A room-temperature oxidation catalyst for battery thermal runaway exhaust gas and its preparation method

Abstract

The present invention belongs to the field of lithium battery safety and environmental protection technology, and in particular relates to a room-temperature oxidation catalyst for battery thermal runaway exhaust gas and a preparation method thereof, comprising the following steps: S1. dissolving a divalent metal nitrate and a trivalent metal nitrate in a precursor sol in a stoichiometric ratio of 1:2 according to the spinel AB2O4 structure, heating and stirring until it forms a gel, and drying to obtain a spinel precursor xerogel; S2. ball-milling and sintering the spinel precursor xerogel with silver nitrate to obtain a silver-containing AB2O4 composite catalyst; S3. mixing the silver-containing AB2O4 composite catalyst with silica sol and oxalic acid and ball-milling to obtain a catalyst slurry, then uniformly impregnating a cordierite honeycomb ceramic with the catalyst slurry and calcining it to obtain a silver-containing AB2O4 composite catalyst on a honeycomb ceramic carrier. The present invention adopts an esterified sol-gel solid-phase one-step synthesis method to prepare the catalyst. The method is simple, environmentally friendly, and low-cost, and can efficiently and synergistically decompose carbon monoxide and hydrogen produced by thermal runaway of lithium-ion batteries at room temperature.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium battery safety and environmental protection, and in particular relates to a room-temperature oxidation catalyst for battery thermal runaway exhaust gas and a preparation method thereof. Background Art

[0002] Lithium-ion batteries are widely used in new energy vehicles and energy storage due to their small size, high power, high energy density, and long service life. However, they are prone to internal overheating and even thermal runaway under abnormal conditions such as overloaded charging and discharging, extreme environments, internal short circuits, and external collisions. During thermal runaway, violent and complex chemical reactions occur within the lithium-ion battery, producing large amounts of toxic and harmful gases such as carbon monoxide, hydrogen, and carbon dioxide. These three main substances generally account for more than 90% (of which carbon monoxide is generally greater than 10% and hydrogen is greater than 30%). When a lithium-ion battery experiences thermal runaway, carbon monoxide concentrations can easily exceed the lethal concentration of 700 ppm, and hydrogen can easily exceed its lower explosive limit of 4% by volume.

[0003] The health hazards caused by carbon monoxide produced by thermal runaway of lithium-ion batteries and the explosion risks caused by hydrogen have become constraints affecting the development of the industry and need to be urgently resolved.

[0004] Spinel-structured catalysts are a common catalyst that can be used for the catalytic oxidation of volatile organic waste gases and carbon monoxide. For example, Application 1, with Patent Application No. 201710010624.5, discloses a nano-spinel catalyst and its preparation method. However, due to the conventional sol-gel method, a large amount of water is present in the sol system, which needs to be evaporated during the drying process, consuming a large amount of energy and being unfavorable for industrial production. In addition, the T50 temperature of the spinel catalyst for VOCs such as toluene is above 180°C, which is far from meeting the requirements for efficient catalysis of harmful gases at room temperature. Application 2, with Patent Application No. 202310317402.3, discloses a preparation method and application of a multi-stage cobalt-manganese spinel array photothermal catalyst. The catalyst preparation method in Application 2 is a hydrothermal synthesis method, which is a high-temperature and high-pressure system. Due to the limitations of the hydrothermal synthesis reactor, it is not suitable for industrial production of the catalyst. The function of a catalyst is not only related to the crystal structure, but also closely related to the specific unit cell size, lattice distortion, band structure, surface morphology, size effect, etc. Catalysts prepared under different preparation conditions often have very different performances.

