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

Abstract

The application discloses a preparation method of a phenolic resin-based monatomic catalytic electrode plate material and a method for selective electrochemical hydrogenation of nitrogen heterocyclic organic compounds, which is based on the principle of in-situ derivation of monatomic catalysts from ZnNi bimetallic organic frameworks, and a phenolic resin-based composite precursor is prepared by grading and fine dispersing and directional construction of microstructure and functional components, so that a Ni monatomic catalytic electrode plate with integrated interlinked three-dimensional conductive network structure and stereoscopic stepped through-porous structure is prepared through a pyrolysis process. The application adopts a green chemical synthesis strategy to design a clean and efficient electrochemical directional conversion path, so that the degradation of nitrogen heterocyclic organic pollutants and the synthesis of high-value aromatic hydrocarbon compounds can be simultaneously realized. Through a novel coupled electrochemical conversion path with low energy consumption, zero emission and without any additives and byproducts, high-value fine chemicals can be produced, so that environmental pollution can be effectively solved, energy consumption can be reduced, and clean oil products with ultra-low nitrogen content and ultra-high aromatic hydrocarbon content can be produced.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical engineering technology, specifically relating to the preparation method of integrated phenolic resin-based single-atom catalytic electrode plate material and the method for selective electrochemical hydrogenation of nitrogen heterocyclic organic compounds. Background Technology

[0002] The depletion of natural resources, energy shortages, and environmental degradation are the three major challenges 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-containing compounds, especially nitrogen heterocyclic organic compounds, in crude oil has a significant negative impact on fuel storage and utilization, leading to the formation of NOx pollutants during combustion and catalyst poisoning during downstream reforming processes. Therefore, hydrorefining reactions play a decisive role in the production of clean fossil fuels.

[0003] However, traditional hydrorefining processes require harsh reaction conditions, including high temperature and pressure, and suffer from poor selectivity of hydrogenation products. They focus only on the removal of nitrogen-containing compounds, neglecting hydrogen consumption and the selectivity of other high-value products (such as aromatics). Effectively utilizing renewable resources and achieving efficient capture and conversion of green energy in chemical production will have a positive impact on the ecological environment; therefore, environmental pollution control and energy conservation are often mutually reinforcing. The synthetic strategy of converting nitrogen-containing heterocyclic organic compounds into high-value-added fine chemicals at ambient temperature and pressure using electrocatalysis technology not only effectively solves environmental problems as well as the challenges of high pressure, high energy consumption, and equipment complexity, but also enables the production of clean oil products with ultra-low nitrogen and ultra-high aromatic content, significantly improving economic efficiency. Summary of the Invention

[0004] Given the superior performance of single-atom catalysts in electrocatalysis, this invention develops a method for preparing an integrated phenolic resin-based single-atom catalytic electrode plate for the catalytic hydrogenation of nitrogen heterocyclic compounds, as well as a method for the selective electrochemical hydrogenation of nitrogen heterocyclic organic compounds. Employing a green chemical synthesis strategy, a clean and efficient electrochemical directional conversion pathway is designed, enabling the simultaneous degradation of nitrogen heterocyclic organic pollutants and the synthesis of high-value aromatic compounds. This novel coupled electrochemical conversion pathway, characterized by low energy consumption, zero emissions, and the absence of any additives or byproducts, produces high-value-added fine chemicals, effectively addressing environmental pollution, reducing energy consumption, and achieving the production of clean oil products with ultra-low nitrogen and ultra-high aromatic content. This truly realizes the transformation of waste into treasure, representing a green and sustainable synthetic route.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] The preparation method of the integrated phenolic resin-based single-atom catalytic electrode plate material utilizes the principle of in-situ derivatization of single-atom catalysts from a ZnNi bimetallic organic framework. It involves hierarchically and finely dispersing a phenolic resin-based composite precursor to construct microstructures and functional components, followed by a pyrolysis process to prepare an integrated Ni single-atom catalytic electrode plate with an interconnected three-dimensional ladder-like porous structure and a three-dimensional conductive network. Specific methods include:

[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℃ for 2-3 hours until completely dried.

[0008] 2) Preparation of phenolic resin-based composite precursor: The ZnNi bimetallic organic framework obtained in step 1) is ground and sieved. 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) are dispersed in phenolic resin. After pressing and solidification under 1-10 MPa pressure, the product is demolded and cured and crosslinked in air with gradient temperature increase: 160-180℃ for 2-3 h, 200-210℃ for 1-1.5 h, 240-260℃ for 4-5 h, and 365-375℃ for 2-2.5 h.

