A SOFC stack tail gas treatment process

Abstract

The present application relates to a kind of high-temperature catalytic combustion catalyst for SOFC stack tail gas treatment and its preparation method and purposes.The catalyst includes: catalyst precursor and catalyst matrix;Catalyst precursor includes the following components: sepiolite powder 10-50wt%, rare earth metal modified Ce, Zr composite oxide 30-80wt%;One or several of soluble salt of cobalt, iron and manganese, cobalt, iron, manganese transition metal oxide content 1-20wt%;Catalyst matrix is at least one of cordierite ceramic matrix, Al2O3 high-temperature ceramic, ZrO2, mullite Al2O3 · SiO2, hexaaluminate.The catalyst is used for high-temperature methane SOFC cell stack tail gas treatment, light-off temperature is low, complete conversion temperature is low, can provide pressure temperature stable heat supply for SOFC stack reaction, improves the efficiency of heat utilization under the premise of guaranteeing the stable operation of SOFC stack.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of SOFC catalytic combustion, and particularly relates to a SOFC stack tail gas treatment process. BACKGROUND

[0002] A solid oxide fuel cell (SOFC) is a clean and efficient power generation device that directly converts chemical energy in fuel into electrical energy at high temperature (600-1000℃). At the same time, the SOFC has strong fuel adaptability and can use synthetic gas, methane, diesel and other fuels to achieve higher energy density, so the SOFC has a wide application prospect in the fields of fixed power stations, distributed power stations, combined heat and power systems, etc. Among them, methane is more easily obtained than other fuels, so the methane solid oxide fuel cell has a very large market in the future.

[0003] Since the reaction of the solid oxide fuel cell needs to be carried out at a relatively high temperature, in order to improve the fuel utilization rate, the anode tail gas after dehydration is usually combusted to contain methane as fuel to provide heat for the reaction of the cell. There is a key disadvantage in applying the flame combustion of the anode tail gas to the solid oxide fuel cell: the flame fluctuation of the flame combustion will cause the pressure fluctuation of the SOFC system, and the long-term pressure fluctuation of the fuel cell stack will reduce the use efficiency and service life of the cell and affect the stability of power generation. Due to the need for heat exchange of the SOFC stack, the temperature of the combustion chamber for providing heat for the stack needs to be stabilized at 900-1000℃.

[0004] Natural gas catalytic combustion is a complete oxidation reaction of low-carbon hydrocarbons with methane as the main component on the surface of a catalyst, which is a flameless combustion method. Compared with the traditional flame combustion, the catalytic combustion has the following advantages: ① high combustion efficiency and low CO and unburned HC emissions; ② stable and controllable combustion process, which is an ideal combustion method. Therefore, the application of the catalytic combustion technology in the SOFC can effectively solve the problem of pressure fluctuation of the stack.

[0005] Currently, the active component of catalytic combustion is noble metal. The noble metals platinum, palladium and rhodium are commonly used active components, mainly because of their large reserves and low volatility at high temperatures. The platinum group elements have high catalytic activity for the oxidation of hydrocarbons, hydrogen and carbon monoxide, and the mixture of palladium, platinum and rhodium has higher catalytic activity. For low concentration catalytic combustion of methane, palladium is the most active noble metal. Although palladium is the first choice for the active component of catalytic combustion of methane, it has many disadvantages, such as the existence of palladium in the form of palladium oxide at normal temperature and pressure, but at high temperature, such as 800℃, the palladium oxide will decompose into metallic palladium and reduce its activity. The volatility, sintering, poisoning and high price of noble metals at high temperature limit their application in high temperature combustion of methane, so they are generally used in the low temperature start-up stage of the burner.

[0006] Metal oxides can also be used as active components for oxidation reactions. High oxidation activity requires the metal to have variable valence. Oxides of metal elements in the fourth period of the periodic table can be used as active components for complete oxidation of hydrocarbons. In general, the catalytic activity of two or three metal oxides is higher than that of single metal oxides. Oxides of copper, chromium, manganese, iron, cobalt and nickel can be used as active components of combustion catalysts, among which Co3O4 is the best combustion catalyst. However, these metal oxides will be severely deactivated at temperatures above 800℃.

[0007] Currently, some foreign researches have applied catalytic combustion technology to the field of SOFC, but there are still some problems. Jae Gi Sung used La0.8Sr0.2Mn0.67Cu0.33O3 perovskite (LSMC(p)) supported CuO or Mn2O3 as a catalyst for SOFC tail gas treatment, which showed better thermal stability than CuMnLa / Al2O3 catalyst, but the T50 (light-off temperature for 95% methane conversion) of CH4 reached 600℃. Due to the high light-off temperature, a large amount of heat is required to reach the light-off temperature. Tae Ho Lee studied the catalytic performance of Pd and Pt supported catalysts in SOFC exhaust gas containing H2O, O2 and CH4, with the highest inlet temperature reaching 580℃ and the optimal methane conversion rate being 75%. The burner exhaust heat is not utilized, and the methane conversion rate is low. SUMMARY

[0008] The first technical problem to be solved by the present application is that the existing direct combustion method has a large SOFC stack pressure fluctuation when applied to SOFC tail gas combustion, which affects the power generation efficiency and stability of the cell. The second technical problem to be solved by the present application is that the existing low-temperature catalytic combustion catalyst has a low noble metal light-off temperature, but the noble metal is prone to sintering and deactivation at high temperatures such as 800-1000℃. The third technical problem to be solved by the present application is that the existing high-temperature catalytic combustion catalyst has a high light-off temperature, which requires a large amount of heat to reach the light-off temperature. Therefore, the present application provides a high-temperature catalytic combustion catalyst for high-temperature methane SOFC stack tail gas treatment, and further provides a preparation method thereof and its use in high-temperature methane SOFC stack tail gas treatment.

