Method for coupling low-concentration acetylene through efficient electrocatalysis of membrane electrode

Abstract

The invention provides a method for high-efficiency electrocatalysis of coupling of low-concentration acetylene by a membrane electrode, and solves the problems existing in preparation of 1, 3-butadiene by a three-electrode flow electrolytic tank. According to the method, a gas diffusion electrode material and a metal-based material which are sprayed with a catalyst copper tert-butyl formate are respectively used as a cathode and an anode, an anion exchange membrane is used for isolation between the cathode and the anode, and coal-based acetylene or high-purity acetylene is used as reaction gas; under the driving of renewable electric energy, a membrane electrode electrolytic tank device is used, and 1, 3-butadiene is synthesized through coupling reaction of electrocatalytic acetylene. Compared with a traditional 1, 3-butadiene synthesis process, the method has the advantages that 1, 3-butadiene can be prepared under milder reaction conditions, dependence on traditional raw materials and complexity of a production process are reduced, and a new path is opened up for green and sustainable production of an important chemical product.

Description

Technical Field

[0001] This invention belongs to the field of membrane electrode catalysis technology, and particularly relates to a method for high-efficiency electrocatalysis of low-concentration acetylene coupling using a membrane electrode, namely, a method for electrosynthesizing 1,3-butadiene using a membrane electrode. Background Technology

[0002] 1,3-Butadiene, a conjugated diene, is the 36th most industrially produced chemical. Its unsaturated double bonds readily undergo various reactions, including addition, substitution, and polymerization. It is widely used in the production of important chemical products such as synthetic rubber, synthetic resins, adiponitrile, and nylon 66. Global 1,3-butadiene production capacity is projected to increase from 14.2 million tons in 2020 to nearly 16 million tons by 2025.

[0003] Currently, over 98% of the world's 1,3-butadiene is derived from the distillation of C4 fractions, a byproduct of ethylene cracking units, and from the dehydrogenation of n-butane or n-butene, making it highly dependent on traditional energy sources and processes. Given my country's basic energy resource situation and the requirements for green chemical development, the aforementioned methods suffer from limitations such as relatively scarce raw material resources, high reaction temperatures, complex processes, and high energy consumption. Therefore, there is an urgent need to develop green and sustainable production processes for 1,3-butadiene.

[0004] Chinese patent CN112342562B discloses a method for the electrocatalytic coupling of acetylene to 1,3-butadiene, using oxides, alloys, and their single atoms as catalysts and employing a three-electrode flow electrolyzer, achieving the green synthesis of 1,3-butadiene for the first time. However, in practical applications, especially when simulating industrial production with low-concentration acetylene (coal-based acetylene, 15% C2H2 by volume), several problems still exist: First, while the three-electrode flow electrolyzer, a commonly used electrolyzer device in scientific research, shows certain advantages in the selectivity of 1,3-butadiene, it still suffers from numerous issues such as a relatively dispersed electrolyzer structure, uneven electrolyte flow and easy overflow, the need for an external reference electrode to precisely control the potential, and poor electrode material stability. These problems prevent the system from accurately reflecting the industrial production conditions such as reaction tank pressure and material stability, making it difficult to meet the actual requirements of industrial production. Secondly, the low reactant concentration of coal-based acetylene feedstock gas and the relatively higher concentration of other gaseous components not only increase the diffusion resistance of active components on the electrode surface and reduce mass transfer efficiency, but also intensify competition for active sites on the catalyst, thereby reducing the main reaction rate and exacerbating side reactions.

[0005] Therefore, the present invention provides a method for high-efficiency electrocatalytic coupling of low-concentration acetylene using a membrane electrode. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing methods for preparing 1,3-butadiene and to provide a method for high-efficiency electrocatalytic coupling of low-concentration acetylene using a membrane electrode.

[0007] The concept of this invention:

[0008] In view of the problems in the preparation of 1,3-butadiene by the three-electrode flow electrolyzer mentioned in the background art, the present invention adopts a membrane electrode electrolyzer with a two-electrode system. This electrolyzer has a more compact modular structure, high energy density, and is easier to integrate to simulate continuous production processes on an industrial scale. Moreover, the relatively low applied potential of the membrane electrode helps to reduce energy consumption.

