Preparation method of integrated phenolic resin-based monatomic catalytic electrode plate material and method for selective electrochemical hydrogenation of nitrogen heterocyclic organic matter

Abstract

The invention relates to a preparation method of an integrated phenolic resin-based monatomic catalytic electrode plate material and a selective electrochemical hydrogenation method for nitrogen heterocyclic organic matters, which are characterized in that a principle of a ZnNi bimetal organic framework in-situ derived monatomic catalyst is utilized, and a phenolic resin-based composite precursor of a microstructure and functional components is directionally constructed through graded fine dispersion; and preparing the integrated Ni monatomic catalytic electrode plate with an inline three-dimensional stepped through porous structure and a three-dimensional conductive network structure through a pyrolysis process. According to the method, a clean and efficient electrochemical directional conversion path is designed by adopting a green chemical synthesis strategy, and the degradation of nitrogen heterocyclic organic pollutants and the synthesis of high-value aromatic hydrocarbon compounds can be realized at the same time. High-added-value fine chemicals are produced through a novel coupling electrochemical conversion path which is low in energy consumption, zero in emission and free of any additives and byproducts, environmental pollution is effectively solved, energy loss is reduced, and production of clean oil products with ultra-low nitrogen content, ultra-high aromatic hydrocarbon content and the like is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical engineering technology, and specifically relates to a method for preparing an integrated phenolic resin-based single-atom catalytic electrode plate material and a method for selective electrochemical hydrogenation of nitrogen heterocyclic organic compounds. Background Art

[0002] Natural resource depletion, energy shortages, and environmental degradation are the three major challenges currently facing global sustainable development, posing potential risks to human energy security and the ecological environment. The production of clean fossil fuels or biomass fuels plays a crucial role in addressing global energy challenges. The presence of nitrogen compounds, particularly nitrogen heterocyclic organic compounds, in crude oil has a significant negative impact on fuel storage and utilization, leading to the generation of NOx pollutants during combustion and catalyst poisoning in downstream reforming processes. Therefore, hydrorefining reactions play a crucial role in the production of clean fossil fuels.

[0003] However, the traditional hydrorefining process has harsh reaction conditions requiring high temperature and high pressure, and the selectivity of hydrogenated products is poor. It only focuses on the removal ability of nitrogen-containing compounds, ignoring the hydrogen consumption during the reaction and the selectivity of other high-value products (such as aromatics). The effective use of renewable resources in chemical production and the efficient capture and conversion of green energy will have a positive impact on the ecological environment, so environmental pollution control and energy conservation often coexist. The synthesis strategy of converting nitrogen heterocyclic organic compounds into high-value-added fine chemicals at room temperature and pressure through electrocatalytic technology not only effectively solves environmental problems as well as high pressure, high energy consumption and equipment complexity problems, but also realizes the production of clean oil products such as ultra-low nitrogen and ultra-high aromatics content, greatly improving economic benefits. Summary of the Invention

[0004] Given the excellent performance of single-atom catalysts in the field of electrocatalysis, the present invention has developed a method for preparing an integrated phenolic resin-based single-atom catalytic electrode plate material for the catalytic hydrogenation reaction of nitrogen heterocycles, as well as a method for the selective electrochemical hydrogenation of nitrogen heterocycle organics. A green chemical synthesis strategy is used to design a clean and efficient electrochemical directional conversion pathway that can simultaneously achieve the degradation of nitrogen heterocycle organic pollutants and the synthesis of high-value aromatic compounds. This novel coupled electrochemical conversion pathway with low energy consumption, zero emissions, and the absence of any additives or by-products is used to produce high-value-added fine chemicals, effectively addressing environmental pollution, reducing energy loss, and enabling the production of clean oil products with ultra-low nitrogen and ultra-high aromatic content, truly transforming waste into treasure. This is a green and sustainable synthesis route.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions:

[0006] The preparation method of the integrated phenolic resin-based single-atom catalytic electrode plate material is based on the principle of in-situ derivatization of single-atom catalysts by ZnNi bimetallic organic frameworks. The phenolic resin-based composite precursor with microstructure and functional components is finely dispersed and directed by graded pyrolysis to prepare an integrated Ni single-atom catalytic electrode plate with an inline three-dimensional stepped porous structure and a three-dimensional conductive network structure. The specific method includes:

[0007] 1) Preparation of ZnNi bimetallic organic framework: A methanol solution of zinc acetate and nickel nitrate was gradually added dropwise to a methanol solution of 2-methylimidazole. The mixture was stirred vigorously at room temperature and reacted at 170-190°C for 2-3 hours until completely dry.

