CN111029595A

CN111029595A - Preparation method of solid oxide fuel cell catalyst

Info

Publication number: CN111029595A
Application number: CN201911335397.9A
Authority: CN
Inventors: 赵凯; 陈旻; 陈东初; 徐庆; 程刚
Original assignee: Foshan University
Current assignee: Foshan University
Priority date: 2019-12-23
Filing date: 2019-12-23
Publication date: 2020-04-17

Abstract

The invention relates to a preparation method of a solid oxide fuel cell catalyst, in particular to a catalyst which takes nickel molybdenum as a metal component and high-performance nano Ce_1‑yCa_yO_2‑δMetal-ceramic type Ni as carrier_1‑xMo_x/Ce_1‑yCa_yO_2‑δPreparation method of SOFC anode catalyst. The anode catalyst has excellent catalytic action on complex hydrocarbon fuels (such as gaseous alkanes such as methane, methanol, ethanol, propane and the like and liquid alkanes such as gasoline and the like), and can efficiently catalyze and convert the hydrocarbons into H-rich hydrocarbons₂And CO-rich fuel gas for providing H for electrochemical reaction of SOFC anode₂And CO reaction gas, so that the electrochemical reaction rate of the anode is accelerated, and the electrochemical performance of the SOFC single cell is improved.

Description

Preparation method of solid oxide fuel cell catalyst

Technical Field

The invention relates to the technical field of solid oxide fuel cells, in particular to a solid oxide fuel cell catalyst and a preparation method thereof, an anode of a solid oxide fuel cell containing the catalyst and the solid oxide fuel cell containing the catalyst.

Background

Solid Oxide Fuel Cells (SOFC) are a new type of energy conversion device. The energy-saving device can convert chemical energy in fuel into electric energy through an electrochemical approach, and has the advantages of high energy conversion efficiency, safety, environmental friendliness and the like. The SOFC adopts functional ceramic oxide as a cell component, has the working temperature of 500-800 ℃, and belongs to a medium-high temperature fuel cell. In this operating temperature range, SOFCs can not only generate electricity using conventional hydrogen fuels, but also inexpensive, readily available hydrocarbons (e.g., natural gas, town gas, gasoline) as their fuels for generating electricity.

Compared with the traditional hydrogen fuel SOFC system, the gasoline fuel SOFC system has the advantages of higher energy density, lower energy cost and the like, and is an important direction for the development of the SOFC technology. However, when the SOFC uses a complex hydrocarbon fuel such as gasoline, the activation energy of the complex hydrocarbon fuel directly undergoing an electrochemical oxidation reaction at the SOFC anode is high, the anode polarization resistance is large, and the cell output power density is low. Meanwhile, the surface of the anode catalyst is easy to generate carbon deposition, so that the performance of the battery is rapidly degraded. In order to ensure the stable operation of the SOFC system, an anode catalyst is carried on the surface of the SOFC anode, so that complex hydrocarbon fuel is catalytically converted into simple H₂And CO mixed gas, thereby improving the output power density and stability of the battery system.

Currently, anode catalysts containing noble metal elements such as Pt, Ru, Rh, Pd and the like are commonly used for the catalysis of complex hydrocarbon fuels to improve the catalytic conversion efficiency and improve the H content in reformed gas₂And the content of CO. For example, CN1428292 discloses a method of using RuO₂An anode catalyst for preparing hydrogen from gasoline. RuO at 780-900 deg.C₂The catalytic conversion rate of the base anode catalyst to gasoline fuel reaches up to 90 percent, and H₂The selectivity of CO and CO is up to 1.6-2.0 mol (H)₂+CO)/mol C<Refers to H produced by catalytic reaction₂And the sum of the total number of moles of CO and the input liquidRatio of moles of C in the gaseous fuel>And excellent catalytic activity is shown. However, the anode catalyst needs to catalyze the decomposition of the hydrocarbon fuel at a high temperature (780-900 ℃), and cannot be matched with the working temperature of the currently developed medium-low temperature SOFC (the working temperature range of the medium-low temperature SOFC is 500-750 ℃). Meanwhile, the adoption of the anode catalyst containing noble metal elements can obviously improve the preparation cost of the SOFC and is not beneficial to the commercial application of the SOFC.

A metallic nickel (Ni) -based anode catalyst is a representative inexpensive metal anode catalyst. It has a catalytic effect on complex hydrocarbon fuel reactions over the operating temperature range of SOFCs. However, the carbon deposition phenomenon of the metallic Ni-based anode catalyst during the catalytic reaction is an important cause of rapid deterioration of the performance of the anode catalyst and deactivation of the anode catalyst. To solve this problem, CN105377426A discloses a Ni/CGO and Ni-Ru/CGO<CGO is Gd-doped CeO₂>The diesel oil prereforming anode catalyst improves the carbon deposition resistance of the Ni-based anode catalyst by utilizing the oxygen ion conduction and the surface exchange performance of CGO. The anode catalyst can be used for catalytically converting diesel type liquid alkane into methane-rich hydrocarbon gas and providing hydrocarbon fuel for the SOFC. The relative content of Ni and a Carrier (CGO) in the Ni/CGO anode catalyst is optimized to inhibit the carbon deposition process in the catalytic reaction; the addition of Ru to the anode catalyst is beneficial to improving the conversion rate (methane yield) of diesel alkane and obtaining more excellent catalytic performance. However, the methane-rich hydrocarbon gas obtained by Ni-Ru/CGO catalysis still needs to be subjected to further catalytic reforming reaction to convert the methane-rich gas into H₂And CO to accelerate the anode electrochemical reaction of the SOFC. Therefore, the Ni-Ru/CGO liquid alkane anode catalyst cannot meet the application requirement of the SOFC anode catalysis of the hydrocarbon fuel.

To facilitate the commercial use of methane in SOFC systems, CN107282086A discloses a "cheap metal-precious metal" bimetallic anode catalyst rh (pt) -Ni/SBA-15 for methane. According to the invention, the content of the noble metal material in the anode catalyst is optimized by regulating and controlling the material composition of the anode catalyst, so that the methane anode catalyst with excellent catalytic performance and stability is obtained. However, the conversion rate of the anode catalyst to methane is only 50% -80% within the working temperature range of 500-800 ℃. Meanwhile, in order to obtain the ideal catalytic performance, the anode catalyst of the catalyst needs to use precious metal elements such as Rh and Pt.

In addition, conventional SOFC cermet anodes consist of a porous mixture of an electronically conductive metal phase (typically nickel or a nickel alloy) and a ceramic phase typically made of an oxygen ion conductor material. Suitable metals with high electrocatalytic activity and low cost (i.e., non-noble metals) are typically transition metals (Ni, Fe, Cu or Co) that are reduced and oxidized based on the fuel and air supplied to the cell at the SOFC operating temperature. This repeated oxidation and reduction reaction is often destructive due to the volume change it causes, and the metal oxide often does not return to its original shape when reduced. Some methods use copper oxide as a sintering aid to improve the resistance of the cell to this process. This is the case for batteries based on the Ceres Power Steel Cell design architecture (see, e.g., WO 02/34628a 1).

There are, however, difficulties due to the microstructural changes of the anode during operation (in particular to the gradual loss of the necks between the metal particles due to surface diffusion), the gradual loss of redox stability during operation, eventually leading to cell failure. It is also well known that accidental operation of a fuel deficient cell almost always results in catastrophic failure due to delamination of the anode/electrolyte assembly (whether delamination occurs at the anode/electrolyte interface or the anode itself is not clear). A stronger ceramic skeletal structure is therefore required. Reducing the nickel content in the anode can result in a lower degradation rate during redox cycling, but at the same time the cell performance also decreases significantly. Therefore, the anode catalyst of the battery needs to use precious metal elements such as Rh and Pt to ensure the battery performance.

Therefore, the development of a cheap metal anode (noble metal free) SOFC catalyst with high catalytic efficiency is of great importance for the commercial application of hydrocarbon-fueled SOFC systems.

Disclosure of Invention

The patent CN105377426A discloses a Ni-Ru/CGO anode catalyst capable of converting complex hydrocarbonThe fuel is converted into methane-rich gas, and Rh-Ni/SBA-15 disclosed in patent CN107282086A can convert methane into H₂And CO. Therefore, the inventors previously tried to realize the stepwise operation of "complicated liquid hydrocarbon fuels (e.g., alkanes)" to "H" by using the above two types of anode catalysts in combination₂And catalytic conversion of CO ". However, in the course of practical research, the inventors found that the use of the composite anode catalyst increases the complexity of the design of the internal catalyst layer of the SOFC anode, which is not favorable for preparing a simplified SOFC cell. On the other hand, the above two types of anode catalysts also use precious metal elements such as Ru, Rh, and Pt, which is not favorable for reducing the material cost of the SOFC. Therefore, the inventor expects to obtain more inexpensive and efficient SOFC anode catalysts to promote the progress of their commercial use.