[0009] To solve the above technical problems, the present application is realized by the following technical solutions:

[0010] In a first aspect, the present application provides a high-temperature catalytic combustion catalyst for SOFC stack tail gas treatment, comprising: a catalyst precursor and a catalyst substrate;

[0011] The catalyst precursor comprises the following components, based on the total weight of the sepiolite powder, the rare earth metal modified Ce, Zr composite oxide and the active component (calculated as the corresponding metal oxide) being 100%:

[0012] A. Sepiolite powder, 10-50wt%, preferably 15-40wt%, preferably 15-30wt%, preferably 15-25wt%, for example 15wt%, 20wt%, 25wt%, 35wt%, 45wt%;

[0013] B. Carrier precursor, i.e. rare earth metal modified Ce, Zr composite oxide, 30-80wt%, preferably 45-78wt%, preferably 50-75wt%, preferably 65-75wt%, for example 50wt%, 60wt%, the rare earth metal being at least one of La and Y (La and / or Y);

[0014] C. Active component, i.e. one or more soluble salts of cobalt, iron, manganese (for example Co 2+ , Fe 3+ , Mn 2+ ), 1-20wt% based on the content of cobalt and / or iron and / or manganese transition metal oxides, preferably 5-18wt%, preferably 8-15wt%, preferably 10-15wt%, for example 8wt%, 15wt%;

[0015] Further, the catalyst precursor further comprises Al2O3, and the addition amount of Al2O3 powder is 1-20wt% based on the total weight of the carrier precursor and the sepiolite powder, preferably 2-10wt%, more preferably 2-5wt%, for example 4wt%.

[0016] The catalyst substrate is selected from at least one of cordierite ceramic substrate, Al2O3 high-temperature ceramic, ZrO2, mullite Al2O3·SiO2, hexaaluminate, preferably cordierite ceramic substrate, more preferably honeycomb cordierite ceramic substrate.

[0017] Further, in the high-temperature catalytic combustion catalyst, the content of La2O3 and Y2O3 in the rare earth metal modified Ce, Zr composite oxide is 5wt%-10wt%, 5wt%-10wt%, preferably 6-9wt%, more preferably 7-8wt%, for example, the mass ratio of La2O3 and Y2O3 can be 1:0.5-1.5; and / or,

[0018] In the rare earth metal modified Ce, Zr composite oxide, the content of CeO2 is 20-40wt%, preferably 25-35wt%, preferably 28-32wt%, for example 30wt%, and the content of ZrO2 is 50-70wt%, preferably 55-65wt%, preferably 58-62wt%, for example 60wt%; and / or,

[0019] The active component is a nitrate salt of cobalt (such as Co 2+ ), a nitrate salt of iron (such as Fe 3+ ), a nitrate salt of manganese (such as Mn 2+ ).

[0020] In a second aspect, the present application provides a preparation method of the high-temperature catalytic combustion catalyst, comprising the following steps:

[0021] 1) Sepiolite treatment

[0022] Take sepiolite, first wash and soak with water (preferably deionized water), then soak with acid (preferably hydrochloric acid), then wash with water (preferably deionized water) (preferably wash until the washing liquid is neutral), filter (preferably suction filtration), dry, calcine, grind (for example, grind to 40-200 mesh, preferably 80-100 mesh, for example 90 mesh), to prepare sepiolite powder;

[0023] 2) Preparation of catalyst carrier

[0024] Take a selected weight of carrier precursor, i.e. rare earth metal modified Ce, Zr composite oxide and the sepiolite powder, add nitric acid and Al2O3 powder, knead and dry to obtain a catalyst carrier;

[0025] 3) Impregnation method to load active component

[0026] Optionally, a selected weight of one or more soluble salts of active components, i.e. cobalt, iron, manganese, is dissolved in water (the water is preferably deionized water, and the temperature of the water is preferably 50-90°C, more preferably 60-80°C, for example 75°C) to prepare an aqueous solution of the one or more soluble salts of active components, i.e. cobalt, iron, manganese, and then the catalyst carrier is immersed in the aqueous solution of the one or more soluble salts of active components, i.e. cobalt, iron, manganese, dried, calcined, to obtain a catalyst precursor;

[0027] 4) Catalyst coating

[0028] The catalyst precursor is dispersed in a solvent (for example deionized water, polyethylene glycol, etc.) to form a slurry, which is coated on at least one of the catalyst substrates, i.e. honeycomb cordierite ceramic substrate, Al2O3 high-temperature ceramic, ZrO2, mullite Al2O3·SiO2, hexaaluminate, to form a coating on the surface of the catalyst substrate, and then calcined to obtain a high-temperature catalytic combustion catalyst.

[0029] Further, in the preparation method of the high-temperature catalytic combustion catalyst described above:

[0030] In step 1), the water soaking is performed for 0.1-96h, preferably 48-72h, for example 24h, 36h, 60h; and / or,

[0031] In step 1), the hydrochloric acid concentration is 0.1-2mol / L, preferably 0.8-1.5mol / L, for example 0.5mol / L, 1.2mol / L, and the hydrochloric acid soaking is performed for 0.1-72h, preferably 36-48h, for example 20h, 35h, 64h; and / or,

[0032] In step 1), the drying temperature is 100-150°C, preferably 110°C, and the drying time is 0.5-5h, preferably 2h, for example 1h, 4h; and / or,

[0033] In step 1), the calcination temperature is 200-500°C, preferably 250-350°C, for example 300°C, 400°C, and the calcination time is 4-12h, preferably 6-8h, for example 7h, 10h; and / or,

[0034] In step 2), the mass ratio of the sepiolite powder to the carrier precursor is 1:1-1:5; preferably 1:2-1:3, for example 1:4; and / or,

[0035] In step 2), the concentration of the nitric acid is 0.1-2wt%, preferably 0.5-1wt%, for example 1.5wt%; and / or,

[0036] In step 2), the amount of nitric acid added is 5-20 wt%, preferably 7-15 wt%, more preferably 8-12 wt%, for example 10 wt%, 18 wt%, relative to the total weight of the carrier precursor and sepiolite powder; and / or,

[0037] In step 2), the amount of Al2O3 powder added is 5-20 wt%, preferably 7-15 wt%, more preferably 10 wt%, for example 12 wt%, relative to the total weight of the carrier precursor and sepiolite powder; and / or,

[0038] In step 2), the kneading is carried out until the mixture is uniform and free of lumps; and / or,

[0039] In step 2), the drying temperature is 100-150°C, preferably 110°C, for example 120°C, and the drying time is 0.5-5h, preferably 2h, for example 3h.