[0005] Loading precious metal catalysts is a common method to improve catalyst activity. Common precious metals include palladium, platinum, rhodium, ruthenium, gold, silver, etc. Among them, the price of silver is only about 3% of other precious metals, which is very beneficial to industrial production. For example, application 3 with patent application number 201110203320.3 discloses a nano-silver room-temperature carbon monoxide oxidation catalyst and its preparation method, and application 4 with patent application number 201110435139.5 discloses a silver-containing room-temperature carbon monoxide integral catalyst and its preparation method. The room-temperature catalysts prepared in the above two applications both contain silver and can catalytically decompose 5 to 1000 ppm of carbon monoxide at room temperature, reaching 85% and 90% or more respectively. However, there is still a large difference from the concentration of 100,000 ppm that causes thermal runaway of lithium-ion batteries. In addition, the catalysts in the two applications both contain molecular sieves or alumina with strong adsorption properties as active components, which are suitable for first adsorbing and then catalytically treating low-concentration carbon monoxide waste gas, but cannot synergistically treat the ultra-high concentration carbon monoxide and hydrogen generated by thermal runaway of lithium-ion batteries. Summary of the Invention

[0006] The purpose of the present invention is to provide a room-temperature oxidation catalyst for battery thermal runaway exhaust gas and a preparation method thereof. To address the exhaust gas safety issues caused by thermal runaway of lithium-ion batteries, an esterification sol-gel-solid-phase one-step synthesis method is used to prepare a silver-containing spinel composite catalyst. The preparation method is simple, low-cost, and suitable for mass production. The catalyst is loaded on a honeycomb ceramic and can efficiently and synergistically decompose carbon monoxide and hydrogen produced by thermal runaway of lithium-ion batteries at room temperature.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preparing a room-temperature oxidation catalyst for battery thermal runaway exhaust gas, comprising the following steps: S1. dissolving a divalent metal nitrate and a trivalent metal nitrate in a precursor sol in a stoichiometric ratio of 1:2 according to a spinel AB2O4 structure, heating and stirring until a gel is formed, and drying to obtain a spinel precursor dry gel, wherein A is a divalent metal and B is a trivalent metal, and the precursor sol is composed of a hydroxyl donor and an acidic regulator, and the volume ratio of the hydroxyl donor to the acidic regulator is 1:2. is 1:(0.2-1), the weight ratio of the precursor sol to the nitrate is (4-10):1; the divalent metal nitrate is one of Zn(NO3)2·6H2O, Cu(NO3)2·3H2O, Ni(NO3)2·6H2O, Co(NO3)2·6H2O, and Mg(NO3)2·6H2O, and the trivalent metal nitrate is at least one of Bi(NO3)3·5H2O and Al(NO3)3·9H2O;

[0009] S2. The spinel precursor xerogel and silver nitrate were ball-milled and sintered to obtain a silver-containing AB2O4 composite catalyst;

[0010] S3. A silver-containing AB2O4 composite catalyst is mixed with silica sol and oxalic acid and ball-milled to obtain a catalyst slurry. A cordierite honeycomb ceramic support is then uniformly impregnated with the catalyst slurry and calcined to obtain a silver-containing AB2O4 composite catalyst on a honeycomb ceramic support; the weight ratio of the silver-containing AB2O4 composite catalyst, silica sol and oxalic acid in the catalyst slurry is 1:(5-20):(1-10), the silica sol concentration is 5-20%, the ball-milling time is 1-4 hours, the calcination temperature is 200-600°C, and the calcination time is 1-4 hours.

[0011] Furthermore, in step S1, the temperature for heating and stirring is 40-70°C, the drying temperature is 100-140°C, and the drying time is 2-4 hours; the hydroxyl donor is at least one of ethanol, ethylene glycol, glycerol, and isopropanol; and the acidity regulator is at least one of citric acid and oxalic acid.

[0012] Furthermore, in step S2, the molar ratio of the divalent metal nitrate to silver nitrate is (5-15):1, the sintering temperature is 500-800° C., and the sintering time is 2-8 hours.

[0013] Furthermore, in step S3, the cordierite honeycomb ceramic carrier is impregnated with the catalyst slurry multiple times and then calcined to obtain a silver-containing AB2O4 composite catalyst having an active component content of 10-30% on the honeycomb ceramic carrier.

[0014] Furthermore, in the steps S1-S3, the heating rates of the heating, stirring, drying, sintering and burning processes are all 5-10°C / min.

[0015] Furthermore, in the steps S2-S3, a planetary ball mill is used for ball milling, the grinding balls are made of alumina or zirconia ceramic balls, the grinding balls have a diameter of 5mm-10mm, the ball-to-material ratio is 5-20:1, and the rotation speed is 100-900rpm / min.