In the further research process, the porous ceramic skeleton is prepared in the SOFC anode, and the anode catalyst is carried, so that the good catalytic performance of hydrocarbon fuel (such as propane) in the SOFC anode can be realized, and the SOFC battery system with ideal catalytic performance, high battery output power density and stable electrochemical performance can be obtained. However, the scheme adopts a high-temperature sintering process of 800-1200 ℃ to prepare the porous ceramic support body (anode catalyst framework), while the ceramic oxide support body prepared by the high-temperature sintering process in advance has a lower specific surface area, and the preparation of the anode catalyst on the substrate is not beneficial to enhancing the dispersion of metal particles in the ceramic substrate, enhancing the interaction between metal and the ceramic carrier, and also not beneficial to fully utilizing the catalytic function of the metal-ceramic anode catalyst. Therefore, the developed new nano-functional ceramic supported SOFC fuel anode catalyst needs to be sintered at a lower temperature, and has sufficient performance (stable life and catalytic performance) for commercial use.

Through continuous search and research on SOFC anode catalysts, the inventor finds that the catalyst is based on NiMo metal base and is applied to nanometer Ce_0.75Zr_0.25O₂NiMo/Ce prepared on ceramic carrier_0.75Zr_0.25O₂An anode catalyst is applied to the SOFC cell taking Ni-YSZ as an anode. Under the operation environment of the SOFC, the air conditioning system is provided with a plurality of air conditioning units,the anode catalyst shows excellent catalytic performance to hydrocarbon (such as isooctane) fuel, and obviously improves the electrochemical performance and the catalytic performance stability of an isooctane fuel SOFC system.

In the further research process, the inventor finds that the composition of the NiMo metal-based anode catalyst carrier material in a wider range can obtain an anode catalyst which has higher catalytic activity on complex hydrocarbon fuel and simultaneously has excellent carbon deposition resistance, and has a promoting effect on the internal reforming reaction of the SOFC anode.

Accordingly, the present invention has been made to solve at least one of the above problems, and an object of the present invention is to provide an anode catalyst for SOFC systems using an inexpensive metal base (NiMo) as a metal base component, which has an excellent catalytic activity and can catalytically convert these hydrocarbons into H with high efficiency₂And CO, and has excellent carbon deposition resistance and sufficient stability.

The invention provides a method for preparing high-performance nano Ce by using low-cost nickel-molybdenum base as a metal component_1-yCa_yO_2-δMetal-ceramic type Ni as carrier_1-xMo_x/Ce_1-yCa_yO_2-δSOFC anode catalyst. The catalyst is used for simulating gasoline fuel (C)₈H₁₈) In the catalytic conversion of (2), H₂The yield of CO and CO is respectively 70 percent to 80 percent, and the fuel conversion rate is up to 90 percent. The catalytic performance is superior to that of a catalyst Rh/Al containing noble metal elements₂O₃At C₈H₁₈Catalytic performance (H) of₂Yield: -40%, fuel conversion: 70%, distribution and Flame 157(2010) 1771-1782). Therefore, the catalyst is an SOFC anode catalyst with great commercial application prospect.

Hereinafter, the contents of the solid oxide fuel cell catalyst, the method of preparing the same, the anode of the solid oxide fuel cell containing the catalyst, and the solid oxide fuel cell containing the catalyst will be described in detail.

A solid oxide fuel cell catalyst comprising:

a metal load; and

a nano-oxide support having a fluorite crystal phase structure;

wherein the general formula of the composition of the metal-supported constituent element is represented by formula (1);

the general formula of the composition of the constituent elements of the nano-oxide carrier with fluorite crystal phase structure is represented by formula (2);

Ni_1-xMo_x(1)

Ce_1-yA_yO_2-δ(2)

the range of x in the formula (1) is more than or equal to 0 and less than or equal to 0.5,

y in the formula (2) is within the range of 0.01-0.40, and A is at least one element selected from Ca and Zr.

The inventors found that nano Ce is adopted_1-yCa_yO_2-δMetal-ceramic type Ni as carrier_1-xMo_x/Ce_1-yCa_yO_2-δThe SOFC anode catalyst has excellent catalytic action on complex hydrocarbon fuels (such as gaseous alkanes such as methane, methanol, ethanol and propane and liquid alkanes such as gasoline) and can efficiently convert the hydrocarbons into H₂And CO for providing H for electrochemical reaction of SOFC anode₂And CO, which accelerates the electrochemical reaction rate of the SOFC anode and improves the electrochemical performance of the SOFC cell. And equivalent or higher cell internal reforming performance can be achieved without using precious metals as the metal load.

By optimizing the composition of the catalyst carrier material, the catalytic activity and the anti-carbon deposition performance of the catalyst on complex hydrocarbon fuel can be optimized; the carrier material with high surface oxidation-reduction cycle stability and high oxygen ion conductivity is adopted, and the carrier material has a promoting effect on the internal reforming reaction of the SOFC anode. Therefore, the invention provides the high-performance nano Ce taking the nickel and the molybdenum as the metal components_1-yCa_yO_2-δMetal-ceramic type Ni as carrier_1-xMo_x/Ce_1-yCa_yO_2-δSOFC anode catalyst. It has excellent catalytic action on complex hydrocarbon fuel (such as gaseous alkane of methane, methanol, ethanol and propane, etc. and liquid alkane of gasoline, etc.), and can effectively catalyze hydrocarbon fuelCatalytic conversion of these hydrocarbons to H-rich₂And CO-rich fuel gas for providing H for electrochemical reaction of SOFC anode₂And CO reaction gas, so that the electrochemical reaction rate of the anode is accelerated, and the electrochemical performance of the SOFC single cell is improved.

Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe catalyst has high-efficiency catalytic reforming effect on complex hydrocarbon fuel and can improve H in anode gas of SOFC (solid oxide fuel cell)₂And the content of CO, thereby improving the output power density of the battery. Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe catalyst has effect in inhibiting carbon deposition process in hydrocarbon fuel catalytic reaction, and can increase Ni_1-xMo_x/Ce_1-yCa_yO_2-δStability of catalytic performance and stability of electrochemical performance of fuel cells. At the same time, Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe anode material (Ni-based anode) of the SOFC has good physical and chemical compatibility with the current anode material (Ni-based anode), and the comprehensive electrochemical performance of the fuel cell is improved.

According to some embodiments of the present invention, x in formula (1) ranges from 0 ≦ x ≦ 0.50. In some embodiments of the invention, 0.001. ltoreq. x.ltoreq.0.50, more usually 0.01. ltoreq. x.ltoreq.0.50, typically 0.1. ltoreq. x.ltoreq.0.30. In the present invention, if x>At 0.5, Mo is not completely dissolved in the crystal lattice of metallic Ni at high temperature to form an alloy. Excess Mo will promote MoO_δAnd NiMoO₄The formation of (a) is not beneficial to improving the catalytic activity of the catalyst and maintaining the high-efficiency catalytic stability of the catalyst. Of course, even if the catalytic performance is reduced to a certain degree, the catalyst still has excellent catalytic activity.

According to some embodiments of the present invention, y in the formula (2) ranges from 0.05. ltoreq. y.ltoreq.0.40. Wherein, y<0.05 time Ce_1-yCa_yO_2-δThe ceramic phase oxygen storage performance and the surface oxygen exchange performance are poor, and the catalyst activity is low; if y>0.4, Ca is not completely dissolved in CeO₂The excess Ca is precipitated as a second phase in the crystal lattice of (1), which is not favorable for the catalytic reaction on the surface of the material. Thus, y ranges from 0Y is suitably 05. ltoreq. y.ltoreq.0.40.

According to some embodiments of the present invention, the catalyst has particles in the size range of 1nm to 500nm, and there is no particular limitation on the type of particle shape that can be used in the present invention. In some embodiments of the invention, the particles are formed into large clusters. This large cluster, which is Ni, can be seen in FIG. 3_1-xMo_x/Ce_1-yCa_yO_2-δTEM (transmission electron microscope) pictures of the catalyst.