[0040] Further, in the above method for preparing a high-temperature catalytic combustion catalyst:

[0041] In step 3), the concentration of the active component, i.e. one or more soluble salts of cobalt, iron, and manganese, in the aqueous solution of the active component, i.e. one or more soluble salts of cobalt, iron, and manganese, is greater than its solubility; and / or,

[0042] In step 3), the impregnation time is 1-3h, preferably 0.5-2h; and / or,

[0043] In step 3), the drying temperature is 100-150°C, preferably 100-120°C, more preferably 110°C, for example 130°C, and the drying time is 0.5-5h, preferably 1-3h, more preferably 2h; and / or,

[0044] In step 3), the calcination temperature is 600-800°C, preferably 600°C, for example 700°C, and the calcination time is 2-5h, preferably 2h, for example 3h; and / or,

[0045] In step 4), the specific gravity of the slurry is 1:1-5 cm 3 / g, preferably 1:1.5-3.5 cm 3 / g, for example 1:2.5 cm 3 / g; and / or,

[0046] In step 4), the thickness of the coating is 0.8-1.5mm, preferably 0.9-1.2mm, more preferably 1mm; and / or,

[0047] In step 4), the calcination temperature is 800-1000°C, preferably 850-950°C, more preferably 900°C, and the calcination time is 1-5h, preferably 1-3h, more preferably 2h.

[0048] In a third aspect, the present application provides a use of the high-temperature catalytic combustion catalyst or the high-temperature catalytic combustion catalyst prepared by the preparation method of the high-temperature catalytic combustion catalyst in SOFC stack tail gas treatment.

[0049] The low-temperature catalytic combustion catalyst comprises a catalyst substrate and a coating layer, a ratio of a surface area of the coating layer to a volume of the catalyst substrate is 400-500 m 2 / L, the coating layer comprises a catalyst carrier and an active metal; wherein the catalyst substrate is selected from at least one of cordierite and Al2O3 ceramic, the catalyst carrier is alumina, and the active metal is selected from at least one of Pt, Pd and a Pt-Pd composite;

[0050] Preferably, in the low-temperature catalytic combustion catalyst, a content of Pt in the coating layer is 1-2 wt%; and / or,

[0051] In the low-temperature catalytic combustion catalyst, a content of Pd in the coating layer is 1-3 wt%; and / or,

[0052] In the low-temperature catalytic combustion catalyst, the catalyst substrate is in a honeycomb cuboid shape.

[0053] In a fourth aspect, the present application provides a SOFC stack tail gas treatment device, which comprises an air compressor, a pressure reducing device (for example, a pressure reducing valve), a first gas flow meter, a second gas flow meter, a first heat exchanger, a second heat exchanger, a SOFC cell stack, a mixing separation tank and a catalytic combustor, wherein the first heat exchanger, the second heat exchanger and the SOFC cell stack are located in a heat preservation cavity, the catalytic combustor comprises an upper section filled with a low-temperature catalytic combustion catalyst and a lower section filled with a high-temperature catalytic combustion catalyst, wherein an air inlet pipeline is connected to an air side inlet of the SOFC cell stack after passing through the air compressor, the first gas flow meter and the first heat exchanger, a natural gas inlet pipeline is connected to a fuel gas side inlet of the SOFC cell stack after passing through an optional pressure reducing device (the pressure reducing device exists or does not exist), the second gas flow meter and the second heat exchanger, the cathode outlet and the anode outlet of the SOFC cell stack are connected to the inlet of the mixing separation tank through pipelines, the outlet of the mixing separation tank is connected to the inlet of the catalytic combustor through a pipeline, and the outlet pipeline of the catalytic combustor is connected to the inlet of the heat preservation cavity, and the outlet of the heat preservation cavity is connected to a tail gas treatment device.

[0054] The first heat exchanger, the second heat exchanger and the SOFC cell stack are accommodated in the heat preservation cavity, and the heat preservation cavity is wrapped with very thick heat preservation material, so that the working temperature of the fuel cell is stabilized at 600-800 ℃.

[0055] In a fifth aspect, the present application provides a SOFC stack tail gas treatment process, which comprises the following steps:

[0056] Air (cathode gas) (air before compression can come from ambient environment) is compressed by air compressor to 1-10 kPa, the air out of the air compressor is optionally filtered to remove particulate impurities in the air, the first gas flow meter adjusts the gas flow, after heat exchange through the first heat exchanger (temperature after heat exchange is 600-800℃), the air enters the air side inlet of the SOFC fuel cell stack, natural gas (anode gas) (natural gas sources can be various, can come from natural gas cylinder group, LNG storage tank, or natural gas pipeline network, etc.) is optionally decompressed by a decompression device (such as a pressure reducing valve) to 5-20 kPa (optional decompression according to the source, for example, if it comes from a high-pressure gas source such as an LNG storage tank, it needs to be decompressed, if it comes from a natural gas pipeline network, it does not need to be decompressed), and is optionally desulfurized by a desulfurization device (the desulfurization device can use a desulfurization device commonly used in the art, such as desulfurization to a sulfur content of less than 0.1 ppm), enters the second gas flow meter to adjust the gas flow (for example, 1-50 L / min, preferably 15-25 L / min; adjust according to the reaction temperature of the catalytic combustor, increase the gas amount appropriately if the reaction temperature is low, and decrease the gas amount if the reaction temperature is high), after heat exchange through the second heat exchanger (temperature after heat exchange is 600-800℃), the natural gas enters the gas side inlet of the SOFC fuel cell stack, the electrical energy generated by the chemical reaction of the SOFC fuel cell stack provides electrical energy (such as delivered to industrial loads and fuel cell power generation auxiliary equipment), wherein the first gas flow meter and the second gas flow meter adjust the flow rate so that the volume ratio of air and gas is 15-30:1, preferably 16-25:1, preferably 16-20:1;

[0057] The solid oxide fuel cell stack cathode outlet gas (the cathode outlet gas is mainly N2 and O2, the composition of the outlet gas is basically the same as air, N2-79%, O2-21%) and the anode outlet gas (the anode outlet gas is methane, a small amount of hydrogen, CO and CO2 and H2O (for example, including CH4: 20-99%, H2: 0-50%, CO: 0-15%; CO2: 0-15%)) enter the mixing separation tank, where the gases are mixed and the water in the stack tail gas is removed, and then enter the catalytic combustor through the pipeline. The mixed gas passes through the catalyst A bed and the catalyst B bed of the catalytic combustor to undergo catalytic combustion reaction. The outlet gas of the catalytic combustor carries heat, which is used to heat the cathode inlet gas and the anode inlet gas and the stack cavity through the heat exchange of the cathode inlet heat exchanger and the anode inlet heat exchanger, and then enters the tail gas treatment device through the pipeline;

[0058] Wherein the catalytic combustor is divided into a low-temperature catalytic combustion section and a high-temperature catalytic combustion section, the catalyst A bed is filled with a low-temperature catalytic combustion catalyst, and a conventional noble metal Pt or Pd catalyst is adopted (a commercially available noble metal Pt or Pd catalyst can be adopted, and the catalytic combustion catalyst is generally composed of a substrate (a honeycomb-shaped cuboid, which increases the contact area) and a coating (containing a carrier and an active metal); the substrate is generally cordierite or Al2O3 ceramic, the carrier is generally alumina, and the active metal is generally Pt (1-2 wt%) or Pd (1-3 wt%) or Pt-Pd composite, wherein the content refers to the mass fraction of the coating. The ratio of the surface area of the coating to the volume of the catalyst substrate can be 400-500 m 2 / L); the catalyst B bed is the high-temperature catalytic combustion catalyst of the application.

