] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0024] Example 1

[0025] Reference Figure 1 and Figure 2, which is the first embodiment of the present invention, and provides a method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF. The method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF comprises the following steps:

[0026] S1. Ultrathin-C3N4 was prepared using melamine as raw material, and the photocatalyst was prepared by loading spinel by solvothermal method. The metal ions involved in the spinel were Mn(NO3)2·4H2O; Co(NO3)2·6H2O; Fe(NO3)3·6H2O, NiCl2·6H2O, and the precipitant was 0.48g urea (NH3)2CO2;

[0027] S2. Disperse HMF and the catalyst in a reaction solvent, and react for a certain period of time under oxygen atmosphere, xenon lamp irradiation and water cooling device to obtain compound DFF.

[0028] Wherein, in step S1, preparing Ultrathin-C3N4 using melamine as raw material comprises the following steps:

[0029] S11, calcining melamine at a high temperature, which is 520° C. in this embodiment;

[0030] S12. After calcination, the modified product is treated with nitric acid for 4-8 hours to obtain Ultrathin-C3N. The concentration of nitric acid is 3M to 5M, preferably 5M. The modification treatment time is preferably 8 hours.

[0031] Solvothermal method refers to using ethylene glycol as solvent, urea as precipitant, solvent thermal reaction time of 12h, annealing temperature of 300-500℃, solvent thermal temperature of 180℃,

[0032] In step S2, the reaction solvent is any one of acetonitrile, DMF, DCM and EA. The concentration of HMF is 0.04-0.24 mM, the amount of catalyst is 2-8 mg / mL, preferably, the concentration of HMF is 0.16 mM, the concentration of catalyst is 6 mg / mL, the reaction atmosphere is oxygen and xenon lamp atmosphere, and the cutoff wavelength is 390-420 nm.

[0033] Example 2

[0034] The second embodiment of the present invention provides a method for preparing DFF based on the selective oxidation of HMF by oxygen photocatalysis.

[0035] Weigh 0.224 g (0.77 mmol) Co(NO3)2·6H2O and 0.394 g (1.54 mmol) Dispersed in 60ml ethylene glycol dispersion containing 0.72g Ultrathin-C3N4, add 0.48g urea and stir until clear. React at 180℃ in an autoclave for 12h, collect the precipitate, wash and dry, and calcine at 350℃ for 3h to obtain 20%CoMn2O4@HCN. Disperse 30mg 20%CoMn2O4@HCN sample in 5ml (0.16mM) HMF acetonitrile solution. After oxygen purge 5 times, seal, insert oxygen ball, and place in a cooling jacket beaker. Irradiate with 300W Xe lamp ≥400nm for 10h. Add 100μl p-xylene to the reaction solution and mix well. After passing through a 0.22mm organic filter membrane, analyze by gas chromatography internal standard method. The HMF conversion rate is 15.20% and the selectivity is 99.23%.

[0036] Example 3

[0037] The third embodiment of the present invention provides a method for preparing DFF based on the selective oxidation of HMF by oxygen photocatalysis.

[0038] Weigh 0.099 g (0.34 mmol) Co(NO3)2·6H2O and 0.174 g (0.68 mmol) Dispersed in 60 ml of ethylene glycol dispersion containing 0.72 g Ultrathin-C3N4, add 0.48 g urea and stir until clear. React in autoclave at 180 ° C for 12 h, collect the precipitate, wash and dry, and calcine at 350 ° C for 3 h to obtain 10% CoMn2O4@HCN. Disperse 30 mg of 20% CMO@HCN sample in 5 ml (0.16 mM) HMF acetonitrile solution. After oxygen purge 5 times, seal, insert oxygen ball, and place in a cooling jacket beaker. Irradiate with 300W Xe lamp with λ≥400 nm for 10 h. Add 100 μl of p-xylene to the reaction solution and mix well. After passing through a 0.22 mm organic filter membrane, analyze by gas chromatography internal standard method. The HMF conversion rate is 43.67% and the selectivity is 43.04%.

[0039] Example 4

[0040] The fourth embodiment of the present invention provides a method for preparing DFF based on the selective oxidation of HMF by oxygen photocatalysis.

[0041] Weigh 0.16 g (0.55 mmol) Co(NO3)2·6H2O and 0.281 g (1.1 mmol) Dispersed in 60 ml of ethylene glycol dispersion containing 0.72 g Ultrathin-C3N4, add 0.48 g urea and stir until clear. React in autoclave at 180 ° C for 12 h, collect the precipitate, wash and dry, and calcine at 350 ° C for 3 h to obtain 15% CoMn2O4@HCN. Disperse 30 mg of 15% CoMn2O4@HCN sample in 5 ml (0.16 mM) HMF acetonitrile solution. After oxygen purge 5 times, seal, insert oxygen ball, and place in a cooling jacket beaker. Irradiate with 300W Xe lamp with λ≥400 nm for 10 h. Add 100 μl of p-xylene to the reaction solution and mix well. After passing through a 0.22 mm organic filter membrane, analyze it by gas chromatography internal standard method. The HMF conversion rate is 36.85% and the selectivity is 50.05%.