[0016] Another object of the present invention is to use the above-mentioned preparation method to prepare a room-temperature oxidation catalyst for battery thermal runaway exhaust gas. The catalyst is mainly used for removing hydrogen and carbon monoxide produced by battery thermal runaway. When in use, the silver-containing spinel composite catalyst loaded on the honeycomb ceramic can be directly installed at the outlet of the lithium-ion battery pressure relief valve, and the carbon monoxide and hydrogen produced by the thermal runaway of the lithium-ion battery can be synergistically and efficiently removed at room temperature, avoiding poisoning and explosion accidents.

[0017] The advantages of the present invention are:

[0018] 1. The present invention adopts an esterification sol-gel-solid phase one-step synthesis method to prepare a silver-containing spinel composite catalyst. It does not require the sol-gel method to prepare the spinel catalyst and then the solid-phase method to prepare the silver-containing spinel catalyst. The solid-phase method is directly coupled with the drying gel process, thereby eliminating the intermediate drying gel sintering process. The preparation method is simple, has a short cycle, low energy consumption, and is suitable for mass production.

[0019] 2. The use of a high-boiling-point organic acidic regulator in the precursor sol of the present invention reduces the corrosive hazard of inorganic acid mist, ensuring environmentally friendly production conditions. Furthermore, the high-boiling-point organic acidic regulator remaining after gel drying is completely decomposed during the sintering process after ball milling with silver nitrate. The carbon dioxide and water vapor generated during the decomposition process facilitate the uniform distribution of silver on the catalyst surface, thereby increasing the specific surface area of the catalyst and enhancing adsorption and catalytic performance.

[0020] 3. The precious metal used in the present invention is inexpensive silver, which is cheap and readily available compared to common precious metals such as platinum, palladium, rhodium, and gold, and has excellent moisture resistance;

[0021] 4. The silver-containing spinel catalyst supported on honeycomb ceramics prepared by the present invention can efficiently and synergistically decompose carbon monoxide and hydrogen produced by thermal runaway of lithium-ion batteries at room temperature. The strong reducing atmosphere of hydrogen and carbon monoxide during the catalytic reaction can accelerate the conversion of silver oxide into elemental silver, reconstruct alloy particles, and quickly realize the repetition of the valence state of highly active silver species, thereby ensuring catalytic efficiency and achieving synergistic catalytic decomposition. The overall installation is simple, the reaction process does not require harsh conditions, and the reliability is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 are scanning electron microscope images of the silver-containing CuBi2O4 catalyst prepared in Example 2 and the silver-containing ZnAlBiO4 catalyst prepared in Example 11;

[0023] Figure 2 These are X-ray diffraction analysis diagrams of the silver-containing CuBi2O4 catalyst prepared in Example 2 and the silver-containing ZnAlBiO4 catalyst prepared in Example 11. DETAILED DESCRIPTION

[0024] In order to highlight the performance of the prepared catalysts in the present invention, multiple examples are used for comparison, among which Examples 1-5 prepare silver-containing ABi2O4 catalysts, Examples 6-10 prepare silver-containing AAl2O4 catalysts, Example 11 prepares silver-containing ZnAlBiO4 catalysts, and Example 12 prepares silver-containing ZnAlBiO4 catalysts on honeycomb ceramic carriers. The preparation methods of all examples are derived from the preparation methods described in the specification of this application. In addition, for multi-faceted comparisons, Comparative Examples 1-17 are also provided, among which Comparative Examples 1-7 are conventional silver-containing divalent and trivalent metal oxide catalysts, and Comparative Examples 8 to 17 prepare silver-free spinel catalysts. When testing the performance of the catalysts prepared in each example and comparative example, the catalysts were directly installed at the outlet of the lithium-ion battery pressure relief valve for simulation testing.