[0059] Preferably, the process conditions of the SOFC are as follows: the stack inlet pressure is 1-10 kPa, preferably 2-8 kPa; the SOFC inlet gas temperature is 600-800 ℃ (preferably 680-750 ℃), the catalytic combustor reaction pressure is 0.1-10 kPa (preferably 1-5 kPa), the inlet temperature is 200-500 ℃ (preferably 250-400 ℃), and the outlet temperature is 800-1000 ℃ (preferably 900-950 ℃).

[0060] Here, the catalytic combustion reactor is a conventional high-temperature resistant packed reactor, the upper section of the packed catalyst is a low-temperature catalytic combustion catalyst, and the lower section is a high-temperature catalytic combustion catalyst. The reaction heat after the activation of the low-temperature catalytic combustion catalyst provides heat for the high-temperature catalytic combustion, so that the high-temperature catalytic combustion catalyst spontaneously performs the catalytic combustion reaction after reaching the ignition temperature. The catalytic combustion temperature is controlled by controlling the air-fuel ratio (the ratio of air (cathode gas) and anode tail gas inlet gas quantity) entering the catalytic combustor and the catalyst loading quantity (space velocity, the space velocity of the catalyst A and B is generally controlled at 4000-20000 h -1 , preferably 8000-12000 h -1 ). The stack cathode gas is air, the cathode gas and the anode gas enter a mixing separation tank for mixing and dehydration, and then directly enter the catalytic combustor. The air and anode tail gas quantity ratio (i.e. the volume ratio of the cathode tail gas and the anode gas tail gas) is 15-30:1, preferably 16-25:1, and more preferably 16-20:1.

[0061] The application has the following beneficial effects:

[0062] (1) The high-temperature catalytic combustion catalyst for tail gas treatment of high-temperature methane SOFC stacks, which is prepared by using sepiolite and rare earth metal modified Ce, Zr composite oxides in a specific ratio as a catalyst carrier, has a low light-off temperature (T10<500℃, preferably <450℃, preferably <410℃) when used for tail gas treatment of high-temperature methane SOFC stacks. The light-off temperature of the catalyst and the complete conversion temperature of the low-temperature catalytic combustion catalyst have overlapping parts, so that the entire catalytic combustion reactor has a low light-off temperature. In addition, the complete conversion temperature of the catalyst is low (T95<600℃, preferably <550℃, preferably <470℃, even <465℃), so that the problems of large pressure fluctuation of SOFC stacks, affecting the power generation efficiency and stability of the battery when the direct combustion method is applied to SOFC tail gas combustion, and the problem of high light-off temperature of high-temperature catalytic combustion catalyst, which requires a large amount of heat to reach the light-off temperature, are solved.

[0063] (2) The process for tail gas treatment of high-temperature methane SOFC stacks, which introduces catalytic combustion into the fuel cell process system to replace the traditional combustion chamber, provides heat for the stack reaction, and stabilizes the pressure of the stack system. The high-temperature catalytic combustion catalyst for tail gas treatment of high-temperature methane SOFC stacks is loaded in the high-temperature catalytic combustion section at the lower part of the catalytic combustor, and the low-temperature catalytic combustion catalyst is loaded in the low-temperature catalytic combustion section at the upper part of the catalytic combustor. The reaction heat of the activated low-temperature catalytic combustion catalyst provides heat for the high-temperature catalytic combustion, so that the high-temperature catalytic combustion catalyst spontaneously catalyzes combustion after reaching the light-off temperature. The use of the staged catalytic combustion technology provides heat for the SOFC inlet gas, and the combination of the staged catalytic combustion process and the optimized staged catalytic combustion process parameters makes the catalytic combustion catalyst have good catalytic combustion stability at high temperatures such as 900-1000℃, which can provide stable heat supply for the SOFC stack reaction. Under the premise of ensuring the stable operation of the SOFC stack, the efficiency of heat utilization is improved. BRIEF DESCRIPTION OF DRAWINGS

[0064] In order to make the content of the present application more easily understood, the present application will be further described in detail below according to specific embodiments of the present application and in conjunction with the accompanying drawings, in which:

[0065] Figure 1 The structure diagram of the high-temperature methane SOFC stack tail gas treatment device of Example 1;

[0066] Wherein, 1-air compressor, 2-first gas flow meter, 3-first heat exchanger, 4-SOFC cell stack, 5-mixing separation tank, 6-catalytic combustor, 7-pressure reducing device, 8-second gas flow meter, 9-second heat exchanger, a-air inlet pipeline, b-first gas flow meter inlet pipeline, c-first heat exchanger inlet pipeline, d-SOFC cell stack air inlet pipeline, e-cathode outlet pipeline, f-catalytic combustor inlet pipeline, g-gas inlet pipeline, h-second gas flow meter inlet pipeline, i-second heat exchanger inlet pipeline, j-SOFC cell stack gas inlet pipeline, k-anode outlet pipeline, l-catalytic combustor outlet pipeline, m-tail gas discharge pipeline. DETAILED DESCRIPTION

[0067] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0068] In the description of the application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "provided with", "connection" and the like should be understood in a broad sense, for example, "connection" can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can be direct connection, can also be indirect connection through intermediate medium, can be internal communication of two elements. The terms "upper", "middle", "outer", "inner", "lower", "periphery" and the like indicate the orientation or positional relationship, which are only for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the components or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0069] As Figure 1As shown, a SOFC stack tail gas treatment device includes an air compressor 1, a pressure reducing device 7, a first gas flow meter 2, a second gas flow meter 8, a first heat exchanger 3, a second heat exchanger 9, a SOFC cell stack 4, a mixing separation tank 5, and a catalytic combustor 6, wherein the first heat exchanger 3, the second heat exchanger 9, and the SOFC cell stack 4 are located in a heat preservation cavity 10, the catalytic combustor 6 includes an upper section filled with a low-temperature catalytic combustion catalyst and a lower section filled with a high-temperature catalytic combustion catalyst, wherein an air inlet pipeline is connected to an air side inlet of the SOFC cell stack 4 after passing through the air compressor 1, the first gas flow meter 2, and the first heat exchanger 3, a natural gas inlet pipeline is connected to a fuel gas side inlet of the SOFC cell stack 4 after passing through the optional pressure reducing device 7, the second gas flow meter 8, and the second heat exchanger 9, a cathode outlet and an anode outlet of the SOFC cell stack are connected to an inlet of the mixing separation tank 5 through pipelines, an outlet of the mixing separation tank 5 is connected to an inlet of the catalytic combustor 6 through a pipeline, and an outlet pipeline of the catalytic combustor 6 is connected to an inlet of the heat preservation cavity 10, and an outlet of the heat preservation cavity 10 is connected to the tail gas treatment device.

