A nitrogen-containing ligand functionalized porous material-encapsulated copper catalyst and a method for preparing formamide by catalyzing flue gas thereof

Abstract

The invention discloses a nitrogen-containing ligand functionalized porous material encapsulated copper catalyst and a method for catalyzing flue gas to prepare formamide. The nitrogen-containing ligand functionalized porous material encapsulated copper is used as a catalyst, amine compounds, hydrogen and CO in the flue gas are reacted to formamide. 2 The present invention uses the catalyst to directly utilize flue gas to produce CO 2 source, no need for CO 2 Purification can effectively save energy while protecting the environment; the copper catalyst encapsulated by the nitrogen-containing ligand functionalized porous material shows excellent catalytic performance and good cycle stability in the N-formylation reaction of amines with flue gas and hydrogen, and can synthesize N-formamide compounds with a high yield. In short, the catalyst of the present invention has the advantages of simple and effective preparation method, strong controllability, excellent catalytic performance, strong practicality, etc., and the catalyst is easy to separate and reusable, which provides a new industrial technology for the efficient utilization of flue gas to produce high-value-added fine chemicals.

Description

Technical Field

[0001] The invention relates to a method for preparing N-formamide from flue gas, in particular to a method for synthesizing N-formamide by catalyzing flue gas and amine compounds using copper encapsulated by nitrogen-containing ligand functionalized porous materials, and belongs to the technical field of green and clean catalysis. Background Art

[0002] Carbon dioxide (CO2) is an important component of the atmosphere and the culprit of the greenhouse effect. At the same time, CO2 is also an important C1 resource with the advantages of safety, non-toxicity, cheap, easy to obtain, and renewable. With the increasing prominence of global warming, the resource utilization of CO2 has become an important scientific topic. Among the many ways to utilize CO2 in a high value way, the preparation of N-formamide by CO2 and amine compounds is one of the most effective ways to utilize CO2 in a resource way. However, the current N-formylation reaction of CO2 and amine compounds uses high-purity CO2 as the gas source. High-purity CO2 needs to capture mixed gases such as high-concentration and low-concentration flue gas, and then compress and seal them after a series of desulfurization, deoxygenation and dehydration purification. The process consumes a lot of energy, has high operating costs, and has many operating steps. Flue gas refers to gaseous substances that pollute the environment when fossil fuels such as coal are burned. It is named because these substances are usually discharged from flues or chimneys. Its main components are nitrogen, carbon dioxide, oxygen, water vapor, and sulfide. If the flue gas treated with desulfurization and denitrification can be directly used as the gas source for reaction, the number of devices can be reduced and the investment cost can be reduced. Therefore, directly using CO2 in flue gas and amine compounds to prepare high value-added N-formamide chemicals has extremely high industrial application value.

[0003] At present, the heterogeneous catalysts used for the N-formylation reaction of CO2 and amines mainly include Al2O3 nanorods (Al2O3-NR) supported Pd catalyst (Chem. Commun., 2014, 50, 189), attapulgite (PAL) supported palladium catalyst Pd / PAL (Chinese J. Catal., 2019, 40, 1141.), TiO2 supported Ir catalyst (Chem. Commun., 2014,50, 9138.), Cu / ZnO (Chem. Commun., 2010, 46, 5770), heterogeneous nitrogen heterocyclic carbene iridium catalyst (Angew. Chem. Int. Ed., 2021, 60,4125-4132.), phosphine-containing polymer supported ruthenium catalyst (ChemSusChem 2020, 13, 1735-1739.), etc. However, there are no reports on heterogeneous catalysts for preparing N-formamide directly from flue gas as a CO2 source and amine compounds. This may be due to the low concentration of CO2 in flue gas, which is about 8-15%, making it difficult for CO2 molecules to recognize, directional adsorb, and activate; in addition, gases such as NOx and SO2 in flue gas can easily cause catalyst deactivation and reduce catalyst stability. Therefore, for the purpose of industrial application, there is a strong demand for the development of highly active, highly selective, and highly stable heterogeneous catalysts for preparing N-formamide compounds from flue gas as a CO2 source and amines. Summary of the invention

[0004] The purpose of the present invention is to provide a nitrogen-containing ligand functionalized porous material-encapsulated copper catalyst; at the same time, to provide a method for preparing N-formamide by catalyzing flue gas as a CO2 source directly with amine compounds using the nitrogen-containing ligand functionalized porous material-encapsulated copper catalyst.

