Non-noble metal cage-like MOFs catalysts for the production of N-benzamide, their preparation methods and uses

Abstract

A non-noble metal cage-shaped MOF catalyst (1, [Ni3]) that can catalyze the conversion of carbon dioxide (CO2) and aromatic amines to form high-value N-benzamide chemicals under mild conditions, its preparation method and uses, and its chemical formula is: [H2N(CH3)2]2{[Ni3(μ3-O)(XN)(BDC)3]·6DMF} n , n is a positive integer greater than 1, and the smallest repeating unit of the non-noble metal cage-shaped MOF contains 1 trinuclear nickel cluster, 1 XN ligand, 3 BDCs 2‑ , 1 μ4-O 2‑ and 2 -H2N(CH3)2 + . The material of the present invention has excellent stability, which provides guarantee for its practical applications in multiple fields, and shows ultra-high catalytic activity in the reaction of converting CO2 and aromatic amines to form high-value N-benzamide chemicals. The advantages of the present invention are: simple preparation method, short preparation cycle, pure product, high product stability, high catalytic reaction efficiency, wide catalytic substrate range, mild catalytic reaction conditions, and good recyclability.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials and relates to a non-noble metal cage-shaped MOFs catalyst material with high catalytic activity, which is constructed based on non-noble metal ions and organic ligands. Background Art

[0002] In recent years, as a greenhouse gas, CO2 has caused a series of environmental problems such as global warming and climate anomalies. The effective capture, sequestration, and conversion of CO2 have always been topics of great research significance and prospects in the fields of chemistry, environment, chemical engineering, and materials. So far, many high-value fine chemicals have been synthesized through CO2 coupling and reduction reactions, including formic acid, carbonates, formaldehyde, methane, urea, formamide, oxazolidinone, and benzimidazole. Among them, the wide application of N-benzamide produced by the catalytic reduction reaction of CO2 and aromatic amines in the organic synthesis of isocyanates, pesticides, and pharmaceuticals has attracted much attention from scientists. So far, although some catalysts have been reported to activate such reactions, most catalysts require more stringent reaction conditions, such as longer time (24 hours), higher temperature (90 °C), and / or higher pressure (2.0 MPa) to obtain higher yields. Even for noble metal catalysts, only one case can exhibit excellent catalytic performance under mild conditions: 1 atm CO2, 2 h, RTAu@Ir-PCN-222, but it requires expensive costs and there is an obvious problem of noble metal Au leakage (0.21%) during the cycle. Therefore, developing non-noble metal catalysts and effectively catalyzing the reduction of CO2 to form aromatic formamides under mild conditions is very important but also full of challenges.

[0003] Due to many structural advantages, non-noble metal cage / cluster-based MOFs are expected to become promising catalyst materials in the CO2 reduction and conversion reaction: 1) The rich cavity / cage structure in the framework is conducive to the enrichment and storage of CO2, locally increasing the concentration of CO2, and can improve the catalytic reaction rate through the confinement effect; 2) Unsaturated non-noble metal active sites are evenly distributed in the cage, effectively activating the substrate and CO2 during the reaction process, and further improving the atomic economy utilization rate; 3) Highly stable MOFs, as heterogeneous catalysts, are extremely easy to separate and recycle from the reaction system, effectively purifying the product and reducing the catalyst cost; 4) The clear structure is conducive to exploring the interaction and catalytic mechanism between CO2, the substrate, and the framework at the molecular level. Constructing new non-noble metal cage / cluster-shaped MOFs is of great significance in the adsorption, storage, and conversion of CO2. Summary of the Invention

[0004] The object of the present invention is to solve the problems of strict reaction conditions or high production costs in the existing catalytic reduction of CO2 to produce aromatic formamides, and to provide a non-precious metal cage-like MOFs catalyst for efficiently catalyzing the conversion of CO2 and aromatic amines to form high-value chemical substances of N-benzamide. At the same time, a preparation method and use of the catalyst are provided.

[0005] Technical solution of the present invention

[0006] The present invention first provides a non-precious metal cage-like MOFs catalyst for efficiently catalyzing the production of N-benzamide from CO2 and aromatic amines, with the chemical formula: [H2N(CH3)2]2{[Ni3(μ3-O)(XN)(BDC)3]·6DMF} n , where n is a positive integer greater than 1, abbreviated as [Ni3]; where -H2N(CH3)2 + is a dimethylamine cation, XN is 6'-(pyridin-4-yl)-4,2':4',4”-terpyridine, and BDC 2- is obtained by deprotonating the ligand terephthalic acid H2BDC; the crystal belongs to the hexagonal crystal system, the space group is P63 / mmc, and the unit cell parameters are: α = 90°, β = 90°, γ = 120°; the asymmetric unit of the non-precious metal cage-like MOFs contains 1 crystallographically independent Ni 2+ , 0.3 independent XN and 2 BDC 2- ions, where 2 free [H2N(CH3)2] + acts as a counter ion to maintain the electrical neutrality of the structure.

[0007] The present invention also provides a preparation method of the non-precious metal cage-like MOFs catalyst material for producing N-benzamide, and the steps are as follows:

[0008] (1), Reaction raw materials: nickel nitrate Ni(NO3)2·6H2O, XN, terephthalic acid H2BDC, solvent DMF and MeOH;

[0009] The dosage ratio of nickel nitrate Ni(NO3)2·6H2O, XN and terephthalic acid H2BDC is 5 mol:2 mol:5 mol; the dosage ratio of solvent DMF and MeOH is 800 L:200 L; the solvents DMF and MeOH are abbreviations of N,N-dimethylformamide and methanol respectively;

[0010] (2), Mix the above reaction raw materials and add them to a high-pressure reaction kettle with a polytetrafluoroethylene inner lining, place it in an oven, raise the temperature to 150 - 160 °C in 3 - 12 hours, keep the temperature constant for reaction for 48 - 96 hours, and then cool to room temperature at 1.4 - 2.7 °C / h;

[0011] (3) After the reaction is completed, the product is washed with methanol to obtain light green octahedral crystals, namely the non-noble metal cage-like MOFs catalyst.

[0012] The present invention also provides the use of the non-noble metal cage-like MOFs catalyst in efficiently catalyzing the reaction of CO2 with aromatic amines to form high-value chemical N-benzamide under mild conditions. The specific application method is as follows:

[0013] The mild conditions include: the dosage ratio of the non-noble metal catalyst [Ni3], the catalytic reaction solvent CH3CN, the catalytic reaction reducing agent PhSiH3 and the co-catalyst Cs2CO3 is 6 mol: 2000 L: 2000 mol: 20 mol; at room temperature, normal pressure, and the catalytic reaction time is 12 h.

[0014] The aromatic amine includes at least N-methylaniline, N,2-dimethylaniline, N,3-dimethylaniline, N,4-dimethylaniline, 4-methoxy-N-methylaniline, 3-chloro-N-methylaniline, 4-chloro-N-methylaniline, N-ethylaniline, N-isopropylaniline, N-butylaniline, N-benzylaniline, and the corresponding catalytic products belong to N-alkyl / aryl benzamides.

[0015] When the aromatic amine selects N-methylaniline to react with CO2, the yield of N-benzamide is as high as 95%, and the selectivity is as high as 100%.

[0016] The non-noble metal cage-like MOFs catalyst [Ni3] with high catalytic activity can be recycled ten times while maintaining the catalytic performance basically unchanged.

[0017] The non-noble metal cage-like MOFs material prepared in the present invention has the following advantages compared with most similar materials:

[0018] (1) The preparation method is simple and can be prepared by solvothermal reaction; (2) The preparation period is short and can be prepared within 4 days; (3) The product is pure; (4) High stability, can stably exist in a variety of organic solvents and at 400 °C; (5) Mild catalytic reaction conditions; (6) Can catalyze a wide range of reaction substrates; (7) Higher yields and selectivities of catalytic products; (8) The product is renewable and can be used as a catalyst for at least ten cycles. Description of the Drawings

[0019] Figure 1 is the crystal structure diagram of the non-noble metal cage-like MOFs material of the present invention;