[0009] To achieve the above objectives, the technical solution provided by this invention is:

[0010] A method for highly efficient electrocatalytic coupling of acetylene using a membrane electrode assembly, characterized by comprising the following steps:

[0011] 1) Copper tert-butylcarboxylate ((CH3)3CCOO)4Cu2 was dispersed as a catalyst in a volatile good solvent, and 5% Nafion solution (binder) was added. The solution was mixed evenly by ultrasonic and magnetic stirring to obtain a catalyst slurry.

[0012] 2) According to 1-25 mg·cm -2 The catalyst slurry obtained in step 1) is uniformly loaded onto a carbon-based gas diffusion plate material and dried thoroughly to obtain a gas diffusion electrode. The purpose of thorough drying is mainly to avoid problems such as electrode expansion and deformation, active layer detachment, and solvent molecules clogging the pores, which would reduce the catalytic effect.

[0013] 3) Using the gas diffusion electrode obtained in step 2) as the cathode and the metal-based material as the anode, the cathode chamber and the anode chamber are separated by an anion exchange membrane to form a membrane electrode electrolysis cell device. The electrocatalytic acetylene coupling reaction is carried out using coal-based acetylene (i.e., C2H2 with a volume fraction of 15%) as the reaction gas to prepare 1,3-butadiene.

[0014] Furthermore, the ratio of catalyst to good solvent to binder is (1–40 mg): (1–4 mL): (0.1–20 μL).

[0015] Further, in step 1), the volatile good solvent is acetone, anhydrous ethanol, isopropanol, or a mixed solution of deionized water and ethanol or isopropanol in any volume ratio.

[0016] The duration of the ultrasound is 30–180 seconds; the duration of the magnetic stirring is 1–30 minutes.

[0017] Furthermore, in step 2), the catalyst slurry is uniformly loaded onto the carbon-based gas diffusion plate material using an air compressor;

[0018] The carbon-based gas diffusion plate material is carbon fiber paper, carbon fiber woven fabric, non-woven fabric, or carbon black paper.

[0019] The working area of ​​the carbon-based gas diffusion plate material is 1 cm². 2 4cm 2 Or 25cm 2 ;

[0020] Dry thoroughly by baking with an infrared lamp for 1 to 10 minutes.

[0021] Further, in step 3), the metal-based material is a current collector obtained by metal ion solution electrodeposition or impregnation and calcination; wherein the metal ion is Fe, Co, Ni, Ru or Ir; and the current collector is a titanium current collector, a nickel current collector or a copper current collector.

[0022] That is, the anode uses titanium current collectors (titanium mesh, titanium felt, etc.), nickel current collectors (nickel plates, nickel sheets or nickel foam, etc.), copper current collectors (copper foil, copper foam, etc.) loaded with metals such as Fe, Co, Ni, Ir, Ru or their alloys or composites.

[0023] Furthermore, in step 3), a constant current is applied to the electrolytic cell using a DC regulated power supply to carry out the electrocatalytic acetylene coupling reaction.

[0024] Further, in step 3), the electrolyte flows through the anode chamber, and the electrolyte-wetted reaction gas flows through the cathode chamber.

[0025] Further, the electrolyte is a 1M KOH solution, a 1M KHCO3 solution, a 0.5M K2CO3 solution, a 0.5M K2SO4 solution, a 1M KI solution, a 1M KBr solution, or a 1M KCl solution.

[0026] Furthermore, in step 3), the reaction gas can be replaced with high-purity acetylene (i.e., C2H2 with a volume fraction of 100%).