According to some embodiments of the present invention, the nano-oxide support having a fluorite crystal phase structure has a porous mesoporous structure with a porosity of 20% to 60%. Typically, the nano-oxide support is also present in the form of porous particles, which is advantageous in increasing the specific surface area of the catalyst support and the metal support and can provide useful chemically catalytically active reaction sites because it enhances the dispersion of the metal support particles in the nano-oxide support and enhances the interaction between the metal support particles and the nano-oxide support. And the particles of the catalyst are made of different materials, mixtures of different materials can be used to prepare the catalyst support particles, such as Ce_1-yA_yO_2-δY is more than or equal to 0.01 and less than or equal to 0.40. A is Ca, Zr or a mixed solid solution of Ca and Zr.

By preparing the catalyst support in a form having a porous mesoporous structure, equivalent or higher catalytic performance can be achieved. The higher the porosity, the smaller the pore size, and generally the larger the surface area, and thus the larger the active surface of the catalyst. And if the porosity is too large and exceeds 60%, the thickness of the catalytic layer is obviously increased, and the complexity of battery preparation is increased. When the porosity is less than 20%, the specific surface area is generally low, and it is difficult to maintain the catalytic activity. Therefore, it is suitable to control the porosity to 20% to 60%. In this case, the nano-oxide support may, or at least substantially, maintain its structural and performance stability under repeated SOFC cycling operations.

According to some embodiments of the present invention, the specific surface area of the nano-oxide support having a fluorite crystal phase structure is 50 to 200m²Per g of approximately spherical particles, which consist of agglomerates of nanoscale crystallites. FIG. 2 is Ce_1-yCa_yO_2-δScanning Electron Microscope (SEM) picture of oxide support, FIG. 3 is Ni_1-xMo_x/Ce_1-yCa_yO_2-δTransmission Electron Microscopy (TEM) pictures of the catalyst. The nano oxide carrier with high specific surface area and the SOFC anode catalyst prepared on the substrate are beneficial to enhancing the dispersion of metal particles in the nano oxide carrier, enhancing the interaction between the metal particles and the nano oxide carrier and realizing the catalytic function of equivalent (compared with the prior art) or higher battery performance of the catalyst.

According to some embodiments of the invention, the metal loading is uniformly distributed on the nano-oxide support having a fluorite crystalline phase structure. Generally, the metal load is uniformly distributed throughout the nano-oxide support matrix, and the metal load is uniformly distributed through the dispersed liquid phase by using an infiltration method, that is, the distribution of the metal load throughout the nano-oxide support matrix is substantially uniform.

According to some embodiments of the invention, the a is Ca. According to other embodiments of the present invention, a is Zr. Still further, according to some embodiments of the invention, a is Ca and Zr. Ca²⁺And Zr⁴⁺And Ce⁴⁺Has similar ionic radius, and can regulate and control CeO by doping proper elements₂The catalytic properties of the base material. Research results show that Ca or Zr is doped to prepare CeO₂The matrix catalyst has high oxygen storage property and surface oxygen exchange performance, which can promote incomplete oxidation reforming reaction of hydrocarbon fuel on the surface of the catalyst. The inventors have found that doping ceria with Ca or/and Zr yields porous particles with excellent properties. Therefore, SOFC catalyst materials containing nickel/molybdenum inexpensive metals and Ca or/and Zr doped with ceria porous particles significantly improve the catalytic activity of the catalyst and/or reduce the amount of catalyst material needed to achieve the same level of catalytic efficiency. At the same time Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe catalyst material also helps to resist catalyst failure during its operation.

According to some embodiments of the invention, the Ni_1-xMo_xLoading with said Ce_1-yA_yO_2-δThe molar ratio of the carrier is 0.1-0.9: 1. ni_1-xMo_xSupported as active catalytic center for the catalytic reaction, Ni_1-xMo_xToo low a loading content will be detrimental to the reforming reaction of hydrocarbon fuel on the catalyst surface; during the high temperature catalytic reaction, Ni_1-xMo_xToo high loading content will cause the metal phase particles to grow up, reduce the surface area of the catalyst and be not beneficial to improving the stability of the catalyst. Thus, the Ni_1-xMo_xLoading with said Ce_1-yA_yO_2-δThe molar ratio of the carrier is 0.1-0.9: 1 is suitable.

In one aspect, the present invention provides a method for preparing a solid oxide fuel cell catalyst, the method comprising the steps of:

s1: adding stoichiometric cerium nitrate, calcium nitrate or/and zirconyl nitrate into deionized water to form a mixed solution;

adding glycine to the mixture to form a solution in which glycine is dissolved;

heating the glycine-dissolved solution to evaporate the remaining amount of water, initiate combustion, and produce a solution having the general composition formula Ce_1-yA_yO_2-δ(2) The nano-oxide powder of (4); and

calcining the nano oxide powder in air at 700-1000 ℃ for 1-4 hours to generate the fluorite crystal phase structure with the general formula of Ce_1-yA_yO_2-δ(2) The nano-oxide support of (a);

s2: adding stoichiometric amounts of nickel nitrate and ammonium paramolybdate to deionized water to form a dissolution solution;

adding the nano oxide carrier into the dissolved solution, uniformly mixing, and evaporating the rest water to obtain mixed powder; calcining the mixed powder at 500-700 ℃ in air; and

in a reducing atmosphere, calcining the mixtureReducing the mixed powder at 600-800 deg.C for 0.5 hr to obtain Ni_1-xMo_x/Ce_1-yA_yO_2-δ(1) The catalyst of (1);

wherein x in the formulas (1) and (2) is in a range of 0-0.5, y is in a range of 0.01-0.40, and A is at least one element selected from Ca and Zr.

The metal support material incorporated into the catalyst is typically incorporated into the porous nano-oxide support as a soluble salt, most typically a solution of the metal salt is mixed with the nano-oxide support. It is added to a porous nano-oxide support and then dried (typically calcined to decompose the metal salt to the metal oxide) to obtain. Such infiltration methods are well known to those skilled in the art and can be accomplished in a variety of ways to ensure that the metal loading is evenly distributed over the porous nano-oxide support and completely coated. The incorporation of the metal support material into the porous nano-oxide support described above can be achieved using incipient wetness impregnation methods in general. However, other techniques known in the art for impregnating catalyst supports may also be used. For example, for metallic support materials, techniques such as ion exchange can also be used in principle.

In some embodiments of the invention, a higher or comparable performance enhancement can be achieved with less catalyst by first introducing the metal loading into the nano-oxide support to form the catalyst, rather than directly introducing the nano-oxide support and metal loading separately and directly into the anode. The smaller the pore size, the larger the surface area in general and, therefore, the larger the active surface of the catalyst. Another benefit of this approach is that there are a variety of porous particles that are stable under SOFC operating conditions, maintaining their structural and performance stability under repeated SOFC cycle operation. Furthermore, the catalyst particles are typically electronically and/or ionically conductive under anodic conditions, and the catalyst can also be incorporated into a printing composition (e.g., screen printing process) to avoid the need to modify existing processing techniques.

According to some embodiments of the invention, the molar ratio of glycine to metal ions in nitrate in the glycine dissolved solution is 1.5 to 3: 1, in a further embodiment, the molar ratio of glycine to metal ions in the nitrate is from 1.5 to 2.8: 1; in a further embodiment, the molar ratio of glycine to metal ions in the nitrate is 1.5 to 2.0: 1. the glycine is used as a combustion agent (combustion promoter) in the process, and the particle morphology of the catalyst powder can be controlled. The catalyst powder is seriously agglomerated due to the low glycine content, and the local high temperature is generated in the powder preparation process due to the high glycine content, so that the particle size of powder particles is increased. Therefore, the molar ratio of the glycine to the metal ions in the nitrate is controlled to be 1.5-3: 1 is suitable. After the combustion process is complete, the glycine should be burned out. Thus, the amount and purity of glycine is less important than other elements, and it is of course foreseeable that we do not wish to introduce some unwanted impurities as a result. In some embodiments of the invention, the purity of the glycine is commercial purity, and in other embodiments of the invention, the purity of the glycine is chemical purity, the two different purities being substantially identical for the properties ultimately exhibited.

According to some embodiments of the invention, the step of calcining the nano-oxide powder comprises: the temperature is raised to 700-1000 ℃ within 4 hours, and then the temperature is maintained for 1-4 hours. The oxide powder is calcined in air for 0.5-2 hours in order to stably form a nano-oxide carrier (Ce) having a fluorite crystal phase structure_1-yA_yO_2-δ) It has a porous structure.