[0070] The heat preservation cavity internally accommodates the first heat exchanger, the second heat exchanger, and the SOFC cell stack, and is externally wrapped with thick thermal insulation material, so that the fuel cell operating temperature is stabilized at 600-800℃.

[0071] In the following examples and comparative examples of the present application, the sepiolite is purchased from the Lingshou County Dongxin Mineral Processing Factory;

[0072] The rare earth metal modified Ce, Zr composite oxide is purchased from Shanghai Huaming Gaona Rare Earth New Material Co., Ltd., LC-LY-35;

[0073] The active components, cobalt nitrate (≥98.0%), manganese nitrate (≥98.0%), manganese acetate (≥98.0%), iron nitrate (≥98.0%), etc. are purchased from the National Pharmaceutical Group Chemical Reagent Co., Ltd., and are of analytical purity;

[0074] The honeycomb cordierite ceramic matrix is purchased from the Pingxiang Beisheng Chemical Filler Co., Ltd.

[0075] Nitric acid is purchased from the Beijing Reagent, and is of premium purity, 65-68wt%, and is used after dilution;

[0076] Al2O3 powder is purchased from the National Pharmaceutical, 20002361 neutral alumina;

[0077] The noble metal Pt catalyst is purchased from the Wuxi Weifu Environmental Protection Catalyst Co., Ltd., and is a natural gas vehicle catalyst (model CNG).

[0078] Preparation of Example 1 75 rare earth metal modified Ce, Zr composite oxide-15 sepiolite-3Fe2O3-5CoO-2MnO2

[0079] The method for preparing 75 rare earth metal modified Ce, Zr composite oxide-15 sepiolite-3Fe2O3-5CoO-2MnO2 in the example comprises the following steps:

[0080] 100 g of sepiolite was cleaned with deionized water, soaked for 48 h, then soaked with 1.5 mol / L hydrochloric acid for 36 h, then washed with deionized water until the washing liquid was neutral, suction filtered, dried at 110°C for 2 h, calcined at 250°C for 6 h, and the calcined sepiolite was ground to 80-100 mesh to prepare sepiolite powder;

[0081] 100 g of rare earth metal modified Ce, Zr composite oxide (in the rare earth metal modified Ce, Zr composite oxide, the content of CeO2 is 30 wt%, the content of ZrO2 is 60 wt%, the content of La2O3 is 5 wt%, and the content of Y2O3 is 5 wt%) and 20 g of sepiolite powder were taken, 10 mL of nitric acid (1 wt%) and 5 g of Al2O3 powder were added and kneaded, and then dried at 110°C for 2 h to obtain a catalyst carrier;

[0082] 7.59 g of iron nitrate nonahydrate, 19.4 g of cobalt nitrate hexahydrate, and 7.1 g of manganese nitrate tetrahydrate were dissolved in 100 mL of deionized water at 70°C to prepare an aqueous solution, 93.75 g of the catalyst carrier was immersed in the aqueous solution for 1 h, dried at 110°C for 2 h, and calcined at 600°C for 2 h to obtain a catalyst precursor;

[0083] The catalyst precursor powder and water were prepared into a slurry with a specific gravity of 2 g / cm 3 The slurry was coated on a honeycomb cordierite ceramic substrate to form a 1 mm coating on the surface of the honeycomb cordierite ceramic substrate, and the coated honeycomb cordierite ceramic substrate was calcined at 900°C for 2 h to obtain 75 rare earth metal modified Ce, Zr composite oxide-15 sepiolite-3Fe2O3-5CoO-2MnO2 (the composition of the catalyst was calculated according to the amount of each component as described above).

[0084] Preparation of 65 rare earth metal modified Ce, Zr composite oxide-25 sepiolite-3Fe2O3-5CoO-2MnO2

[0085] The method for preparing 65 rare earth metal modified Ce, Zr composite oxide-25 sepiolite-3Fe2O3-5CoO-2MnO2 in the example comprises the following steps:

[0086] 100 g of sepiolite was cleaned with deionized water, soaked for 48 h, then soaked with 1.5 mol / L hydrochloric acid for 36 h, then washed with deionized water until the washing liquid was neutral, suction filtered, dried, and calcined at 250°C for 6 h. The calcined sepiolite was ground to 80-100 mesh to prepare sepiolite powder;

[0087] Take 86.7 g of rare earth metal modified Ce, Zr composite oxide (in the rare earth metal modified Ce, Zr composite oxide, the content of CeO2 is 30 wt%, the content of ZrO2 is 60 wt%, the content of La2O3 is 5 wt%, and the content of Y2O3 is 5 wt%) and 33.3 g of sepiolite powder, add 10 mL of dilute nitric acid (1 wt%) and 5 g of Al2O3 powder, then dry at 110℃ for 2h, to obtain a catalyst carrier;

[0088] Take 7.59 g of iron nitrate nonahydrate, 19.4 g of cobalt nitrate hexahydrate, and 7.1 g of manganese nitrate tetrahydrate, dissolve in 100 mL of 70℃ deionized water to prepare an aqueous solution, immerse 93.71 g of the catalyst carrier in the aqueous solution for 1h, dry at 110℃ for 2h, and calcine at 600℃ for 2h to obtain a catalyst precursor;

[0089] The catalyst precursor and water are prepared into a slurry with a specific gravity of 2 g / cm 3 , which is coated on the honeycomb cordierite ceramic substrate to form a 1mm coating on the surface of the honeycomb cordierite ceramic substrate, and then calcined at 900℃ for 2h to obtain 65 rare earth metal modified Ce, Zr composite oxide-25 sepiolite-3Fe2O3-5CoO-2MnO2 (the composition of the catalyst is calculated by the amount of each component as described above). Example 1