[0005] The invention provides a catalyst, comprising a nitrogen-containing ligand functionalized porous carrier and copper encapsulated in the nitrogen-containing ligand functionalized porous carrier; the nitrogen-containing ligand functionalized porous carrier is obtained by polymerizing vinyl nitrogen-containing ligands inside the porous carrier; the porous carrier is silicon dioxide, carbon nanotubes, FDU-12, or MCM-41 molecular sieve.

[0006] The nitrogen-containing ligand functionalized porous carrier is obtained by polymerizing vinyl nitrogen-containing ligands inside the porous carrier.

[0007] The porous carrier is silicon dioxide, carbon nanotube, FDU-12 or MCM-41 molecular sieve.

[0008] The mass percentage of the copper in the catalyst is 0.5-30%. The mass ratio of the vinyl nitrogen-containing ligand to the carrier is 0.1-0.5:1.

[0009] The vinyl nitrogen-containing ligand is one or more of 3,8-divinyl-1,10-phenanthroline, 2,9-divinyl-1,10-phenanthroline, 5,5'-divinyl-2,2'-bipyridine, and 4,4'-divinyl-2,2'-bipyridine.

[0010] The present invention encapsulates copper in the confined space inside the nitrogen-containing ligand functionalized porous carrier, thereby increasing the catalyst's ability to recognize, adsorb, and activate CO2 molecules and improving the catalyst's catalytic activity. At the same time, the coordination between the nitrogen-containing ligand functional groups in the porous carrier and the active component copper prevents the loss of the active component copper and improves the catalyst's stability.

[0011] The present invention also provides a method for preparing the catalyst described in the above technical solution, comprising the following steps: mixing a vinyl nitrogen-containing ligand, a porous carrier, an initiator and an organic solvent for polymerization reaction to obtain a nitrogen-containing ligand functionalized porous carrier; impregnating a copper precursor into the nitrogen-containing ligand functionalized porous carrier to obtain the catalyst.

[0012] Wherein, the polymerization reaction temperature is 70-120°C and the time is 12-36h.

[0013] The organic solvent is one or more of N,N-dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, acetonitrile, methanol, ethanol, isopropanol and dioxane; the mass ratio of the organic solvent to the carrier is 2-20:1;

[0014] The initiator is 2,2'-azobisisobutyronitrile, di-tert-butyl peroxide, dibenzoyl peroxide, or tert-butyl perbenzoate; the mass ratio of the initiator to the vinyl nitrogen-containing ligand monomer is 1-10:100.

[0015] The copper precursor is one or more of copper acetate, potassium copper nitrate, basic copper carbonate, and copper acetylacetonate.

[0016] The preparation method provided by the invention has simple steps, strong controllability and practicability, low cost and is suitable for large-scale production and application.

[0017] The invention discloses an application of a copper catalyst encapsulated by a nitrogen-containing ligand functionalized porous carrier in catalyzing an N-formylation reaction, wherein an amine undergoes an N-formylation reaction with flue gas and hydrogen in an organic solvent under the action of the catalyst to generate formamide compounds.

[0018] The structural formula of the amine is:

[0019]

[0020] In the structural formula:

[0021] R 1is hydrogen, substituted or unsubstituted C1-C 20 Alkyl, substituted or unsubstituted C4-C 10 Cycloalkyl, substituted or unsubstituted C6-C 24 Aryl or heteroaryl, substituted or unsubstituted C7-C 25 Arylalkyl or heteroarylalkyl, -(CH2)n-OR 3 or -(CH2)n-NR 4 R 5 , where n=1-8;

[0022] R 2 is substituted or unsubstituted C1-C 20 Alkyl, substituted or unsubstituted C4-C 10 Cycloalkyl, substituted or unsubstituted C6-C 24 Aryl or heteroaryl, substituted or unsubstituted C7-C 25 Arylalkyl or heteroarylalkyl, -(CH2)n-OR 3

[0023] or - (CH2) n-NR 4 R 5 , where n=1-8;

[0024] R 1 With R 2 Can be linked to substituted or unsubstituted C4-C 10 Cycloalkyl.

[0025] Among them, R 3 , R 4 , R 5 are independently selected from: hydrogen, substituted or unsubstituted C1-C 20 Alkyl, substituted or unsubstituted C6-C 24 Aryl, substituted or unsubstituted C7-C 25 Arylalkyl or heteroaryl, where R 4 With R 5 Can be linked to substituted or unsubstituted C3-C 10 Cycloalkyl, C6-C 24 Aryl or heteroaryl.

