Membrane electrode device applied to hydrogen production from ethanol, proton exchange membrane electrolytic tank and method for hydrogen production from ethanol

Abstract

The invention discloses a membrane electrode device applied to hydrogen production from ethanol, which comprises an anode gas diffusion layer, an anode thermal catalytic layer, an anode electro-catalytic layer, a proton exchange membrane, a cathode electro-catalytic layer and a cathode gas diffusion layer which are sequentially designed in a stacked manner, and the anode thermal catalytic layer is at least one of carbon nano tube loaded gamma aluminum oxide and carbon loaded gamma aluminum oxide. The invention also discloses a proton exchange membrane electrolytic cell comprising the membrane electrode device, and application of the proton exchange membrane electrolytic cell to preparation of hydrogen from ethanol. According to the membrane electrode device, the carbon nanotube-loaded gamma aluminum oxide or carbon-loaded gamma aluminum oxide catalyst layer is added in the membrane electrode device, under the thermocatalysis condition, ethanol is dehydrated to generate ethylene, and the ethylene is subjected to electrooxidation reaction in the anode electrocatalysis layer to generate carbon dioxide and hydrogen.

Description

Technical Field

[0001] The invention belongs to the field of electrocatalysis, and in particular relates to a membrane electrode device used for producing hydrogen from ethanol, a proton exchange membrane electrolysis cell and a method for producing hydrogen from ethanol. Background Art

[0002] Ethanol is derived from the fermentation of abundant biomass and is one of the most promising bio-based raw materials that can replace fossil fuels and produce valuable chemicals. The selective electrooxidation of ethanol coupled with the hydrogen evolution reaction has been considered as a technology for green hydrogen production and high value-added fine chemical products (such as acetaldehyde and acetic acid). However, due to the slow kinetics of ethanol electrooxidation, a relatively high electrolysis voltage (~ 0.8V) is required. Although great efforts have been made at home and abroad to optimize electrocatalysts or increase the operating temperature to improve catalytic performance, large power consumption is still required to achieve sufficient current density (>100 mA cm -2 ).

[0003] The patent application with publication number CN 117210839 A discloses a membrane electrode, a proton exchange membrane electrolyzer, and a method for preparing hydrogen and carbon monoxide. When the membrane electrode and gas diffusion layer and other components are assembled into a proton exchange membrane electrolyzer and used for methanol to produce hydrogen and carbon monoxide, hydrogen can be transferred from the anode of the methanol dehydrogenation area to the cathode, breaking through the thermodynamic equilibrium limitation of the methanol dehydrogenation reaction and improving the efficiency of the methanol dehydrogenation reaction; and the electrochemical transfer process allows hydrogen to be precipitated directly at the cathode, effectively improving the purity of hydrogen and omitting the additional separation and purification steps of hydrogen. However, the first anode and the second anode both use precious metal catalysts, and the overall cost is relatively high. On the other hand, the membrane electrode cannot be used for ethanol hydrogen production. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide a membrane electrode device, a proton exchange membrane electrolyzer and a method for producing hydrogen from ethanol.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is: A membrane electrode device used for ethanol hydrogen production comprises an anode gas diffusion layer, an anode thermal catalytic layer, an anode electrocatalytic layer, a proton exchange membrane, a cathode electrocatalytic layer and a cathode gas diffusion layer which are stacked in sequence, wherein the anode thermal catalytic layer is at least one of carbon nanotube-supported γ-alumina and carbon-supported γ-alumina.

[0006] As a general inventive concept, the present invention also provides a membrane electrode device for ethanol hydrogen production, comprising an anode thermal catalytic layer, an anode gas diffusion layer, an anode electrocatalytic layer, a proton exchange membrane, a cathode electrocatalytic layer and a cathode gas diffusion layer designed to be stacked in sequence, wherein the anode thermal catalytic layer is at least one of carbon nanotube-supported γ-alumina and carbon-supported γ-alumina.