[0090] The exhaust gas treatment device of the high-temperature methane SOFC stack of this embodiment includes:

[0091] An air compressor 1, a pressure reducing device 7, a first gas flow meter 2, a second gas flow meter 8, a first heat exchanger 3, a second heat exchanger 9, an SOFC cell stack 4, a mixing and separation tank 5, and a catalytic combustor 6, wherein the first heat exchanger 3, the second heat exchanger 9, and the SOFC cell stack 4 are located in a heat preservation cavity 10, the catalytic combustor 6 includes an upper section filled with a low-temperature catalytic combustion catalyst and a lower section filled with a high-temperature catalytic combustion catalyst, wherein an air inlet pipeline connects the air side inlet of the SOFC cell stack 4 after passing through the air compressor 1, the first gas flow meter 2, and the first heat exchanger 3, a natural gas inlet pipeline connects the gas side inlet of the SOFC cell stack 4 after passing through the optional pressure reducing device 7, the second gas flow meter 8, and the second heat exchanger 9, the cathode outlet and the anode outlet of the SOFC cell stack are connected to the inlet of the mixing and separation tank 5 through pipelines, the outlet of the mixing and separation tank 5 is connected to the inlet of the catalytic combustor 6 through a pipeline, the outlet pipeline of the catalytic combustor 6 is connected to the inlet of the heat preservation cavity 10, and the outlet of the heat preservation cavity 10 is connected to the exhaust gas treatment device.

[0092] The heat preservation cavity contains the first heat exchanger, the second heat exchanger, and the SOFC cell stack inside, and is wrapped with thick thermal insulation material outside, so that the working temperature of the fuel cell is stabilized at 600-800℃.

[0093] The high-temperature methane SOFC stack tail gas treatment process of the embodiment includes the following steps: air (cathode gas) (air before compression can come from the surrounding environment) is compressed to about 5 kPa by air compressor 1 through pipeline a, the air that goes out of the air compressor is filtered to remove particulate impurities in the air, passes through pipeline b, the first gas flow meter 2 adjusts the gas flow, enters the air side inlet of the SOFC cell stack 4 after heat exchange through the first heat exchanger 3 (the temperature after heat exchange is 600-800℃), the natural gas (anode gas) from the LNG storage tank is optionally reduced in pressure to about 10 kPa by a pressure reducing device (pressure reducing valve) 7, then passes through pipeline h, desulfurization is performed to less than 0.1 ppm of sulfur content by a desulfurization device, enters the second gas flow meter 8 to adjust the gas flow, and enters the fuel gas side inlet of the SOFC fuel cell stack 4 after heat exchange (the temperature after heat exchange is 600-800℃), the electrical energy generated by the SOFC fuel cell stack after chemical reaction is provided to industrial loads and fuel cell power generation auxiliary equipment 11, wherein the first gas flow meter 2 and the second gas flow meter 8 adjust the flow so that the volume ratio of air and fuel gas is 16:1;

[0094] The cathode outlet gas (the cathode outlet gas is mainly N2 and O2, the composition of the outlet gas is basically consistent with air, N2-79%, O2-21%) and the anode outlet gas (the anode outlet gas is methane, a small amount of hydrogen, CO and CO2 and H2O) of the high-temperature methane solid oxide fuel cell stack enter a mixing and separation tank, gas mixing is performed in the mixing and separation tank, and water in the stack tail gas is removed, and then enters a catalytic combustor through a pipeline. The mixed gas passes through the catalyst A bed and the catalyst B bed of the catalytic combustor, and catalytic combustion reaction is performed. The outlet gas of the catalytic combustor has heat, which is used for heat exchange of the cathode inlet heat exchanger and the anode inlet heat exchanger, and the cathode inlet gas and the anode inlet gas and the stack cavity are heated, and then enter a tail gas treatment device through pipeline m.

[0095] The catalytic combustor is divided into a low-temperature catalytic combustion section and a high-temperature catalytic combustion section, the catalyst A bed is filled with a low-temperature catalytic combustion catalyst, and a common precious metal Pt catalyst (natural gas vehicle catalyst (model CNG) from Wifeng Environmental Catalyst Co., Ltd.) is used; the catalyst B bed is the high-temperature catalytic combustion catalyst of embodiment 1 of the application.

[0096] The process conditions of the SOFC are as follows: the ratio of air and fuel gas is 16:1 (vol), and the inlet pressure of the stack is 3 kPa; the volume ratio of CH4, O2 and N2 of the raw gas of the catalytic combustor is 1:3:12.

[0097] In the catalytic combustor, the low-temperature catalytic combustion catalyst, i.e. the noble metal Pt catalyst, was loaded in the upper part, and the high-temperature catalytic combustion catalyst prepared in Example 1, i.e. the 75 rare earth metal modified Ce, Zr composite oxide-15 sepiolite-3 Fe2O3-5 CoO-2 MnO2, was loaded in the lower part. The inlet temperature of the catalytic combustor was controlled at 280°C by the electric heater in the initial stage, and the space velocities of the low-temperature catalytic combustion catalyst and the high-temperature catalytic combustion catalyst were both 8000h-1. -1 .

[0098] By controlling the air-fuel ratio, the outlet temperature of the catalytic combustor was stabilized at 905-918°C. Within 250h, the methane conversion rate was always >95%, and the inlet gas temperatures of the anode gas and the cathode gas of the SOFC stack were both stabilized at 720°C after the heat exchange of the outlet gas of the catalytic combustor, and the cavity temperature of the stack was stabilized at 726-735°C. The test results are shown in Table 1.

[0099] As can be seen from Example 1, the high-temperature catalytic combustion catalyst prepared in Preparation Example 1, i.e. the 75 rare earth metal modified Ce, Zr composite oxide-15 sepiolite-3 Fe2O3-5 CoO-2 MnO2, has good high-temperature stability. Example 2

[0100] The same conditions as in Example 1 were adopted except that the catalyst prepared in Preparation Example 2 was used, and the results are shown in Table 1. Comparative Example 1

[0101] Preparation of 65 Ce, Zr composite oxide-25 Al2O3-3 Fe2O 3- 5 CoO -2 MnO2

[0102] The method for preparing 65 Ce, Zr composite oxide-25 Al2O3-3 Fe2O 3- 5 CoO -2 MnO2comprises the following steps:

[0103] 86.7g of Ce, Zr composite oxide (the content of CeO2in the Ce, Zr composite oxide is 35wt%, and the content of ZrO2is 65wt%) and 33.3g of Al2O3powder were taken, 10mL of dilute nitric acid (1wt%) was added and kneaded, and then the catalyst carrier was obtained by drying at 110°C for 2h;

[0104] 7.59g of iron nitrate nonahydrate, 19.4g of cobalt nitrate hexahydrate and 7.1g of manganese nitrate tetrahydrate were dissolved in 100mL of 70°C deionized water to prepare an aqueous solution, 90g of catalyst carrier powder was immersed in the aqueous solution for 1h, dried at 110°C for 2h, and calcined at 600°C for 2h to obtain the catalyst precursor;

[0105] The catalyst precursor powder and water were mixed to form a solution with a specific gravity of 2 g / cm³. 3 The slurry was coated onto a honeycomb cordierite ceramic substrate to form a 1 mm coating on the surface of the honeycomb cordierite ceramic substrate. After calcination at 900℃ for 2 h, a 65Ce, Zr composite oxide -25Al2O3-3Fe2O3-5CoO-2MnO2 was obtained.