[0042] Example 5

[0043] The fifth embodiment of the present invention provides a method for preparing DFF based on the selective oxidation of HMF by oxygen photocatalysis.

[0044] Weigh 0.2 g (0.69 mmol) Co(NO3)2·6H2O and 0.353 g (1.38 mmol) Dispersed in 60 ml of ethylene glycol dispersion containing 0.72 g Ultrathin-C3N4, add 0.48 g urea and stir until clear. React at 180 ° C in an autoclave for 12 h, collect the precipitate, wash and dry, and calcine at 350 ° C for 3 h to obtain 18% CoMn2O4@HCN. Disperse 30 mg of 18% CoMn2O4@HCN sample in 5 ml (0.16 mM) HMF acetonitrile solution. After oxygen purge 5 times, seal, insert oxygen ball, and place in a cooling jacket beaker. Irradiate with a 300W Xe lamp with λ ≥ 400 nm for 10 h. Add 100 μl of p-xylene to the reaction solution and mix well. After passing through a 0.22 mm organic filter membrane, analyze it by gas chromatography internal standard method. The HMF conversion rate is 22.12% and the selectivity is 55.45%.

[0045] Example 6

[0046] The sixth embodiment of the present invention provides a method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF.

[0047] Weigh 0.267 g (0.92 mmol) Co(NO3)2·6H2O and 0.47 g (1.84 mmol) Dispersed in 60 ml of ethylene glycol dispersion containing 0.72 g Ultrathin-C3N4, add 0.48 g urea and stir until clear. React in autoclave at 180 ° C for 12 h, collect the precipitate, wash and dry, and calcine at 350 ° C for 3 h to obtain 23% CoMn2O4@HCN. Disperse 30 mg of 23% CoMn2O4@HCN sample in 5 ml (0.16 mM) HMF acetonitrile solution. After oxygen purge 5 times, seal, insert oxygen ball, and place in a cooling jacket beaker. Irradiate with 300W Xe lamp with λ≥400 nm for 10 h. Add 100 μl of p-xylene to the reaction solution and mix well. After passing through a 0.22 mm organic filter membrane, analyze it by gas chromatography internal standard method. The HMF conversion rate is 13.25% and the selectivity is 80.75%.

[0048] according to Figure 1 It can be concluded that with the increase of spinel loading, the conversion selectivity of 5-hydroxymethylfurfural to 2,5-diformylfuran increases, but decreases after the loading exceeds 0.2, and the activity decreases accordingly.

[0049] Example 7

[0050] The seventh embodiment of the present invention provides a method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF.

[0051] Weigh 0.224g (0.77mmol) Co(NO3)2·6H2O and 0.622g (1.54mmol) Fe(NO3)2·4H2O and disperse them in 60ml ethylene glycol dispersion containing 0.72g Ultrathin-C3N4. Add 0.48g urea and stir until clear. React at 180℃ in an autoclave for 12h. Collect the precipitate, wash and dry it, and calcine it at 350℃ for 3h to obtain 20%CoFe2O4@HCN. Disperse 30mg 20%CoFe2O4@HCN sample in 5ml (0.16mM) HMF acetonitrile solution. Purge oxygen 5 times and seal it. Insert oxygen ball and place it in a cooling jacket beaker. Irradiate with 300W Xe lamp with ≥400nm for 10h. Add 100μl p-xylene to the reaction solution and mix well. After passing through 0.22mm organic filter, analyze it by gas chromatography internal standard method. The HMF conversion rate was 29.79% and the selectivity was 42.54%.

[0052] Example 8

[0053] The eighth embodiment of the present invention provides a method for preparing DFF based on the selective oxidation of HMF by oxygen photocatalysis.

[0054] Weigh 0.191g (0.82mmol) NiCl2·6H2O and 0.666g (1.65mmol) Fe(NO3)2·4H2O and disperse them in 60ml ethylene glycol dispersion containing 0.72g Ultrathin-C3N4, add 0.48g urea and stir until clear. React at 180℃ in an autoclave for 12h, collect the precipitate, wash and dry, and calcine at 350℃ for 3h to obtain 20%NiFe2O4@HCN. Disperse 30mg 20%NiFe2O4@HCN sample in 5ml (0.16mM) HMF acetonitrile solution. Purge with oxygen 5 times and seal, insert oxygen ball, and place in a cooling jacket beaker. Irradiate with 300W Xe lamp with ≥400nm for 10h. Add 100μl p-xylene to the reaction solution and mix well. After passing through a 0.22mm organic filter, analyze by gas chromatography internal standard method. The HMF conversion rate was 18.41% and the selectivity was 71.22%.

