Ag molecular catalyst and preparation method thereof, and gaseous olefin electrocatalytic oxidation method

Abstract

The invention relates to an Ag molecular catalyst, a preparation method thereof and a gaseous olefin electrocatalytic oxidation method. The Ag molecular catalyst comprises an Ag-phenanthroline complex and a carbon carrier, and the complex is loaded on the carbon carrier. The catalyst disclosed by the invention is relatively high in catalytic performance, relatively high olefin oxidation production rate and Faraday efficiency are realized, and meanwhile, the consumption of Ag is relatively low, so that the cost is remarkably reduced. The preparation method disclosed by the invention is simple and low in process cost, and the catalyst disclosed by the invention can realize large-scale synthesis.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemical catalysts, and particularly relates to an Ag molecular catalyst and a preparation method thereof, and a method for electrocatalytic oxidation of gaseous olefins by using the catalyst. BACKGROUND

[0002] The catalytic oxidation reaction of olefins is a very important industrial reaction. For example, 1,2-propanediol produced by oxidation of propylene is widely used in the pharmaceutical, cosmetic, food manufacturing and other industries. According to relevant data statistics, in 2023, the world annual output of 1,2-propanediol reached 2.7 million tons, and kept a rising trend year by year, with a global market value of more than 4 billion US dollars.

[0003] In the olefin oxidation process, the mainstream process is Cl2 oxidation at high temperature or oxidation mediated by H2O2. The chlorohydrination process of Cl2 oxidation of olefins uses strong corrosive and toxic chlorine gas and produces a large amount of wastewater and slag; the co-oxidation method mediated by H2O2 needs to use expensive oxidants. According to statistics, in the industrial production process, 4.7 tons of CO2 are discharged for every ton of 1,2-propanediol produced, so it is necessary to develop a mild and sustainable olefin oxidation process.

[0004] Electrocatalysis provides a promising alternative method, and the current strategies include direct electro-oxidation and indirect electro-oxidation. The indirect gaseous olefin oxidation has been developed to produce Cl2 and generate chlorine-containing wastewater, therefore, direct electro-oxidation has attracted widespread attention. At present, the catalysts for direct electro-oxidation are mainly platinum, palladium and silver-based catalysts, among which silver-based catalysts are more economical and have more abundant reserves, and can selectively produce propylene glycol products, but the reported Ag-based catalysts still have a lot of room for improvement in terms of production rate, cost control and the like.

[0005] CN116356360A discloses a supported silver-based catalyst and its application in the preparation of 1,2-propanediol. The catalyst is formed by a complex of silver salt and pyrazole compound, and then the complex is loaded on a carrier to obtain the catalyst, which is used for catalyzing direct oxidation of propylene to prepare 1,2-propanediol, and has high selectivity and good stability. However, the Faraday efficiency of the electrocatalytic reaction is still not high, and the highest Faraday efficiency does not reach 20%, and the amount of silver salt is high, the ratio of the amount of carrier to silver nitrate is 160mg:68mg, and the cost is high.

[0006] CN116254565A discloses a silver single-atom catalyst and its use in the preparation of 1,2-propylene glycol. Although this catalyst exhibits a high Faradaic efficiency for the electrocatalytic oxidation of propylene to produce 1,2-propylene glycol, the catalyst preparation process is complex, requiring the use of special reagents (such as zirconium chloride and 2,2'-bipyridine-5,5'-dicarboxylic acid) to prepare a metal-organic framework (MOF), which is then mixed with a dispersant (such as an organic solvent such as tetrahydrofuran) and then with a silver salt solution. This process not only increases process costs but is also environmentally unfriendly and unsuitable for industrial production. Summary of the Invention

[0007] Problems to be solved by the invention

[0008] In order to overcome the technical problems existing in the prior art, the present invention provides an Ag molecular catalyst and a preparation method thereof, as well as a method for electrocatalytic oxidation of gaseous olefins using the catalyst. The catalyst is used for the electrocatalytic oxidation of gaseous olefins, has a high production rate and Faraday efficiency, can achieve good catalytic performance, and at the same time, uses less Ag, which can reduce costs.