[0106] The catalyst prepared above was used as a high-temperature combustion catalyst, and exhaust gas treatment tests were conducted under basically the same conditions as in Example 1. The results are shown in Table 1. Comparative Example 2

[0107] 90Sepiolite-3Fe2O 3- Preparation of 5CoO-2MnO2

[0108] This comparative example prepared 90 sepiolite-3Fe2O 3- The method of 5CoO-2MnO2 includes the following steps:

[0109] Take 100g of sepiolite, wash it with deionized water, soak it for 48h, then soak it with 1.5mol / L hydrochloric acid for 36h, wash it with deionized water until the washing liquid is neutral, filter it, dry it, calcine it at 250℃ for 6h, grind the calcined sepiolite to 80-100 mesh to obtain the catalyst support.

[0110] Take 7.59g of ferric nitrate nonahydrate, 19.4g of cobalt nitrate hexahydrate, and 7.1g of manganese nitrate tetrahydrate salts and dissolve them in 100mL of deionized water to prepare an aqueous solution. Immerse 90g of catalyst support powder in the aqueous solution for 1 hour, dry and calcine to obtain the catalyst precursor.

[0111] The catalyst precursor powder was made into a slurry and coated onto a honeycomb cordierite ceramic substrate to form a 1 mm coating on the surface of the honeycomb cordierite ceramic substrate. After calcination at 900℃ for 2 h, 90 sepiolite-3Fe2O3-5CoO-2MnO2 was obtained.

[0112] The catalyst prepared above was used as a high-temperature combustion catalyst, and exhaust gas treatment tests were conducted under basically the same conditions as in Example 1. The results are shown in Table 1. Comparative Example 3

[0113] The difference between this comparative example and the exhaust gas treatment device of the high-temperature methane SOFC battery stack in Example 3 is that the catalytic burner of this comparative example is filled with low-temperature catalytic combustion catalyst, while the rest of the devices and their connections are the same as those in Example 3.

[0114] The difference between the exhaust gas treatment process of this comparative example and that of the high-temperature methane SOFC battery stack in Example 1 is that the catalyst space velocity for low-temperature catalytic combustion is 8000 h⁻¹.-1 .

[0115] Air and gas ratio 16:1 (vol), stack inlet pressure 3 KPa; the volume ratio of CH4:O2:N2 in the raw gas of catalytic combustor is 1:3:12.

[0116] In the catalytic combustor, all filled with low-temperature catalytic combustion catalyst, the initial temperature of catalytic combustor inlet is controlled at 280℃ by electric heater, and the catalyst space velocity is 8000h -1 ;

[0117] By controlling the air-fuel ratio, the outlet temperature of the catalytic combustor reaches 900℃, but within 50h, the methane conversion rate gradually decreases from the initial 98% to 68%, and finally cannot maintain the catalytic combustor outlet temperature above 900℃, which cannot provide stable heat for the fuel cell stack. In order to prevent the performance of the stack from being damaged, the experiment is stopped.

[0118] From Comparative Example 3, it can be seen that the commonly used low-temperature catalytic combustion catalyst noble metal Pt catalyst (Pt is the active component) does not have good high-temperature stability, and therefore is not suitable for fuel cell tail gas catalytic combustion working conditions greater than 900℃.

[0119] Table 1

[0120]

[0121] T10 CH4 conversion temperature and T95 CH4 conversion temperature were determined as follows: the composition at the outlet of the catalytic combustor was determined by chromatography, and the methane conversion rate was calculated according to the formula, and the reaction temperature of the reactor when the methane conversion rate reached 10% and 95% was recorded (measured by a thermocouple in the catalytic combustor).

[0122] From Table 1, (1) compared with Ce, Zr composite oxide (not modified with rare earth metal) + Al2O3 in Comparative Example 1, the rare earth metal modified Ce, Zr composite oxide in Examples 1-2 has more excellent conversion effect at T10 and T95, lower light-off temperature and complete conversion temperature; the lower light-off temperature means that there is a higher reaction temperature coincidence range with the complete conversion temperature of the low-temperature conversion catalyst, so there is a wider operating condition range in the two-stage catalytic combustion reaction; (2) Comparative Example 2 uses pure sepiolite as the carrier, although it can increase the specific surface area, but the light-off temperature and complete conversion temperature are higher, which is not conducive to the two-stage catalytic combustion reaction.

[0123] Obviously, the above embodiments are merely example for clearly illustrating but not limitation to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments need not and can not be enumerated. The obvious changes or variations derived from this still fall within the protection scope of the present application.

Claims

1. A solid oxide fuel cell stack off-gas treatment process, characterized by, Air is compressed by an air compressor to 1-10 kPa through a pipeline, and the air discharged from the air compressor is optionally filtered to remove particulate impurities in the air. A first gas flow meter is used to adjust the gas flow. After heat exchange in a first heat exchanger, the air enters the air side inlet of the solid oxide fuel cell stack. Natural gas is optionally decompressed to 5-20 kPa by a decompression device through a pipeline, and then enters a second gas flow meter to adjust the gas flow after desulfurization by a desulfurization device through a pipeline. After heat exchange in a second heat exchanger, the natural gas enters the fuel gas side inlet of the solid oxide fuel cell stack. The solid oxide fuel cell stack generates electrical energy through a chemical reaction. The first gas flow meter and the second gas flow meter adjust the flow rate so that the volume ratio of air to natural gas is 15-30:

