Co (at) ZrC catalyst, preparation method thereof and application of Co (at) ZrC catalyst in hydrodeoxygenation of furfural compounds

Abstract

The invention provides a Co-coated ZrC catalyst and a preparation method and application thereof in furfural compound hydrodeoxygenation, and the preparation method of the catalyst comprises the following steps: taking fumaric acid and zircon salt as raw materials, preparing a catalyst precursor Zr-MOF by a solvothermal synthesis method, dipping the precursor by cobalt salt, and performing in-situ high-temperature pyrolysis carbonization reduction to prepare the Co-coated ZrC catalyst. The catalyst is respectively used for preparing 2-methylfuran from furfural through selective hydrodeoxygenation and preparing 2, 5-dimethylfuran from 5-hydroxymethylfurfural through selective hydrodeoxygenation, and target products are obtained at high yield. The catalyst is simple in preparation method, high in activity and selectivity, good in stability, mild in furfural selective hydrodeoxygenation reaction condition and high in product yield, and has obvious industrial production advantages.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and specifically relates to a Co@ZrC catalyst and a preparation method thereof, and application thereof in the selective hydrogenation and deoxygenation of furfural compounds. Background Art

[0002] With the decreasing reserves of fossil resources and the increasingly serious environmental pollution, the research on the conversion of widely available and inexpensive renewable resources into high value-added products has received much attention. Among the many biomass derivatives, furfural compounds furfural and 5-hydroxymethylfurfural are recognized as one of the most valuable platform compounds. The selective hydrodeoxygenation products of furfural compounds, methylfurans (2-methylfuran and 2,5-dimethylfuran), are widely used in the synthesis of medicines, pesticides, fine chemicals, etc. During the hydrodeoxygenation process of furfural, side reactions such as furan ring hydrogenation and ring opening are also accompanied. Therefore, the development of catalysts with excellent catalytic performance plays a vital role in the selective hydrodeoxygenation process of furfural compounds.

[0003] CN111905759A discloses a supported bimetallic catalyst (Pd-M / C) for selective hydrodeoxygenation of furfural to 2-methylfuran. The literature (Applied Catalysis B: Environment and Energy, 2024, 346: 123719) reported a CoAl mixed oxide supported Pd catalyst for selective hydrodeoxygenation of furfural to 2-methylfuran, with a yield of 92.1%. However, the high price of precious metals leads to high production costs. The literature (Journal of Energy Chemistry, 2023, 78: 195-202) reported a N, O co-doped carbon-anchored Co catalyst for selective hydrodeoxygenation of furfural to 2-methylfuran, which reacted at 240 ° C for 3 h, with a furfural conversion rate of 100% and a 2-methylfuran yield of 94.6%. At present, non-precious metal catalysts often require high temperatures, high catalyst dosages, etc., and the reaction conditions are harsh. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing a non-precious metal catalyst Co@ZrC, and the prepared catalyst is used in the selective hydrodeoxygenation of furfural to prepare 2-methylfuran and the selective hydrodeoxygenation of 5-hydroxymethylfurfural to prepare 2,5-dimethylfuran. The Co@ZrC catalyst prepared by the method of the present invention has high activity, high selectivity, good stability, mild reaction conditions and high yield.

[0005] To achieve the above experimental purpose, the present invention provides the following scheme: The preparation method of Co@ZrC catalyst comprises the following steps: Step 1: dissolving fumaric acid and Zr salt in a solvent, performing a solvothermal reaction at 110-180 °C for 12-48 h, filtering and washing after cooling, and then vacuum drying the washed solid at 80-100 °C for 8-12 h to obtain a catalyst precursor Zr-MOF-801; Step 2: dissolving the cobalt salt in deionized water, then adding the Zr-MOF-801 prepared in step 1 to the above solution, stirring and mixing evenly at room temperature, and impregnating at room temperature, and vacuum drying at 80-100 ° C for 8-12 h to obtain the catalyst precursor Co / Zr-MOF-801; Step 3: The above-mentioned precursor Co / Zr-MOF-801 is heated and cracked in an inert gas atmosphere for in-situ carbonization, and the Co salt in the system is reduced to Co in situ by using a large amount of reducing gas released by the decomposition of the carbon source during the carbonization process. 0 , cooled to room temperature to obtain the Co@ZrC catalyst.