[0009] Solutions for solving problems

[0010] In order to solve the above problems, the present invention provides the following technical solutions:

[0011] [1]. An Ag molecular catalyst for the electrocatalytic oxidation of gaseous olefins, wherein the Ag molecular catalyst comprises an Ag-phenanthroline complex and a carbon support, and the complex is supported on the carbon support.

[0012] [2] The Ag molecular catalyst according to [1], wherein the Ag loading in the Ag molecular catalyst is 0.05% by mass to 10% by mass, preferably 0.1% by mass to 8% by mass, based on the mass of the carbon support.

[0013] [3] The Ag molecular catalyst according to [1] or [2], wherein the carbon support comprises any one or more of XC-72R, Ketjen black, acetylene black, graphene and carbon nanotubes.

[0014] [4] A method for preparing an Ag molecular catalyst according to any one of [1] to [3], wherein the method comprises the following steps: (1) preparing a carbon carrier dispersion; (2) preparing a mixture of a silver salt and o-phenanthroline; (3) mixing the carbon carrier dispersion and the mixture of the silver salt and o-phenanthroline, stirring and drying to obtain the Ag molecular catalyst.

[0015] [5] The preparation method according to [4], wherein the silver salt comprises any one or more of silver nitrate, silver sulfate, silver acetate, silver acetylacetonate and silver trifluoroacetate.

[0016] [6] The preparation method according to [4] or [5], wherein the molar ratio of the o-phenanthroline to the silver salt is (1-10):1, preferably (3-5):1.

[0017] [7]. The preparation method according to any one of [4] to [6], wherein the concentration of the silver salt in the mixed solution of the silver salt and o-phenanthroline is 0.1 mM to 10 M.

[0018] [8]. A method for electrocatalytic oxidation of gaseous olefins, wherein the method comprises the following steps: (1) using carbon paper as an anode catalyst collector, coating the collector with a dispersion containing the Ag molecular catalyst described in any one of [1] to [3]; (2) adding electrolyte to both the anode electrolytic cell and the cathode electrolytic cell, and passing gaseous olefins into the anode electrolytic cell; and (3) applying voltage.

[0019] [9] The method according to [8], wherein the gaseous olefin comprises any one or more of ethylene, propylene, butene and butadiene.

[0020]

[10] The method according to [8] or [9], wherein the cathode comprises any one or more of a graphite rod, a platinum sheet, nickel foam, carbon paper and carbon felt; and the voltage is 0V to 10V vs Ag / AgCl, preferably 1V to 5V vs Ag / AgCl.

[0021] Effects of the Invention

[0022] The present invention provides an Ag molecular catalyst with o-phenanthroline as a ligand. Compared with reported Ag-based catalysts or catalysts with other nitrogen-containing heteroaromatic compounds as ligands, the catalyst of the present invention achieves a higher production rate and Faradaic efficiency for olefin oxidation.

[0023] In the Ag molecular catalyst of the present invention, the amount of Ag used is relatively small, thereby significantly reducing the cost.

[0024] Compared with traditional palladium-based and platinum-based catalysts, Ag is cheaper, and the o-phenanthroline ligand can be purchased commercially at a low price.

[0025] The preparation method of the Ag molecular catalyst of the present invention is simple, does not require the use of special reagents and special methods, has low process cost, and the catalyst can be synthesized in large quantities. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1This is a spherical aberration corrected high-angle annular dark field-scanning transmission image of the catalyst prepared in Example 1 of the present invention;

[0027] Figure 2 1 is a scanning transmission electron microscope image of the catalyst prepared in Example 1 of the present invention and the corresponding elemental analysis spectrum;

[0028] Figure 3 The electrocatalytic performance results of the catalyst prepared in Example 1 of the present invention are shown; wherein the value represented by the bar graph is the production rate of 1,2-propylene glycol, and the value represented by the dot graph is the Faraday efficiency;

[0029] Figure 4 The electrocatalytic performance results of the catalyst prepared in Example 2 of the present invention are shown; wherein the value represented by the bar graph is the production rate of 1,2-propylene glycol, and the value represented by the dot graph is the Faraday efficiency;