[0009] 3) Preparation of integrated phenolic resin-based Ni single-atom catalytic composite electrode plate: The phenolic resin-based composite precursor obtained in step 2) is pyrolyzed in a nitrogen atmosphere at 800-900℃ for 2-3h, with a heating rate of 1.5-3℃ / min.

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

[0011] The ZnNi bimetallic organic framework is mixed with phenolic resin at different particle sizes in the following mass ratios: 30 mesh ≤ particle size < 40 mesh, 3%–10%; 40 mesh ≤ particle size < 50 mesh, 3%–10%; 50 mesh ≤ particle size < 100 mesh, 3%–10%; 100 mesh ≤ particle size < 200 mesh, 10%–30%; and 200 mesh ≤ particle size ≤ 400 mesh, 10%–30%; with phenolic resin accounting for 10%–30%.

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

[0013] The method for selective electrochemical hydrogenation of nitrogen-containing heterocyclic organic compounds uses an electrode plate material prepared by the aforementioned integrated phenolic resin-based single-atom catalytic electrode plate material as the cathode. Specifically, it involves using a solid-state proton conductor electrochemical reactor, under ambient temperature and pressure with external electrical energy, using water as the hydrogen source to provide proton hydrogen. The proton hydrogen passes through a proton exchange membrane to reach the cathode, where it combines with electrons and is reduced to adsorbed hydrogen. Highly selective hydrogenation of nitrogen-containing heterocyclic organic compounds is then performed at the cathode, directionally preparing high-value aromatic compounds. This provides a novel coupled electrochemical synthesis strategy for the production of high-value-added fine chemicals.

[0014] The applied electrical energy refers to a constant current mode with a current density of 1–100 mA / cm². 2 .

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

[0016] The anode is a carbon paper substrate supporting a Pt / C catalyst layer, wherein the Pt loading is 0.5–4.5 mg / cm³. 2 .

[0017] The cathode contains Ni metal single atoms that serve as active center sites.

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

[0019] Compared with existing technologies, the beneficial effects of this invention are:

[0020] 1) Employing a green chemical synthesis strategy to co-convert waste into innovative products, using inexpensive phenolic resin as the catalytic matrix, and targeting the characteristics of nitrogen heterocyclic catalytic hydrogenation reactions, a clean and efficient electrochemical directional conversion pathway is designed to improve the energy conversion efficiency of the entire reaction system, maximize the return on energy investment and atom economy, and is a sustainable electrochemical synthesis route.

[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 sites, while nitrogen-doped carbon generated from the pyrolysis of organic ligands and phenolic resin acts as anchoring points for the Ni single atoms. By utilizing hierarchical fine-tuning techniques and the characteristic of Zn evaporating due to its low boiling point during pyrolysis, an interconnected, three-dimensional porous structure and a three-dimensional conductive network are formed within the composite electrode material. This prevents nanoparticle aggregation without affecting material transport and transfer, facilitates the formation of an internal electric field and the exposure of interfacial chemical active sites, thereby improving the overall performance of the composite electrode material.

[0022] 3) A novel green electrocatalytic selective hydrogenation method is developed using a renewable electricity synthesis strategy to replace traditional thermocatalysis. By selecting electrode materials and controlling reaction conditions in conjunction with the molecular structure characteristics of the cathode organic substrate, the hydrogenation routes of nitrogen heterocyclic rings and CN bond cleavage are determined, thus protecting the aromatic structure and retaining high-value-added components in crude oil. This method can fundamentally solve the problems of high consumption, chemical additives and by-product pollution caused by traditional multi-step reactions, and also demonstrates the potential value of liquid-phase compound electrocatalytic hydrogenation processes in advanced hydrogen storage applications.

[0023] 4) This invention provides a green, sustainable, and directed electrochemical conversion process for nitrogen heterocyclic organic compounds under ambient temperature and pressure conditions, which is characterized by low energy consumption, zero emissions, and no additives or byproducts. Attached Figure Description

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

[0025] Figure 2 This is a schematic diagram of the selective hydrogenation of nitrogen heterocyclic compounds by electrochemistry.

[0026] In the diagram: 1. Anode; 2. Cathode; 3. Proton exchange membrane. Detailed Implementation

[0027] The present invention is further illustrated below by way of embodiments, but these embodiments are not intended to limit the invention to the scope of the embodiments described. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0028] This invention provides an integrated phenolic resin-based Ni single-atom catalytic composite electrode plate material and a novel electrocatalytic selective hydrogenation coupling reaction system thereof. Specifically, it utilizes the principle of in-situ derivatization of single-atom catalysts from a ZnNi bimetallic organic framework. A phenolic resin-based composite precursor with microstructure and functional components is constructed through hierarchical fine dispersion. An integrated Ni single-atom catalytic electrode plate with an interconnected three-dimensional porous structure and a three-dimensional conductive network is prepared via pyrolysis. This electrode plate is then used as the cathode in a solid-state proton conductor electrochemical reactor to construct a novel electrocatalytic selective hydrogenation coupling reaction system. Under ambient temperature and pressure with external electrical energy, water is used as the hydrogen source to provide protonated hydrogen. The protonated hydrogen reaches the cathode through a proton exchange membrane and is reduced to adsorbed hydrogen by combining with electrons. High-selectivity hydrogenation of nitrogen-containing heterocyclic organic compounds is then performed at the cathode, directionally preparing high-value aromatic compounds. This provides 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 solution of zinc acetate and nickel nitrate mixed in methanol was gradually added dropwise to a 0.45 mol / L solution of 2-methylimidazolium in methanol, with a molar ratio of zinc acetate to nickel nitrate of 1:1. 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 dried, yielding a purple solid. This solid was then ground, sieved, and set aside. The resulting purple powders of different particle sizes were mixed with phenolic resin in the following proportions: 30 mesh ≤ particle size < 40 mesh 6%, 40 mesh ≤ particle size < 50 mesh 6%, and 50 mesh 6%. 6.5% of the material has a particle size of ≤100 mesh, 25% has a particle size of 100 mesh ≤200 mesh, and 26.5% has a particle size of 200 mesh ≤400 mesh. 30% of the material is phenolic resin. After pressing and solidifying under 8 MPa pressure, the material is demolded and then cured and crosslinked in air with a gradient temperature increase: 170℃ for 2 hours, 200℃ for 1 hour, 250℃ for 4 hours, and 375℃ for 2 hours. After cooling, the material is ready for use. The solid plate is then placed in a tubular furnace and pyrolyzed at 900℃ under a nitrogen atmosphere for 3 hours with a heating rate of 3℃ / min.

[0032] Selective electrochemical hydrogenation experiments on nitrogen heterocyclic organic compounds;

[0033] 1. The aforementioned integrated Ni / NC cathode 2 was used as the cathode, with carbon paper as the substrate and a loading of 4 mg / cm³. 2 Pt / C was used as the anode 1, and a Nafion 117 membrane was used as the proton exchange membrane 3. Anode 1 used water as the hydrogen source to provide protonated hydrogen. A 0.5 mol / L quinoline / acetonitrile solution was introduced into cathode 2, with potassium dihydrogen phosphate and potassium dihydrogen phosphate used as electrolytes. During the reaction, the outflowing solution was recirculated back into cathode 2 at a rate of 30 mL / min. When the electrochemical reactor operated at 30 mA / cm²... 2 After 1.5 hours of constant current operation, the products from cathode 2 were collected and analyzed. The hydrogenation conversion rate of quinoline at cathode was 91%, with a heterocyclic hydrogenation selectivity of 99%, including 1,4-tetrahydroquinoline, o-propylaniline, propylbenzene, etc., and almost no aromatic ring hydrogenation products were detected.

[0034] 2. The aforementioned integrated Ni / NC cathode 2 was used as the cathode, with carbon paper as the substrate and a loading of 4.5 mg / cm³. 2 Pt / C was used as anode 1, and a Nafion 117 membrane was used as proton exchange membrane 3. Anode 1 used water as the hydrogen source to provide protonated hydrogen. A 0.3 mol / L quinoxaline / acetonitrile solution was introduced into cathode 2, with potassium dihydrogen phosphate and potassium dihydrogen phosphate used as electrolytes. During the reaction, the outflowing solution was recirculated back into cathode 2 at a circulation rate of 50 mL / min. When the electrochemical reactor operated at 50 mA / cm²...2 After 2 hours of constant current operation, the cathode product 2 was collected and analyzed. The hydrogenation conversion rate of quinoxaline at the cathode was 89%, with a heterocyclic hydrogenation selectivity of 99%, including dihydroquinoxaline, 1,2,3,4-tetrahydroquinoxaline, etc., and almost no aromatic ring hydrogenation products were detected.

[0035] 3. The aforementioned integrated Ni / NC cathode 2 was used as the cathode, with carbon paper as the substrate and a loading of 3.5 mg / cm³. 2 Pt / C was used as anode 1, and a Nafion 117 membrane was used as proton exchange membrane 3. Anode 1 used water as the hydrogen source to provide protonated hydrogen, and cathode 2 was fed with a 0.15 mol / L indole / acetonitrile solution. During the reaction, the outflowing solution was recirculated back into the cathode at a circulation rate of 20 mL / min. When the electrochemical reactor operated at 100 mA / cm²... 2 After 2.5 hours of constant current operation, the cathode 2 product was collected and analyzed. The hydrogenation conversion rate of indole at the cathode was 60%, with a heterocyclic hydrogenation selectivity of 99%, including 1,2-dihydroindole, o-ethylaniline, ethylbenzene, etc., and almost no aromatic ring hydrogenation products were detected.

[0036] Comparative example: conventional thermocatalytic hydrogenation;

[0037] The reaction was carried out in a high-temperature and high-pressure reactor. The reactants were a 0.05 mol / L quinoline / acetonitrile solution, and the catalyst was Ni / NC-Al₂O₃. Hydrogen gas was introduced to replace the air in the reactor, and the pressure reducing valve was adjusted to achieve an initial pressure of 4 MPa. The liquid hourly space velocity was 10 h⁻¹. -1 The reaction temperature was 320℃, the reaction time was 4 hours, the reaction vessel was allowed to cool statically, the exhaust gas was released, and the product was taken out for gas chromatography analysis. The hydrogenation conversion rate of quinoline was 76.9%, of which aromatic ring hydrogenation products accounted for 54%, including 5,8-tetrahydroquinoline, decahydroquinoline, etc.; the heterocyclic hydrogenation selectivity was 46%, including 1,4-tetrahydroquinoline, o-propylaniline, propylbenzene, etc.

[0038] In summary, traditional thermocatalytic hydrogenation exhibits poor selectivity, with heterocyclic hydrogenation selectivity below 50%. In contrast, the integrated Ni / NC catalytic composite electrode plate coupled with a solid-state proton conductor electrochemical reactor demonstrates superior selectivity for hydrogenation of nitrogen-containing heterocyclic organic compounds such as quinoline, quinoxaline, and indole, with heterocyclic hydrogenation selectivity generally exceeding 99%, and virtually no detectable aromatic ring hydrogenation products. Therefore, the integrated phenolic resin-based single-atom catalytic electrode plate material designed in this invention, along with its novel electrocatalytic selective hydrogenation coupling reaction system, enables a directional conversion pathway for the degradation of nitrogen-containing heterocyclic organic pollutants while simultaneously synthesizing high-value aromatic compounds.

[0039] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within 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, and the mixture was stirred at room temperature and reacted at 170-190℃ for 2-3 hours. 2) Preparation of phenolic resin-based composite precursor: The ZnNi bimetallic organic framework obtained in step 1) is ground and sieved. 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 are dispersed in phenolic resin. After pressing and solidification under a pressure of 1-10 MPa, the resin is demolded and cured and crosslinked in an air atmosphere with gradient temperature increase: 160-180℃ for 2-3 h, 200-210℃ for 1-1.5 h, 240-260℃ for 4-5 h, and 365-375℃ for 2-2.5 h. 3) Preparation of integrated phenolic resin-based Ni single-atom catalytic composite electrode plate: The phenolic resin-based composite precursor obtained in step 2) is pyrolyzed in a nitrogen atmosphere at 800-900℃ for 2-3h, with a heating rate of 1.5-3℃ / min.

2. The preparation method of the integrated phenolic resin-based single-atom catalytic electrode plate material according to claim 1, characterized in that, The molar ratio of nickel nitrate to 2-methylimidazole is 1:(2-5), and the molar ratio of zinc acetate to 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 ZnNi bimetallic organic framework is mixed with phenolic resin at different particle sizes in the following mass ratios: 30 mesh ≤ particle size < 40 mesh 3%–10%, 40 mesh ≤ particle size < 50 mesh 3%–10%, 50 mesh ≤ particle size < 100 mesh 3%–10%, 100 mesh ≤ particle size < 200 mesh 10%–30%, and 200 mesh ≤ particle size ≤ 400 mesh 10%–30%, with phenolic resin accounting for 10%–30%.

4. The preparation method of 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 internal three-dimensional ladder-like interconnected porous structure and a three-dimensional conductive network structure.

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

6. The method for selective electrochemical hydrogenation of nitrogen-containing heterocyclic organic compounds according to claim 5, characterized in that, The applied electrical energy refers to a constant current mode with a current density of 1–100 mA / cm². 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 a Pt / C catalyst layer supported on a carbon paper substrate, wherein the Pt loading is 0.5–4.5 mg / cm³. 2 .

9. The method for selective electrochemical hydrogenation of nitrogen heterocyclic organic compounds according to claim 5, characterized in that, The cathode contains Ni metal single atoms that serve as active center sites.

10. The method for selective electrochemical hydrogenation of nitrogen-containing 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 0.01–0.5 mol / L. The solvent is acetonitrile, and the electrolyte is one or both of dipotassium hydrogen phosphate and potassium dihydrogen phosphate. The flow rate of the cathode mixture is 20–50 mL / min.

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