1. The cathode outlet gas and the anode outlet gas of the solid oxide fuel cell stack enter a mixing separation tank, where the gases are mixed and water is removed from the stack tail gas. The mixed gas enters a catalytic combustor through a pipeline. The mixed gas passes through a catalyst A bed and a catalyst B bed in the catalytic combustor to undergo a catalytic combustion reaction. The outlet gas of the catalytic combustor has heat, which is used to heat the cathode inlet gas and the anode inlet gas in the cathode inlet heat exchanger and the anode inlet heat exchanger. The heated gases and the stack cavity then enter a tail gas treatment device through a pipeline. The reaction pressure of the catalytic combustor is 0.1-10 kPa, the inlet temperature is 200-500°C, and the outlet temperature is 800-1000°C. The catalytic combustor is divided into a low-temperature catalytic combustion section and a high-temperature catalytic combustion section. The catalyst A bed is filled with a low-temperature catalytic combustion catalyst, which is a noble metal Pt or Pd catalyst. The catalyst B bed is a high-temperature catalytic combustion catalyst, which includes a catalyst substrate and a catalyst precursor coated on the catalyst substrate. The catalyst precursor includes the following components, based on the total weight of the sepiolite powder, the rare earth metal modified Ce, Zr composite oxide, and the active component being 100%, and calculated based on the corresponding metal oxides: A. Sepiolite powder, 10-50 wt%; B. Carrier precursor, i.e., rare earth metal modified Ce, Zr composite oxide, 30-80 wt%. The rare earth metal is La and Y. In the rare earth metal modified Ce, Zr composite oxide, the content of CeO2 is 20-40 wt%, the content of ZrO2 is 50-70 wt%, and the sum of the contents of La2O3 and Y2O3 is 5 wt%-10 wt%. The mass ratio of La2O3 to Y2O3 is 1:0.5-1.

5. C. Active component, transition metal oxides of cobalt, iron, and manganese, 1-20 wt% based on the content of cobalt, iron, and manganese transition metal oxides. The catalyst substrate is selected from at least one of cordierite ceramic substrate, Al2O3 high-temperature ceramic, ZrO2, mullite Al2O3·SiO2, and hexaaluminate.

2. The solid oxide fuel cell stack off-gas treatment process of claim 1, wherein, The temperature of the first heat exchanger after heat exchange is 600-800°C, and the temperature of the second heat exchanger after heat exchange is 600-800°C.

3. The solid oxide fuel cell stack off-gas treatment process of claim 1, wherein, The second gas flow meter adjusts the gas flow to 1-50 L / min according to the reaction temperature of the catalytic burner.

4. The solid oxide fuel cell stack off-gas treatment process of claim 1, wherein, The first gas flow meter and the second gas flow meter adjust the flow so that the volume ratio of air and natural gas is 16-20:

1.

5. The solid oxide fuel cell stack off-gas treatment process of claim 4, wherein, The first gas flow meter and the second gas flow meter adjust the flow so that the volume ratio of air and natural gas is 16-20:

1.

6. The solid oxide fuel cell stack off-gas treatment process of claim 1, wherein, The cathode outlet gas is mainly N2 and O2, and the anode outlet gas is methane, hydrogen, CO, CO2 and H2O.

7. The solid oxide fuel cell stack off-gas treatment process of claim 1, wherein, The catalyst substrate is a cordierite ceramic substrate.

8. The solid oxide fuel cell stack off-gas treatment process of claim 7, wherein, The catalyst substrate is a honeycomb-shaped cordierite ceramic substrate.

9. The solid oxide fuel cell stack off-gas treatment process of claim 1, wherein, The catalyst precursor comprises the following components: A, sepiolite powder, 15-40 wt%; B, carrier precursor, i.e. rare earth metal modified Ce, Zr composite oxide, 45-78 wt%; C, active component, transition metal oxide of cobalt, iron and manganese, 5-18 wt% based on the content of transition metal oxide of cobalt, iron and manganese.

10. The solid oxide fuel cell stack tail gas treatment process according to claim 1, wherein, The catalyst precursor comprises the following components: A, sepiolite powder, 15-30 wt%; B, carrier precursor, i.e. rare earth metal modified Ce, Zr composite oxide, 50-75 wt%; C, active component, transition metal oxide of cobalt, iron and manganese, 8-15 wt% based on the content of transition metal oxide of cobalt, iron and manganese.

11. The solid oxide fuel cell stack tail gas treatment process according to claim 10, wherein, The catalyst precursor comprises the following components: A, sepiolite powder, 15-25 wt%; B, carrier precursor, i.e. rare earth metal modified Ce, Zr composite oxide, 65-75 wt%; C, active component, transition metal oxide of cobalt, iron and manganese, 10-15 wt% based on the content of transition metal oxide of cobalt, iron and manganese.

12. The solid oxide fuel cell stack off-gas treatment process of claim 1, wherein, The content of La2O3 and Y2O3 in the rare earth metal modified Ce, Zr composite oxide is 6-10 wt%; and / or, The content of CeO2 in the rare earth metal modified Ce, Zr composite oxide is 25-35 wt%, and the content of ZrO2 is 55-65 wt%.

13. The solid oxide fuel cell stack off-gas treatment process of claim 12, wherein, The content of La2O3 and Y2O3 in the rare earth metal modified Ce, Zr composite oxide is 6-10 wt%; and / or, The content of CeO2 in the rare earth metal modified Ce, Zr composite oxide is 25-35 wt%, and the content of ZrO2 is 55-65 wt%.

14. The solid oxide fuel cell stack off-gas treatment process of claim 1, wherein, It also includes 1-20 wt% of Al2O3 relative to the total weight of the carrier precursor and sepiolite powder.

15. The solid oxide fuel cell stack off-gas treatment process of claim 14, wherein, It also includes 2-10 wt% of Al2O3 relative to the total weight of the carrier precursor and sepiolite powder.

16. The solid oxide fuel cell stack off-gas treatment process of claim 15, wherein, It also includes 2-5 wt% of Al2O3 relative to the total weight of the carrier precursor and sepiolite powder.

17. The solid oxide fuel cell stack off-gas treatment process of claim 1, wherein, The process conditions of the solid oxide fuel cell are 1-10 kPa, and the inlet gas temperature of the solid oxide fuel cell is 600-800℃.

18. The solid oxide fuel cell stack off-gas treatment process of claim 17, wherein, The process conditions of the solid oxide fuel cell are: 2-8 kPa; the inlet gas temperature of the solid oxide fuel cell is 680-750 ℃, the reaction pressure of the catalytic burner is 1-5 kPa, the inlet temperature is 250-400 ℃, and the outlet temperature is 900 ℃-950 ℃.

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