According to some embodiments of the present invention, the mixed powder is calcined by raising the temperature to 500 to 700 ℃ and then maintaining for 0.5 to 2 hours. Further, the mixed powder is calcined in a reducing atmosphere at 600 to 800 ℃ for 0.5 hour for the purpose of stabilizing the active metal and forming Ni_1-xMo_x/Ce_1-yA_yO_2-δA catalyst. Reduction treatment or activation of the catalyst is necessary because part of the nickel is inevitably converted to the inactive nickel oxide form when the mixed powder is calcined in air during preparation of the catalyst composition. According to some embodiments of the invention, the temperature is raised to 700 ℃ within 4 hours and then maintained for 1 hour. In the airCalcining the oxide powder for 2 hours, and further calcining the mixed powder in a reducing atmosphere at 600 ℃ for 0.5 hour to obtain stably activated Ni_1-xMo_x/Ce_1-yA_yO_2-δA catalyst.

According to some embodiments of the present invention, the calcined mixed powder is reduced using hydrogen and an inert gas. The hydrogen accounts for 10 mol%, the inert gas accounts for 90 mol%, and the inert gas is one of nitrogen, argon and helium. In some embodiments of the invention, the catalyst is activated by reduction with hydrogen and nitrogen at about 500 ℃ for 0.5 hour. In some embodiments, hydrogen comprises about 10 mol% and nitrogen comprises about 90 mol%. The hydrogen content controls the rate of catalyst reduction during catalyst reduction activation. In order to uniformly reduce the catalyst, the content of hydrogen in the reducing gas is generally controlled to 10 mol%.

According to some embodiments of the invention, the catalyst is used on the surface of an anode of a solid oxide fuel cell to convert hydrocarbon fuel to H-rich₂And a CO-rich gas. Methane can be used as a fuel for Solid Oxide Fuel Cells (SOFC), but currently SOFCs do not perform well in methane. It is contemplated that the present invention is directed to the efficient conversion of alkanes to hydrogen and carbon monoxide. Compared with the catalytic conversion of hydrocarbon fuel into methane, hydrogen and carbon monoxide have lower requirements on the SOFC anode, and are more suitable for the commercial application of SOFCs. According to some embodiments of the invention, Ni_1-xMo_x/Ce_1-yA_yO_2-δCatalyst is used on anode surface of solid oxide fuel cell to convert hydrocarbon fuel into rich H₂And CO-rich gas, H₂And the yield of CO is more than 60% and more than 70%, and the fuel conversion rate is up to more than 80%. According to some embodiments of the invention, Ni_1- _xMo_x/Ce_1-yA_yO_2-δCatalyst for anode surface of solid oxide fuel cell, H₂And the yield of CO is more than 70% and more than 80%, and the fuel conversion rate is up to more than 90%.

According to some embodiments of the present invention, the catalyst has high catalytic activity and stability compared to prior art catalysts, thereby achieving high catalytic efficiency and fuel conversion efficiency of Solid Oxide Fuel Cell (SOFC) systems.

In one aspect, the present invention provides an anode for a solid oxide fuel cell, comprising:

a matrix comprising a doped metal oxide; and

a catalyst composed of a metal-supported nano oxide carrier having a fluorite crystal phase structure;

Ni_1-xMo_x(1)，

Ce_1-yA_yO_2-δ(2)，

In some embodiments of the invention, y in formula (2) ranges from 0.05. ltoreq. y.ltoreq.0.20 and A is Ca.

In some embodiments of the invention, the metal oxide-doped matrix further comprises nickel.

In some embodiments of the invention, the metal oxide doped matrix is a conductive ceramic material. As this material is well suited for the operating conditions of solid oxide fuel cells. Typically the conductive ceramic material is rare earth doped ceria or zirconia. This material is not only stable under SOFC operating conditions, it also provides good electrochemical and structural properties, and can be well fixed to substrates, especially metal substrates. In particular, the rare earth doped ceria is gadolinium doped Ceria (CGO). In some embodiments of the invention, the rare earth doped zirconia is yttrium doped zirconia.

In some embodiments of the invention, the rare earth doped ceria is one or a combination of samarium doped ceria and gadolinium doped ceria. In some embodiments of the invention, the doped metal oxide-containing matrix is one of Ni-samarium doped ceria, Ni-gadolinium doped ceria, or a combination thereof. In particular, the matrix containing the doped metal oxide is Ni-yttria doped zirconia.

In some embodiments of the invention, the matrix may further comprise one or more components selected from the group consisting of: sintering aids, conductors, catalyst materials, binders, dispersants, or combinations thereof. Some of these materials are removed during sintering (e.g., binders and dispersants), but they have a positive effect in forming the matrix composition and are therefore typically added.

In some embodiments of the invention, the catalyst is distributed throughout the matrix comprising the doped metal oxide. In particular, the catalyst is homogeneously distributed. The addition of the catalyst also improves the conductivity properties of the matrix (as most are metals or metal-conductive ceramics) and promotes internal reforming of the fuel. The amount of the catalyst material (or oxide thereof) used in the present invention is not particularly limited, but too much addition may have a detrimental effect on the electrochemical oxidation performance of the anode. Thus, to achieve the optimum balance of properties, the catalyst material content is typically equal to or less than about 80% wt, more typically equal to or less than about 75%, and still more typically in the range of 5% to 70% wt, even more typically in the range of 10% to 60% wt, and even more typically in the range of 20% to 55% wt. Typically, the catalyst material is present in an amount of from 10% to 50% wt, more typically from 15% to 45%, more typically from 20% to 40%, and in some embodiments of the invention, from 25% to 35%. The hydrocarbon fuel SOFC anode unit has both a chemical catalysis function and an electrochemical oxidation function. The anode catalyst mainly catalyzes a hydrocarbon fuel reforming reaction, and the anode electrochemical functional layer mainly catalyzes the electrochemical oxidation of small-molecule hydrocarbon gas. When the content of the anode catalyst is lower than 5 wt%, the chemical catalytic effect is weak, and the effective conversion of the fuel gas cannot be promoted; when the catalyst content is too high (> 80% wt), the anode electrochemical layer content is low, which is not favorable for electrochemical oxidation of hydrocarbon gas. Therefore, it is appropriate to control the catalyst content in the SOFC anode to 5-80% wt.

In one aspect, the present invention provides a solid oxide fuel cell comprising:

an anode comprising a catalyst and a metal-ceramic based material;

a cathode; and

an electrolyte matched with the anode and positioned between the anode and the cathode;

wherein the catalyst comprises Ni_1-xMo_x(1) The metal loading of (2); and

having a fluorite crystal phase structure and having a composition formula of Ce_1-yA_yO_2-δ(2) A nano-oxide support;

In some embodiments of the invention, the metal-ceramic based material is one of Ni-samarium doped ceria, Ni-gadolinium doped ceria, Ni-yttria doped zirconia.

In general, SOFC single cells supported by electrodes have low ohmic resistance and are widely used in cell stack and cell system research. Earlier researches show that the co-firing of the cathode support body and the electrolyte is difficult, the cathode polarization resistance is high, and the preparation of the high-performance SOFC single cell is not facilitated. The anode-supported cell configuration can be prepared by a conventional co-firing process, and simultaneously, the ohmic resistance and the polarization resistance of the cell configuration are low, so that the cell configuration is a representative configuration of the SOFC. In some embodiments of the invention, at least one of the anode, the cathode, and the electrolyte serves as a support for the solid oxide fuel cell. Typically, the solid oxide fuel cell is an anode-supported solid oxide fuel cell, as shown in fig. 7, the anode-supported SOFC cross-section is shown schematically (a: anode layer, E: electrolyte layer, C: cathode layer). In particular, the electrolyte layer and the cathode layer may be located together on a supporting layer anode, which in some embodiments of the invention is a porous material to allow, to a large extent, gaseous fuel to pass through the catalyst and contact the anode. In other embodiments of the present invention, the support for the solid oxide fuel cell may be a cathode or an electrolyte. Fig. 8 shows a schematic representation of the cross-section of an electrolyte-supported SOFC (a: anode layer, E: electrolyte layer, C: cathode layer) and fig. 9 shows a schematic representation of the cross-section of a cathode-supported SOFC (a: anode layer, E: electrolyte layer, C: cathode layer), respectively.

In addition, in the present invention, it is not most preferable to use the electrolyte layer as the support layer of the solid oxide fuel cell. Since the larger the thickness of the electrolyte, the larger the internal resistance of the solid oxide fuel cell, the more energy loss in the cell and the smaller the output power. Particularly, when the operating temperature of the solid oxide fuel cell is lower than 700 ℃, the resistance energy loss of the electrolyte becomes one of the main energy losses of the solid oxide fuel cell, and therefore, in order to increase the output power of the cell, it is necessary to reduce the thickness of the electrolyte or increase the ionic conductivity of the electrolyte.