[0030] Figure 5 : The electrocatalytic performance results of the catalyst prepared in Example 3 of the present invention; wherein the value represented by the bar graph is the production rate of 1,2-propylene glycol, and the value represented by the dot graph is the Faraday efficiency;

[0031] Figure 6 The electrocatalytic performance results of the catalyst prepared in Comparative Example 1 of the present invention are shown; wherein the value represented by the bar graph is the production rate of 1,2-propylene glycol, and the value represented by the dot graph is the Faraday efficiency;

[0032] Figure 7 The electrocatalytic performance results of the catalyst prepared in Comparative Example 2 of the present invention are shown; wherein the value represented by the bar graph is the generation rate of 1,2-propylene glycol, and the value represented by the dot graph is the Faraday efficiency;

[0033] Figure 8 The electrocatalytic performance results of the catalyst prepared in Comparative Example 3 of the present invention are shown; wherein the value represented by the bar graph is the production rate of 1,2-propylene glycol, and the value represented by the dot graph is the Faraday efficiency;

[0034] Figure 9 These are the electrocatalytic performance results of the catalyst prepared in Comparative Example 4 of the present invention; wherein, the value represented by the bar graph is the generation rate of 1,2-propylene glycol, and the value represented by the dot graph is the Faraday efficiency. DETAILED DESCRIPTION

[0035] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior or preferred over other embodiments.

[0036] In addition, numerous specific details are provided in the following detailed description to better illustrate the present invention. Those skilled in the art will appreciate that the present invention can be practiced without certain specific details. In other instances, methods, means, equipment, and steps well known to those skilled in the art are not described in detail in order to highlight the main points of the present invention.

[0037] Unless otherwise stated, the units used in this specification are international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0038] In this specification, the use of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0039] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "embodiments," etc., mean that the specific elements (e.g., features, structures, properties, and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0040] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0041] In this specification, the numerical range expressed using "a numerical value A or more" means a range including the endpoint numerical value A.

[0042] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15 to 30°C, further 15 to 25°C, for example, 20°C.

[0043] In this specification, the structures of o-phenanthroline, bipyridine, and phthalocyanine are as follows:

[0044]

[0045] After intensive research, the inventors unexpectedly discovered a catalyst composed of a complex of silver and o-phenanthroline supported on a carbon support. This catalyst exhibits excellent catalytic performance and can be used for the electrocatalytic oxidation of gaseous olefins (for example, the electrocatalytic oxidation of propylene to 1,2-propylene glycol). Compared to catalysts prepared with other nitrogen-containing ligands (such as pyrazole, pyridine, bipyridine, and phthalocyanine), this catalyst exhibits higher production rates and higher Faradaic efficiencies. Furthermore, compared to existing silver-based catalysts, this catalyst requires significantly less silver, significantly reducing costs.

[0046] Ag Molecular Catalysts for Electrocatalytic Oxidation of Gaseous Olefins

[0047] Specifically, the present invention provides an Ag molecular catalyst for electrocatalytic oxidation of gaseous olefins, which comprises an Ag-phenanthroline complex and a carbon support, wherein the complex is supported on the carbon support.

[0048] In some embodiments, in the Ag molecular catalyst, the Ag loading is 0.05 mass% to 10 mass%, based on the mass of the carbon support, for example, 0.08 mass%, 0.1 mass%, 0.3 mass%, 0.5 mass%, 1 mass%, 2 mass%, 3 mass%, 4 mass%, 5 mass%, 6 mass%, 7 mass%, 8 mass%, 9 mass%, etc., preferably 0.1 mass% to 8 mass%.

[0049] In some embodiments, in the Ag molecular catalyst, the loading of the Ag-phenanthroline complex is 0.1 mass% to 50 mass%, based on the mass of the carbon support, for example, 0.5 mass%, 0.8 mass%, 1 mass%, 1.5 mass%, 2 mass%, 3 mass%, 10 mass%, 20 mass%, 30 mass%, 40 mass%, etc., preferably 1 mass% to 40 mass%.

[0050] In some embodiments, the carbon support comprises any one or more of XC-72R, Ketjen black, acetylene black, graphene, and carbon nanotubes. In some embodiments, the carbon support is carbon nanotubes.

[0051] In some embodiments, the complex is a complex obtained by coordination of +1-valent silver ions and o-phenanthroline.

[0052] Preparation method of Ag molecular catalyst

[0053] The present invention also provides a preparation method of the Ag molecular catalyst, which comprises the following steps: (1) preparing a carbon carrier dispersion; (2) preparing a mixed solution of a silver salt and o-phenanthroline; and (3) mixing the carbon carrier dispersion and the mixed solution of the silver salt and o-phenanthroline, stirring and drying to obtain the Ag molecular catalyst.

[0054] In some embodiments, the particle size (or diameter) of the carbon support is 5 to 200 nm, for example, 10 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, etc.

[0055] In some embodiments, the solvent in the carbon support dispersion includes any one or more of water, ethanol, methanol, acetonitrile, diethyl ether, ethyl acetate, and N,N-dimethylformamide. In some preferred embodiments, the solvent is acetonitrile.

[0056] In some embodiments, in step (1), in the carbon carrier dispersion, the ratio of the carbon carrier to the solvent is 1 mg: (10-100) mL, for example, 1 mg: 20 mL, 1 mg: 30 mL, 1 mg: 40 mL, 1 mg: 60 mL, etc.

[0057] In some embodiments, the carbon carrier dispersion is prepared by dispersing the carbon carrier in a solvent to obtain the carbon carrier dispersion.

[0058] In some specific embodiments, the carbon carrier dispersion is prepared by ultrasonically dispersing the carbon carrier in a solvent to obtain the carbon carrier dispersion.

[0059] In some embodiments, the silver salt comprises any one or more of silver nitrate, silver sulfate, silver acetate, silver acetylacetonate and silver trifluoroacetate. In some preferred embodiments, the silver salt is silver nitrate.

[0060] In some embodiments, the mass of the silver salt is 0.05% to 10% based on the mass of the carbon support, for example, 0.08%, 0.1%, 0.3%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, etc., preferably 0.1% to 8%.

[0061] In some embodiments, the molar ratio of the o-phenanthroline to the silver salt is (1-10):1, for example, 2:1, 3:1, 4:1, 5:1, 7:1, 9:1, etc., preferably (3-5):1.

[0062] In some embodiments, the concentration of the silver salt in the mixture of silver salt and 1,1-phenanthroline is 0.1 mM to 10 M, for example, 0.5 mM, 0.8 mM, 1 mM, 1.2 mM, 1.5 mM, 2 mM, 5 mM, 8 mM, 50 mM, 100 mM, 500 mM, 1 M, 5 M, etc.

[0063] In some embodiments, the mixture of silver salt and o-phenanthroline is in a solution state.

[0064] In some embodiments, the mixture of silver salt and o-phenanthroline is in a suspension state.

[0065] In some embodiments, the preparation method of the mixed solution of silver salt and o-phenanthroline is: mixing the silver salt and a solvent, adding the o-phenanthroline, and obtaining the mixed solution of silver salt and o-phenanthroline.

[0066] In some embodiments, the solvent in the mixture of silver salt and o-phenanthroline includes any one or more of water, ethanol, methanol, acetonitrile, ether, ethyl acetate and N,N-dimethylformamide. In some preferred embodiments, the solvent is acetonitrile.

[0067] In some embodiments, the volume ratio of the mixed solution of silver salt and o-phenanthroline to the carbon support dispersion is (0.001-10):1, for example, 0.005:1, 0.01:1, 0.02:1, 0.04:1, 0.1:1, 0.2:1, 0.4:1, 0.6:1, 1:1, 5:1, etc.

[0068] In some embodiments, in step (3), the mixture of the silver salt and o-phenanthroline is added to the carbon support dispersion.

[0069] In some embodiments, in step (3), the stirring time is 1 to 108 h, for example, 10 h, 20 h, 24 h, 30 h, 48 h, 72 h, etc.

[0070] In some embodiments, in step (3), after stirring, centrifugation is performed and the precipitate is dried to obtain the Ag molecular catalyst.

[0071] In some embodiments, the drying time is 8 to 30 hours, for example, 10 hours, 12 hours, 15 hours, 20 hours, etc.

[0072] In some embodiments, the drying temperature is room temperature, such as 10°C, 15°C, 20°C, 25°C, 30°C, 40°C, etc.

[0073] Method for electrocatalytic oxidation of gaseous olefins

[0074] The present invention also provides the use of the aforementioned Ag molecular catalyst in the electrocatalytic oxidation of gaseous olefins. Specifically, the present invention provides a method for the electrocatalytic oxidation of gaseous olefins, comprising the following steps: (1) using carbon paper as an anode catalyst current collector, and coating the current collector with a dispersion containing the aforementioned Ag molecular catalyst; (2) adding an electrolyte to both an anode electrolytic cell and a cathode electrolytic cell, and passing gaseous olefin into the anode electrolytic cell; and (3) applying a voltage.

[0075] In some embodiments, the gaseous olefins include any one or more of ethylene, propylene, butene, and butadiene.

[0076] In some specific embodiments, the gaseous olefin is ethylene and the product is ethylene glycol.

[0077] In some specific embodiments, the gaseous olefin is propylene, and the product is 1,2-propylene glycol.

[0078] In some specific embodiments, the gaseous olefin is butene, and the product is 1,2-butanediol.

[0079] In some specific embodiments, the gaseous olefin is butadiene, and the product is one or both of butanetetraol and butenediol.

[0080] In some embodiments, the flow rate of the gaseous olefin is from 1 s.ccm to 100 s.ccm, for example, 10 s.ccm, 20 s.ccm, 30 s.ccm, 40 s.ccm, 60 s.ccm, 80 s.ccm, etc.

[0081] In some embodiments, the cathode comprises any one or more of a graphite rod, a platinum sheet, nickel foam, carbon paper, and carbon felt. In some specific embodiments, the cathode is a millstone rod.

[0082] In some embodiments, the voltage is 0V to 10V vs Ag / AgCl, for example, 0.5V vs Ag / AgCl, 1V vs Ag / AgCl, 1.2V vs Ag / AgCl, 1.5V vs Ag / AgCl, 1.7V vs Ag / AgCl, 2V vs Ag / AgCl, 2.4V vs Ag / AgCl, 2.6V vs Ag / AgCl, 3V vs Ag / AgCl, 5V vs Ag / AgCl, 7V vs Ag / AgCl, 9V vs Ag / AgCl, etc., preferably 1V to 5V vs Ag / AgCl.

[0083] In some embodiments, the electrolytic cell is an H-type electrolytic cell.

[0084] In some embodiments, the dispersion containing the Ag molecular catalyst further contains methanol and Nafion 117 solution.

[0085] In some embodiments, the electrolyte comprises any one or more of sodium sulfate, potassium sulfate, sodium perchlorate, potassium perchlorate, sodium nitrate, potassium nitrate, calcium nitrate, sulfuric acid, nitric acid, and perchloric acid. In some specific embodiments, the electrolyte is sodium perchlorate.

[0086] In some embodiments, the concentration of the electrolyte is 10 mM to 5 M, such as 50 mM, 80 mM, 100 mM, 120 mM, 150 mM, 300 mM, 500 mM, 1 M, 2 M, 4 M, etc.

[0087] In some embodiments, the coating method is spraying.

[0088] In some specific embodiments, the product generation rate is 10 μmol / cm 2 / h or more, for example 13 μmol / cm 2 / h, 15μmol / cm 2 / h, 20μmol / cm 2 / h, 30μmol / cm 2 / h, 40μmol / cm 2 / h, 50μmol / cm 2 / h、100μmol / cm 2 / h, 120μmol / cm 2 / h, 150μmol / cm 2 / h, 170μmol / cm 2 / h, 180μmol / cm 2 / h, 200 μmol / cm 2 / h、300μmol / cm 2 / h, etc.

[0089] In some specific embodiments, the Faradaic efficiency of the product is greater than 10%, for example, 13%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, etc.

[0090] Example

[0091] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be obtained commercially.

[0092] The particle size of the carbon nanotubes used in the examples and comparative examples was 10 nm.