[0025] Example 1

[0026] The present embodiment provides a silver-containing ZnBi2O4 catalyst, wherein A is divalent metal Zn. The preparation method thereof is as follows: separately dissolving divalent metal nitrate Zn(NO3)2·6H2O and trivalent metal nitrate Bi(NO3)3·5H2O in a precursor sol according to a spinel ABi2O4 stoichiometric ratio of 1:2, stirring at 60°C until a gel is formed, wherein the weight ratio of nitrate to precursor sol is 1:5, wherein the volume ratio of ethanol, glycerol and oxalic acid in the precursor sol is 2:2:1, and drying at 120°C to obtain a spinel precursor dry gel; ball-milling and sintering the spinel precursor dry gel with AgNO3 to obtain a silver-containing ABi2O4 composite catalyst, wherein the molar ratio of ABi2O4 to AgNO3 is 10:1, using 5 mm alumina ceramic balls with a ball-to-material ratio of 10:1, and ball milling at 600 rpm / min for 3 hours; and sintering at a temperature of 650°C for 5 hours.

[0027] Example 2

[0028] The difference between Example 2 and Example 1 is that: a silver-containing CuBi2O4 catalyst is provided, wherein A is a divalent metal Cu, and the divalent metal nitrate is Cu(NO3)2·3H2O.

[0029] Example 3

[0030] The difference between Example 3 and Example 1 is that: a silver-containing NiBi2O4 catalyst is provided, wherein A is a divalent metal Ni, and the divalent metal nitrate is Ni(NO3)2·6H2O.

[0031] Example 4

[0032] The difference between Example 4 and Example 1 is that: a silver-containing CoBi2O4 catalyst is provided, wherein A is a divalent metal Co, and the divalent metal nitrate is Co(NO3)2·6H2O.

[0033] Example 5

[0034] The difference between Example 5 and Example 1 is that: a silver-containing MgBi2O4 catalyst is provided, wherein A is a divalent metal Mg, and the divalent metal nitrate is Mg(NO3)2·6H2O.

[0035] Example 6

[0036] The difference between Example 6 and Example 1 is that: a silver-containing ZnAl2O4 catalyst is provided, wherein A is a divalent metal Zn, the divalent metal nitrate is Zn(NO3)2·6H2O, and the trivalent metal nitrate is Al(NO3)3·9H2O.

[0037] Example 7

[0038] The difference between Example 7 and Example 1 is that: a silver-containing CuAl2O4 catalyst is provided, wherein A is a divalent metal Cu, the divalent metal nitrate is Cu(NO3)2·3H2O, and the trivalent metal nitrate is Al(NO3)3·9H2O.

[0039] Example 8

[0040] The difference between Example 8 and Example 1 is that: a silver-containing NiAl2O4 catalyst is provided, wherein A is a divalent metal Ni, the divalent metal nitrate is Ni(NO3)2·3H2O, and the trivalent metal nitrate is Al(NO3)3·9H2O.

[0041] Example 9

[0042] The difference between Example 9 and Example 1 is that: a silver-containing CoAl2O4 catalyst is provided, wherein A is a divalent metal Co, the divalent metal nitrate is Co(NO3)2·3H2O, and the trivalent metal nitrate is Al(NO3)3·9H2O.

[0043] Example 10

[0044] The difference between Example 10 and Example 1 is that: a silver-containing MgAl2O4 catalyst is provided, wherein A is a divalent metal Mg, the divalent metal nitrate is Mg(NO3)2·3H2O, and the trivalent metal nitrate is Al(NO3)3·9H2O.

[0045] Example 11

[0046] This embodiment provides a silver-containing ZnAlBiO4 catalyst, the preparation method of which is as follows: divalent metal nitrate Zn(NO3)2·6H2O and trivalent metal nitrates Al(NO3)3·9H2O and Bi(NO3)3·5H2O are dissolved in a precursor sol in a spinel ZnAlBiO4 stoichiometric ratio of 1:1:1, and stirred at 60°C until a gel is formed, wherein the weight ratio of nitrate to precursor sol is 1:5, and the acetylene in the precursor sol is 1:1. The volume ratio of alcohol, propylene glycol and oxalic acid is 2:2:1, and the mixture is dried at 120°C to obtain a spinel precursor dry gel; the spinel precursor dry gel and AgNO3 are ball-milled and sintered to obtain a silver-containing ZnAlBiO4 composite catalyst, wherein the molar ratio of ZnAlBiO4 to AgNO3 is 10:1, 5mm alumina ceramic balls are used, the ball-to-material ratio is 10:1, and the catalyst is ball-milled at 600 rpm / min for 3 hours; the sintering temperature is 650°C, and the sintering time is 5 hours.