[0027] Advantages of this invention:

[0028] 1. This invention uses a gas diffusion electrode material coated with copper tert-butylformate catalyst and a metal-based material as the cathode and anode, respectively, separated by an anion exchange membrane. Coal-based acetylene or high-purity acetylene is used as the reaction gas. Driven by renewable electrical energy, a membrane electrode electrolysis cell is used to synthesize 1,3-butadiene through an electrocatalytic coupling reaction of acetylene. Compared with traditional 1,3-butadiene synthesis processes, this invention can produce 1,3-butadiene under milder reaction conditions (i.e., room temperature and pressure), reducing dependence on traditional raw materials and the complexity of the production process, thus opening a new path for the green and sustainable industrial production of this important chemical product.

[0029] 2. The technical effect of this invention in the electrosynthesis of 1,3-butadiene using membrane electrodes is that it can achieve a 1,3-butadiene Faradaic efficiency of 86% in high-purity acetylene, and the highest Faradaic efficiency for 1,3-butadiene in coal-based acetylene can also reach 80%. Compared with a three-electrode flow electrolyzer, this invention not only achieves technical effects comparable to those using a three-electrode flow electrolyzer, but its compact modular components and serpentine flow field effectively improve problems such as uneven electrolyte flow, electrolyte overflow, potential drift, and high integration difficulty, making it more suitable for industrial production.

[0030] 3. This invention improves upon the high energy consumption and complex process of traditional 1,3-butadiene synthesis, and solves the problem of difficulty in large-scale application of three-electrode flow electrolysis cells. It exhibits excellent electrosynthesis performance of 1,3-butadiene regardless of whether high-purity acetylene or coal-based acetylene is used as raw material. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a membrane electrode electrolytic cell assembly for the electrosynthesis of 1,3-butadiene.

[0032] Figure 2 For high-purity acetylene, copper tert-butylcarbamate catalyst was used at a concentration of 1 cm. 2 The Faraday distribution and cell voltage of 1,3-butadiene products synthesized by membrane electrode electrolysis cell at various current densities.

[0033] Figure 3 The Faradaic distribution and cell pressure of 1,3-butadiene products synthesized by copper tert-butylformate catalyst under coal-based acetylene at various current densities using membrane electrode electrolysis cells of different sizes: (a) 1 cm 2 (b) 4cm 2 . Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0035] This invention proposes a method for the electrosynthesis of 1,3-butadiene using a membrane electrode assembly. The cathode is formed by spraying copper tert-butylformate catalyst onto a carbon-based gas diffusion plate material, and the anode is a metal-based material prepared by electrodeposition or calcination. An anion exchange membrane separates the cathode and anode, together forming a membrane electrode electrolytic cell. Figure 1 As shown.

[0036] 1. Preparation of gas diffusion electrode

[0037] 1–40 mg of the copper-based catalyst complex (copper tert-butylformate powder) was dispersed in 1–4 mL of a volatile good solvent, and 0.1–20 μL of 5% Nafion solution was added. The solution was mixed evenly by sonication (30–180 s) and magnetic stirring (1–30 min) to prepare a catalyst slurry of a certain concentration; according to 1–25 mg·cm⁻¹… -2 To determine the loading amount, 100–1500 μL of catalyst slurry was transferred using a pipette, and the catalyst was uniformly loaded onto a carbon-based gas diffusion plate material using an air compressor. After baking with an infrared lamp for 1–10 minutes, a gas diffusion electrode was obtained.

[0038] The catalyst is copper tert-butylcarboxylate. Since the synthesis of copper tert-butylcarboxylate catalyst is known to those skilled in the art of organic synthesis, it will not be described in detail here.

[0039] Good solvents that are easily volatile include acetone, anhydrous ethanol, isopropanol, or a mixture of deionized water and ethanol or isopropanol in any volume ratio.

[0040] The carbon-based gas diffusion plate material is made of carbon fiber paper, carbon fiber woven fabric, non-woven fabric, or carbon black paper, etc.; the working area of ​​this carbon-based gas diffusion plate material is 1 cm². 2 4cm 2 25cm 2 wait.