In other embodiments of the present invention, the support of the solid oxide fuel cell may be a metal-supported solid oxide fuel cell. Specifically, the metal support serves as a matrix for the anode, electrolyte and cathode layers of the fuel cell. The substrate may be porous to allow air fuel to pass through the metal support substrate in contact with the anode. The substrate metal may be any metal substrate commonly used in metal-supported SOFCs. In these designs, the anode is located on a perforated area, and this configuration provides gas to the anode through the perforated (typically laser drilled) area. The metal substrate is typically a stainless steel substrate, typically a ferritic stainless steel, because ferritic stainless steel has a similar coefficient of thermal expansion to the most commonly used ceria-doped, gadolinium-doped ceria (often abbreviated GDC or CGO) to reduce stresses within the SOFC cell during heating/cooling cycles.

In some embodiments of the invention, the anode-matched electrolyte is at least one of samarium-doped ceria, gadolinium-doped ceria, yttria-doped zirconia, and is correspondingly matched to the matrix of the doped metal oxide. The corresponding matching to the matrix of the doped metal oxide here means: the rare earth element in the doped metal oxide is the same as the rare earth element in the electrolyte, for example, when the matrix is Ni-samarium doped ceria, the corresponding electrolyte is ceria (SDC) containing at least samarium doping, and the electrolyte may be SDC alone or a combination of SDC and CGO or/and YSZ.

In some embodiments of the present invention, the cathode is one of lanthanum strontium manganese oxide, lanthanum strontium cobalt iron oxide, barium strontium cobalt iron oxide having a perovskite crystalline phase structure. The general formula of the lanthanum strontium manganese oxide is La_1-mSr_mMnO_3-δWherein 0 is<m<1. Further, in some embodiments of the invention, La_1-mSr_mMnO_3-δ，0<m≤0.5。

In some embodiments of the present invention, the lanthanum strontium cobalt iron oxide has a general formula of La_1-aSr_aCo_1- _bFe_bO_3-δWherein 0 is<a<1,0<b is less than or equal to 1. Further, in some embodiments of the invention, La_1-aSr_aCo_1-bFe_bO_3-δWherein a is 0.1 to 0.9, b is 0.3 to 1.0, or a is 0.2 to 0.8, and b is 0.2 to 1.0). Further, in one embodiment of the present invention, La_1-aSr_aCo_1-bFe_bO_3-δIn the formula, a is 0.4 and b is 0.8.

In some embodiments of the present invention, the general formula of the barium strontium cobalt iron oxide is Ba_1-aSr_aCo_1- _bFe_bO_3-δWherein 0 is<a<1,0<b is less than or equal to 1. Further, in some embodiments of the invention, Ba_1-aSr_aCo_1-bFe_bO_3-δWherein a is 0.1 to 0.9, b is 0.3 to 1.0, or a is 0.2 to 0.8, and b is 0.2 to 1.0). Further, in one embodiment of the present invention, Ba_1-aSr_aCo_1-bFe_bO_3-δIn the formula, a is 0.4 and b is 0.8.

In some embodiments of the invention, the solid oxide fuel cell is used to convert hydrocarbon fuels to H-rich₂And CO-rich forms. In the present invention, the hydrocarbon fuel is an alkane having carbon atoms of C1 to C8, and specifically may be methane, ethane, propane, butane, pentane, hexane, ethylene, propylene, butene, cyclopropane, cyclobutane, cyclopentane and isomers thereof, and a liquid alkane such as gasoline.

In some embodiments of the invention, the solid oxide fuel cell is used to convert gasoline-type alkanes to H-rich₂And CO-rich forms.

The invention has the beneficial effects that:

the solution according to the invention is an improvement over the prior art in at least the following respects.

(1)Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe anode catalyst has high-efficiency catalytic action on complex hydrocarbon fuel and can improve H in SOFC anode gas₂And the content of CO, thereby improving the output power density of the battery.

(2)Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe anode catalyst also has an inhibiting effect on a carbon deposition process in a catalytic reaction of the hydrocarbon fuel, and can improve the stability of the catalytic performance and the stability of the electrochemical performance of the SOFC.

(3)Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe anode catalyst has good physical and chemical compatibility with the current SOFC anode materials (Ni-based anode, such as Ni-yttria stabilized zirconia (Ni-YSZ), Ni-samarium doped ceria (Ni-SDC), Ni-gadolinium doped ceria (Ni-GDC) and the like), and improves the comprehensive electrochemical performance of the fuel cell.

(4)Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe anode catalyst has a potentially positive environmental impact and it is expected that the combination of on-board SOFCs can significantly reduce greenhouse gas emissions because it significantly increases H in the anode gas₂And CO production efficiency, and reduceThe formation of carbon deposits.

(5)Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe anode catalyst can efficiently catalyze complex hydrocarbon fuels (including gaseous alkanes such as methane, methanol, ethanol and propane, and liquid alkanes such as gasoline), and can remarkably improve H in fuel gas₂And the content of CO.

(6) The invention provides cheap metal-ceramic Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe catalyst has catalytic performance equivalent to that of noble metal catalysts such as Pt, Ru, Rh and the like. By using Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe catalyst can obviously reduce the preparation cost of the hydrocarbon fuel SOFC and accelerate the commercial application of the complex hydrocarbon fuel (such as gasoline fuel and the like) SOFC.

Drawings

FIG. 1: (a) ce_1-yCa_yO_2-δCatalyst support and (b) Ni_1-xMo_x/Ce_1-yCa_yO_2-δXRD pattern of catalyst.

FIG. 2: ce_1-yCa_yO_2-δSEM photograph of the catalyst support: (a) y is 0.01, (b) y is 0.1, (c) y is 0.2, and (d) y is 0.4.

FIG. 3: ni_1-xMo_x/Ce_1-yCa_yO_2-δTEM pictures of the catalyst: (a) x is 0.1 and y is 0.01; (b) x is 0.1, y is 0.1; (c) x is 0.3, and y is 0.2; (d) x is 0.5 and y is 0.4.

FIG. 4: ni_1-xMo_x/Ce_1-yCa_yO_2-δCatalytic simulation of gasoline fuel (C) at 750 deg.C₈H₁₈) Hydrogen yield at time: (a) x is 0.00 and y is 0.01; (b) x is 0.10, y is 0.10; (c) x is 0.30, and y is 0.20; (d) x is 0.50 and y is 0.40.

FIG. 5: ni_1-xMo_x/Ce_1-yCa_yO_2-δCatalytic simulation of gasoline fuel (C) at 750 deg.C₈H₁₈) Carbon monoxide yield when: (a) x is 0.00 and y is 0.01; (b) x is 0.10, y is 0.10;(c)x＝0.30，y＝0.20；(d)x＝0.50，y＝0.40。

FIG. 6: ni_1-xMo_x/Ce_1-yCa_yO_2-δCatalytic simulation of gasoline fuel (C) at 750 deg.C₈H₁₈) Fuel conversion at time: (a) x is 0.00 and y is 0.01; (b) x is 0.10, y is 0.10; (c) x is 0.30, and y is 0.20; (d) x is 0.50 and y is 0.40.

FIG. 7: anode-supported SOFC single cells are shown schematically in cross-section (a: anode, E: electrolyte, C: cathode).

FIG. 8: cross-sections of electrolyte-supported SOFC single cells are shown schematically (a: anode, E: electrolyte, C: cathode).

FIG. 9: cathode-supported SOFC single cells are shown schematically in cross-section (a: anode, E: electrolyte, C: cathode).

FIG. 10: ni_1-xMo_x/Ce_1-yCa_yO_2-δSchematic representation of the application of the catalyst in an anode supported SOFC single cell (a: anode, E: electrolyte, C: cathode).

FIG. 11: ni_1-xMo_x/Ce_1-yCa_yO_2-δCatalytic simulation of gasoline fuel (C) on SOFC anode surface₈H₁₈) Hydrogen yield at conversion: (a) x is 0.00 and y is 0.01; (b) x is 0.10, y is 0.10; (c) x is 0.30, and y is 0.20; (d) x is 0.50 and y is 0.40.

FIG. 12: ni_1-xMo_x/Ce_1-yCa_yO_2-δCatalytic simulation of gasoline fuel (C) on SOFC anode surface₈H₁₈) Carbon monoxide yield at conversion: (a) x is 0.00 and y is 0.01; (b) x is 0.10, y is 0.10; (c) x is 0.30, and y is 0.20; (d) x is 0.50 and y is 0.40.