[0026] Here, the term "substituted" refers to that one or more hydrogen atoms in the group are replaced by a substituent selected from the group consisting of halogen, C1-C4 alkyl, C1-C4 haloalkyl, C2-C6 alkenyl, C2-C6 alkynyl, C1-C6 alkoxy, hydroxyl, amine, and thiol.

[0027] The molar ratio of the amine to the copper catalyst encapsulated by the nitrogen-containing ligand functionalized porous carrier is 1:0.02-1:0.5; the molar concentration of the amine in the organic solvent is 0.02-1mmol / mL.

[0028] The N-formylation reaction temperature is 60-200°C, the reaction time is 4-48 hours, the hydrogen pressure is 0.3-6MPa, and the flue gas pressure is 0.3-8MPa.

[0029] The solvent for the N-formylation reaction is selected from tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, ethylene glycol dimethyl ether, tert-butyl methyl ether, benzene, toluene, xylene, methanol, ethanol, isopropanol, tert-butanol or a combination thereof.

[0030] When the amine compound is dimethylamine or its equivalent dimethylamine carbon dioxide, the product is N,N-dimethylformamide.

[0031] In summary, the catalyst provided by the present invention exhibits excellent catalytic performance and good cycle stability in the N-formylation reaction of amine with flue gas and hydrogen, and can synthesize N-formamide compounds with a high yield. The catalyst provided by the present invention has the advantages of simple preparation method, low catalyst cost, large-scale operation, suitability for large-scale industrial production, high stability, excellent catalytic performance, strong practicality, etc., and the catalyst is easy to separate and reusable. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a scanning electron microscope image of the catalyst prepared in Example 3;

[0033] Figure 2 is the X-ray diffraction pattern of the catalyst prepared in Example 3;

[0034] Figure 3 This is the infrared spectrum of the catalyst prepared in Example 3. DETAILED DESCRIPTION

[0035] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0036] Example 1

[0037] Under an inert atmosphere, 1.0 g of FDU-12, 0.5 g of 3,8-divinyl-1,10-phenanthroline, 10 mL of N,N-dimethylformamide and 12.5 mg of azobisisobutyronitrile were stirred in a hydrothermal reactor at 25 °C for 3.0 h; the polymerization reaction was carried out at 100 °C for 24 h and then filtered. The filtered solid was washed three times with 20 mL of dichloromethane and then vacuum dried at 50 °C for 12 h to obtain FDU-12 functionalized with a nitrogen-containing ligand.

[0038] 0.5 g of FDU-12 functionalized with nitrogen-containing ligands was dispersed in 40 mL of N,N-dimethylformamide, stirred for 30 min, and then 5 mL of 10 mg / mL copper acetate solution was added and mixed. After stirring at room temperature for 24 h, the mixture was filtered. The filtered solid was washed three times with 20 mL of MeOH and vacuum dried at 50 ° C for 12 h to obtain a nitrogen-containing ligand functionalized FDU-12 copper-encapsulated catalyst, which was recorded as catalyst A.

[0039] Example 2

[0040] The catalyst was prepared according to the method of Example 1, except that FDU-12 was replaced by carbon nanotubes.

[0041] Example 3

[0042] The catalyst was prepared according to the method of Example 1, except that FDU-12 was replaced by MCM-41.

[0043] Figure 1 This is a scanning electron microscope (SEM) photograph of the catalyst prepared in Example 3 of the present invention. It can be seen from the figure that the prepared catalyst is spherical particles, and the diameter of the spheres is about 10-20 nm. Figure 2 The X-ray diffraction (XRD) diagram of the catalyst prepared in Example 3 of the present invention shows a broad diffraction peak at about 22.5 degrees, which is attributed to the amorphous carbon structure formed by the polymerization of 1,10-phenanthroline. No diffraction peak of copper species was observed in the XRD diagram, indicating that the copper species is highly dispersed in MCM-41. Figure 3 The infrared (FT-IR) spectrum of the catalyst prepared in Example 3 of the present invention shows that the prepared catalyst contains the structural fragment of the organic nitrogen ligand 1,10-phenanthroline.

[0044] Example 4

[0045] The catalyst was prepared according to the method of Example 1, except that FDU-12 was replaced by silica.

[0046] Example 5

[0047] The catalyst was prepared according to the method of Example 1, except that 0.5 g of 3,8-divinyl-1,10-phenanthroline was replaced by 0.2 g of 2,9-divinyl-1,10-phenanthroline.

[0048] Example 6

[0049] The catalyst was prepared according to the method of Example 1, except that 0.5 g of 3,8-divinyl-1,10-phenanthroline was replaced by 0.1 g of 5,5-divinyl-2,2-bipyridine.