[0006] Furthermore, the Zr salt is zirconium oxychloride or zirconium tetrachloride; the Co salt is cobalt nitrate, cobalt acetate or cobalt chloride; the content of metal Co in the catalyst is 5-25 wt%, and the mass ratio of Co to Zr is 1:1-5.

[0007] Furthermore, the molar ratio of the Zr salt to fumaric acid in step 1 is 1:0.5-3; the solvent is a mixed solution of N,N-dimethylformamide and formic acid, and the volume ratio of N,N-dimethylformamide to formic acid is 10:1-5.

[0008] Furthermore, the inert gas in step three is nitrogen, the pyrolysis temperature is 400-900°C, and the pyrolysis time is 1-6 h.

[0009] The present invention also proposes a Co@ZrC catalyst, wherein the catalyst is prepared from Zr-MOF-801 as a catalyst precursor Co / Zr-MOF-801, and an in-situ carbonization reduction strategy is adopted to pyrolyze and carbonize Co / Zr-MOF-801 at high temperature, and in-situ reduce Co metal ions to Co 0 , and obtained the porous carbon-embedded Co@ZrC catalyst.

[0010] A Co@ZrC catalyst prepared by the present invention can be well applied to the selective hydrodeoxygenation of furfural to prepare 2-methylfuran and the selective hydrodeoxygenation of 5-hydroxymethylfurfural to prepare 2,5-dimethylfuran. The application method is: using furfural or 5-hydroxymethylfurfural as raw materials, in a high-pressure reactor, in a reaction solvent, under the action of Co@ZrC catalyst, and in a hydrogen atmosphere, a hydrodeoxygenation reaction is carried out to prepare 2-methylfuran or 2,5-dimethylfuran. The reaction equation is as follows:

[0011] In the formula, the substituent R is a hydroxymethyl group or hydrogen.

[0012] Furthermore, the mass ratio of the Co@ZrC catalyst to the furfural compound (furfural or 5-hydroxymethylfurfural) is 1:3-10, the reaction temperature is 130-180° C., and the reaction hydrogen pressure is 0.5-3 MPa.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The present invention innovatively proposes a simple and effective method for preparing Co@ZrC catalyst, and applies the catalyst to furfural hydrodeoxygenation to prepare 2-methylfuran and 5-hydroxymethylfurfural selective hydrodeoxygenation to prepare 2,5-dimethylfuran. The Co@ZrC catalyst provided by the present invention uses non-precious metal Co as the first metal and as the hydrogenation active site, and uses non-precious metal Zr as the second metal, so as to improve the dispersion and hydrogenation activity of metal Co, and utilize the acidity and alkalinity of ZrO2 to promote the deoxidation reaction, thereby promoting the generation of the target product; carbon coating is adopted to improve the stability of the catalyst; Zr-MOF-801 is used as a carrier to prepare the catalyst precursor material Co / Zr-MOF-801, and the porous structure and metal defects of Zr-MOF-801 can make Co successfully loaded in the carrier, and improve the dispersion and uniformity of metal Co and Zr, thereby improving the activity of the catalyst; an in-situ carbonization reduction strategy is adopted, Co / Zr-MOF-801 is used as the catalyst precursor material, and high-temperature pyrolysis and carbonization are performed to convert Co metal ions into in-situ reduced Co 0 , and obtained the porous carbon-embedded Co@ZrC catalyst.