[0041] 2. Preparation of metal anodes

[0042] (1) Electrodeposition method

[0043] The current collector was ultrasonically cleaned sequentially with 1M KOH, 3M HCl, and deionized water. A three-electrode electrolytic cell was assembled using the cleaned current collector as the working and counter electrodes, an Ag / AgCl electrode as the reference electrode, and a mixed solution with a Fe:Ni:Co molar ratio of 1:1:0.5 as the electrolyte. Electrodeposition was performed on the current collector using a Chenhua electrochemical workstation at a constant current of -10mA for 600s. The electrodeposited current collector was rinsed with deionized water and dried in a 60℃ oven for 12h to obtain the electrodeposited NiFeCo LDH metal-based anode material.

[0044] The current collectors include titanium current collectors (titanium mesh, titanium felt, etc.), nickel current collectors (nickel plates, nickel sheets or nickel foam, etc.), and copper current collectors (copper foil, copper foam, etc.).

[0045] (2) Impregnation and calcination method

[0046] The current collector was ultrasonically cleaned sequentially with acetone, ethanol and deionized water; the cleaned current collector was placed in an acid solution and etched at 100°C for 1 hour; the etched current collector was immersed in an isopropanol solution containing metal ions for 10 minutes and calcined in a muffle furnace at 500°C for 10 minutes; the above immersion and calcination process was repeated to obtain the anode material with a sintered metal layer.

[0047] The current collectors include titanium current collectors (titanium mesh, titanium felt, etc.), nickel current collectors (nickel plates, nickel sheets or nickel foam, etc.), and copper current collectors (copper foil, copper foam, etc.).

[0048] The acid solution is sulfuric acid, hydrochloric acid, oxalic acid, or a mixture thereof.

[0049] The metal ions are Fe, Co, Ni, Ru, Ir, etc.

[0050] 3. Assembly and performance testing of membrane electrode electrolyzers

[0051] Using the gas diffusion electrode and metal anode prepared above as the cathode and anode respectively, and separating the cathode and anode with an anion exchange membrane, a two-electrode membrane electrode electrolytic cell was formed. A constant current was applied to the membrane electrode electrolytic cell using a DC regulated power supply to test the performance of electrosynthesis of 1,3-butadiene. During the electrocatalytic reaction, the electrolyte was pumped into the anode chamber inlet at a peristaltic speed of 5-10 rpm and pumped out of the anode chamber outlet using a peristaltic pump. The cathode chamber did not require electrolyte flow; only the reaction gas moistened with electrolyte was introduced into the cathode chamber inlet at a flow rate of 5-100 sccm through a gas mass flow meter. The electrolysis products flowed out from the cathode chamber outlet and were collected. The composition and content of the gas flowing out from the gas chamber outlet were detected using online gas chromatography, and the Faraday efficiency of the target product was calculated.

[0052] The electrolyte is a 1M (M represents mol / L) KOH solution, a 1M KHCO3 solution, a 0.5M K2CO3 solution, a 0.5M K2SO4 solution, a 1M KI solution, a 1M KBr solution, or a 1M KCl solution.

[0053] The reaction gas is high-purity acetylene (100% C2H2 by volume) or coal-based acetylene (15% C2H2 by volume).

[0054] The performance of copper tert-butylcarbamate in the electrosynthesis of 1,3-butadiene was tested below, taking into account specific catalysts and reaction conditions.

[0055]

Example 1

[0056] (1) A gas diffusion electrode coated with copper tert-butylformate catalyst is used as the cathode, and nickel foam electrodeposited with NiFeCo LDH is used as the anode, separated by an anion exchange membrane, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0057] (2) High-purity acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 60 sccm using a gas mass flow meter.

[0058] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0059] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -20mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0060]

Example 2

[0061] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a calcined IrO2 / titanium mesh is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0062] (2) High-purity acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 60 sccm using a gas mass flow meter.

[0063] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0064] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -20mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0065]

Example 3

[0066] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0067] (2) High-purity acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 60 sccm using a gas mass flow meter.

[0068] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0069] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -20mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0070]

Example 4

[0071] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0072] (2) High-purity acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 60 sccm using a gas mass flow meter.

[0073] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0074] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -40mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0075]

Example 5

[0076] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0077] (2) Coal-based acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 15 sccm using a gas mass flow meter.

[0078] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0079] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -20mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0080]

Example 6

[0081] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0082] (2) Coal-based acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 15 sccm using a gas mass flow meter.

[0083] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0084] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -40mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0085]

Example 7

[0086] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0087] (2) Coal-based acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 30 sccm using a gas mass flow meter.

[0088] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0089] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -20mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0090]

Example 8

[0091] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0092] (2) Coal-based acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 30 sccm using a gas mass flow meter.

[0093] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0094] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -40mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0095]

Example 9

[0096] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0097] (2) Coal-based acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 60 sccm using a gas mass flow meter.

[0098] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0099] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -20mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0100]

Example 10

[0101] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0102] (2) Coal-based acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 60 sccm using a gas mass flow meter.

[0103] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0104] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -40mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0105]

Example 11

[0106] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0107] (2) Coal-based acetylene impregnated with 0.5M K2CO3 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 60 sccm using a gas mass flow meter.

[0108] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0109] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -20mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0110]

Example 12

[0111] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0112] (2) Coal-based acetylene impregnated with 0.5M K2CO3 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 60 sccm using a gas mass flow meter.

[0113] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0114] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -40mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0115]

Example 13

[0116] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​1 cm². 2Membrane electrode electrolytic cell.

[0117] (2) Coal-based acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 100 sccm using a gas mass flow meter.

[0118] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0119] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -20mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0120]

Example 14

[0121] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0122] (2) Coal-based acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 100 sccm using a gas mass flow meter.

[0123] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0124] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -40mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0125]

Example 15

[0126] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a titanium felt with sintered ruthenium and iridium is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​4 cm². 2 Membrane electrode electrolytic cell.

[0127] (2) Coal-based acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 60 sccm using a gas mass flow meter.

[0128] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0129] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -20mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0130]

Example 16

[0131] (1) A gas diffusion electrode coated with copper tert-butylcarbamate catalyst is used as the cathode, and a titanium felt with sintered ruthenium and iridium is used as the anode, with an anion exchange membrane separating the two, forming a working area of ​​4 cm². 2 Membrane electrode electrolytic cell.

[0132] (2) Coal-based acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 60 sccm using a gas mass flow meter.

[0133] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0134] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -40mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0135] Comparative Example 1

[0136] (1) A gas diffusion electrode coated with copper acetate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating them, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0137] (2) Coal-based acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 60 sccm using a gas mass flow meter.

[0138] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0139] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -20mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0140] Comparative Example 2

[0141] (1) A gas diffusion electrode coated with copper acetate catalyst is used as the cathode, and a sintered ruthenium-iridium titanium felt is used as the anode, with an anion exchange membrane separating them, forming a working area of ​​1 cm². 2 Membrane electrode electrolytic cell.

[0142] (2) Coal-based acetylene impregnated with 0.5M K2SO4 solution was used as the reaction raw material and introduced into the electrolytic cell through the cathode chamber inlet at a flow rate of 60 sccm using a gas mass flow meter.

[0143] (3) Use 1M KOH solution as the anolyte and pump it into the anode chamber inlet at a peristaltic speed of 10 rpm using a peristaltic pump.

[0144] (4) The catalytic performance of the catalyst for the electrosynthesis of 1,3-butadiene was evaluated using a DC regulated power supply at a constant current of -40mA, and the composition and content of the electrolysis products were analyzed by online gas chromatography.

[0145] The specific evaluation results are shown in Table 1.

[0146] Table 1

[0147]

[0148]

[0149]

[0150] Through the above embodiments and comparative examples, it can be clearly seen that:

[0151] Comparative Example 1 uses a membrane electrode assembly, with copper acetate as the catalyst, titanium felt as the anode, and high-purity acetylene (100% C2H2) as the reaction gas. The test current is -20mA.

[0152] Comparative document 1 (corresponding to background technology CN112342562B) uses a flow electrolysis cell device, with cuprous oxide as the catalyst, iridium oxide as the anode, and a mixture of acetylene and ethylene as the reaction gas. The test current is -46mA.