[0050] Example 7

[0051] The catalyst was prepared according to the method of Example 1, except that 5 mL of the copper acetate solution with a mass concentration of 10 mg / mL was replaced by 10 mL of the copper nitrate solution with a mass concentration of 10 mg / mL.

[0052] Example 8

[0053] The catalyst was prepared according to the method of Example 1, except that 5 mL of the copper acetate solution with a mass concentration of 10 mg / mL was replaced by 2 mL of the copper acetylacetonate solution with a mass concentration of 5 mg / mL.

[0054] Example 9

[0055] The catalyst was prepared according to the method of Example 1, except that 10 mL of N, N-dimethylformamide organic solvent was replaced by 5 mL of tetrahydrofuran.

[0056] Example 10

[0057] The catalyst was prepared according to the method of Example 1, except that 10 mL of N, N-dimethylformamide organic solvent was replaced by 20 mL of acetonitrile.

[0058] Embodiment 11

[0059] The catalyst was prepared according to the method of Example 1, except that the polymerization reaction conditions (100° C., 24 h) were replaced with 80° C., 48 h; and 12.5 mg of azobisisobutyronitrile initiator was replaced with 5.0 mg of dibenzoyl peroxide.

[0060] Comparative Example 1

[0061] In Comparative Example 1, the porous support was not functionalized with nitrogen-containing ligands, and 0.5 g of FDU-12 functionalized with nitrogen-containing ligands was replaced with 0.5 g of FDU-12 during the impregnation process. The resulting FDU-12-supported copper catalytic material was recorded as Comparative Catalyst A.

[0062] Comparative Example 2

[0063] In Comparative Example 2, the porous support was not functionalized with nitrogen-containing ligands, and 0.5 g of carbon nanotubes functionalized with nitrogen-containing ligands was replaced with 0.5 g of carbon nanotubes during the impregnation process. The obtained carbon nanotube-supported copper catalytic material was recorded as Comparative Catalyst B.

[0064] Comparative Example 3

[0065] In Comparative Example 3, the porous support was not functionalized with nitrogen-containing ligands, and 0.5 g of MCM-41 functionalized with nitrogen-containing ligands was replaced with 0.5 g of MCM-41 during the impregnation process. The resulting MCM-41-supported copper catalytic material was recorded as Comparative Catalyst C.

[0066] The catalysts prepared in Examples 1-11 and Comparative Examples 1-3 were used to catalyze the N-formylation reaction with dimethylamine, flue gas and hydrogen as raw materials, respectively, to illustrate the catalytic performance of different catalysts; the specific steps were: 2.68 g (20 mmol, equivalent to 40 mmol dimethylamine) of dimethylammonium·dimethyl (DIMCARB), 40 mg of catalyst and 4 mL of methanol were added to a 100 mL high-pressure reactor equipped with a magnetic stirrer; after sealing the high-pressure reactor, it was replaced with flue gas three times, and then filled with 6 MPa of flue gas, and then 3 MPa of hydrogen was filled into the high-pressure reactor to a total pressure of 9 MPa; the reaction was carried out at 180° C. for 24 h to obtain N,N-dimethylformamide; after the reaction was completed, the reactor was cooled to room temperature and the pressure was slowly released, 20 mL of methanol was added, and then mesitylene (336 mg, 2 mmol) was added to the reaction system as 1 The internal standard of H NMR analysis was used to determine the yield. The catalytic performance data of different catalysts are shown in Table 1.

[0067]

[0068] It can be seen from Table 1 that the catalyst provided by the present invention has good catalytic performance for preparing formamide compounds using amine, flue gas and hydrogen as raw materials.

[0069] Taking the catalyst prepared in Example 1 as an example, the reusability of the copper catalyst supported on a nitrogen-containing ligand functionalized porous carrier in catalyzing the N-formylation reaction of dimethylamine and flue gas was verified.

[0070] In a 100mL autoclave equipped with a magnetic stirrer, 2.68g (20mmol, equivalent to 40mmol dimethylamine) of dimethylammonium·dimethyl (DIMCARB), 40mg of catalyst and 4mL of methanol were added; the autoclave was sealed, replaced with flue gas three times, and filled with 6MPa flue gas and 3MPa of H2; the reaction was carried out at 180℃ for 24h. After the reaction was completed, the reactor was cooled to room temperature and the pressure was slowly released. 20mL of methanol was added to the reaction mixture to dilute it, and then 336mg (2mmol) of trimethoxybenzene was added as 1 The internal standard of H NMR analysis was used to determine the yield. The reaction solution was then transferred to a centrifuge tube and centrifuged to obtain the catalyst, which was washed three times with 8 mL of methanol and once with 8 mL of acetone. After being exposed to air at room temperature to dry, it was directly placed in a kettle for the next reuse. The reaction data of the catalyst reuse are shown in Table 2.