[0014] The catalyst provided by the invention has low cost, simple preparation, economical and effective, strong universality, high catalyst activity and good stability, and is applied to the process of preparing 2-methylfuran by hydrogenation and deoxygenation of furfural and preparing 2,5-dimethylfuran by selective hydrogenation and deoxygenation of 5-hydroxymethylfurfural. The reaction conditions are mild, green and environmentally friendly, the yields of 2-methylfuran and 2,5-dimethylfuran are high, and the production cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The XRD spectra of Zr-MOF-801, Co / Zr-MOF-801 prepared in the present invention, the carrier ZrC-700-3h obtained by pyrolysis, the catalyst Co@ZrC-700-3h and the recycled Co@ZrC-700-3h are compared.

[0016] Figure 2 This is a TEM image of the catalyst Co@ZrC-700-3h prepared in the present invention. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with embodiments, but the protection scope of the present invention is not limited thereto.

[0018] Preparation of Co@ZrC catalyst, taking Co@ZrC-700-3h as an example, the specific operation process is as follows: Dissolve 1.45 g (12.5 mmol) of fumaric acid and 4.05 g (12.5 mmol) of ZrOCl2·8H2O in 50 mL N,N -dimethylformamide and 17.5 mL formic acid, stirred at room temperature for 30 min, then transferred to a hydrothermal synthesis reactor and kept at 120 °C for 24 h. After the hydrothermal synthesis was completed, it was naturally cooled to room temperature, the reactor was disassembled, and the precipitate was collected by centrifugation. N,N -Dimethylformamide was washed three times, and then washed three times with methanol. Subsequently, the solid was vacuum dried at 110 °C for 12 h to obtain a white solid powder Zr-MOF-801. 0.484 g Co(NO3)2·6H2O was weighed and dissolved in deionized water, and then a certain amount of dried Zr-MOF-801 carrier was added to the above solution, stirred and mixed evenly at room temperature, and impregnated at room temperature for 24 h, and dried at 100 °C for 10 h to obtain Co / Zr-MOF-801. It was placed in a tubular calcining furnace and calcined at 700 °C for 3 h in a nitrogen atmosphere to obtain the catalyst Co@ZrC-700-3h.

[0019] According to the same method as above, different Co@ZrC catalysts were prepared by changing the calcination temperature or calcination time of Co / Zr-MOF-801, named Co@ZrC-AB, where A is the calcination temperature and B is the calcination time.

[0020] The XRD spectrum of the catalyst prepared by the present invention is as follows: Figure 1As shown in the figure: the characteristic peaks of Zr-MOF-801 were observed at 8.5°, 9.8°, and 30.7° on the unpyrolyzed catalyst, indicating that the carrier is a successfully prepared Zr-MOF-801 material. In the catalyst pyrolyzed at 700°C, the characteristic diffraction peaks of Zr-MOF-801 disappeared, and the strong peaks at 30.3°, 50.4°, and 60.0° were the characteristic diffraction peaks of ZrO2, indicating that the structure of the catalyst formed by the self-assembly of the central Zr metal ion and the organic ligand fumaric acid was destroyed after pyrolysis, and ZrO2 was generated. The diffraction peaks of the Co@ZrC-700-3h catalyst at 2θ = 44.2°, 52.2°, and 75.8° correspond to the (111), (200), and (220) planes of Co, respectively, and the two weak peaks at 35.6° and 63.0° are attributed to the (111) and (220) diffraction peaks of CoO. The diffraction peak of Co is relatively broad, which indicates that the Co grains are smaller.

[0021] The TEM spectrum of the Co@ZrC catalyst prepared by the present invention is as follows: Figure 2 Shown: TEM images reveal the presence of highly dispersed Co NPs on the Co@ZrC catalyst. Example 1

[0022] 0.30 g (3 mmol) of furfural, 60 mg of Co@ZrC-700-3h catalyst and 5 mL of isopropanol were added to a 25 mL autoclave. The autoclave was sealed, purged with nitrogen five times, and pressurized to 1.0 MPa with H2. The reaction temperature was 170 °C, the reaction time was 4 h, the furfural conversion rate was 100%, and the 2-methylfuran yield was 96.5%. Example 2