[0020] Figure 2 is the PXRD (powder diffraction) pattern of the non-noble metal cage-like MOFs material of the present invention;

[0021] Figure 3 These are the PXRD (powder diffraction) patterns of the non-noble metal cage-like MOFs material of the present invention after being soaked in different kinds of organic solvents;

[0022] Figure 4 These are the PXRD (powder diffraction) patterns of the non-noble metal cage-like MOFs material of the present invention after being soaked in acid and alkali solutions of different concentrations;

[0023] Figure 5 This is the thermogravimetric curve of the non-noble metal cage-like MOFs material of the present invention;

[0024] Figure 6 This is the catalytic product yield diagram of the non-noble metal cage-like MOFs material of the present invention for the cyclic reaction of CO2 and N-methylaniline ten times;

[0025] Figure 7 These are the PXRD (powder diffraction) patterns of the non-noble metal cage-like MOFs material of the present invention after the cyclic reaction of CO2 and N-methylaniline ten times.

[0026] Figure 8 These are the XPS (X-ray photoelectron spectroscopy) patterns of the non-noble metal cage-like MOFs material of the present invention after the cyclic reaction of CO2 and N-methylaniline ten times. Detailed implementation mode

[0027] Example 1: Preparation of non-noble metal cage-like MOFs catalyst [Ni3]

[0028] Reaction raw materials: nickel nitrate Ni(NO3)2·6H2O, 4′-(4-pyridyl)4,2′:2′,4″-bipyridine XN, terephthalic acid H2BDC, N,N-dimethylformamide DMF, and methanol MeOH.

[0029] Add 0.05 mmol of Ni(NO3)2·6H2O, 0.02 mmol of XN, and 0.05 mmol of terephthalic acid H2BDC to 8 mL of DMF and 2 mL of MeOH solvent and stir evenly. Transfer the above reaction raw materials to a high-pressure reaction kettle with a polytetrafluoroethylene liner, place it in an oven, raise the temperature to 160 °C in 3 hours, keep the temperature constant for 48 hours, then cool it to room temperature at a rate of 2.7 °C / h, and wash the product with methanol to obtain pure light green octahedral crystals, namely the non-noble metal cage-like MOFs catalyst [Ni3].

[0030] The non-noble metal cage-like MOFs catalyst [Ni3] prepared in the present invention has a product chemical formula of: [H2N(CH3)2]2{[Ni3(μ3-O)(XN)(BDC)3]·6DMF} n , where n is a positive integer greater than 1, and -H2N(CH3)2 +is the dimethylamine cation, XN is 6'-(pyridin-4-yl)-4,2':4',4”-terpyridine, and BDC 2- is obtained by deprotonating the ligand terephthalic acid H2BDC; the crystal belongs to the hexagonal crystal system, the space group is P63 / mmc, and the unit cell parameters are: α = 90°, β = 90°, γ = 120°; the asymmetric unit of this cage-like MOFs contains 1 crystallographically independent Ni 2+ , 0.3 independent XNs and 2 BDCs 2- ions, among which 2 free [H2N(CH3)2] + act as counterions to maintain the electrical neutrality of the structure.

[0031] This asymmetric unit can be assembled through symmetry operations to form a cage-like three-dimensional anionic framework structure with a Ni3 cluster (as Figure 1 shown), and all nickel atoms Ni have a six-coordinate configuration. This cage-like metal-organic framework structure can stably exist in a variety of organic solvents and acid-base solutions with a pH of 2 to 12. The characteristic cage-like pore structure and good chemical stability of the materials of the present invention lay a solid foundation for their application in the reaction of catalytic conversion of CO2 to form high-value chemical substances, and provide a strong guarantee for their practical applications such as industrialization.

[0032] In the present invention, the cage cavity diameter of the cage-like catalyst material is The large pore size promotes the transport of guest molecules, providing good basic conditions for the adsorption and enrichment of CO2 molecules and catalytic substrates in later catalytic applications (attached Figure 1 ).