FIG. 13: ni_1-xMo_x/Ce_1-yCa_yO_2-δCatalytic simulation of gasoline fuel (C) on SOFC anode surface₈H₁₈) Fuel conversion at conversion: (a) x is 0.00 and y is 0.01; (b) x is 0.10, y is 0.10; (c) x is 0.30, and y is 0.20; (d) x is 0.50 and y is 0.40.

FIG. 14: the discharge performance stability of the solid oxide fuel cell in simulated gasoline fuel.

Detailed Description

For a better understanding of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings 1-14.

The embodiments described herein use chemically pure cerium nitrate, calcium nitrate, zirconyl nitrate, glycine, nickel nitrate, ammonium paramolybdate, commercially available from Sigma Aldrich. It should be noted that the examples of the chemical supply trade company are only examples of the commercial availability of the raw materials, and those skilled in the art can fully recognize that the technical scheme of the patent is not limited thereto.

Ni of the invention_1-xMo_x/Ce_1-yCa_yO_2-δThe catalyst was prepared as follows.

adding glycine to the mixed solution to form a solution in which glycine is dissolved;

in the air, the nano oxide powder is heated to 700-1000 ℃ within 4 hours and calcined for 1-4 hours, and fluorite crystal phase structure with the composition general formula of Ce is generated_1-yA_yO_2-δ(2) The nano-oxide support of (a);

adding the nano oxide carrier into the dissolved solution, uniformly mixing, and evaporating the rest water to obtain mixed powder; heating the mixed powder to 500-700 ℃ in air within 4 hours, and calcining for 0.5-2 hours; and

reducing the calcined mixed powder at 600-800 ℃ for 0.5 hour in a reducing atmosphere, and producing a composite powderIs represented by the general formula Ni_1-xMo_x/Ce_1-yA_yO_2-δ(1) The catalyst of (1);

When the calcined mixed powder is reduced by using hydrogen and inert gas, the hydrogen accounts for 10 mol%, the inert gas accounts for 90 mol%, and the inert gas is one of nitrogen, argon and helium. In some embodiments of the invention, the catalyst is activated by reduction with hydrogen and nitrogen at about 500 ℃ for 0.5 hour. In some embodiments, hydrogen comprises about 10 mol% and nitrogen comprises about 90 mol%. The hydrogen content controls the rate of catalyst reduction during catalyst reduction activation. In order to uniformly reduce the catalyst, the content of hydrogen in the reducing gas is generally controlled to 10 mol%.

Table 1: examples 1-24 Experimental conditions

Note: t1 is the calcination temperature of the nano oxide powder in step S1, and T1 is the calcination time; t2 is the calcining temperature of the mixed powder in the step S2, and T2 is the calcining time; t3 is the reduction temperature of the mixed powder calcined in step S2 in a reducing atmosphere.

According to embodiments 1 to 24 of the present invention, the specific surface area of the nano-oxide support having a fluorite crystal phase structure is 50 to 200m²Per g of approximately spherical particles, which consist of agglomerates of nanoscale crystallites. The sample numbers obtained in examples 1 to 24 of the present invention correspond to A1 to A24, respectively. The solid oxide fuel cell catalyst is used to produce SOFC anodes containing the catalyst and SOFC solid oxide fuel cells containing the catalyst, and the produced SOFCs are respectively designated as B1-B24. And areThe phase composition, SEM electron microscope, hydrocarbon fuel catalytic performance, cell stability and the like of the catalyst and the SOFC containing the catalyst are tested, the test result is stable, in consideration of more experimental data, 4 groups of samples (A1-B1, A8-B8, A10-B10 and A12-B12) are randomly extracted from examples 1-24 to carry out performance characterization display, and the specific results are shown in FIGS. 1-14. It will be appreciated by those skilled in the art that random samples can reflect the average level of other technical solutions under the present invention.

Table 2: solid oxide fuel cell

In the present invention, Ce_1-yCa_yO_2-δThe particles are impregnated with a suitable metal catalyst to make Ce_1-yCa_yO_2-δThe pores of the particles are uniformly distributed with the active metal. In all of the examples described herein, the active metal catalyst is Ni_1-xMo_xAnd (3) alloying. It has been confirmed that Ni is present in the invention_1-xMo_xHas higher catalytic activity for the conversion of hydrocarbon fuel and the formation of hydrogen and carbon monoxide (which are important steps in the electrochemical oxidation of hydrogen in the anode of the SOFC). In FIG. 1, Ni is shown_1-xMo_x/Ce_1-yCa_yO_2-δXRD pattern of catalyst, XRD analysis result shows that the catalyst powder is mainly Ce_1-yCa_yO_2-δPhase and Ni_1-xMo_xAn alloy phase. Here, "mainly" means that no other phase is detected in the lower limit range of detection of XRD.

FIG. 2 shows Ce_1-yCa_yO_2-δSEM photograph of the catalyst support: (a) y is 0.01, (b) y is 0.1, (c) y is 0.2, and (d) y is 0.4. In FIG. 3, Ni is shown_1-xMo_x/Ce_1-yCa_yO_2-δTEM image of catalyst: (a) x is 0.1 and y is 0.01; (b) x is 0.1, y is 0.1; (c) x is 0.3, and y is 0.2; (d) x is 0.3 and y is 0.4. Showing Ni_1-xMo_xThe alloy phase is uniformly distributed in Ce_1-yCa_yO_2-δOn a ceramic matrix, the catalyst having particles in the size range of 1nm to 500nm, Ni_1-xMo_xThe grain size of the alloy phase is about 10nm or less.

Ni is shown in FIG. 4_1-xMo_x/Ce_1-yCa_yO_2-δCatalyst catalyzes simulated gasoline fuel (C) at 750 DEG C₈H₁₈) Hydrogen yield at reforming: (a) x is 0.00 and y is 0.01; (b) x is 0.10, y is 0.10; (c) x is 0.30, and y is 0.20; (d) x is 0.50 and y is 0.40. FIG. 5 shows Ni_1-xMo_x/Ce_1-yCa_yO_2-δCatalytic simulation of gasoline fuel (C) at 750 deg.C₈H₁₈) Carbon monoxide yield at reforming: (a) x is 0.00 and y is 0.01; (b) x is 0.10, y is 0.10; (c) x is 0.30, and y is 0.20; (d) x is 0.50 and y is 0.40.

The present invention uses a fixed bed reactor method (the fluid passes through a bed formed by fixed solid materials) to investigate Ni_1-xMo_x/Ce_1-yCa_yO_2-δCatalyst at 750 deg.C for simulating gasoline fuel (C)₈H₁₈) The catalytic performance of (2). Wherein the flow rate of the liquid fuel is 3ml/h, and the air flow rate is 100ml/min (O)₂The ratio/C is 0.4), the gas hourly space velocity is 45,000/H, then H₂The calculation formulas of the CO and the fuel conversion rate are respectively as follows:

H₂yield 2 × yield H₂(18X input C)₈H₁₈Mole number of (2)

CO yield-moles CO produced/(8 × input C)₈H₁₈Mole number of (2)

Fuel conversion rate of CO and CO₂、CH₄Molar sum/(8 × input C)₈H₁₈Mole number of). FIGS. 4 and 5 (b), (c) and (d) show the invention H₂And the yields of CO may be 70% or more and 80% or more, respectively. And (a) x is 0.00 and y is 0.01 in fig. 4 and 5 (a 1)) The stability has a certain degree of downward slip with time, to around 40%. The samples A8, a10, a12 were not the best combination of properties, but even the conversion dropped to around 40% had comparable catalytic performance to the existing base metal catalysts. In further studies of the present invention, it was found that the addition of Mo to Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe stability of the catalyst has higher promotion effect.

FIG. 6 shows Ni_1-xMo_x/Ce_1-yCa_yO_2-δCatalytic simulation of gasoline fuel (C) at 750 deg.C₈H₁₈) Fuel conversion at reforming: (a) x is 0.00 and y is 0.01; (b) x is 0.10, y is 0.10; (c) x is 0.30, and y is 0.20; (d) x is 0.50 and y is 0.40. It can be seen that the fuel conversion in the present invention is as high as 90%. The catalytic performance is obviously superior to that of a catalyst Rh/Al containing noble metal elements₂O₃At C₈H₁₈Catalytic performance (H) of₂Yield-40%, fuel conversion-70%, Combustion and flame 157(2010) 1771-1782). Thus, Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe catalyst is an SOFC anode catalyst with good commercial application prospect.