[0023] 0.30 g (3 mmol) of furfural, 60 mg of Co@ZrC-550-4h catalyst and 5 mL of isopropanol were added to a 25 mL autoclave. The autoclave was sealed, purged with nitrogen five times, and pressurized to 1.0 MPa with H2. The reaction temperature was 170 °C, the reaction time was 6 h, the furfural conversion rate was 100%, and the yield of 2-methylfuran was 95.8%. Example 3

[0024] 0.30 g (3 mmol) of furfural, 30 mg of Co@ZrC-550-4h catalyst and 5 mL of isopropanol were added to a 25 mL autoclave. The autoclave was sealed, purged with nitrogen five times, and pressurized to 1.0 MPa with H2. The reaction temperature was 170 °C, the reaction time was 6 h, the furfural conversion rate was 100%, and the yield of 2-methylfuran was 81.1%. Example 4

[0025] 0.30 g (3 mmol) of furfural, 60 mg of Co@ZrC-550-4h catalyst and 5 mL of tetrahydrofuran were added to a 25 mL autoclave. The autoclave was sealed, purged with nitrogen five times, and pressurized to 1.0 MPa with H2. The reaction temperature was 170 °C, the reaction time was 5 h, the furfural conversion rate was 100%, and the yield of 2-methylfuran was 85.0%. Example 5

[0026] 0.30 g (3 mmol) of furfural, 60 mg of Co@ZrC-700-2h catalyst and 5 mL of isopropanol were added to a 25 mL autoclave. The autoclave was sealed, purged with nitrogen five times, and pressurized to 1.0 MPa with H2. The reaction temperature was 170 °C, the reaction time was 5 h, the furfural conversion rate was 100%, and the yield of 2-methylfuran was 85.2%. Example 6

[0027] 0.38 g (3 mmol) of 5-hydroxymethylfurfural, 60 mg of Co@ZrC-700-3h catalyst and 5 mL of tetrahydrofuran were added to a 25 mL autoclave. The autoclave was sealed, purged with nitrogen five times, and pressurized to 1.0 MPa with H2. The reaction temperature was 150 °C, the reaction time was 8 h, the conversion rate of 5-hydroxymethylfurfural was 100%, and the yield of 2,5-dimethylfuran was 90.7%. Example 7

[0028] 0.38 g (3 mmol) of 5-hydroxymethylfurfural, 50 mg of Co@ZrC-700-3h catalyst and 5 mL of tetrahydrofuran were added to a 25 mL autoclave. The autoclave was sealed, purged with nitrogen five times, and pressurized to 1.0 MPa with H2. The reaction temperature was 150 °C, the reaction time was 8 h, the conversion rate of 5-hydroxymethylfurfural was 100%, and the yield of 2,5-dimethylfuran was 96.8%. Example 8

[0029] 0.38 g (3 mmol) of 5-hydroxymethylfurfural, 60 mg of Co@ZrC-700-3h catalyst and 5 mL of water were added to a 25 mL autoclave. The autoclave was sealed, purged with nitrogen five times, and pressurized to 1.0 MPa with H2. The reaction temperature was 150 °C, the reaction time was 10 h, the conversion rate of 5-hydroxymethylfurfural was 100%, and the yield of 2,5-dimethylfuran was 71.2%. Example 9

[0030] 0.38 g (3 mmol) of 5-hydroxymethylfurfural, 50 mg of Co@ZrC-700-3h catalyst and 5 mL of tetrahydrofuran were added to a 25 mL autoclave. The autoclave was sealed, purged with nitrogen five times, and pressurized to 1.0 MPa with H2. The reaction temperature was 170 °C, the reaction time was 4 h, the conversion rate of 5-hydroxymethylfurfural was 100%, and the yield of 2,5-dimethylfuran was 79.8%. Examples 10-17

[0031] The other operations were the same as those in Example 1, and the number of times the catalyst was recycled was changed (after each reaction, the catalyst was centrifuged and recycled), and the following reaction results were obtained (Table 1): Table 1

[0032] In summary, this patent introduces a Co@ZrC catalyst, its preparation method and its application in the hydrodeoxygenation of furfural compounds. The catalyst is prepared by solvent thermal synthesis to obtain the catalyst precursor Zr-MOF, and then the precursor is impregnated with cobalt salt, and in-situ high-temperature pyrolysis and carbonization reduction are performed to prepare the Co@ZrC catalyst. The catalyst is used for the selective hydrodeoxygenation of furfural to produce 2-methylfuran and the selective hydrodeoxygenation of 5-hydroxymethylfurfural to produce 2,5-dimethylfuran, and the target products are obtained in high yield.