[0008] 2) Preparation of phenolic resin-based composite precursor: Grind and sieve the ZnNi bimetallic organic framework prepared in step 1), and gradedly disperse different particle sizes: 30 mesh ≤ particle size < 40 mesh, 40 mesh ≤ particle size < 50 mesh, 50 mesh ≤ particle size < 100 mesh, 100 mesh ≤ particle size < 200 mesh, 200 mesh ≤ particle size ≤ 400 mesh into phenolic resin, press solid under a pressure of 1 to 10 MPa, and then demold, and gradually heat in an air atmosphere to cure and crosslink, maintaining at 160-180° C. for 2-3 hours, 200-210° C. for 1-1.5 hours, 240-260° C. for 4-5 hours, and 365-375° C. for 2-2.5 hours, to obtain;

[0009] 3) Preparation of an integrated phenolic resin-based Ni single-atom catalytic composite electrode plate: The phenolic resin-based composite precursor prepared in step 2) is pyrolyzed in a nitrogen atmosphere at 800-900° C. for 2-3 h at a heating rate of 1.5-3° C. / min to obtain the obtained product.

[0010] The molar ratio of the nickel nitrate to the 2-methylimidazole is 1:(2-5), and the molar ratio of the zinc acetate to the nickel nitrate is (1-2):1.

[0011] The mass ratio of the ZnNi bimetallic organic framework mixed with the phenolic resin according to different particle sizes is as follows: 30 mesh ≤ particle size < 40 mesh accounts for 3% to 10%, 40 mesh ≤ particle size < 50 mesh accounts for 3% to 10%, 50 mesh ≤ particle size < 100 mesh accounts for 3% to 10%, 100 mesh ≤ particle size < 200 mesh accounts for 10% to 30%, 200 mesh ≤ particle size ≤ 400 mesh accounts for 10% to 30%, and the phenolic resin accounts for 10% to 30%.

[0012] The integrated phenolic resin-based single-atom catalytic electrode plate material is a Ni single-atom catalytic electrode plate with an inline three-dimensional stepped porous structure and a three-dimensional conductive network structure.

[0013] The method for selective electrochemical hydrogenation of nitrogen heterocyclic organic compounds uses the electrode plate material prepared by the preparation method of the integrated phenolic resin-based single-atom catalytic electrode plate material as a cathode. The specific content includes: using a solid proton conductor electrochemical reactor, under normal temperature and pressure conditions with external electric energy, using water as a hydrogen source to provide proton hydrogen, the proton hydrogen reaches the cathode through a proton exchange membrane, and combines with electrons at the cathode to be reduced to adsorbed hydrogen. The nitrogen heterocyclic organic compounds are highly selectively hydrogenated at the cathode to directionally prepare high-value aromatic compounds, providing a new coupled electrochemical synthesis strategy for the production of high-value-added fine chemicals.

[0014] The external electric energy refers to the constant current mode, and the current density is 1-100 mA / cm 2 .

[0015] The proton exchange membrane is a perfluorosulfonic acid proton exchange membrane.

[0016] The anode is made of carbon paper as a substrate and carries a Pt / C catalyst layer, wherein the Pt loading is 0.5 to 4.5 mg / cm 2 .

[0017] The Ni metal single atom in the cathode serves as the active center site.

[0018] The nitrogen heterocyclic organic compound is one of quinoline, isoquinoline, quinoxaline, and indole, with a concentration of 0.01 to 0.5 mol / L. The solvent is acetonitrile. The electrolyte is one or both of dipotassium hydrogen phosphate and potassium dihydrogen phosphate. The cathode mixed solution flow rate is 20 to 50 mL / min.

[0019] Compared with the existing technology, the beneficial effects of the present invention are:

[0020] 1) A green chemical synthesis strategy is used to synergistically transform waste into innovative products. Using inexpensive phenolic resin as the catalytic matrix, a clean and efficient electrochemical directed conversion pathway is designed based on the characteristics of the catalytic hydrogenation reaction of nitrogen heterocycles. This improves the energy conversion efficiency of the entire reaction system, maximizes energy investment return and atom economy, and is a sustainable electrochemical synthesis approach.

[0021] 2) An integrated phenolic resin-based Ni single-atom catalytic composite electrode material was developed using coordination engineering design. Ni metal single atoms serve as active centers, while organic ligands and nitrogen-doped carbon produced by the pyrolysis of phenolic resin serve as anchoring sites for the Ni single atoms. By utilizing graded fine-tuning techniques and the evaporation of Zn due to its low boiling point during pyrolysis, the composite electrode material forms an interconnected, three-dimensional, stepped porous structure and a three-dimensional conductive network. This prevents nanoparticle agglomeration while maintaining material transport and transfer, facilitating the formation of an internal electric field and the exposure of interfacial chemically active sites, ultimately enhancing the overall performance of the composite electrode material.