In addition, the catalytic performance of the hydrocarbon fuel catalyst in the traditional fixed bed reactor is greatly different from that of the hydrocarbon fuel catalyst in the SOFC anode, and the catalytic performance is closely related to the working environment of the SOFC anode. In SOFC operation, the anodic electrochemical reaction produces H₂O，CO₂And oxygen ions conducted in the anode can change O in the anode gas₂the/C ratio, which in turn affects the catalytic conversion process of the hydrocarbon fuel. Therefore, the invention also considers Ni in the simulation of the operation state of the SOFC_1-xMo_x/Ce_1-yCa_yO_2-δThe catalytic performance of the catalyst.

In the present invention, at least one of the anode, the cathode and the electrolyte serves as a support of the solid oxide fuel cell. Typically, the solid oxide fuel cell is an anode-supported solid oxide fuel cell, as shown in fig. 7, the anode-supported SOFC cross-section is shown schematically (a: anode layer, E: electrolyte layer, C: cathode layer). Specifically, in the embodiments of the invention B1-B8, the solid oxide fuel cell is supported for the anode, the electrolyte layer and the cathode layer are together on a supporting layer anode, and the anode is a porous material to allow the gaseous fuel to pass through the catalyst and contact the anode to a greater extent. In the embodiment of B20-B24 of the present invention, the support as a solid oxide fuel cell is an electrolyte-supported solid oxide fuel cell, as shown in FIG. 8: the cross-section of the electrolyte-supported SOFC is shown schematically (a: anode layer, E: electrolyte layer, C: cathode layer). In the embodiment of the invention B9-B12, the support as a solid oxide fuel cell is a cathode-supported solid oxide fuel cell, as shown in fig. 9: cathode-supported SOFC cross-sections are shown schematically (a: anode layer, E: electrolyte layer, C: cathode layer).

In addition, in the present invention, it is not most preferable to use the electrolyte layer as the support layer of the solid oxide fuel cell. Since the larger the thickness of the electrolyte, the larger the internal resistance of the solid oxide fuel cell, the more energy loss in the cell and the smaller the output power. Particularly, when the operating temperature of the solid oxide fuel cell is lower than 700 ℃, the resistance energy loss of the electrolyte becomes one of the main energy losses of the solid oxide fuel cell, and therefore, in order to increase the output power of the cell, it is necessary to reduce the thickness of the electrolyte or increase the ionic conductivity of the electrolyte. Anode-supported or cathode-supported solid oxide fuel cells are therefore usually chosen.

In embodiments of the invention B13-B19, the support of the solid oxide fuel cell is a metal-supported solid oxide fuel cell. Specifically, the metal support serves as a matrix for the anode, electrolyte and cathode layers of the fuel cell. The substrate is porous to allow air fuel to pass through the metal support substrate and contact the anode. The substrate metal is any one or combination of metal substrates used in metal supported SOFCs. In these designs, the anode is located on a perforated area, and this configuration provides gas to the anode through the perforated (typically laser drilled) area. Such as ferritic stainless steel substrates, which have similar coefficients of thermal expansion to the most commonly used doped ceria, doped rolled ceria (commonly abbreviated GDC or CGO), can reduce stresses within the SOFC cell during heating/cooling cycles.

In embodiments of the invention B1-B24, the matrix of doped metal oxide is a conductive ceramic material. As this material is well suited for the operating conditions of solid oxide fuel cells. Typically the conductive ceramic material is rare earth doped ceria or zirconia. This material is not only stable under SOFC operating conditions, it also provides good electrochemical and structural properties, and can be well fixed to substrates, especially metal substrates. In particular, in embodiments of the invention 12-B24 is gadolinium doped Ceria (CGO). In the embodiments of B1-B4 of the present invention, the rare earth doped zirconia is yttrium doped zirconia. The rare earth doped ceria is one or a combination of samarium doped ceria and gadolinium doped ceria. In embodiments of the invention B1-B24, the doped metal oxide containing matrix is one of Ni-samarium doped ceria, Ni-gadolinium doped ceria or a combination thereof. In particular, the matrix containing the doped metal oxide is Ni-yttria doped zirconia.

In embodiments of the invention B21-B24, the matrix further comprises one or more components selected from the group consisting of: sintering aids, conductors, catalyst materials, binders, dispersants, or combinations thereof. Some of these materials are removed during sintering (e.g., binders and dispersants), but they have a positive effect in forming the matrix composition.

The SOFC anode catalyst of the present invention improves on the one hand the electrical conductivity of the matrix (since most are metals or metal-conductive ceramics) and on the other hand promotes internal reforming of the fuel. The catalyst is uniformly distributed throughout the matrix comprising the doped metal oxide. The amount of the catalyst material (or its oxide) used is not particularly limited. At the same time, although the introduction of a catalyst-containing material into the SOFC anode results in an improvement in its performance, too much addition can have a detrimental effect on the electrochemical oxidation performance of the anode. Thus, to achieve the optimum balance of properties, the catalyst material content is typically equal to or less than about 80% wt, more typically equal to or less than about 75%, and still more typically in the range of 5% to 70% wt, even more typically in the range of 10% to 60% wt, and even more typically in the range of 20% to 55% wt. Typically, the catalyst material is present in an amount of from 10% to 50% wt, more typically from 15% to 45%, more typically from 20% to 40%, and in some embodiments of the invention, from 25% to 35%. The hydrocarbon fuel SOFC anode unit has both a chemical catalysis function and an electrochemical oxidation function. The anode catalyst mainly catalyzes a hydrocarbon fuel reforming reaction, and the anode electrochemical functional layer mainly catalyzes the electrochemical oxidation of small-molecule hydrocarbon gas. When the content of the anode catalyst is lower than 5 wt%, the chemical catalytic effect is weak, and the effective conversion of the fuel gas cannot be promoted; when the catalyst content is too high (> 80% wt), the anode electrochemical layer content is low, which is not favorable for electrochemical oxidation of hydrocarbon gas. Therefore, it is appropriate to control the catalyst content in the SOFC anode to 5-80% wt.

In the invention, Ni_1-xMo_x/Ce_1-yCa_yO_2-δApplication of catalyst to solid oxide fuel cell, verification of Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe geometric shape of the SOFC single cell is a flat plate shape or a hollow cylindrical shape. Wherein, the thickness of the Ni-based anode is as follows: 10 microns-20 mm, and the material composition is as follows: ni-yttria stabilized zirconia (Ni-YSZ), Ni-samarium doped ceria (Ni-SDC), Ni-gadolinium doped ceria (Ni-GDC), and the like; the thickness of the electrolyte was: 10 microns-20 mm, and the material composition is as follows: YSZ, SDC, GDC; the thickness of the cathode is: 10 microns-20 mm, and the material composition is as follows: lanthanum strontium manganese oxide (La)_1-mSr_mMnO_3-δ,0<m<1) Lanthanum strontium cobalt iron oxide (La)_1-aSr_aCo_1-bFe_bO_3-δ,0<a<1, 0<b<1) Barium strontium cobalt iron oxide (Ba)_1-aSr_aCo_1-bFe_bO_3-δ,0<a<1,0<b<1)。

In embodiments of the invention B1-B24, the electrolyte is one of samarium doped ceria, gadolinium doped ceria, yttria doped zirconia, and is correspondingly matched to the matrix of the doped metal oxide. In particular embodiment B1-B4 of the present invention, the electrolyte comprises YSZ and the anodic metal-ceramic based material is Ni-YSZ. In embodiments B5-B11, the electrolyte is SDC containing and the anode metal-ceramic based material is Ni-SDC. In embodiments B12-B24, the electrolyte is CGO-containing and the anodic metal-ceramic based material is Ni-CGO.

In the embodiments of the present invention B1-B24, the cathode is one of lanthanum strontium manganese oxide (e.g., B5, B6, etc.), lanthanum strontium cobalt iron oxide (e.g., B1, B2, etc.), barium strontium cobalt iron oxide (B12, etc.) having a perovskite crystalline structure. The general formula of the lanthanum strontium manganese oxide is La_1-mSr_mMnO_3-δWherein 0 is<m<1. Further, in some embodiments of the invention, La_1- _mSr_mMnO_3-δ，0<m is less than or equal to 0.5. The general formula of the composition of lanthanum strontium cobalt iron oxide is La_1-aSr_aCo_1-bFe_bO_3-δWherein 0 is<a<1, 0<b is less than or equal to 1. Further, in some embodiments of the invention, La_1-aSr_aCo_1-bFe_bO_3-δWherein a is 0.1 to 0.9, b is 0.3 to 1.0, or a is 0.2 to 0.8, and b is 0.2 to 1.0). Further, in embodiment B1 of the present invention, La_1-aSr_aCo_1-bFe_bO_3-δIn the formula, a is 0.4 and b is 0.8. The general formula of the composition of the barium strontium cobalt iron oxide is Ba_1-aSr_aCo_1-bFe_bO_3-δWherein 0 is<a<1,0<b is less than or equal to 1. Further, a is 0.1 to 0.9, b is 0.3 to 1.0, or a is 0.2 to 0.8, and b is 0.2 to 1.0). Further, in embodiment B12 of the present invention, Ba_1-aSr_aCo_1-bFe_bO_3-δIn the formula, a is 0.4 and b is 0.8.