[0007] In the membrane electrode device for ethanol hydrogen production, preferably, the γ-alumina loading in the anode thermal catalytic layer is 0.1 mg cm -2 ~ 3 mg cm -2 . In the above-mentioned membrane electrode device for ethanol hydrogen production, preferably, the anode electrocatalytic layer includes at least one of carbon-supported platinum, carbon-supported palladium, carbon-supported ruthenium and carbon-supported platinum-ruthenium; The cathode electrocatalyst includes at least one of carbon-supported platinum and carbon-supported palladium; The proton exchange membrane is a phosphoric acid-doped polymer membrane.

[0008] In the membrane electrode device for ethanol hydrogen production, preferably, the noble metal loading in the anode electrocatalyst layer is 0.1 mg cm -2 ~ 3 mg cm -2 ; The noble metal loading in the cathode electrocatalyst layer is 0.1 mg cm -2 ~ 3 mg cm -2 .

[0009] As a general inventive concept, the present invention also provides a proton exchange membrane electrolyzer, comprising the above-mentioned membrane electrode device.

[0010] As a general inventive concept, the present invention also provides a method for producing hydrogen from ethanol, using the above-mentioned proton exchange membrane electrolysis cell to produce hydrogen from ethanol.

[0011] In the above-mentioned method for producing hydrogen from ethanol, preferably, vaporized ethanol is placed in a proton exchange membrane electrolyzer for electrocatalytic reaction to obtain ethylene on the anode thermal catalytic layer, and ethylene enters the anode electrocatalytic layer under the blowing of ethanol gas and water vapor to obtain hydrogen on the cathode electrocatalytic layer.

[0012] In the above-mentioned method for producing hydrogen from ethanol, preferably, the voltage of the electrocatalytic reaction is 0.3 V ~ 0.8 V.

[0013] In the above-mentioned method for producing hydrogen from ethanol, preferably, the temperature of the electrocatalytic reaction is 100°C to 240°C.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention adds a carbon nanotube-supported γ-alumina or carbon-supported γ-alumina catalyst layer in a membrane electrode device to dehydrate ethanol to produce ethylene under thermal catalysis. The ethylene undergoes an electro-oxidation reaction in the anode electrocatalytic layer to produce carbon dioxide and hydrogen.

[0015] (2) The present invention adopts an anode thermal catalytic layer and an anode electrocatalytic layer as a double catalytic layer anode, controls the type of catalyst in the catalytic layer, assembles it with components such as a gas diffusion layer into a proton exchange membrane electrolysis cell and uses it to produce acetaldehyde and hydrogen from ethanol. Ethanol undergoes a thermal catalytic dehydration reaction in the anode thermal catalytic layer to form ethylene and water, and is oxidized in the anode electrocatalytic layer to form acetaldehyde, carbon dioxide and hydrogen. Hydrogen undergoes an electrochemical oxidation reaction in the anode electrocatalytic layer to form protons and electrons. The protons combine with electrons in the cathode electrocatalytic layer through the proton exchange membrane to produce hydrogen. At the same time, the ethylene and hydrogen produced in the anode catalytic layer are consumed, and the partial pressure is reduced, so that the equilibrium of the ethanol dehydration reaction and the ethanol dehydrogenation reaction moves toward the direction of hydrogen production, thereby promoting the generation efficiency of hydrogen and acetaldehyde and increasing the production rate of hydrogen and acetaldehyde.

[0016] (3) When the proton exchange membrane electrolyzer of the present invention is used to produce hydrogen and acetaldehyde from ethanol, ethanol is dehydrogenated at the anode electrocatalytic layer to form acetaldehyde and hydrogen, and hydrogen is transferred from the anode to the cathode in the ethanol dehydrogenation region, breaking through the thermodynamic equilibrium limitation of the ethanol dehydrogenation reaction and improving the efficiency of the ethanol dehydrogenation reaction, that is, increasing the gas production rate of hydrogen and acetaldehyde; the two simultaneously promote the efficient electro-oxidation of ethanol, and the electrochemical transfer process causes hydrogen to be directly precipitated at the cathode, effectively improving the purity of hydrogen and omitting the additional separation and purification steps of hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the X-ray XRD pattern of γ-alumina.