[0033] Attached Figure 2 shows the PXRD (powder diffraction) pattern of the cage-like MOFs material of the present invention. As can be seen from attached Figure 2 , the product obtained in the present invention has a relatively high phase purity. Most MOFs materials are prepared with a large amount of by-products, while the product of the present invention is very pure and almost free of impurities; attached Figure 3 and attached Figure 4 show the PXRD (powder diffraction) patterns of the MOFs material of the present invention after being soaked in different kinds of organic solvents and acid-base solutions with different concentrations. As can be seen from attached Figure 3 and attached Figure 4 , the product obtained in the present invention has high stability. Most MOFs materials cannot stably exist in strong acids, strong bases or organic solvents, and their structures are prone to collapse or decomposition, while the MOFs material in the present invention has good chemical stability and can stably exist in acid-base solutions with a pH of 2 - 12 and different organic solvents.

[0034] Example 2: Use of Non-Noble Metal Caged MOFs Catalysts

[0035] As the use of the present invention, the caged MOFs material obtained in the present invention can be used as a non-noble metal catalyst to efficiently catalyze the conversion of CO2 and aromatic amines to form high-value chemical substances such as N-benzamide under mild conditions. Among them, the aromatic amines include at least N-methylaniline, N,2-dimethylaniline, N,3-dimethylaniline, N,4-dimethylaniline, 4-methoxy-N-methylaniline, 3-chloro-N-methylaniline, 4-chloro-N-methylaniline, N-ethylaniline, N-isopropylaniline, N-butylaniline, N-benzylaniline, and the corresponding catalytic products belong to N-alkyl / aryl benzamides.

[0036] Table 1 shows the reaction of the non-noble metal caged MOFs catalyst of the present invention to catalyze the conversion of CO2 and N-methylaniline to form N-benzamide under different conditions;

[0037] Table 1

[0038]

[0039]

[0040] [a] Reaction conditions: CO2 pressure (1 atm), N-methylaniline (a, 1 mmol, 107 mg), PhSiH3 (2 mmol, 216 mg). [b] Using 1,3,5-trimethoxybenzene as an internal standard, the yields of b and c were determined by nuclear magnetic resonance ( 1 1H NMR).

[0041] Table 2 shows the substrate expansion reaction of the non-noble metal caged MOFs catalyst of the present invention under the optimal reaction conditions;

[0042] Table 2

[0043]

[0044] [a] Reaction conditions: CO2 pressure (1 atm), aromatic amine (1, 1 mmol), PhSiH3 (2 mmol, 216 mg), catalyst 1 (0.006 mmol, 10 mg), cesium carbonate Cs2CO3 (0.02 mmol, 6 mg), acetonitrile CH3CN (2 mL), room temperature.

[0045] [b] Using 1,3,5-trimethoxybenzene as an internal standard, the yields of 2a-2k were determined by nuclear magnetic resonance ( 1 1H NMR).

[0046] As can be seen from Table 1 and Table 2, the materials obtained in the present invention, as non-noble metal catalysts, have mild catalytic conditions and low costs. The catalysts reported previously for this catalytic reaction have harsh conditions. To achieve an ideal yield, a long reaction time, a high reaction temperature, and / or a large reaction pressure are required. Although some noble metal catalysts can obtain good catalytic activity, they require expensive costs and there is metal ion leakage during the cyclic catalysis process. However, the non-noble metal catalyst in the present invention can efficiently catalyze the reaction of CO2 with N-methylaniline to form N-benzamide at normal temperature and pressure. The product yield is as high as 94%, the selectivity is as high as 100%, and it can be recycled at least ten times while maintaining the catalytic activity without weakening, which is in line with the concepts of green chemistry and sustainable development.

[0047] Appendix Figure 6 shows the catalytic yield diagram of the non-noble metal cage-like MOFs catalyst of the present invention for the cyclic catalysis of N-methylaniline and CO2 to form N-benzamide ten times, and the catalytic activity remains basically unchanged; Appendix Figure 7 and Appendix Figure 8 show the PXRD (powder diffraction) diagram and XPS (X-ray photoelectron spectroscopy) of the cage-like MOFs catalyst material of the present invention after ten times of cyclic catalysis of the functional reduction reaction of CO2 with N-methylaniline. From Appendix Figure 6 to Appendix Figure 8 it can be seen that the cage-like MOFs catalyst material of the present invention can be recycled ten times while maintaining good catalytic activity and stability, and it can be confirmed by the PXRD diagram and the XPS diagram.