[0047] Example 12

[0048] The present embodiment provides a silver-containing ZnAlBiO4 catalyst on a honeycomb ceramic carrier, and the preparation method thereof is as follows: the silver-containing ZnAlBiO4 composite catalyst obtained in Example 11 is mixed with silica sol and oxalic acid, and ball-milled to obtain a catalyst slurry, wherein the weight ratio of the composite catalyst, silica sol and oxalic acid in the catalyst slurry is 1:10:5, the silica sol concentration is 10%, and the ball-milling time is 2 hours; then, a 200-mesh cordierite honeycomb ceramic is uniformly impregnated with the catalyst slurry and then calcined to obtain a silver-containing ZnAlBiO4 composite catalyst on a honeycomb ceramic carrier, the calcination temperature is 300°C, and the calcination time is 1 hour; the above impregnation and calcination steps are repeated three times to obtain a honeycomb catalyst containing approximately 15% silver-containing ZnAlBiO4 composite catalyst loaded on the cordierite ceramic.

[0049] Comparative Example 1

[0050] This comparative example provides a silver-containing ZnO catalyst, prepared by dissolving Zn(NO₃)₂·6H₂O in a precursor sol at a weight ratio of 1:5, stirring at 60°C until a gel forms, and drying at 120°C to obtain a xerogel; wherein the volume ratio of ethanol, glycerol, and oxalic acid in the precursor sol is 2:2:1. The precursor xerogel is ball-milled and sintered with AgNO₃ to obtain a silver-containing ZnO composite catalyst, wherein the molar ratio of Zn(NO₃)₂·6H₂O to AgNO₃ is 10:1, the sintering temperature is 650°C, and the sintering time is 5 hours.

[0051] Comparative Example 2

[0052] This comparative example provides a silver-containing CuO catalyst, prepared by dissolving Cu(NO₃)₂·3H₂O in a precursor sol at a weight ratio of 1:5, stirring at 60°C until a gel forms, and drying at 120°C to obtain a xerogel; wherein the volume ratio of ethanol, glycerol, and oxalic acid in the precursor sol is 2:2:1. The precursor xerogel is ball-milled and sintered with AgNO₃ to obtain a silver-containing CuO composite catalyst, wherein the molar ratio of Cu(NO₃)₂·3H₂O to AgNO₃ is 10:1, the sintering temperature is 650°C, and the sintering time is 5 hours.

[0053] Comparative Example 3

[0054] The silver-containing ZnAlBiO4 catalyst obtained in Example 11 and the silver-containing ZnAlBiO4 catalyst on the honeycomb ceramic support obtained in Example 12 were tested for purification efficiency of thermal runaway simulated exhaust gas. The test space velocity of the silver-containing ZnAlBiO4 catalyst was 20000h -1 The test space velocity of silver-containing ZnAlBiO4 catalyst on honeycomb ceramic carrier is 10000h -1 The other test methods are the same as those of the comparative example. The test results of the above catalysts and the test results of the silver-containing ZnBi2O4 catalyst obtained in Example 1, the silver-containing CuBi2O4 catalyst obtained in Example 2, and the silver-containing ZnAl2O4 catalyst obtained in Example 6 are summarized in Table 3.

[0055] This comparative example provides a silver-containing NiO catalyst, prepared by dissolving Ni(NO₃)₂·6H₂O in a precursor sol at a weight ratio of 1:5, stirring at 60°C until a gel forms, and drying at 120°C to obtain a xerogel; wherein the volume ratio of ethanol, glycerol, and oxalic acid in the precursor sol is 2:2:1. The precursor xerogel is ball-milled and sintered with AgNO₃ to obtain a silver-containing NiO composite catalyst, wherein the molar ratio of Ni(NO₃)₂·6H₂O to AgNO₃ is 10:1, the sintering temperature is 650°C, and the sintering time is 5 hours.

[0056] Comparative Example 4

[0057] This comparative example provides a silver-containing CoO catalyst, prepared by dissolving Co(NO₃)₂·6H₂O in a precursor sol at a weight ratio of 1:5, stirring at 60°C until a gel forms, and drying at 120°C to obtain a xerogel; the precursor sol comprises a volume ratio of ethanol, glycerol, and oxalic acid of 2:2:1. The precursor xerogel is ball-milled and sintered with AgNO₃ to obtain a silver-containing CoO composite catalyst, wherein the molar ratio of Co(NO₃)₂·6H₂O to AgNO₃ is 10:1, the sintering temperature is 650°C, and the sintering time is 5 hours.