[0093] Example 1

[0094] 30 mg of carbon nanotubes were ultrasonically dispersed in 30 mL of acetonitrile to obtain a carbon nanotube dispersion. 0.116 mg of silver nitrate was dissolved in 0.7 mL of acetonitrile, and 0.49 mg of o-phenanthroline was added to obtain a silver-ligand solution. The silver-ligand solution was added to the carbon nanotube dispersion, stirred for 24 hours, centrifuged, and dried at room temperature for 12 hours to obtain the Ag molecular catalyst.

[0095] 8 mg of the molecular catalyst was dispersed in 2 mL of methanol, 50 μL of a 5% Nafion 117 solution was added, and ultrasonication was performed for 30 minutes to obtain a dispersion. The dispersion was evenly sprayed onto a 2×2 cm² carbon paper. This was used as the working electrode, and a graphite rod was used as the counter electrode to construct an H-type electrolytic cell. 0.1 M sodium perchlorate solution was used as the electrolyte. Propylene was introduced into the electrolytic cell at a rate of 30 s.ccm, and electrocatalytic oxidation was carried out at 1.6 V vs. Ag / AgCl.

[0096] The Ag molecular catalyst was characterized, and the results are shown in Figure 1 and Figure 2 . Figure 1 This is a spherical aberration corrected high-angle annular dark field-scanning transmission image of the catalyst prepared in Example 1 of the present invention. Figure 1 It can be seen that the Ag-o-phenanthroline complex is dispersed in the carbon nanotubes in the form of single molecules, among which the bright spots are Ag in the form of single atoms. Figure 2 The following is a scanning transmission electron microscope image of the catalyst prepared in Example 1 and the corresponding elemental analysis spectrum. Figure 2 It can be seen that Ag, C, and N are evenly distributed. The results of the electrocatalytic oxidation reaction can be found in Figure 3 The production rate of 1,2-propylene glycol was 13.8 μmol / cm 2 / h, and the Faradaic efficiency is 13.5%.

[0097] Example 2

[0098] 30 mg of carbon nanotubes were ultrasonically dispersed in 30 mL of acetonitrile to obtain a carbon nanotube dispersion. 2 mg of silver nitrate was dissolved in 12 mL of acetonitrile, and 8.5 mg of o-phenanthroline was added to obtain a silver-ligand solution. The silver-ligand solution was added to the carbon nanotube dispersion, stirred for 24 hours, centrifuged, and dried at room temperature for 12 hours to obtain the Ag molecular catalyst.

[0099] 8 mg of the molecular catalyst was dispersed in 2 mL of methanol, 50 μL of a 5% Nafion 117 solution was added, and ultrasonication was performed for 30 minutes to obtain a dispersion. The dispersion was evenly sprayed onto a 2×2 cm² carbon paper. This was used as the working electrode, and a graphite rod was used as the counter electrode to construct an H-type electrolytic cell. 0.1 M sodium perchlorate solution was used as the electrolyte. Propylene was introduced into the electrolytic cell at a rate of 30 s.ccm, and electrocatalytic oxidation was carried out at 1.6 V vs. Ag / AgCl.

[0100] The results of electrocatalytic oxidation reaction can be found in Figure 4 The production rate of 1,2-propylene glycol was 33.1 μmol / cm 2 / h, and the Faraday efficiency is 42.1%.

[0101] Example 3

[0102] 30 mg of carbon nanotubes were ultrasonically dispersed in 30 mL of acetonitrile to obtain a carbon nanotube dispersion. 2 mg of silver nitrate was dissolved in 12 mL of acetonitrile, and 8.5 mg of o-phenanthroline was added to obtain a silver-ligand solution. The silver-ligand solution was added to the carbon nanotube dispersion, stirred for 24 hours, centrifuged, and dried at room temperature for 12 hours to obtain the Ag molecular catalyst.

[0103] 8 mg of the molecular catalyst was dispersed in 2 mL of methanol, 50 μL of a 5% Nafion 117 solution was added, and ultrasonication was performed for 30 minutes to obtain a dispersion. The dispersion was evenly sprayed onto a 2×2 cm² carbon paper. This was used as the working electrode, and a graphite rod was used as the counter electrode to construct an H-type electrolytic cell. 0.1 M sodium perchlorate solution was used as the electrolyte. Propylene was introduced into the electrolytic cell at a rate of 30 s.ccm, and electrocatalytic oxidation was carried out at 2.2 V vs. Ag / AgCl.