Claims

1. A non-noble metal cage-like MOFs catalyst for efficiently catalyzing the production of N-benzamide from CO2 and aromatic amines, characterized in that, The chemical formula is: [H2N(CH3)2]2{[Ni3( µ 3-O)(XN)(BDC)3]·6DMF} n , where n is a positive integer greater than 1, abbreviated as [Ni3]; among them, -H2N(CH3)2 + is the dimethylamine cation, XN is 6'-(pyridin-4-yl)-4,2':4',4''-bipyridine, and BDC 2- is obtained by deprotonating the ligand terephthalic acid H2BDC; the crystal belongs to the hexagonal crystal system, and the space group is P 63 / mmc , and the unit cell parameters are: a = 16.9212(6) Å, b = 16.9212(6) Å, c = 14.9982(8) Å, α = 90°, b = 90°, γ = 120°; the asymmetric unit of this non-noble metal cage-like MOF contains 1 crystallographically independent Ni 2+ , 0.3 independent XNs and 2 BDC 2- ions, among which 2 free [H2N(CH3)2] + act as counterions to maintain the electrical neutrality of the structure.

2. A preparation method of the non-precious metal cage-shaped MOFs catalyst described in claim 1 for efficiently catalyzing the production of N-benzamide from CO2 and aromatic amines, characterized in that including the following steps: (1) Reaction raw materials: nickel nitrate Ni(NO3)2·6H2O, XN, terephthalic acid H2BDC, solvent DMF and MeOH; The dosage ratio of nickel nitrate Ni(NO3)2·6H2O, XN and terephthalic acid H2BDC is 5 mol: 2 mol: 5 mol; the dosage ratio of solvent DMF and MeOH is 800 L: 200 L; (2) Mix the above reaction raw materials and add them into a high-pressure reactor with a polytetrafluoroethylene liner, place it in an oven, heat it to 150-160 °C in 3-12 hours, carry out a constant-temperature reaction for 48-96 hours, and then cool it to room temperature at 1.4-2.7 °C / h; (3) After the reaction is completed, wash the product with methanol to obtain light green octahedral crystals.

3. Use of the non-precious metal cage-like MOFs catalyst as claimed in claim 1 for efficiently catalyzing the production of N-benzamide from CO2 and aromatic amines, characterized in that: This non-noble metal cage-like MOFs catalyst can be used to efficiently catalyze the reaction of CO2 with aromatic amines to form N-benzamides under mild conditions.

4. The use according to claim 3, characterized in that: The mild conditions include that the dosage ratio of the non-noble metal catalyst [Ni3], the catalytic reaction solvent CH3CN, the catalytic reaction reducing agent PhSiH3 and the co-catalyst Cs2CO3 is 6 mol: 2000 L: 2000 mol: 20 mol.

5. The use according to claim 3, wherein: The mild conditions include normal temperature, normal pressure, and the catalytic reaction time is 12 h.

6. The use according to claim 3, characterized in that: The aromatic amines include N-methylaniline, N, 2-dimethylaniline, N, 3-dimethylaniline, N, 4-dimethylaniline, 4-methoxy-N-methylaniline, 3-chloro-N-methylaniline, 4-chloro-N-methylaniline, N-ethylaniline, N-isopropylaniline, N-butylaniline, N-benzylaniline, and the corresponding catalytic products belong to N-alkyl / aryl benzamides.

7. The use according to claim 3, characterized in that: For one of the aromatic amines, the yield of N-benzamide obtained from the reaction of N-methylaniline with CO2 is as high as 95%, and the selectivity is as high as 100%.

8. The use according to any one of claims 3-7, characterized in that: The non-noble metal cage-like MOFs catalyst [Ni3] can be recycled ten times while maintaining the catalytic performance basically unchanged.

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