[0058] Comparative Example 5

[0059] This comparative example provides a silver-containing MgO catalyst, prepared by dissolving Mg(NO₃)₂·6H₂O in a precursor sol at a weight ratio of 1:5, stirring at 60°C until a gel forms, and drying at 120°C to obtain a xerogel; wherein the volume ratio of ethanol, glycerol, and oxalic acid in the precursor sol is 2:2:1. The precursor xerogel is ball-milled and sintered with AgNO₃ to obtain a silver-containing MgO composite catalyst, wherein the molar ratio of Mg(NO₃)₂·6H₂O to AgNO₃ is 10:1, the sintering temperature is 650°C, and the sintering time is 5 hours.

[0060] Comparative Example 6

[0061] This comparative example provides a silver-containing Bi2O3 catalyst, prepared by dissolving Bi(NO3)3·5H2O in a precursor sol at a weight ratio of 1:5, stirring at 60°C until a gel forms, and drying at 120°C to obtain a xerogel; the precursor sol contains ethanol, glycerol, and oxalic acid in a volume ratio of 2:2:1. The precursor xerogel is ball-milled and sintered with AgNO3 to obtain a silver-containing Bi2O3 composite catalyst, wherein the molar ratio of Bi(NO3)3·5H2O to AgNO3 is 10:1, the sintering temperature is 650°C, and the sintering time is 5 hours.

[0062] Comparative Example 7

[0063] This comparative example provides a silver-containing Al2O3 catalyst, prepared by dissolving Al(NO3)3·9H2O in a precursor sol at a weight ratio of 1:5, stirring at 60°C until a gel forms, and drying at 120°C to obtain a xerogel; wherein the volume ratio of ethanol, glycerol, and oxalic acid in the precursor sol is 2:2:1. The precursor xerogel is ball-milled and sintered with AgNO3 to obtain a silver-containing Al2O3 composite catalyst, wherein the molar ratio of Al(NO3)3·9H2O to AgNO3 is 10:1, the sintering temperature is 650°C, and the sintering time is 5 hours.

[0064] Comparative Example 8

[0065] This comparative example provides a ZnBi2O4 catalyst, wherein A is divalent metal Zn, and its preparation method is as follows: divalent metal nitrate Zn(NO3)2·6H2O and trivalent metal nitrate Bi(NO3)3·5H2O are separately dissolved in a precursor sol according to the spinel ABi2O4 stoichiometric ratio of 1:2, and stirred at 60°C until they become a gel, wherein the weight ratio of nitrate to precursor sol is 1:5, wherein the volume ratio of ethanol, propylene glycol and oxalic acid in the precursor sol is 2:2:1, and the dry gel is obtained by drying at 120°C, sintering at 650°C for 5 hours, and ball milling to obtain the ZnBi2O4 catalyst.

[0066] Comparative Example 9

[0067] Comparative Example 9 is different from Comparative Example 8 in that: a CuBi2O4 catalyst is provided, wherein A is a divalent metal Cu, a divalent metal nitrate Cu(NO3)2·6H2O.

[0068] Comparative Example 10

[0069] Comparative Example 10 differs from Comparative Example 8 in that a NiBi2O4 catalyst is provided, wherein A is a divalent metal Ni, a divalent metal nitrate Ni(NO3)2·6H2O.

[0070] Comparative Example 11

[0071] Comparative Example 11 differs from Comparative Example 8 in that: a CoBi2O4 catalyst is provided, wherein A is a divalent metal Co, a divalent metal nitrate Co(NO3)2·6H2O.

[0072] Comparative Example 12

[0073] Comparative Example 12 differs from Comparative Example 8 in that: a MgBi2O4 catalyst is provided, wherein A is a divalent metal Mg, a divalent metal nitrate Mg(NO3)2·6H2O.