[0153] The catalyst used in Examples 1-3 of this invention is copper tert-butylformate, and the anodes are NiFeCo LDH / nickel foam and IrO, respectively. x The experiment, conducted using a membrane electrode assembly (MEA) with titanium mesh, ruthenium-iridium sintered titanium felt, and a reaction gas of moistened high-purity acetylene (100% C2H2), was carried out at a current of -20 mA. Comparisons show that ruthenium-iridium sintered titanium felt as the anode exhibited excellent catalytic performance at both -20 mA and -40 mA (i.e., Examples 3 and 4), demonstrating performance comparable to or even better than Comparative Example 1 and Comparative Document 1. Therefore, ruthenium-iridium sintered titanium felt was used as the anode in subsequent examples.

[0154] Examples 6-9, 12, and 14 of this invention employ a membrane electrode assembly (MEA) with coal-based acetylene (15% C2H2) as the reactant gas. Tests were conducted at different gas flow rates (15, 30, 60, and 100 sccm) and different currents (-20 and -40 mA). It is noteworthy that using low-concentration acetylene as the reactant gas significantly reduces the electrocatalytic effect. This is because the number of C2H2 molecules decreases, while the number of other gaseous components (inert gas Ar is used in these examples) relatively increases. This leads to increased diffusion resistance of the active component on the electrode surface, reduced mass transfer efficiency, intensified competition for catalyst active sites, and a decreased reaction rate, among other problems. Therefore, a decrease in the Faradaic efficiency for the target product is understandable. Even so, the method provided by this invention still achieves a high Faradaic efficiency at higher currents (-40 mA), with most maintaining above 65%, even outperforming the performance of copper acetate using high-purity acetylene as the reactant gas at this current. In addition, gas flow rate also affects this type of reaction: as the flow rate increases, the Faraday efficiency generally shows a trend of first increasing and then decreasing, with the optimal flow rate being 60 sccm.

[0155] The electrolytic cell used in Comparative Document 1 is a three-electrode flow electrolytic cell. This device achieves relatively stable potential due to the introduction of a reference electrode (however, this is difficult to achieve in industrial catalysis, and therefore cannot accurately simulate industrial applications). Furthermore, the cathode chamber of this device has circulating cathode electrolyte, which facilitates the catalytic mass transfer process, and the products can be carried away by the electrolyte in a timely manner. The focus of this invention is on using a membrane electrode assembly (MEA) to efficiently achieve low-concentration acetylene coupling, thus better simulating industrial catalysis conditions (as described in the background section). When using a MEA, the system cell pressure more closely resembles the conditions faced in industrial catalysis. However, the cathode chamber of this device lacks flowing liquid electrolyte, only allowing the introduction of humidified reaction gas. Therefore, the gas mass transfer process is affected, resulting in the electrocatalytic performance of the MEA being inferior to that of a flow cell. Even so, most of the results of this invention are comparable to, or even superior to, the performance results obtained in Comparative Document 1 using a flow cell.

[0156] like Figure 2 As shown, a membrane electrode electrolysis cell was used with copper tert-butylformate as the catalyst, titanium felt as the anode, and wetted high-purity acetylene as the reactant gas at a flow rate of 60 sccm. The product distribution and cell pressure variation diagrams (corresponding to Examples 3 and 4) are shown for the range of -20 to -70 mA. It can be seen that the catalyst maintains a Faradaic efficiency of over 50% for the target product throughout the entire test range, and over 70% within the range of -20 to -50 mA, reaching a maximum of 86%. Furthermore, the cell pressure of the system is low, below 2V. Overall, it exhibits superior electrocatalytic acetylene coupling performance compared to the comparative examples and prior art.