[0104] The results of electrocatalytic oxidation reaction can be found in Figure 5 The production rate of 1,2-propylene glycol was 179 μmol / cm 2 / h, and the Faradaic efficiency is 29.8%.

[0105] Comparative Example 1

[0106] 30 mg of carbon nanotubes were ultrasonically dispersed in 30 mL of acetonitrile to obtain a carbon nanotube dispersion. 0.12 mg of silver nitrate was dissolved in 0.7 mL of acetonitrile, and 0.19 mg of pyrazole was added to obtain a silver-ligand solution. The silver-ligand solution was added to the carbon nanotube dispersion, stirred for 24 hours, centrifuged, and dried at room temperature for 12 hours to obtain the Ag molecular catalyst.

[0107] 8 mg of the molecular catalyst was dispersed in 2 mL of methanol, 50 μL of a 5% Nafion 117 solution was added, and ultrasonication was performed for 30 minutes to obtain a dispersion. The dispersion was evenly sprayed onto a 2×2 cm² carbon paper. This was used as the working electrode, and a graphite rod was used as the counter electrode to construct an H-type electrolytic cell. 0.1 M sodium perchlorate solution was used as the electrolyte. Propylene was introduced into the electrolytic cell at a rate of 30 s.ccm, and electrocatalytic oxidation was carried out at 1.6 V vs. Ag / AgCl.

[0108] The results of electrocatalytic oxidation reaction can be found in Figure 6 The production rate of 1,2-propylene glycol was 2.3 μmol / cm 2 / h, and the Faraday efficiency is 2.4%.

[0109] Comparative Example 2

[0110] 30 mg of carbon nanotubes were ultrasonically dispersed in 30 mL of acetonitrile to obtain a carbon nanotube dispersion. 0.12 mg of silver nitrate was dissolved in 0.7 mL of acetonitrile, and 0.22 mg of pyridine was added to obtain a silver-ligand solution. The silver-ligand solution was added to the carbon nanotube dispersion, stirred for 24 hours, centrifuged, and dried at room temperature for 12 hours to obtain the Ag molecular catalyst.

[0111] 8 mg of the molecular catalyst was dispersed in 2 mL of methanol, 50 μL of a 5% Nafion 117 solution was added, and ultrasonication was performed for 30 minutes to obtain a dispersion. The dispersion was evenly sprayed onto a 2×2 cm² carbon paper. This was used as the working electrode, and a graphite rod was used as the counter electrode to construct an H-type electrolytic cell. 0.1 M sodium perchlorate solution was used as the electrolyte. Propylene was introduced into the electrolytic cell at a rate of 30 s.ccm, and electrocatalytic oxidation was carried out at 1.6 V vs. Ag / AgCl.

[0112] The results of electrocatalytic oxidation reaction can be found in Figure 7 The production rate of 1,2-propylene glycol is 2.0 μmol / cm 2 / h, and the Faradaic efficiency is 2.2%.

[0113] Comparative Example 3

[0114] 30 mg of carbon nanotubes were ultrasonically dispersed in 30 mL of acetonitrile to obtain a carbon nanotube dispersion. 0.12 mg of silver nitrate was dissolved in 0.7 mL of acetonitrile, and 0.44 mg of bipyridine was added to obtain a silver-ligand solution. The silver-ligand solution was added to the carbon nanotube dispersion, stirred for 24 hours, centrifuged, and dried at room temperature for 12 hours to obtain the Ag molecular catalyst.

[0115] 8 mg of the molecular catalyst was dispersed in 2 mL of methanol, 50 μL of a 5% Nafion 117 solution was added, and ultrasonication was performed for 30 minutes to obtain a dispersion. The dispersion was evenly sprayed onto a 2×2 cm² carbon paper. This was used as the working electrode, and a graphite rod was used as the counter electrode to construct an H-type electrolytic cell. 0.1 M sodium perchlorate solution was used as the electrolyte. Propylene was introduced into the electrolytic cell at a rate of 30 s.ccm, and electrocatalytic oxidation was carried out at 1.6 V vs. Ag / AgCl.