[0071]

[0072] It can be seen from Table 2 that the catalytic material prepared by the present invention can be recycled and reused, and after being reused six times, it still has the same catalytic activity as when it was initially used.

[0073] According to the above method, 20 mmol of different amines were used to replace 40 mmol of dimethylammonium dimethyl, and 40 mg of the catalyst prepared in Example 1 was used to catalyze flue gas, amines and hydrogen to prepare N-formamide compounds. The specific types of amine compounds and prepared formamide compounds are listed in Table 3.

[0074]

[0075]

[0076] It can be seen from Table 3 that the catalyst prepared by the present invention can be applied to the N-formylation reaction of different amines with flue gas and hydrogen, and exhibits high catalytic activity.

[0077] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A nitrogen-containing ligand functionalized porous material-supported copper catalyst, characterized in that: It comprises a nitrogen-containing ligand functionalized porous carrier and copper contained in the nitrogen-containing ligand functionalized porous carrier; The nitrogen-containing ligand functionalized porous carrier is obtained by polymerizing vinyl nitrogen-containing ligands inside the porous carrier, and the copper package is loaded in the confined space inside the nitrogen-containing ligand functionalized porous carrier; The vinyl nitrogen-containing ligand is one or more of 3,8-divinyl-1,10-phenanthroline, 2,9-divinyl-1,10-phenanthroline, 5,5'-divinyl-2,2'-bipyridine, and 4,4'-divinyl-2,2'-bipyridine; The porous carrier is silicon dioxide, carbon nanotube, FDU-12 or MCM-41 molecular sieve.

2. The catalyst according to claim 1, characterized in that The mass percentage of the copper in the catalyst is 0.5-30%; the mass ratio of the vinyl nitrogen-containing ligand to the carrier is 0.1-0.5:

1.

3. A method for preparing a catalyst according to any one of claims 1 to 2, comprising the following steps: The vinyl nitrogen-containing ligand, the porous carrier, the initiator and the organic solvent are mixed to carry out polymerization reaction to obtain the nitrogen-containing ligand functionalized porous carrier; The copper precursor is impregnated into a nitrogen-containing ligand functionalized porous carrier to obtain a nitrogen-containing ligand functionalized porous material-encapsulated copper catalyst.

4. The preparation method according to claim 3, characterized in that: The polymerization reaction temperature is 70-120° C. and the reaction time is 12-36 hours.

5. The preparation method according to claim 3, characterized in that: The organic solvent is one or more of N,N-dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, acetonitrile, methanol, ethanol, isopropanol and dioxane; The initiator is 2,2'-azobisisobutyronitrile, di-tert-butyl peroxide, dibenzoyl peroxide or tert-butyl perbenzoate; the mass ratio of the initiator to the vinyl nitrogen-containing ligand monomer is 1-10:

100.

6. The preparation method according to claim 3, characterized in that: The copper precursor is one or more of copper acetate, potassium copper nitrate, basic copper carbonate, and copper acetylacetonate.

7. Use of the copper catalyst encapsulated by the nitrogen-containing ligand functionalized porous material according to claim 1 in catalyzing the preparation of formamide compounds using amine, flue gas and hydrogen as raw materials.

8. The use of the nitrogen-containing ligand functionalized porous material-supported copper catalyst according to claim 7 in catalyzing the preparation of formamide compounds using amine, flue gas and hydrogen as raw materials, characterized in that: Under the action of copper catalyst encapsulated by nitrogen-containing ligand functionalized porous material, amine reacts with flue gas and hydrogen in an organic solvent to generate formamide compounds; the N-formylation reaction temperature is 60-200°C and the reaction time is 4-48h.

9. The use of the nitrogen-containing ligand functionalized porous material-supported copper catalyst according to claim 8 in catalyzing the preparation of formamide compounds using amine, flue gas and hydrogen as raw materials, characterized in that: The molar ratio of the amine to the nitrogen-containing ligand functionalized porous carrier-supported copper catalyst is 1:0.02-1:0.5; the molar concentration of the amine in the organic solvent is 0.02-1mmol / mL; the hydrogen pressure is 0.3-6MPa, and the flue gas pressure is 0.3-8MPa.

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