[0018] Figure 2 This is the in-situ gas phase FID spectrum of Comparative Example 1.

[0019] Figure 3 The current density-voltage diagrams of Example 1 and Comparative Example 2 measured by linear sweep voltammetry are shown in FIG.

[0020] Figure 4 The current density-voltage diagrams of Examples 2 and 3 and Comparative Example 3 measured by linear scanning voltammetry are shown in FIG.

[0021] Figure 5 The acetaldehyde yield of the anode liquid product of Example 2 and Comparative Example 3. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0023] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0024] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0025] Embodiment 1: The membrane electrode device used for ethanol hydrogen production in this embodiment includes an anode gas diffusion layer, an anode thermal catalyst layer, an anode electrocatalytic layer, a proton exchange membrane, a cathode electrocatalytic layer and a cathode gas diffusion layer stacked in sequence, wherein the anode thermal catalyst layer is 1.0 mg cm -2 The carbon nanotube-supported γ-alumina catalyst has a catalyst content of 2 mg cm in the anode electrocatalyst layer. -2 The Pt / C catalyst was used as the proton exchange membrane, the polybenzimidazole membrane doped with phosphoric acid, and the catalyst in the cathode electrocatalyst layer was 1.0 mg cm -2 The carbon-supported platinum catalyst, the material of the anode gas diffusion layer is hydrophobic carbon paper with a thickness of 251 μm, and the material of the cathode gas diffusion layer is hydrophobic carbon paper with a thickness of 254 μm.

[0026] The preparation process of the proton exchange membrane electrolyzer in this embodiment includes: (1) Preparation of membrane electrode: an anode thermocatalytic layer, an anode electrocatalytic layer, a proton exchange membrane, and a cathode electrocatalytic layer are stacked in sequence and hot pressed at 180°C and 1.0 MPa for 10 min. The catalyst in the anode thermocatalytic layer is 1.0 mg cm -2 The carbon nanotube-supported γ-alumina catalyst (XRD spectrum of the hot catalyst is shown in Figure 1) and the catalyst in the anode electrocatalyst layer is 2 mg cm -2 The Pt / C catalyst was used as the proton exchange membrane, the polybenzimidazole membrane doped with phosphoric acid, and the catalyst in the cathode catalyst layer was 1.0 mg cm -2 of carbon-supported platinum catalyst.

[0027] (2) Assembling a proton exchange membrane electrolyzer: Assembling a membrane electrode with an anode gas diffusion layer, a cathode gas diffusion layer, an anode plate, a cathode plate, and an end plate into a high-temperature proton exchange membrane electrolyzer device. The assembled high-temperature proton exchange membrane electrolyzer comprises an end plate, an anode plate, an anode gas diffusion layer, an anode thermocatalytic layer, an anode electrocatalytic layer, a proton exchange membrane, a cathode electrocatalytic layer and a cathode gas diffusion layer, a cathode plate, and an end plate, which are stacked in sequence; wherein the end plate close to the anode plate has an air inlet and an air outlet, and the end plate close to the cathode plate has an air outlet. The anode gas diffusion layer is made of hydrophobic carbon paper with a thickness of 251 μm, the cathode gas diffusion layer is made of hydrophobic carbon paper with a thickness of 254 μm, the anode plate is made of graphite carbon with a thickness of 0.43 cm, the cathode plate is made of graphite carbon with a thickness of 0.42 cm, and the end plate is made of titanium steel with a thickness of 1.4 cm.

[0028] The process of using the proton exchange membrane electrolysis cell in this embodiment to produce hydrogen from ethanol includes: -1 The flow rate of ethanol was transported to the vaporization chamber at 180°C through a peristaltic pump to evaporate and vaporize it. The vaporized ethanol vapor then entered the air inlet on the end plate next to the anode plate, and then an electrocatalytic reaction was carried out in a high-temperature proton exchange membrane electrolyzer device at a temperature of 200°C. The linear sweep voltammetry method was used to scan 0~0.9 V. The current density-voltage graph is shown in the figure. Figure 3 As shown, compared with the linear scanning line of the comparative example 2 without the anode thermal catalytic layer, at 0.8 V, the current density is increased by 60%. Since the proton exchange membrane of this system only passes protons, the synchronous hydrogen production efficiency of the cathode is increased by 60%.

[0029] Embodiment 2: The proton exchange membrane electrolyzer of Example 2 is different from that of Example 1 in that the catalyst in the anode electrocatalyst layer is different. The catalyst in the anode electrocatalyst layer of Example 2 is 2 mg cm -2 of PtRu / C.

[0030] The process of using the proton exchange membrane electrolysis cell in this embodiment to produce hydrogen from ethanol includes: -1 The flow rate is transported to the vaporization chamber at 180°C through a peristaltic pump to evaporate and vaporize. The vaporized ethanol vapor enters the air inlet on the end plate next to the anode plate, and then an electrocatalytic reaction is carried out in a high-temperature proton exchange membrane electrolyzer device at a temperature of 200°C. The linear sweep voltammetry method is used to scan 0~0.9 V, and the products at open circuit potential (OCV), 0.3 V, and 0.6 V are tested respectively. The current density-voltage diagram is shown in Figure 4As shown, the linear scanning voltammetry curves of the reaction systems with two different structural designs are shown in Example 2, Example 3, and Comparative Example 3. After adding the anode thermal catalytic layer, the peak potential of the current curve is significantly advanced. Under the same 0.8 V condition, Example 2 and Example 3 are improved by about 185% and 70% respectively compared with Comparative Example 3.

[0031] The hydrogen produced on the cathode side (0.3 V and 0.6 V) was analyzed by gas chromatography using a thermal conductivity detector (TCD), and the carbon dioxide produced on the anode side was analyzed by gas chromatography using a hydrogen flame ionization detector. The results are shown in Table 1. The gas phase products of the reaction are mainly CO and a small amount of C2 products. The test results of the thermal conductivity detector (TCD) are shown in Table 1 after processing. The addition of the anode thermal catalytic layer can greatly increase the hydrogen yield.

[0032] The anode liquid product was analyzed using nuclear magnetic resonance. The results are as follows Figure 5 As shown, the addition of anode thermal catalyst has little effect on the liquid products.

[0033] Embodiment 3: The membrane electrode device used for ethanol hydrogen production in this embodiment includes an anode thermal catalytic layer, an anode gas diffusion layer, an anode electrocatalytic layer, a proton exchange membrane, a cathode electrocatalytic layer and a cathode gas diffusion layer stacked in sequence, wherein the anode thermal catalytic layer is 1.0 mg cm -2 The carbon nanotube-supported γ-alumina catalyst has a catalyst content of 2 mg cm in the anode electrocatalyst layer. -2 The Pt / C catalyst was used as the proton exchange membrane, the polybenzimidazole membrane doped with phosphoric acid, and the catalyst in the cathode electrocatalyst layer was 1.0 mg cm -2 The carbon-supported palladium catalyst, the material of the anode gas diffusion layer is hydrophobic carbon paper with a thickness of 251 μm, and the material of the cathode gas diffusion layer is hydrophobic carbon paper with a thickness of 254 μm.

[0034] Then, the membrane electrode device for ethanol hydrogen production was prepared into a proton exchange membrane electrolyzer in the same manner as in Example 1.

[0035] The process of using the proton exchange membrane electrolysis cell in this embodiment to produce hydrogen from ethanol includes: -1 The flow rate of ethanol is transported to the vaporization chamber at 180°C through a peristaltic pump to evaporate and vaporize it. The vaporized ethanol vapor then enters the air inlet on the end plate next to the anode plate, and then an electrocatalytic reaction is carried out in a high-temperature proton exchange membrane electrolyzer device at a temperature of 200°C, using linear sweep voltammetry to scan 0~0.9 V.