Adopting zirconium oxide (YSZ) with stable Ni-yttrium oxide as anode; YSZ/samarium doped cerium oxide (SDC) is taken as electrolyte; la_0.6Sr_0.4Co_0.2Fe_0.8O_3-δA single cell that is a cathode ". FIG. 10 shows Ni_1-xMo_x/Ce_1-yCa_yO_2-δSchematic representation of the use of the catalyst in an anode-supported SOFC (a: anode, E: electrolyte, C: cathode).

FIG. 11, FIG. 12 and FIG. 13 are Ni_1-xMo_x/Ce_1-yCa_yO_2-δCatalyst for simulating gasoline fuel (C) in SOFC single cell configuration₈H₁₈) The performance of the catalytic reforming is characterized, and the simulated working temperature is 750 ℃. Wherein, FIG. 11 shows Ni_1-xMo_x/Ce_1- _yCa_yO_2-δCatalytic simulation of gasoline fuel (C) on SOFC anode surface₈H₁₈) Hydrogen yield at conversion: (a) x is 0.00 and y is 0.01; (b) x is 0.10, y is 0.10; (c) x is 0.30, and y is 0.20; (d) x is 0.50 and y is 0.40.

FIG. 12 shows Ni_1-xMo_x/Ce_1-yCa_yO_2-δCatalytic simulation of gasoline fuel (C) on SOFC anode surface₈H₁₈) Carbon monoxide yield at conversion: (a) x is 0.00 and y is 0.01; (b) x is 0.10, y is 0.10; (c) x is 0.30, and y is 0.20; (d) x is 0.50 and y is 0.40.

FIG. 13 shows Ni_1-xMo_x/Ce_1-yCa_yO_2-δCatalytic simulation of gasoline fuel (C) on SOFC anode surface₈H₁₈) Fuel conversion at conversion: (a) x is 0.00 and y is 0.01; (b) x is 0.10, y is 0.10; (c) x is 0.30, and y is 0.20; (d) x is 0.50 and y is 0.40.

The above results show that Ni_1-xMo_x/Ce_1-yCa_yO_2-δConversion to fuel of about 78%, H₂And the yields of CO were about 55% and 60%, respectively. The results and the catalyst Ru-CeO containing the noble metal elements reported in the literature₂The catalytic performance in SOFC anodes is comparable. Meanwhile, the performance is superior to the catalytic performance of a cheap metal catalyst NiMo/Ceria-zirconia in the SOFC anode (fuel conversion rate: 71%, H)₂Yield 46%, CO yield 44%, Applied Catalysis B Environmental 224(2018)500-507). Ni in comparison to NiMo/Ceria-zirconia SOFC catalysts_1- _xMo_x/Ce_1-yCa_yO_2-δCeramic support Ce in catalyst_1-yCa_yO_2-δThe catalyst has higher oxygen ion conduction performance, promotes incomplete oxidation of complex hydrocarbon fuel on the surface of the catalyst, and enables the catalyst to show higher and more stable catalytic activity.

Fig. 14 is a comparative graph of discharge performance stability of solid oxide fuel cells in simulated gasoline fuel. The single cell configuration of the comparative example was an anode-supported solid oxide fuel cell in which Ni-Ce was used_0.8Sm_0.2O_2-δIs an anode; the electrolyte is (Y)₂O₃)_0.08(ZrO₂)/Ce_0.8Sm_0.2O_2-δ；La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δIs the cathode. Simulating (C) in gasoline fuel at 750 deg.C working temperature₈H₁₈) Discharge performance stability curve of (1). It can be seen that the single cell, which did not contain the anode catalyst layer of the present invention, was at 250mA/cm²Shows a significant performance decay with a voltage decay rate of up to 232 mV/h over 3 hours. After the catalyst of the invention is applied to the surface of the single cell Ni-YSZ anode (the structure diagram of the single cell is shown in figure 10), the voltage decay rate is reduced to 3 mV/h. SOFC single cell stability test shows that Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe catalyst can realize the high-efficiency conversion of complex hydrocarbon fuel and improve the stability of the electrochemical performance of the SOFC. This stability result is superior to that of RuO containing the noble metal element₂-CeO₂The performance of a single cell of the catalyst (Journal of Power Sources 157(2006) 422-429) in the same fuel is also superior to the catalytic performance of the existing base metal (represented by Ni) anode catalyst. Thus, the present invention provides inexpensive metal-ceramic type Ni_1-xMo_x/Ce_1-yCa_yO_2-δThe catalyst shows excellent practical value in the aspect of application of the complex hydrocarbon fuel SOFC, and has great commercial application prospect.

In addition, theNi according to the invention_1-xMo_x/Ce_1-yCa_yO_2-δThe catalytic results (composition of reformed gas) of the catalyst on the simulated gasoline fuel are equivalent to the catalytic results of the Pd-Pt series catalyst disclosed in CN101803097A on the propane fuel, and the SOFC single cell shows similar performance stability in the simulated gasoline fuel and the propane fuel. However, liquid simulated gasoline fuel (C) as compared to gaseous propane fuel₈H₁₈) Is a more complex hydrocarbon fuel, catalytic C₈H₁₈Conversion to H₂And CO, require a catalyst with higher catalytic activity and carbon deposition resistance, and the cell stability results of this similarity in the present invention demonstrate Ni_1- _xMo_x/Ce_1-yCa_yO_2-δThe catalyst has high-efficiency catalytic characteristics and excellent stability on complex hydrocarbon fuels.

Although features described herein are part of the invention as "comprising", it will also be understood that the invention may be "consisting" or "consisting essentially of" one or more of the described features. Moreover, all numerical ranges are not to be read literally, but are modified by the term "about" to include numerical values that are literally, but not necessarily deviate by the technical material.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by using equivalent alternatives or equivalent variations fall within the scope of the present invention.

Claims

1. A method of making a solid oxide fuel cell catalyst, comprising the steps of:

adding glycine to the mixture to form a solution in which glycine is dissolved;

heating the glycine dissolved solution to evaporate the balance of the water, initiating combustion, andto form a compound with the general formula of Ce_1-yA_yO_2-δ(2) The nano-oxide powder of (4); and

reducing the calcined mixed powder at 600-800 ℃ for 0.5 h in a reducing atmosphere to produce a mixed powder having the general composition of Ni_1-xMo_x/Ce_1-yA_yO_2-δ(1) The catalyst of (1);

2. The method for preparing a solid oxide fuel cell catalyst according to claim 1, wherein the molar ratio of glycine in the glycine-dissolved solution to metal ions in nitrate is 1.5 to 3: 1.

3. the method of making a solid oxide fuel cell catalyst according to claim 1, wherein the catalyst has particles in the size range of 1nm to 500 nm.

4. The method of preparing a solid oxide fuel cell catalyst according to claim 1, wherein the step of calcining the nano-oxide powder comprises: the temperature is raised to 700-1000 ℃ within 4 hours, and then the temperature is maintained for 1-4 hours.

5. The method of preparing a solid oxide fuel cell catalyst according to claim 1, wherein the step of calcining the mixed powder comprises: the temperature is raised to 500-700 ℃ within 4 hours, and then the temperature is maintained for 0.5-2 hours.

6. The method of making a solid oxide fuel cell catalyst as claimed in claim 1, wherein the catalyst is applied to an anode surface of a solid oxide fuel cell to convert hydrocarbon fuel to H-rich₂And a CO-rich gas.

7. The method of producing a solid oxide fuel cell catalyst according to any one of claims 1 to 6, characterized in that the mixed powder after calcination is reduced with hydrogen and an inert gas.

8. The method of preparing a solid oxide fuel cell catalyst according to claim 7, wherein the hydrogen gas is 10 mol%.

9. The method of preparing a solid oxide fuel cell catalyst according to claim 7, wherein the inert gas is 90 mol%.

10. The method of preparing a solid oxide fuel cell catalyst according to claim 9, wherein the inert gas is one of nitrogen, argon, helium.