[0074] Comparative Example 13

[0075] The difference between Comparative Example 13 and Comparative Example 8 is that: a ZnAl2O4 catalyst is provided, wherein A is a divalent metal Zn, a divalent metal nitrate Zn(NO3)2·6H2O, and a trivalent metal nitrate is Al(NO3)3·9H2O.

[0076] Comparative Example 14

[0077] Comparative Example 14 differs from Comparative Example 8 in that a CuAl2O4 catalyst is provided, wherein A is a divalent metal Cu, the divalent metal nitrate is Cu(NO3)2·6H2O, and the trivalent metal nitrate is Al(NO3)3·9H2O.

[0078] Comparative Example 15

[0079] The difference between Comparative Example 15 and Comparative Example 8 is that: a NiAl2O4 catalyst is provided, wherein A is a divalent metal Ni, the divalent metal nitrate is Ni(NO3)2·6H2O, and the trivalent metal nitrate is Al(NO3)3·9H2O.

[0080] Comparative Example 16

[0081] Comparative Example 16 differs from Comparative Example 8 in that a CoAl2O4 catalyst is provided, wherein A is a divalent metal Co, the divalent metal nitrate is Co(NO3)2·6H2O, and the trivalent metal nitrate is Al(NO3)3·9H2O.

[0082] Comparative Example 17

[0083] The difference between Comparative Example 17 and Comparative Example 8 is that: a MgAl2O4 catalyst is provided, wherein A is a divalent metal Mg, a divalent metal nitrate Mg(NO3)2·6H2O, and a trivalent metal nitrate is Al(NO3)3·9H2O.

[0084] Experimental testing and analysis

[0085] The silver-containing divalent and trivalent metal oxide catalysts obtained in Comparative Examples 1 to 7: silver-containing ZnO catalyst, silver-containing CuO catalyst, silver-containing NiO catalyst, silver-containing CoO catalyst, silver-containing MgO catalyst, silver-containing Bi2O3 catalyst, and silver-containing Al2O3 catalyst; and the silver-free spinel catalysts obtained in Comparative Examples 8 to 17: ZnBi2O4 catalyst, CuBi2O4 catalyst, NiBi2O4 catalyst, CoBi2O4 catalyst, MgBi2O4 catalyst, ZnAl2O4 catalyst, CuAl2O4 catalyst, NiAl2O4 catalyst, CoAl2O4 catalyst, and MgAl2O4 catalyst were tested for purification efficiency using thermal runaway simulated exhaust gas. The simulated thermal runaway exhaust gas was a customized standard gas, in which hydrogen accounted for 30%, carbon monoxide accounted for 10%, and carbon dioxide accounted for 60%; the combustion-supporting gas was a customized standard gas, in which oxygen accounted for 50% and nitrogen accounted for 50%. During the experiment, the above-mentioned simulated thermal runaway exhaust gas and the combustion-supporting gas were mixed in equal proportions through a mass flow meter, and then introduced into a tubular quartz reactor with a catalyst added. The test space velocity was 20,000 h -1 When the outlet concentration is stable, the inlet and outlet concentrations are tested and converted into purification efficiency of carbon monoxide and hydrogen. The test results are shown in Table 1.

[0086] Table 1

[0087] Catalyst type Hydrogen purification efficiency (%) Carbon monoxide purification efficiency (%) Silver-containing ZnO catalyst ＜5％ 6.9％ Silver-containing CuO catalyst 12.5％ ＜5％ Silver-containing NiO catalyst ＜5％ ＜5％ Silver-containing CoO catalyst 7.5％ 11％ Silver-containing MgO catalyst ＜5％ ＜5％ <![CDATA[Silver-containing Bi2O3 catalyst]]> 17.7％ 26.2％ <![CDATA[Silver-containing Al2O3 catalyst]]> ＜5％ ＜5％ <![CDATA[ZnBi2O4 catalyst]]> 7.9％ 6.5％ <![CDATA[CuBi2O4 catalyst]]> 14.1％ 16.9％ <![CDATA[NiBi2O4 catalyst]]> 13.7％ 15.2％ <![CDATA[CoBi2O4 catalyst]]> 21.1％ 29.3％ <![CDATA[MgBi2O4 catalyst]]> ＜5％ 5.3％ <![CDATA[ZnAl2O4 catalyst]]> ＜5％ ