Electrochemical reactor and catalyst and preparation method and application thereof

Abstract

The application relates to the technical field of solid oxide electrolysis cells, and discloses an electrochemical reactor and a catalyst as well as a preparation method and application thereof. The electrochemical reactor comprises an anode, a cathode and an electrolyte layer arranged between the anode and the cathode, and is characterized in that the anode comprises an anode carrier, an anode catalyst and a binder, the cathode comprises a cathode carrier and a cathode catalyst, the main component of the anode carrier is gadolinium oxide doped cerium oxide, and the anode has a microchannel structure. The electrochemical reactor can be used for large-scale methane-to-ethane and methane-to-ethylene reactions, and the obtained ethane and ethylene products have high selectivity.

Description

Technical Field

[0001] This invention relates to the field of solid oxide electrolysis cell technology, specifically to an electrochemical reactor and catalyst, their preparation methods, and applications. Background Technology

[0002] Methane is a major component of carbon-based energy sources such as natural gas and biogas. With the development of resource exploration and extraction technologies, such as shale gas, methane prices have remained relatively low in recent years. However, in many oil fields, a significant amount of methane is still disposed of through direct combustion, resulting in substantial resource waste and carbon emissions. Therefore, it is necessary to seek efficient ways to convert methane into high-value-added chemicals. Ethylene, as a basic organic feedstock in the petrochemical industry, can be used to produce a variety of important bulk chemical products. If methane molecules can be efficiently converted into ethylene, it is expected that the chemical applications of methane and the efficient production of ethylene can be simultaneously realized, bringing significant economic and environmental benefits.

[0003] Currently, the main methods for converting methane to ethylene include direct cracking dehydrogenation and oxidative dehydrogenation. From a thermodynamic perspective, direct cracking dehydrogenation of methane to olefins can only be achieved at very high temperatures (1000-1200℃), resulting in high energy consumption and low olefin selectivity. To reduce energy consumption, an oxidant can be introduced into the system to promote the reaction. When CO2 is introduced as the oxidant, the reaction is a dry reforming (DRM) of methane (CH4 + 3CO2 → 4CO + 2H2O). The advantage of this reaction is that it can convert and utilize CO2, but it has a large endothermic effect (2.56 eV), a high reaction temperature (>900℃), a low equilibrium conversion rate (CH4 and CO2 equilibrium conversion rates are approximately 47.6% and 35.0%, respectively), many side reactions, and difficult product separation. Moreover, the ethylene selectivity is extremely low, mainly producing syngas, and the product value is not high. When O2 is introduced as the oxidant, the reaction is a methane oxidative dehydrogenation (MTO) of methane (2CH4 + O2 → C2H4 + 2H2O). The advantage of this reaction is that the reaction temperature can be reduced to below 850℃, and it can produce high-value-added ethylene. However, it is difficult to avoid the generation of CO2, a deep oxidation product, in this reaction.

[0004] The oxidative dehydrogenation (MTO) reaction of methane has not yet been industrialized, largely because the reaction system is extremely sensitive to oxygen levels. The oxygen content window for ethylene production is extremely narrow and difficult to control. Specifically, if the oxygen pressure in the reaction atmosphere is slightly high, both the reactant methane and the product ethylene may be over-oxidized, producing large amounts of deeply oxidized products (CO, CO2), reducing ethylene selectivity, increasing the exothermic reaction, making heat removal difficult, causing localized temperature runaway, and even potentially leading to combustion and explosion, posing a high risk to industrialization. Conversely, if the oxygen pressure in the reaction atmosphere is slightly low, the amount of lattice oxygen in the catalyst (generally containing transition metal oxides) will decrease, and the activity of lattice oxygen will also decrease, further hindering the already inert activation and conversion process of methane.

[0005] To solve the above problems, it is necessary to develop a new electrochemical reactor and a method for producing ethane and ethylene from methane. Summary of the Invention

[0006] The purpose of this invention is to overcome the problem of low selectivity of ethane and ethylene products in the large-scale reaction of methane to ethane and ethylene in existing electrochemical reactors, and to provide an electrochemical reactor and catalyst, as well as their preparation method and application.

[0007] To achieve the above objectives, a first aspect of the present invention provides an electrochemical reactor with the function of producing ethane and ethylene from methane. The electrochemical reactor includes an anode and a cathode and an electrolyte layer disposed between the anode and the cathode. The anode includes an anode support, an anode catalyst and a binder, and the cathode includes a cathode support and a cathode catalyst. The main component of the anode support is gadolinium oxide-doped cerium oxide, and the anode has a microchannel structure.

[0008] The second aspect of the present invention provides the application of the electrochemical reactor described in the first aspect of the present invention in the production of ethane and ethylene from methane.

[0009] A third aspect of the present invention provides a method for producing ethane and ethylene from methane, characterized in that the method includes, under electrolytic reaction conditions, introducing methane-containing gas into the anode of the electrochemical reactor described in the first aspect of the present invention, and collecting the resulting ethane and ethylene gases.

[0010] A fourth aspect of the present invention provides a catalyst, characterized in that the catalyst comprises an anolyte catalyst, gadolinium oxide-doped cerium oxide, and a binder; wherein the definitions of the anolyte catalyst and the binder correspond to the definitions described in the first aspect of the present invention.

[0011] The fifth aspect of the present invention provides a method for preparing a catalyst.

[0012] The sixth aspect of the present invention provides the application of the catalyst described in the fourth aspect of the present invention in an electrochemical reactor.

[0013] Through the above technical solution, the present invention has the following advantages and outstanding technical effects: The present invention proposes a novel solid oxide electrolytic cell anode, which has a microchannel porous anode, an electrolyte isolation layer, and a cathode support layer. This anode can form an electrolytic cell to realize the electrocatalytic oxidation of methane to ethane and ethylene, and has high selectivity for C2 products (including ethane and ethylene). Specifically, when the operating temperature is 850℃, the electrolysis voltage is 1.8V, and methane is electrolyzed on the anode side, the electrolysis current density can reach 250 mA·cm⁻¹. -2 The selectivity of C2 products in the anode gas products can reach 76.2%; when the operating temperature is 850℃, the electrolysis voltage is 2.5V, and methane is electrolyzed on the anode side, the electrolysis current density can reach 500mA·cm. -2 The selectivity of C2 products (including ethane and ethylene) in the anode gas products can reach 73.4%, which shows good prospects for industrial application. Attached Figure Description

[0014] Figure 1 This is a morphological image of the novel SOEC anode with a microchannel structure under an electron microscope.

[0015] Figure 2 This describes the elemental distribution in a novel SOEC anode with a microchannel structure.

[0016] Figure 3 It shows the cross-sectional morphology of a novel solid oxide electrolytic cell.

[0017] Figure 4 This describes the cross-sectional morphology and elemental distribution of a novel solid oxide electrolytic cell.

[0018] Figure 5 This is the transmission electron microscopy morphology and elemental distribution of the anode of the solid oxide electrolytic cell in Example 1.

[0019] Figure 6 The transmission electron microscope (TEM) morphology and elemental distribution of the anode of the solid oxide electrolytic cell in Comparative Example 1 are shown. Detailed Implementation

[0020] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] As previously stated, the first aspect of the present invention provides an electrochemical reactor with the function of producing ethane and ethylene from methane. The electrochemical reactor includes an anode and a cathode and an electrolyte layer disposed between the anode and the cathode. The anode is characterized in that it includes an anode support, an anode catalyst and a binder, the cathode includes a cathode support and a cathode catalyst, and the main component of the anode support is gadolinium oxide-doped cerium oxide (GDC). The anode has a microchannel structure.

[0022] The term "main component" refers to components that account for more than 80% of the total weight of the anode and cathode carriers, and generally more than 90%.

[0023] In some embodiments of the present invention, preferably, the closed-pore ratio of the microchannel structure of the anode is 0-4.5%, more preferably 0-1%.

[0024] In this invention, a closed hole refers to a hole that is not connected to the outside. The closed hole ratio is also called the closed hole rate, which is the ratio of the volume of the closed hole to the volume of the external appearance.

[0025] In this invention, the proportion of closed pores is measured using a nano-computed tomography (Nano CT) method.

[0026] GDC can be any commercially available gadolinium oxide-doped cerium oxide product, for example, the gadolinium oxide / cerium oxide weight ratio can be 10-25:100. Specifically, it can be the GDC provided by Ningbo Sofor Energy Technology Co., Ltd. 10 Brand name, GDC 20 The product is a graded product (particle size 0.5-3μm, purity >99.5%). This weight ratio range allows the synthesized anode and cathode supports to achieve moderate strength and excellent pore morphology.

[0027] In some embodiments of the present invention, preferably, the microchannel structure of the anode is a layered pore, and the aspect ratio of the pore cross-section is 1-15:1, preferably 1-8:1.

[0028] In this invention, the layered pores refer to parallel channels within the anode and cathode supports, with a nearly rectangular cross-sectional shape. A length-to-width ratio within the aforementioned range allows the electrochemical reactor to achieve improved selectivity for C2 and ethylene, as well as increased Faraday efficiency. The length and width of the channel cross-section can be obtained by scanning electron microscopy (SEM) or nano-computed tomography (NanoCT) of the anode / cathode supports.

[0029] In some embodiments of the present invention, preferably, the average length of the pore cross-section of the microchannel structure of the anode at the end away from the electrolyte layer is 2-260 micrometers, more preferably 2-180 micrometers; and the average width is 2-90 micrometers, more preferably 2-45 micrometers.

[0030] In some embodiments of the present invention, preferably, the average thickness of the pore wall of the microchannel structure is 0.1-10 micrometers, and more preferably 0.5-6 micrometers.

[0031] In this invention, the pore size and pore wall thickness are measured by scanning electron microscopy (SEM) or nano-computed tomography (Nano CT).

[0032] In this invention, the layered pores of the anode carrier and the cathode carrier can provide a certain mechanical strength and achieve self-support.

[0033] In some embodiments of the present invention, preferably, the content of the anode catalyst is 10-60 wt%, more preferably 20-50 wt%, based on the total mass of the anode.

[0034] In some embodiments of the present invention, preferably, the content of the anode carrier is 40-90 wt%, more preferably 50-80 wt%, based on the total mass of the anode.

[0035] In some embodiments of the present invention, preferably, the anode catalyst comprises rare earth elements, alkaline earth metal elements, group VIII elements, and oxygen elements, and more preferably includes La, Sr, Co, Fe, and O elements; more preferably, the anode catalyst is La. 1-x Sr x Co 1-y Fe y O 3-δ Where 0.1≤x≤0.5, 0.1≤y≤0.3, and 0≤δ≤0.5.

[0036] In some embodiments of the present invention, preferably, the cathode support is at least one selected from yttrium-stabilized zirconium oxide, gadolinium-doped cerium oxide, and lanthanum strontium gallium magnesium oxide (LSGM), and the cathode catalyst is NiO or La. 1-x Sr x Cr y Mn 1- y O 3-δ La 1–x Sr x FeO 3-δ and La 1-x Sr x TiO 3-δ At least one of the following, wherein 0≤x≤0.5, 0≤y≤0.1, 0≤δ≤0.5, and the content of cathode catalyst is 10-60wt% based on the total amount of the cathode.

[0037] In this invention, δ is the value required to satisfy the valence of elements other than oxygen atoms in the anode catalyst.

[0038] In some embodiments of the present invention, preferably, the binder is selected from at least one of alumina and silicon oxide.

[0039] In some embodiments of the present invention, preferably, the elements constituting the anode are evenly distributed.

[0040] In some embodiments of the present invention, preferably, the anode support and the anode catalyst exhibit a uniform distribution at the micron level.

[0041] In this invention, the uniform distribution of each element, the anode support, and the anode catalyst can be observed by transmission electron microscopy (TEM).

[0042] In order to obtain an anode with uniform distribution of various elements, in some embodiments of the present invention, preferably, the anode preparation method includes: mixing the anode support, the anode catalyst, the binder precursor and optional binder, and then freezing and calcining to obtain the anode.

[0043] In some embodiments of the present invention, preferably, the mixing is carried out in the presence of a solvent.

[0044] In some embodiments of the present invention, preferably, the solvent is water.

[0045] In some embodiments of the present invention, preferably, the mass ratio of the anode catalyst to the anode support is 1:0.5-2, and more preferably any value or a range of any two values ​​among 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 and 1:2.

[0046] In this invention, the chemical structures of the anode catalyst and the GDC can be characterized by XRD patterns; their contents can be determined by X-ray photoelectron spectroscopy.

[0047] In some embodiments of the present invention, preferably, the mass ratio of the anode carrier to the binder precursor is 5-20:1, for example, it can be any value or a range of any two values ​​among 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1 and 20:1.

[0048] In some embodiments of the present invention, preferably, the binder precursor is selected from sodium aluminosilicate and / or magnesium aluminum silicate.

[0049] In some embodiments of the present invention, preferably, the mass ratio of the anode catalyst to the binder precursor is 5-20:1, for example, it can be any value or a range of any two values ​​among 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1 and 20:1.

[0050] Preferably, the mass ratio of the adhesive additive to the adhesive precursor is 0-10:1;

[0051] Preferably, the adhesive is selected from at least one of sodium polyacrylate, triethanolamine, polyvinylpyrrolidone, and polyvinyl butyral, more preferably a composition of adhesive in which the weight ratio of sodium polyacrylate, triethanolamine, and polyvinylpyrrolidone is 1-5:0-3:1, and even more preferably 2-5:0.25-3:1.

[0052] In some embodiments of the present invention, preferably, the mixing method includes at least one of stirring, ultrasonic mixing, and ball milling. The ultrasonic conditions are 1000W continuous ultrasonication for 15 minutes, and the ball milling conditions are 300r / min continuous unidirectional ball milling.

[0053] According to a preferred embodiment of the present invention, the method for preparing the anode includes: first mixing the anode support and the anode catalyst, then adding a portion of the binder (such as sodium polyacrylate or triethanolamine) to the mixed system and sonicating it, then adding a binder precursor and the remaining binder (such as polyvinylpyrrolidone) to the sonicated system, ball milling, freezing, and calcining to obtain the anode.

[0054] In some embodiments of the present invention, preferably, the mass ratio of a portion of the adhesive to the remaining portion of the adhesive is 2-10:1.

[0055] In some embodiments of the present invention, preferably, the freezing includes pre-freezing and vacuum freeze-drying.

[0056] In some embodiments of the present invention, preferably, the pre-freezing temperature is -100 to -10°C, for example, it can be any value or a range of any two values ​​among -100°C, -90°C, -80°C, -70°C, -60°C, -50°C, -40°C, -30°C, -20°C, and -10°C.

[0057] In some embodiments of the present invention, preferably, the pre-freezing time is 6-24 hours.

[0058] In some embodiments of the present invention, preferably, the temperature of the vacuum freeze drying is -100 to -10°C, for example, it can be any value or a range of any two values ​​among -100°C, -90°C, -80°C, -70°C, -60°C, -50°C, -40°C, -30°C, -20°C, and -10°C.

[0059] In some embodiments of the present invention, preferably, the vacuum freeze-drying time is 6-24 hours.

[0060] In some embodiments of the present invention, preferably, the calcination temperature is 1000-1500℃, for example, it can be any value or a range of any two values ​​among 1000℃, 1050℃, 1100℃, 1200℃, 1300℃, 1400℃ and 1500℃.

[0061] In some embodiments of the present invention, preferably, the calcination time is 1-6 hours.

[0062] In some embodiments of the present invention, preferably, the electrolyte layer is composed of yttrium oxide-doped zirconium oxide, and the porosity of the electrolyte layer is <5%.

[0063] In this invention, the porosity is the ratio of the number of through pores to the total number of pores, which is measured by a nano-computed tomography (Nano CT) scanner.

[0064] In this invention, the cathode support is a mixture of NiO and yttrium oxide-doped zirconium oxide in a mass ratio of approximately 1:0.5-2. This cathode support and the electrolyte layer (collectively referred to as a half-cell) can be commercially available from Ningbo Sofor Energy Technology Co., Ltd.

[0065] The second aspect of the present invention provides the application of the electrochemical reactor described in the first aspect of the present invention in the production of ethane and ethylene from methane.

[0066] A third aspect of the present invention provides a method for producing ethane and ethylene from methane, characterized in that the method includes, under electrolytic reaction conditions, introducing methane-containing gas into the anode of the electrochemical reactor described in the first aspect of the present invention, and collecting the resulting ethane and ethylene gases.

[0067] In some embodiments of the present invention, preferably, the electrolysis reaction conditions include: a temperature of 600-900℃ and a gas flow rate of 10-200 mL / min / cm. 2 The current density is 10-1000 mA / cm² 2 .

[0068] A fourth aspect of the present invention provides a catalyst, characterized in that the catalyst comprises an anolyte catalyst, gadolinium oxide-doped cerium oxide, and a binder;

[0069] The definitions of the anode catalyst and the binder are the same as those described in the first aspect of this invention.

[0070] A fifth aspect of this invention provides a method for preparing a catalyst, characterized in that the method comprises: mixing an anode support, an anode catalyst, a binder precursor, and an optional binder, and sequentially subjecting the mixture to freezing and calcination to obtain the anode. The anode support, anode catalyst, binder precursor, binder, operating conditions, etc., are as described above and will not be repeated here.

[0071] The sixth aspect of the present invention provides the application of the catalyst described in the fourth aspect of the present invention in an electrochemical reactor.

[0072] In some embodiments of the present invention, preferably, the method for preparing the electrochemical reactor includes: bonding the anode and the half-cell together with an adhesive, and then calcining to obtain the electrochemical reactor.

[0073] In this invention, the method for preparing the binder used in the electrochemical reactor may include: using La 1- x Sr x Co 1-y Fe y O 3-δ The binder is obtained by mixing GDC, terpineol and ethyl cellulose and ball milling.

[0074] In this invention, a half-cell refers to a structure that includes an electrolyte layer and a cathode (including a mixture of ceramic components and a cathode catalyst). Compared to the finished battery product (i.e., an electrochemical reactor), it lacks an anode portion (i.e., an anode support and an anode catalyst supported on the anode support), hence the name half-cell.

[0075] In this invention, there is no particular limitation on the amount of terpineol and ethyl cellulose used, as long as the amount of La is sufficient to achieve the desired effect. 1-x Sr x Co 1-y Fe y O 3-δ The effect of bonding with GDC is sufficient.

[0076] In some embodiments of the present invention, preferably, the half-cell is a mixture of NiO and yttrium oxide-doped zirconium oxide in a mass ratio of approximately 1:0.5-2. The cathode support and electrolyte layer (collectively referred to as the half-cell) can be commercially available from Ningbo Sofor Energy Technology Co., Ltd.

[0077] In this invention, the bonding pressure is 1-50 kPa and the time is 0.5-24 h.

[0078] In some embodiments of the present invention, preferably, the calcination temperature during the preparation of the electrochemical reactor is 1000-1500°C, for example, any value or a range of any two values ​​among 1000°C, 1050°C, 1100°C, 1200°C, 1300°C, 1400°C and 1500°C.

[0079] In some embodiments of the present invention, preferably, the calcination time during the preparation of the electrochemical reactor is 1-6 hours.

[0080] The present invention will be described in detail below through examples. In the following examples, in the present invention, ethylene selectivity (%) = 2 × total yield of ethane and ethylene (moles) / methane consumption (moles) × 100%; GDC is GDC produced by Ningbo Sofor Energy Technology Co., Ltd. 10 For commercially available products of this grade, the weight ratio of gadolinium oxide to cerium oxide is 10:90; La 1- x Sr x Co 1-y Fe y O 3-δ Commercially available products (La) manufactured by Ningbo Sofor Energy Technology Co., Ltd. 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ The raw materials used were: (particle size 0.5-3 μm, purity >99.5%); triethanolamine (commercially available from INNOCHEM); sodium polyacrylate (commercially available from INNOCHEM); sodium metasilicate (commercially available from INNOCHEM); polyvinylpyrrolidone carboxymethyl cellulose (commercially available from INNOCHEM); unless otherwise specified, all other raw materials and equipment were commercially available. Ultrasonication was performed at 1000W for 15 minutes, and ball milling was performed at 300 rpm for continuous unidirectional ball milling.

[0081] Preparation Example 1

[0082] Weigh out 2.9g of La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ2.9g GDC was mixed with 10g water. Then, 0.05g sodium polyacrylate and 0.005g triethanolamine were added to the solution, and the mixture was stirred for 30 minutes to ensure thorough mixing. The mixture was then ultrasonically treated (power set at 1000W) for 15 minutes to further refine the powder. Next, 0.2g sodium metasilicate and 0.01g polyvinylpyrrolidone were added to the mixture under magnetic stirring, followed by ball milling to obtain a slurry. The slurry was poured into a cryogenic mold and pre-frozen at -60℃ to solidify it. It was then transferred to a vacuum freeze dryer and dried for 12 hours to obtain the anode precursor. The anode precursor was calcined at 1200℃ for 2 hours to obtain a novel solid oxide electrolytic cell anode.

[0083] The closed-pore ratio of the microchannel structure is 0.1%.

[0084] The average length-to-width ratio of the channel cross-section is 5:1.

[0085] The average length of the pore cross-section at the end of the microchannel structure furthest from the electrolyte layer is 20 micrometers, and the average width is 4 micrometers.

[0086] The average wall thickness of the microchannel structure is 4 micrometers.

[0087] The morphology of the anode of the novel solid oxide electrolytic cell was tested using electron microscopy, and the results are as follows: Figure 1 As shown. By Figure 1 As can be seen, the anode body possesses a microchannel structure with an average pore diameter of approximately 20 micrometers and a pore wall thickness of approximately 2.5 micrometers. EDS analysis was used to determine the elemental distribution within the pore walls of the novel solid oxide electrolytic cell anode, and the results are as follows: Figure 2 As shown. By Figure 2 As can be seen, in the pore wall portion, the two main components of the electrode, LSCF (La, Sr, and Fe elements in the figure) and GDC (Ce and Gd elements in the figure), are uniformly distributed without obvious element enrichment areas.

[0088] Preparation Example 2

[0089] Weigh out 2.9g of La 0.9 Sr 0.1 Co 0.9 Fe 0.1 O 3-δ2.9g GDC was mixed with 10g water. Then, 0.055g sodium polyacrylate and 0.055g triethanolamine were added to the solution, and the mixture was stirred for 30 minutes to ensure thorough mixing. The mixture was then ultrasonically treated (power set at 1000W) for 15 minutes to further refine the powder. Next, 0.25g sodium metasilicate and 0.02g polyvinylpyrrolidone were added to the mixture under magnetic stirring, followed by ball milling to obtain a slurry. The slurry was poured into a cryogenic mold and pre-frozen at -50℃ to solidify it. It was then transferred to a vacuum freeze dryer and dried for 12 hours to obtain the anode precursor. The anode precursor was calcined at 1250℃ for 5 hours to obtain a novel solid oxide electrolytic cell anode.

[0090] The closed-pore ratio of the microchannel structure is 0.2%.

[0091] The average length-to-width ratio of the channel cross-section is 6:1.

[0092] The average length of the cross-section of the microchannel structure at the end furthest from the electrolyte layer is 30 micrometers, and the average width is 5 micrometers.

[0093] The average wall thickness of the microchannel structure is 3 micrometers.

[0094] Preparation Example 3

[0095] Weigh out 3g of La 0.5 Sr 0.5 Co 0.5 Fe 0.5 O 3-δ 3g of GDC and 10g of water were mixed, followed by the addition of 0.05g of sodium polyacrylate and 0.005g of triethanolamine. The mixture was stirred for 30 minutes to ensure thorough mixing, and then ultrasonically treated (at a power of 1000W) for 15 minutes to further refine the powder. Next, 0.3g of sodium metasilicate and 0.02g of polyvinylpyrrolidone were added to the mixture under magnetic stirring, followed by ball milling to obtain a slurry. The slurry was poured into a cryogenic mold and pre-frozen at -55℃ to solidify it. It was then transferred to a vacuum freeze dryer and dried for 10 hours to obtain the anode precursor. The anode precursor was calcined at 1180℃ for 2 hours to obtain a novel solid oxide electrolytic cell anode.

[0096] The closed-pore ratio of the microchannel structure is 0.8%.

[0097] The average length-to-width ratio of the channel cross-section is 3:1.

[0098] The average length of the pore cross-section at the end of the microchannel structure furthest from the electrolyte layer is 30 micrometers, and the average width is 10 micrometers.

[0099] The average wall thickness of the microchannel structure is 2 micrometers.

[0100] Example 1

[0101] Weigh out 0.5g of La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ 0.5g GDC, 0.05g ethyl cellulose, and 1g terpineol were mixed and ball-milled at 80 rpm for 1 hour to prepare a binder. A suitable amount of the binder was then applied to the surface of the half-cell (the half-cell was purchased from Hydrogen Power Technology Co., Ltd.) using a brush. The anode prepared in Example 1 was then placed on the surface of the half-cell, and a pressure of 10 kPa was applied to the anode surface for 2.5 hours to allow the anode and half-cell to initially adhere, forming a full cell. The full cell was then sintered at 1300°C to obtain the electrochemical reactor C1.

[0102] The electrochemical reactor in this embodiment includes:

[0103] Electrolyte layer: 8% yttrium oxide-doped zirconium oxide (8YSZ), which has a dense structure and a porosity of <5%;

[0104] Based on the total mass of the anode, the content of the anode catalyst is 50 wt%.

[0105] Based on the total mass of the anode, the content of the anode carrier is 50 wt%.

[0106] The cross-sectional morphology of the novel solid oxide electrolytic cell was tested using scanning electron microscopy, and the results are as follows: Figure 3 As shown in the electron microscope image, from left to right, a loose and porous cathode region (composed of a mixture of NiO and 8YSZ with a mass ratio of approximately 1:1), a dense electrolyte region (approximately 10 micrometers thick and composed of 8YSZ), and a loose and porous anode region are visible.

[0107] The cross-sectional morphology and elemental distribution of the novel solid oxide electrolytic cell were tested using EDS, and the results are as follows: Figure 4 As shown. From Figure 4The electron image shows a porous cathode region, a dense electrolyte region (approximately 10 micrometers thick), and a porous anode region, visible from left to right. Combined with the energy dispersive spectroscopy (EDS) distribution, the main metallic components of the porous cathode region on the far left are Ni and Zr; the dense electrolyte region in the middle consists of two layers: a Zr-dominated YSZ layer and a Ce-dominated GDC layer; the porous anode region on the right is a microchannel structure anode region, with GDC (based on Ce) and LSCF (based on La and Fe) uniformly distributed on its pore walls.

[0108] The elemental distribution in the anode microchannel region of a novel solid oxide electrolytic cell was magnified and tested using transmission electron microscopy (TEM). The results are as follows: Figure 5 As shown. From Figure 5 In the electronic images, the GDC crystalline region of the anode support and the La anode catalyst are visible, respectively. 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ Both types of crystalline regions exhibit a uniform distribution at the micrometer level, and interfaces can be seen between different crystalline regions.

[0109] Example 2

[0110] Weigh 0.6g La 0.9 Sr 0.1 Co 0.9 Fe 0.1 O 3-δ 0.4 g GDC, 0.05 g ethyl cellulose, and 1 g terpineol were mixed and ball-milled at 80 rpm for 1 hour to prepare a binder. A suitable amount of the binder was then applied to the surface of the half-cell (the half-cell was purchased from Hydrogen Power Technology Co., Ltd., and the composition and content of the cathode and electrolyte were the same as in Example 1) using a brush. The anode prepared in Example 2 was then placed on the surface of the half-cell, and a pressure of 15 kPa was applied to the anode surface for 5 hours to allow the anode to initially adhere to the half-cell, forming a full cell. The full cell was then sintered at 1280 °C to obtain the electrochemical reactor C2.

[0111] The electrochemical reactor in this embodiment includes:

[0112] Electrolyte layer: 8% yttrium oxide-doped zirconium oxide (8YSZ), which has a dense structure and a porosity of <5%;

[0113] Based on the total mass of the anode, the content of the anode catalyst is 50 wt%.

[0114] Based on the total mass of the anode, the content of the anode carrier is 50 wt%.

[0115] Example 3

[0116] Weigh out 0.4g of La 0.5 Sr 0.5 Co 0.5 Fe 0.5 O 3-δ 0.6 g GDC, 0.045 g ethyl cellulose, and 1.05 g terpineol were mixed and ball-milled at 80 rpm for 1 hour to prepare a binder. A suitable amount of the binder was then applied to the surface of the half-cell (the half-cell was purchased from Hydrogen Power Technology Co., Ltd., and the composition and content of the cathode and electrolyte were the same as in Example 1) using a brush. The anode prepared in Example 3 was then placed on the surface of the half-cell, and a pressure of 12 kPa was applied to the anode surface for 3 hours to allow the anode to initially adhere to the half-cell, forming a full cell. The full cell was then sintered at 1260 °C to obtain the electrochemical reactor C3.

[0117] The electrochemical reactor in this embodiment includes:

[0118] Electrolyte layer: 8% yttrium oxide-doped zirconium oxide (8YSZ), which has a dense structure and a porosity of <5%;

[0119] Based on the total mass of the anode, the content of the anode catalyst is 50 wt%.

[0120] Based on the total mass of the anode, the content of the anode carrier is 50 wt%.

[0121] Example 4

[0122] An electrochemical reactor was prepared according to the method of Example 1, except that La was used. 0.6 Sr 0.4 MnO 3-δ Replace La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ Electrochemical reactor C4 was obtained.

[0123] Example 5

[0124] An electrochemical reactor was prepared according to the method of Example 1, except that the La was adjusted. 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ The mass ratio of GDC to GDC is 6:4, resulting in electrochemical reactor C5.

[0125] Comparative Example 1

[0126] 6g of GDC powder was weighed and mixed with 10mL of water. Then, 2 drops of concentrated ammonia were added to adjust the pH to 9. Next, under magnetic stirring, 0.18g of sodium polyacrylate, 0.12g of polyvinylpyrrolidone, 0.5g of polyacrylamide binder, 0.3g of polyaluminum chloride, 0.25g of polyferric sulfate, and 0.45g of magnesium aluminum silicate were added to the mixed solution. The mixture was stirred thoroughly and then treated in an ultrasonic cleaner for 1.5h. The slurry was then transferred to a ball mill and ball-milled for 2.5h to obtain a mixed slurry. The mixed slurry was poured into a low-temperature constant-temperature reactor and pre-frozen at -45℃ for 1.5h to form the slurry. Then, under frozen conditions, it was transferred to a vacuum freeze dryer and freeze-dried under vacuum at -60℃ and 1.0Pa for 14h to obtain a porous GDC anode framework preform with a microchannel structure. The microchannel porous anode skeleton green body was subjected to high-temperature calcination at 1150℃ (2 hours) and thinning treatment to obtain the microchannel porous GDC anode skeleton.

[0127] 10g of terpineol and 0.6g of ethyl cellulose were weighed and thoroughly mixed. The mixture was then placed in an oven overnight to allow the ethyl cellulose to completely dissolve in the terpineol, resulting in a composite binder. 5g of the composite binder and 6g of GDC fine powder were weighed into a mortar and ground thoroughly for 1 hour to obtain a white, fluid GDC binder slurry. An appropriate amount of this GDC binder slurry was coated onto the surface of a half-cell (the half-cell was purchased from Hydrogen Power Technology Co., Ltd.). The microchannel porous GDC anode framework prepared in Preparation Example 1 was pressed onto the electrolyte GDC side of the half-cell (a circular surface with a diameter of 1.8cm), and a certain amount of mechanical pressure was applied to ensure that the porous GDC anode framework and the electrolyte interface were fully bonded. Subsequently, it was transferred to a muffle furnace and calcined at 1400℃ for 2 hours to obtain the electrolytic cell framework.

[0128] Preparation of electrochemical reactors:

[0129] According to the molecular formula La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ According to stoichiometric ratios, 0.03 mol of lanthanum nitrate, 0.02 mol of strontium nitrate, 0.04 mol of cobalt nitrate, and 0.01 mol of ferric nitrate were weighed and dissolved in 100 mL of deionized water to obtain an anode catalyst precursor solution. An appropriate amount of the anode catalyst precursor solution was impregnated into a porous GDC anode framework using a pipette, and then calcined at 800 °C for 2 hours. The above impregnation-sintering steps were repeated until La... 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δWhen the anode catalyst loading reaches 25% of the total anode mass, an electrochemical reactor D1 containing a microchannel anode is obtained. The XRD pattern demonstrates that La... 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ The anode catalyst has a perovskite structure, and the porosity of the microchannel structure of the anode support is 45%; the thickness of the anode catalyst support layer is approximately 230 nm.

[0130] The closed-pore ratio of the microchannel structure is 0.2%.

[0131] The average length-to-width ratio of the channel cross-section is 5:1.

[0132] The average pore diameter of the microchannel structure at the end furthest from the electrolyte layer is 25 micrometers in the length direction and 5 micrometers in the width direction.

[0133] The average wall thickness of the microchannel structure is 3 micrometers.

[0134] As can be seen from the transmission electron microscopy image, the anode support composition (GDC) and the anode catalyst composition (La) are different. 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ The anode is not uniformly distributed; instead, a complete layer of anode catalyst is loaded onto the anode support surface. Therefore, only the catalyst component is exposed on the anode surface, while the anode support component is not exposed. Figure 6 ).

[0135] Comparative Example 2

[0136] The electrochemical reactor was prepared using the same method as in Example 1, except that the anode and cathode were commercially available products (the anode was La from Ningbo Sofor Energy Technology Co., Ltd.). 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ -GDC mixed powder (the cathode is nickel suboxide powder from Ningbo Sofor Energy Technology Co., Ltd.) neither has a microchannel structure, but a sponge-like porous structure, thus obtaining electrochemical reactor D2.

[0137] Comparative Example 3

[0138] An electrochemical reactor was fabricated using the same method as in Example 1, except that the anode and cathode supports were yttrium-stabilized zirconium oxide (YSZ, purchased from Tosoh Corporation, Japan, grade 8Y), meaning that the main component was yttrium-stabilized zirconium oxide instead of gadolinium-doped cerium oxide, resulting in electrochemical reactor D3.

[0139] Comparative Example 4

[0140] An electrochemical reactor was fabricated using the same method as in Example 1, except that the anode was prepared by conventional screen printing and had a conventional porous structure instead of a microchannel structure, resulting in electrochemical reactor D4.

[0141] Test Example 1

[0142] A hydrogen / carbon dioxide mixture (volume ratio 1:3, total flow rate 20 mL / min) was introduced into the cathode of each electrochemical reactor described in the embodiments and comparative examples; pure methane gas (flow rate 20 mL / min) was introduced into the anode. At 850 °C, with an electrolysis voltage of 2.05 V, the electrolysis current density reached 250 mA·cm⁻¹. -2 Under these conditions, an electrolysis reaction was carried out, and the exhaust gas generated at the anode was collected using a gas bag. The composition of the gas was analyzed by chromatography, and the results are shown in Table 1.

[0143] Table 1

[0144]

[0145]

[0146] As can be seen from the results in Table 1, compared with the comparative example, the electrochemical reactor prepared by the embodiment of the present invention has the beneficial effect of higher C2 (including ethane and ethylene) selectivity in the reaction of methane to ethane and ethylene. Compared with the reaction conditions of low methane concentration and high gas flow rate (e.g., methane flow rate of 2 mL / min and nitrogen flow rate of 72 mL / min), the present invention is more suitable for the reaction of methane to ethane and ethylene under the reaction conditions of high methane concentration and low gas flow rate (e.g., pure methane with a flow rate of 20 mL / min).

[0147] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An electrochemical reactor with the function of producing ethane and ethylene from methane, the electrochemical reactor comprising an anode and a cathode and an electrolyte layer disposed between the anode and the cathode, characterized in that, The anode includes an anode support, an anode catalyst, and a binder, and the cathode includes a cathode support and a cathode catalyst. The main component of the anode support is gadolinium oxide-doped cerium oxide, and the anode has a microchannel structure.

2. The electrochemical reactor according to claim 1, wherein, The closed-pore ratio of the microchannel structure of the anode is 0-4.5%, preferably 0-1%.

3. The electrochemical reactor according to claim 1 or 2, wherein, The microchannel structure of the anode consists of layered pores, and the aspect ratio of the pore cross-section is 1-15:1, preferably 1-8:

1.

4. The electrochemical reactor according to any one of claims 1-3, wherein, The average length of the pore cross-section of the microchannel structure of the anode at the end away from the electrolyte layer is 2-260 micrometers, preferably 2-180 micrometers; the average width is 2-90 micrometers, preferably 2-45 micrometers.

5. The electrochemical reactor according to any one of claims 1-4, wherein, The average wall thickness of the microchannel structure is 0.1-10 micrometers, preferably 0.5-6 micrometers.

6. The electrochemical reactor according to any one of claims 1-5, wherein, Based on the total mass of the anode, the content of the anode catalyst is 10-60 wt%, preferably 20-50 wt%. And / or, based on the total mass of the anode, the content of the anode carrier is 40-90 wt%, preferably 50-80 wt%.

7. The electrochemical reactor according to any one of claims 1-6, wherein, The anode catalyst comprises rare earth elements, alkaline earth metal elements, group VIII elements, and oxygen elements, preferably including La, Sr, Co, Fe, and O elements; more preferably, the anode catalyst is La. 1-x Sr x Co 1-y Fe y O 3-δ Where 0.1≤x≤0.5, 0.1≤y≤0.3, and 0≤δ≤0.5; And / or, the binder is selected from at least one of alumina and silicon dioxide; And / or, the anode support and the anode catalyst exhibit a uniform distribution at the micron level; And / or, the method for preparing the anode includes: mixing the anode support, the anode catalyst, the binder precursor and optional binder, and then sequentially freezing and calcining to obtain the anode.

8. The electrochemical reactor according to any one of claims 1-7, wherein, The cathode support is at least one selected from yttrium-stabilized zirconium oxide, gadolinium-doped cerium oxide, and lanthanum strontium gallium magnesium oxide (LSGM), and the cathode catalyst is NiO or La. 1-x Sr x Cr y Mn 1-y O 3-δ La 1–x Sr x FeO 3-δ and La 1-x Sr x TiO 3-δ At least one of the following, wherein 0≤x≤0.5, 0≤y≤0.1, 0≤δ≤0.5, and the content of cathode catalyst is 10-60wt% based on the total amount of the cathode.

9. The electrochemical reactor according to claim 7 or 8, wherein, The mixing method includes at least one of stirring, ultrasonic mixing, and ball milling; Preferably, the mass ratio of the anode catalyst to the anode support is 1:0.5-2; Preferably, the mass ratio of the anode carrier to the binder precursor is 5-20:1; Preferably, the binder precursor is selected from sodium aluminosilicate and / or magnesium aluminum silicate; Preferably, the mass ratio of the anode catalyst to the binder precursor is 5-20:1; Preferably, the mass ratio of the adhesive additive to the adhesive precursor is 0-10:1; Preferably, the adhesive is selected from at least one of sodium polyacrylate, triethanolamine, polyvinylpyrrolidone, and polyvinyl butyral, and more preferably, it is an adhesive composition in which the weight ratio of sodium polyacrylate, triethanolamine, and polyvinylpyrrolidone is 1-5:0-3:

1. Preferably, the freezing includes pre-freezing and vacuum freeze-drying; Preferably, the pre-freezing temperature is -100 to -10°C; Preferably, the pre-freezing time is 6-24 hours; Preferably, the temperature for vacuum freeze drying is -100 to -10°C; Preferably, the vacuum freeze-drying time is 6-24 hours; Preferably, the calcination temperature is 1000-1500℃; Preferably, the calcination time is 1-6 hours; Preferably, the electrolyte layer is composed of yttrium oxide-doped zirconium oxide, and the porosity of the electrolyte layer is <5%.

10. The application of the electrochemical reactor according to any one of claims 1-9 in the production of ethane and ethylene from methane.

11. A method for producing ethane and ethylene from methane, characterized in that, The method includes, under electrolytic reaction conditions, introducing methane-containing gas into the anode of the electrochemical reactor according to any one of claims 1-9, and collecting the resulting ethane and ethylene gases.

12. The method according to claim 11, wherein, The electrolysis reaction conditions include: a temperature of 600-900℃ and a gas flow rate of 10-200 mL / min / cm². 2 The current density is 10-1000 mA / cm² 2 .

13. A catalyst, characterized in that, The catalyst comprises an anode catalyst, gadolinium oxide-doped cerium oxide, and a binder; The definitions of the anode catalyst and the binder are the same as those in any one of claims 1-9.

14. A method for preparing a catalyst, characterized in that, The method includes: mixing an anode support, an anode catalyst, a binder precursor, and an optional binder, and then sequentially freezing and calcining the mixture to obtain the anode; The definitions of the anode support, anode catalyst, binder precursor, and binder aid are the same as those in any one of claims 1-9.

15. The method according to claim 14, wherein, The mixing method includes at least one of stirring, ultrasonic mixing, and ball milling; Preferably, the freezing includes pre-freezing and vacuum freeze-drying; Preferably, the pre-freezing temperature is -100 to -10°C; Preferably, the pre-freezing time is 6-24 hours; Preferably, the temperature for vacuum freeze drying is -100 to -10°C; Preferably, the vacuum freeze-drying time is 6-24 hours; Preferably, the calcination temperature is 1000-1500℃; Preferably, the calcination time is 1-6 hours.

16. The use of the catalyst of claim 13 in an electrochemical reactor.

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