[0022] 3) A new green electrocatalytic selective hydrogenation method is developed using a renewable electricity synthesis strategy to replace traditional thermal catalysis. By selecting electrode materials and regulating reaction conditions in conjunction with the molecular structure characteristics of the cathode organic substrate, the hydrogenation routes of nitrogen heterocycles and CN bond severance are determined, thereby protecting the aromatic structure and retaining the high-value-added components in crude oil. This can fundamentally solve the problems of high consumption, chemical additives and by-product pollution emissions brought about by traditional multi-step reactions, and also reflects the potential value of the liquid phase compound electrocatalytic hydrogenation process in advanced hydrogen storage applications.

[0023] 4) The present invention provides a green, sustainable and directional electrochemical conversion process of nitrogen heterocyclic organic matter using an electrochemical reactor under normal temperature and pressure conditions with low energy consumption, zero emissions, no additives and no by-products. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of an integrated phenolic resin-based Ni single-atom catalytic composite electrode plate.

[0025] Figure 2 Schematic diagram of electrochemical selective hydrogenation of nitrogen heterocyclic compounds.

[0026] In the figure: 1. Anode; 2. Cathode; 3. Proton exchange membrane. DETAILED DESCRIPTION

[0027] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. Based on the examples of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] The present invention provides an integrated phenolic resin-based Ni single-atom catalytic composite electrode plate material and a novel electrocatalytic selective hydrogenation coupling reaction system constructed therefrom. Specifically, the material utilizes the principle of in-situ derivatization of a single-atom catalyst using a ZnNi bimetallic organic framework, and a phenolic resin-based composite precursor with microstructure and functional components is structured and finely dispersed in a hierarchical manner. An integrated Ni single-atom catalytic electrode plate with an inline three-dimensional stepped porous structure and a three-dimensional conductive network structure is prepared through a pyrolysis process. The Ni single-atom catalytic electrode plate is then used as a cathode in a solid proton conductor electrochemical reactor to construct a novel electrocatalytic selective hydrogenation coupling reaction system. Under normal temperature and pressure conditions with the addition of external electrical energy, water is used as a hydrogen source to provide proton hydrogen, which reaches the cathode through a proton exchange membrane and combines with electrons at the cathode to be reduced to adsorbed hydrogen. Nitrogen heterocyclic organic matter is highly selectively hydrogenated at the cathode to directionally prepare high-value aromatic compounds, thereby providing a novel coupled electrochemical synthesis strategy for the production of high-value-added fine chemicals.

[0029] Example:

[0030] Preparation of integrated phenolic resin-based Ni single-atom catalytic composite electrode plate material (Ni / NC):

[0031] A 0.3 mol / L mixed methanol solution of zinc acetate and nickel nitrate was gradually added dropwise to a 0.45 mol / L 2-methylimidazole methanol solution, wherein the molar ratio of zinc acetate to nickel nitrate was 1:1, and the mixture was vigorously stirred at 25°C for 0.5 h, then heated to 190°C and reacted for 2.5 h until completely dry to obtain a purple solid, which was ground and sieved for later use; the purple powders of different particle sizes obtained above were mixed with phenolic resin, with the specific proportions being: 30 mesh ≤ particle size < 40 mesh accounting for 6%, 40 mesh ≤ particle size < 50 mesh accounting for 6%, 50 mesh accounting for 6%, The particle size of ≤<100 mesh accounts for 6.5%, the particle size of 100 mesh ≤<200 mesh accounts for 25%, the particle size of 200 mesh ≤≤400 mesh accounts for 26.5%, and the phenolic resin accounts for 30%. After pressing and solidification under a pressure of 8 MPa, demoulding is carried out, and the temperature is gradually increased in an air atmosphere to cure and cross-link, maintaining at 170°C for 2h, 200°C for 1h, 250°C for 4h, and 375°C for 2h, cooling, and standby; the solid plate is placed in a tubular heating furnace and pyrolyzed at 900°C in a nitrogen atmosphere for 3h with a heating rate of 3°C / min to obtain.