[0036] Comparative Example 1: The catalyst content of the anode thermal catalyst layer is 1 mg cm -2 Carbon-supported γ-alumina catalyst, catalyst without anode electrocatalytic layer, tested anode gas products at 200°C, 220°C and 240°C. Gas chromatography analysis of ethylene produced on the anode side was performed using a hydrogen flame ionization detector.

[0037] The in-situ gas phase FID spectrum of this comparative example is as follows: Figure 2 As shown, ethylene is produced in the working range, and the ethylene yield increases with increasing temperature.

[0038] Comparative Example 2: The proton exchange membrane electrolyzer of this comparative example is different from that of Example 1 in that it does not have an anode thermal catalytic layer.

[0039] The process of using the proton exchange membrane electrolysis cell in this comparative example to produce hydrogen from ethanol includes: heating a 10 mol / L ethanol solution at 0.7 mL min -1 The flow rate of ethanol was transported to the vaporization chamber at 180°C by a peristaltic pump to evaporate and vaporize it. The vaporized ethanol vapor then entered the gas inlet on the end plate next to the anode plate, and then the electrocatalytic reaction was carried out in the high-temperature proton exchange membrane electrolyzer device at a temperature of 200°C, and the linear sweep voltammetry was used to scan 0~0.9 V. The hydrogen produced on the cathode side (0.3 V and 0.6 V) was analyzed by gas chromatography using a thermal conductivity detector (TCD), and the carbon dioxide produced on the anode side was analyzed by gas chromatography using a hydrogen flame ionization detector. The results are shown in Table 1.

[0040] Table 1 Hydrogen production rate and purity of Example 2 and Comparative Example 2

[0041] Comparative Example 3: The proton exchange membrane electrolyzer of this comparative example is different from that of Example 2 in that it does not have an anode thermal catalytic layer.

[0042] The process of using the proton exchange membrane electrolysis cell in this comparative example to produce hydrogen from ethanol includes: heating a 10 mol / L ethanol solution at 0.7 mL min -1The flow rate of ethanol was transported to the vaporization chamber at 180°C through a peristaltic pump to evaporate and vaporize it. The vaporized ethanol vapor then entered the air inlet on the end plate next to the anode plate, and then an electrocatalytic reaction was carried out in a high-temperature proton exchange membrane electrolyzer device at a temperature of 200°C. The linear sweep voltammetry method was used to scan 0~0.9 V, and the products at open circuit potential (OCV), 0.3 V, and 0.6 V were tested respectively. The hydrogen produced on the cathode side (0.3 V and 0.6 V) was analyzed by gas chromatography using a thermal conductivity detector, and the carbon dioxide produced on the anode side (0.3 V and 0.6 V) was analyzed by gas chromatography using a hydrogen flame ionization detector. The results of the acetaldehyde yield of the anode liquid product are shown in Figure 5 shown.

[0043] Comparative Example 4: The membrane electrode of this comparative example: the first anode catalyst layer, the second anode catalyst layer, the proton exchange membrane and the cathode catalyst layer are stacked in sequence, and hot pressed at 180°C and 1.0 MPa for 10 min. The catalyst in the first anode catalyst layer is 2.0 mg / cm 2 The carbon-supported ruthenium catalyst has a thickness of 60 μm and the catalyst in the second anode catalyst layer is 0.2 mg / cm 2 The carbon-supported palladium catalyst has a thickness of 6 μm, the proton exchange membrane is a phosphoric acid-doped polybenzimidazole membrane with a thickness of 40 μm, and the catalyst in the cathode catalyst layer is 1.0 mg / cm 2 The carbon-supported palladium catalyst has a thickness of 30 μm.

[0044] Assembling a proton exchange membrane electrolyzer: assembling a membrane electrode with an anode gas diffusion layer, a cathode gas diffusion layer, an anode plate, a cathode plate, and an end plate into a high-temperature proton exchange membrane electrolyzer device, wherein the assembled high-temperature proton exchange membrane electrolyzer comprises an end plate, an anode plate, an anode gas diffusion layer, a first anode catalyst layer, a second anode catalyst layer, a proton exchange membrane, a cathode electrocatalytic layer, a cathode gas diffusion layer, a cathode plate, and an end plate which are sequentially stacked; wherein the end plate close to the anode plate has an air inlet and an air outlet, and the end plate close to the cathode plate has an air outlet, the anode gas diffusion layer is made of hydrophobic carbon paper with a thickness of 251 μm, the cathode gas diffusion layer is made of hydrophobic carbon paper with a thickness of 254 μm, the anode plate is made of graphite carbon with a thickness of 0.43 cm, the cathode plate is made of graphite carbon with a thickness of 0.42 cm, and the end plate is made of titanium steel with a thickness of 1.4 cm.

[0045] Test method: 10 mol / L ethanol solution was stirred at 0.7 mL min -1The flow rate of ethanol is transported to the vaporization chamber at 180°C through a peristaltic pump to evaporate and vaporize it. The vaporized ethanol vapor then enters the air inlet on the end plate next to the anode plate, and then undergoes an electrocatalytic reaction in a high-temperature proton exchange membrane electrolyzer device at 200°C. Linear sweep voltammetry is used to scan 0~0.9 V, and the results are shown in Figure 4.

Claims

1. A membrane electrode device for producing hydrogen from ethanol, characterized in that: It comprises an anode gas diffusion layer, an anode thermal catalytic layer, an anode electrocatalytic layer, a proton exchange membrane, a cathode electrocatalytic layer and a cathode gas diffusion layer which are stacked in sequence, wherein the anode thermal catalytic layer is at least one of carbon nanotube-supported γ-alumina and carbon-supported γ-alumina.

2. A membrane electrode device for producing hydrogen from ethanol, characterized in that: The invention comprises an anode thermal catalytic layer, an anode gas diffusion layer, an anode electrocatalytic layer, a proton exchange membrane, a cathode electrocatalytic layer and a cathode gas diffusion layer which are stacked in sequence. The anode thermal catalytic layer is at least one of carbon nanotube-supported gamma-alumina and carbon-supported gamma-alumina.

3. The membrane electrode device for ethanol hydrogen production according to claim 1 or 2, characterized in that: The γ-alumina loading in the anode thermal catalyst layer is 0.1 mg cm -2 ~ 3 mg cm -2 .

4. The membrane electrode device for ethanol hydrogen production according to claim 1 or 2, characterized in that: The anode electrocatalytic layer includes at least one of carbon-supported platinum, carbon-supported palladium, carbon-supported ruthenium, and carbon-supported platinum-ruthenium; The cathode electrocatalyst includes at least one of carbon-supported platinum and carbon-supported palladium; The proton exchange membrane is a phosphoric acid-doped polymer membrane.

5. The membrane electrode device for ethanol hydrogen production according to claim 4, characterized in that: The noble metal loading in the anode electrocatalyst layer is 0.1 mg cm -2 ~ 3 mg cm -2 ; The noble metal loading in the cathode electrocatalyst layer is 0.1 mg cm -2 ~ 3 mg cm -2 .

6. A proton exchange membrane electrolyzer comprising a membrane electrode device as described in any one of claims 1 to 5.

7. A method for producing hydrogen from ethanol, characterized in that: Ethanol is prepared into hydrogen using the proton exchange membrane electrolysis cell as described in claim 6.

8. The method for producing hydrogen from ethanol as claimed in claim 7, characterized in that: The vaporized ethanol is placed in a proton exchange membrane electrolyzer for electrocatalytic reaction, and ethylene is obtained on the anode thermal catalytic layer. The ethylene enters the anode electrocatalytic layer under the blowing of ethanol gas and water vapor, and then hydrogen is obtained on the cathode electrocatalytic layer.

9. The method for producing hydrogen from ethanol as claimed in claim 8, characterized in that: The voltage of the electrocatalytic reaction is 0.3 V to 0.8 V.

10. The method for producing hydrogen from ethanol as claimed in claim 8, characterized in that: The temperature of the electrocatalytic reaction is 100°C to 240°C.

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