[0157] like Figure 3 As shown, the product distribution of 1,3-butadiene was synthesized using copper tert-butylcarbamate as a catalyst, titanium felt as an anode, and moistened coal-based acetylene as the reactant gas at a gas flow rate of 60 sccm, employing membrane electrode assemblies with different working areas. (a) shows the product distribution at 1 cm⁻¹. 2 (a) corresponds to Examples 9 and 10; (b) is 4cm 2 This corresponds to Examples 15 and 16. Even with low C2H2 reactant concentrations, the method provided by this invention still exhibits good catalytic performance. Specifically, the Faraday efficiency for the target product can be maintained above 70% at -20 to -50 mA, and the cell voltage can be maintained below 2V. This performance is comparable to that of the prior art, indicating that the catalyst can achieve highly efficient electrocatalytic coupling of low-concentration acetylene via a membrane electrode assembly. In particular, the cell voltage of the large-area membrane electrode assembly can be maintained below 1.8V, which helps to further reduce energy consumption.

[0158] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. A method for high-efficiency electrocatalytic coupling of low-concentration acetylene using a membrane electrode assembly, characterized in that, Includes the following steps: 1) Copper tert-butylcarbamate was dispersed as a catalyst in a volatile good solvent, and 5% Nafion solution was added. The solution was mixed evenly by ultrasonic and magnetic stirring to obtain a catalyst slurry. 2) According to 1-25 mg·cm -2 The catalyst slurry obtained in step 1) is uniformly loaded onto a carbon-based gas diffusion plate material and dried thoroughly to obtain a gas diffusion electrode. 3) Using the gas diffusion electrode obtained in step 2) as the cathode and the metal-based material as the anode, the cathode chamber and the anode chamber are separated by an anion exchange membrane to form a membrane electrode electrolysis cell device. Coal-based acetylene is used as the reaction gas to carry out an electrocatalytic acetylene coupling reaction to prepare 1,3-butadiene.

2. The method for high-efficiency electrocatalytic coupling of low-concentration acetylene using a membrane electrode according to claim 1, characterized in that: In step 1), the ratio of catalyst to good solvent to binder is (1-40 mg): (1-4 mL): (0.1-20 μL).

3. The method for high-efficiency electrocatalytic coupling of low-concentration acetylene using a membrane electrode according to claim 1 or 2, characterized in that: In step 1), the readily volatile solvent is acetone, anhydrous ethanol, isopropanol, or a mixed solution of deionized water and ethanol or isopropanol in any volume ratio; the ultrasonic duration is 30–180 s; and the magnetic stirring duration is 1–30 min.

4. The method for high-efficiency electrocatalytic coupling of low-concentration acetylene using a membrane electrode according to claim 3, characterized in that: In step 2), the catalyst slurry is uniformly loaded onto the carbon-based gas diffusion plate material using an air compressor; The carbon-based gas diffusion plate material is carbon fiber paper, carbon fiber woven fabric, non-woven fabric, or carbon black paper. Dry thoroughly by baking with an infrared lamp for 1 to 10 minutes.

5. The method for high-efficiency electrocatalytic coupling of low-concentration acetylene using a membrane electrode according to claim 4, characterized in that: In step 3), the metal-based material is a current collector obtained by metal ion solution electrodeposition or impregnation and calcination; Among them, the metal ions are Fe, Co, Ni, Ru or Ir; The current collector is a titanium current collector, a nickel current collector, or a copper current collector.

6. The method for high-efficiency electrocatalytic coupling of low-concentration acetylene using a membrane electrode according to claim 5, characterized in that: In step 3), a constant current is applied to the electrolytic cell using a DC regulated power supply to carry out the electrocatalytic acetylene coupling reaction.

7. The method for high-efficiency electrocatalytic coupling of low-concentration acetylene using a membrane electrode according to claim 6, characterized in that: In step 3), electrolyte flows through the anode chamber, and electrolyte-wetted reaction gas flows through the cathode chamber.

8. The method for high-efficiency electrocatalytic coupling of low-concentration acetylene using a membrane electrode according to claim 7, characterized in that: The electrolyte is a 1M KOH solution, a 1M KHCO3 solution, a 0.5M K2CO3 solution, a 0.5M K2SO4 solution, a 1M KI solution, a 1M KBr solution, or a 1M KCl solution.

9. The method for high-efficiency electrocatalytic coupling of low-concentration acetylene using a membrane electrode according to claim 8, characterized in that: In step 3), the reaction gas can be replaced with high-purity acetylene.

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