[0116] The results of electrocatalytic oxidation reaction can be found in Figure 8 The production rate of 1,2-propylene glycol was 4.2 μmol / cm 2 / h, and the Faraday efficiency is 3.8%.

[0117] Comparative Example 4

[0118] 30 mg of carbon nanotubes were ultrasonically dispersed in 30 mL of acetonitrile to obtain a carbon nanotube dispersion. 0.12 mg of silver nitrate was dissolved in 0.7 mL of acetonitrile, and 1.5 mg of phthalocyanine was added to obtain a silver-ligand solution. The silver-ligand solution was added to the carbon nanotube dispersion, stirred for 24 hours, centrifuged, and dried at room temperature for 12 hours to obtain the Ag molecular catalyst.

[0119] 8 mg of the molecular catalyst was dispersed in 2 mL of methanol, 50 μL of a 5% Nafion 117 solution was added, and ultrasonication was performed for 30 minutes to obtain a dispersion. The dispersion was evenly sprayed onto a 2×2 cm² carbon paper. This was used as the working electrode, and a graphite rod was used as the counter electrode to construct an H-type electrolytic cell. 0.1 M sodium perchlorate solution was used as the electrolyte. Propylene was introduced into the electrolytic cell at a rate of 30 s.ccm, and electrocatalytic oxidation was carried out at 1.6 V vs. Ag / AgCl.

[0120] The results of electrocatalytic oxidation reaction can be found in Figure 9 The production rate of 1,2-propylene glycol was 1.7 μmol / cm 2 / h, and the Faradaic efficiency is 1.8%.

[0121] It should be noted that, although the technical solutions of the present invention are described with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto.

[0122] While various embodiments of the present invention have been described above, the above descriptions are intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. An Ag molecular catalyst for electrocatalytic oxidation of gaseous olefins, characterized in that: The Ag molecular catalyst comprises an Ag-o-phenanthroline complex and a carbon support, wherein the complex is supported on the carbon support.

2. The Ag molecular catalyst according to claim 1, characterized in that In the Ag molecular catalyst, the loading amount of Ag is 0.05 mass % to 10 mass %, preferably 0.1 mass % to 8 mass %, based on the mass of the carbon support.

3. The Ag molecular catalyst according to claim 1 or 2, characterized in that The carbon support includes any one or more of XC-72R, Ketjen black, acetylene black, graphene and carbon nanotubes.

4. A method for preparing the Ag molecular catalyst according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: (1) preparing a carbon carrier dispersion; (2) preparing a mixed solution of silver salt and o-phenanthroline; and (3) mixing the carbon carrier dispersion and the mixed solution of silver salt and o-phenanthroline, stirring and drying to obtain the Ag molecular catalyst.

5. The preparation method according to claim 4, characterized in that The silver salt includes any one or more of silver nitrate, silver sulfate, silver acetate, silver acetylacetonate and silver trifluoroacetate.

6. The preparation method according to claim 4 or 5, characterized in that The molar ratio of the o-phenanthroline to the silver salt is (1-10):1, preferably (3-5):

1.

7. The preparation method according to any one of claims 4 to 6, characterized in that In the mixed solution of the silver salt and o-phenanthroline, the concentration of the silver salt is 0.1 mM to 10 M.

8. A method for electrocatalytic oxidation of gaseous olefins, characterized in that: The method comprises the following steps: (1) using carbon paper as an anode catalyst current collector, coating the current collector with a dispersion containing the Ag molecular catalyst according to any one of claims 1 to 3; (2) adding electrolytes to both the anode electrolytic cell and the cathode electrolytic cell, and introducing gaseous olefins into the anode electrolytic cell; and (3) applying voltage.

9. The method according to claim 8, characterized in that The gaseous olefins include any one or more of ethylene, propylene, butene and butadiene.

10. The method according to claim 8 or 9, characterized in that The cathode includes any one or more of a graphite rod, a platinum sheet, nickel foam, carbon paper, and carbon felt; and the voltage is 0V to 10V vs Ag / AgCl, preferably 1V to 5V vs Ag / AgCl.

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