[0055] according to Figure 2 It can be concluded that the loading of cobalt manganese oxide spinel has a higher selectivity for the overall photocatalyst for the target reaction compared with other spinels.

[0056] Example 9

[0057] The ninth embodiment of the present invention provides a method for preparing DFF based on the selective oxidation of HMF by oxygen photocatalysis.

[0058] Weigh 0.233g (0.8mmol) Co(NO3)2·6H2O and 0.41g (1.6mmol) Mn(NO3)2·4H2O and disperse them in 60ml ethylene glycol dispersion containing 0.72g Ultrathin-C3N4. Add 0.48g urea and stir until clear. React at 180℃ in an autoclave for 12h. Collect the precipitate, wash and dry it, and calcine it at 350℃ for 3h to obtain 10%CMO@HCN. Disperse 30mg 20%CMO@HCN sample in 5ml (0.16mM) HMF EA solution. Purge oxygen 5 times and seal it. Insert oxygen ball and place it in a cooling jacket beaker. Irradiate with 300W Xe lamp with ≥400nm for 10h. Add 100μl p-xylene to the reaction solution and mix well. After passing through 0.22mm organic filter, analyze it by gas chromatography internal standard method. The HMF conversion rate was 20.16% and the selectivity was 60.67%.

[0059] Example 10

[0060] The tenth embodiment of the present invention provides a method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF.

[0061] Weigh 0.233g (0.8mmol) Co(NO3)2·6H2O and 0.41g (1.6mmol) Mn(NO3)2·4H2O and disperse them in 60ml ethylene glycol dispersion containing 0.72g Ultrathin-C3N4. Add 0.48g urea and stir until clear. React at 180℃ in an autoclave for 12h. Collect the precipitate, wash and dry it, and calcine it at 350℃ for 3h to obtain 10%CMO@HCN. Disperse 30mg 20%CMO@HCN sample in 5ml (0.16mM) HMF DMF solution. Purge oxygen 5 times and seal it. Insert oxygen ball and place it in a cooling jacket beaker. Irradiate with 300W Xe lamp with ≥400nm for 10h. Add 100μl p-xylene to the reaction solution and mix well. After passing through 0.22mm organic filter, analyze it by gas chromatography internal standard method. The HMF conversion rate was 22.38% and the selectivity was 42.36%.

[0062] according to Figure 3 It can be concluded that in a polar solvent such as acetonitrile, the conversion of HMF to DFF has a higher selectivity.

[0063] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF, characterized in that: include, Ultrathin-C3N4 was prepared using melamine as raw material, and the photocatalyst was prepared by loading spinel through solvothermal method. The metal ions involved in the spinel were Mn(NO3)2·4H2O; Co(NO3)2·6H2O; Fe(NO3)3·6H2O, NiCl2·6H2O; Dispersing HMF and the catalyst in a reaction solvent, reacting for a certain period of time under an oxygen atmosphere, xenon lamp irradiation and a water cooling device, the compound DFF is obtained; The preparation of Ultrathin-C3N4 using melamine as raw material includes the following steps: Calcining melamine at a high temperature, wherein the high temperature is 520° C.; After calcination, it is modified with nitric acid for 4-8h to obtain Ultrathin-C3N4; The solvothermal method refers to using ethylene glycol as solvent, urea as precipitant, solvothermal reaction time of 12 hours, and solvothermal temperature of 180°C.

2. The method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF according to claim 1, characterized in that: The nitric acid concentration is 3M to 5M.

3. The method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF according to claim 2, characterized in that: The nitric acid concentration is 5M, and the modification treatment time is 8h.

4. The method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF according to claim 3, characterized in that: The reaction solvent is any one of acetonitrile, DMF, DCM and EA.

5. The method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF according to claim 4, characterized in that: The concentration of HMF is 0.04-0.24 mM, and the amount of catalyst is 2-8 mg / mL.

6. The method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF according to claim 5, characterized in that: The HMF concentration was 0.16 mM and the catalyst concentration was 6 mg / mL.

7. The method for preparing DFF based on oxygen photocatalytic selective oxidation of HMF according to claim 6, characterized in that: The reaction atmosphere is oxygen and xenon lamp atmosphere, and the cut-off wavelength is 390-420nm.

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