Claims

1. A method for preparing a Co@ZrC catalyst, characterized in that: The following steps are involved: Step 1: dissolving fumaric acid and Zr salt in a solvent, performing a solvothermal reaction at 110-180 °C for 12-48 h, filtering and washing after cooling, and then vacuum drying the washed solid at 80-100 °C for 8-12 h to obtain a catalyst precursor Zr-MOF-801; Step 2: dissolving the cobalt salt in deionized water, then adding the Zr-MOF-801 prepared in step 1 to the above solution, stirring and mixing evenly at room temperature, and impregnating at room temperature, and vacuum drying at 80-100 ° C for 8-12 h to obtain the catalyst precursor Co / Zr-MOF-801; Step 3: The precursor Co / Zr-MOF-801 prepared in step 2 is heated and cracked in an inert gas atmosphere for in-situ carbonization, and the Co salt in the system is reduced to Co in situ by using a large amount of reducing gas released by the decomposition of the carbon source during the carbonization process. 0 , cooled to room temperature to obtain the Co@ZrC catalyst.

2. The method for preparing a Co@ZrC catalyst according to claim 1, characterized in that: The Zr salt is zirconium oxychloride or zirconium tetrachloride; the Co salt is cobalt nitrate, cobalt acetate or cobalt chloride; the content of metal Co in the catalyst is 5-25wt%, and the mass ratio of Co to Zr is 1:1-5.

3. The method for preparing a Co@ZrC catalyst according to claim 1, characterized in that: The molar ratio of the Zr salt to fumaric acid in step 1 is 1:0.5-3; the solvent is a mixed solution of N,N-dimethylformamide and formic acid, and the volume ratio of N,N-dimethylformamide to formic acid is 10:1-5.

4. The method for preparing a Co@ZrC catalyst according to claim 1, characterized in that: The pyrolysis temperature in step 3 is 400-900°C, and the pyrolysis time is 1-6 h.

5. A Co@ZrC catalyst, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 4.

6. A Co@ZrC catalyst according to claim 5, characterized in that: The catalyst uses Zr-MOF-801 as a material to prepare a catalyst precursor Co / Zr-MOF-801, adopts an in-situ carbonization reduction strategy, pyrolyzes Co / Zr-MOF-801 at high temperature to carbonize it, and in-situ reduces Co metal ions to Co 0 , and obtained the porous carbon-embedded Co@ZrC catalyst.

7. Use of the Co@ZrC catalyst as claimed in claim 5 in the hydrodeoxygenation of furfural compounds, characterized in that: The Co@ZrC catalyst is respectively used for selective hydrodeoxygenation of furfural to prepare 2-methylfuran and selective hydrodeoxygenation of 5-hydroxymethylfurfural to prepare 2,5-dimethylfuran. The application method is: using furfural or 5-hydroxymethylfurfural as a raw material, in a high-pressure reactor, in a reaction solvent, under the action of the Co@ZrC catalyst, a hydrodeoxygenation reaction is carried out in a hydrogen atmosphere to prepare 2-methylfuran or 2,5-dimethylfuran.

8. Use of the Co@ZrC catalyst as claimed in claim 7 in the hydrodeoxygenation of furfural compounds, characterized in that: The mass ratio of the Co@ZrC catalyst to the furfural compound is 1:3-10, the reaction temperature is 130-180° C., and the reaction hydrogen pressure is 0.5-3 MPa.

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