[0032] Experiment on selective electrochemical hydrogenation of nitrogen heterocyclic organic compounds;

[0033] 1. The integrated Ni / NC prepared above was used as cathode 2, carbon paper was used as substrate, and the loading was 4 mg / cm 2 The Pt / C is used as anode 1, and the Nafion117 membrane is used as proton exchange membrane 3. The anode 1 uses water as the hydrogen source to provide proton hydrogen, and the cathode 2 is fed with a 0.5 mol / L quinoline / acetonitrile solution, dipotassium hydrogen phosphate and potassium dihydrogen phosphate as electrolytes. During the reaction, the outflowing solution is recirculated into the cathode 2 at a circulation rate of 30 mL / min. When the electrochemical reactor is operated at 30 mA / cm 2 After 1.5 hours of galvanostatic operation, cathode 2 products were collected and analyzed. The cathode quinoline hydrogenation conversion was 91%, with a 99% selectivity for heterocyclic hydrogenation, including 1,4-tetrahydroquinoline, o-propylaniline, and propylbenzene. Aromatic ring hydrogenation products were virtually undetectable.

[0034] 2. The integrated Ni / NC prepared above was used as cathode 2, with carbon paper as the matrix and a loading of 4.5 mg / cm 2 The Pt / C is used as anode 1, and the Nafion117 membrane is used as proton exchange membrane 3. The anode 1 uses water as the hydrogen source to provide proton hydrogen, and the cathode 2 is fed with a 0.3 mol / L quinoxaline / acetonitrile solution, dipotassium hydrogen phosphate and potassium dihydrogen phosphate as electrolytes. During the reaction, the outflowing solution is recirculated into the cathode 2 at a circulation rate of 50 mL / min. When the electrochemical reactor is operated at 50 mA / cm2 After 2 hours of constant current operation, cathode 2 products were collected and analyzed. The cathode quinoxaline hydrogenation conversion was 89%, with a 99% selectivity for heterocyclic hydrogenation, including dihydroquinoxaline and 1,2,3,4-tetrahydroquinoxaline. Aromatic ring hydrogenation products were virtually undetectable.

[0035] 3. The integrated Ni / NC prepared above was used as cathode 2, with carbon paper as substrate and a loading of 3.5 mg / cm 2 The Pt / C is used as anode 1, and the Nafion117 membrane is used as proton exchange membrane 3. The anode 1 uses water as the hydrogen source to provide proton hydrogen, and the cathode 2 is fed with a 0.15 mol / L indole / acetonitrile solution. During the reaction, the outflowing solution is recirculated into the cathode at a circulation rate of 20 mL / min. When the electrochemical reactor is operated at 100 mA / cm 2 After 2.5 h of constant current operation, the cathode 2 product was collected and analyzed. The hydrogenation conversion rate of cathode indole was 60%, of which the heterocyclic hydrogenation selectivity was 99%, including 1,2-dihydroindole, o-ethylaniline, ethylbenzene, etc., and almost no aromatic ring hydrogenation products were detected.

[0036] Comparative example: traditional thermal catalytic hydrogenation;

[0037] The reaction was carried out in a high-temperature and high-pressure reactor. The reactant was 0.05 mol / L quinoline / acetonitrile solution, the catalyst was Ni / NC-Al2O3, hydrogen was introduced to replace the air in the reactor, and the pressure reducing valve was adjusted to make the initial pressure in the reactor reach 4 MPa. The liquid hourly space velocity was 10 h -1 The reaction temperature was 320°C for 4 hours. The reactor was allowed to cool, vented, and the product removed for gas chromatography analysis. The hydrogenation conversion rate of quinoline was 76.9%, of which 54% were aromatic ring hydrogenation products, including 5,8-tetrahydroquinoline and decahydroquinoline. The heterocyclic hydrogenation selectivity was 46%, including 1,4-tetrahydroquinoline, o-propylaniline, and propylbenzene.

[0038] In summary, traditional thermal catalytic hydrogenation has poor selectivity, with heterocyclic hydrogenation selectivity below 50%. In contrast, the integrated Ni / NC catalytic composite electrode plate coupled to a solid proton conductor electrochemical reactor shows better selectivity for hydrogenation of nitrogen heterocyclic organic compounds such as quinoline, quinoxaline, and indole, with heterocyclic hydrogenation selectivity substantially exceeding 99%, and almost no aromatic ring hydrogenation products detected in the hydrogenation products. Therefore, the integrated phenolic resin-based single-atom catalytic electrode plate material designed in this invention and the novel electrocatalytic selective hydrogenation coupling reaction system constructed therefrom can achieve a targeted conversion pathway for the degradation of nitrogen heterocyclic organic pollutants while simultaneously synthesizing high-value aromatic hydrocarbon compounds.

[0039] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing an integrated phenolic resin-based single-atom catalytic electrode plate material, characterized in that: Specific methods include: 1) Preparation of ZnNi bimetallic organic framework: A methanol solution of zinc acetate and nickel nitrate was gradually added dropwise to a methanol solution of 2-methylimidazole, stirred at room temperature, and reacted at 170-190°C for 2-3 hours; 2) Preparation of phenolic resin-based composite precursor: Grind and sieve the ZnNi bimetallic organic framework prepared in step 1), and disperse different particle sizes: 30 mesh ≤ particle size < 40 mesh, 40 mesh ≤ particle size < 50 mesh, 50 mesh ≤ particle size < 100 mesh, 100 mesh ≤ particle size < 200 mesh, 200 mesh ≤ particle size ≤ 400 mesh into phenolic resin, press solid under a pressure of 1 to 10 MPa, and then demold. Gradual heating is performed in an air atmosphere to cure and crosslink, maintaining at 160-180° C. for 2-3 hours, 200° C.-210° C. for 1-1.5 hours, 240-260° C. for 4-5 hours, and 365-375° C. for 2-2.5 hours; 3) Preparation of an integrated phenolic resin-based Ni single-atom catalytic composite electrode plate: The phenolic resin-based composite precursor prepared in step 2) is pyrolyzed in a nitrogen atmosphere at 800-900°C for 2-3 hours at a heating rate of 1.5-3°C / min.

2. The method for preparing the integrated phenolic resin-based single-atom catalytic electrode plate material according to claim 1, characterized in that: The molar ratio of the nickel nitrate to the 2-methylimidazole is 1:(2-5), and the molar ratio of the zinc acetate to the nickel nitrate is (1-2):

1.

3. The method for preparing the integrated phenolic resin-based single-atom catalytic electrode plate material according to claim 1, characterized in that: The mass ratio of the ZnNi bimetallic organic framework mixed with the phenolic resin according to different particle sizes is as follows: 30 mesh ≤ particle size < 40 mesh accounts for 3% to 10%, 40 mesh ≤ particle size < 50 mesh accounts for 3% to 10%, 50 mesh ≤ particle size < 100 mesh accounts for 3% to 10%, 100 mesh ≤ particle size < 200 mesh accounts for 10% to 30%, 200 mesh ≤ particle size ≤ 400 mesh accounts for 10% to 30%, and the phenolic resin accounts for 10% to 30%.

4. The method for preparing the integrated phenolic resin-based single-atom catalytic electrode plate material according to claim 1, characterized in that: The integrated phenolic resin-based single-atom catalytic electrode plate material is a Ni single-atom catalytic electrode plate with an inline three-dimensional stepped porous structure and a three-dimensional conductive network structure.

5. A method for selective electrochemical hydrogenation of nitrogen heterocyclic organic compounds, characterized in that: The cathode is an electrode plate material prepared by the preparation method of the integrated phenolic resin-based single-atom catalytic electrode plate material as described in any one of claims 1 to 4. The specific content includes: using an electrochemical reactor, under normal temperature and pressure conditions with external electric energy, using water as a hydrogen source to provide proton hydrogen, the proton hydrogen reaches the cathode through a proton exchange membrane, and combines with electrons at the cathode to be reduced to adsorbed hydrogen, and selectively hydrogenates nitrogen heterocyclic organic matter at the cathode to directionally prepare aromatic compounds.

6. The method for selective electrochemical hydrogenation of nitrogen heterocyclic organic compounds according to claim 5, characterized in that: The external electric energy refers to the constant current mode, and the current density is 1-100 mA / cm 2 .

7. The method for selective electrochemical hydrogenation of nitrogen heterocyclic organic compounds according to claim 5, characterized in that: The proton exchange membrane is a perfluorosulfonic acid proton exchange membrane.

8. The method for selective electrochemical hydrogenation of nitrogen heterocyclic organic compounds according to claim 5, characterized in that: The anode is made of carbon paper as a substrate and carries a Pt / C catalyst layer, wherein the Pt loading is 0.5 to 4.5 mg / cm 2 .

9. The method for selective electrochemical hydrogenation of nitrogen heterocyclic organic compounds according to claim 5, characterized in that: The Ni metal single atom in the cathode serves as the active center site.

10. The method for selective electrochemical hydrogenation of nitrogen heterocyclic organic compounds according to claim 5, characterized in that: The nitrogen heterocyclic organic compound is one of quinoline, isoquinoline, quinoxaline, and indole, with a concentration of 0.01 to 0.5 mol / L. The solvent is acetonitrile. The electrolyte is one or both of dipotassium hydrogen phosphate and potassium dihydrogen phosphate. The cathode mixed solution flow rate is 20 to 50 mL / min.

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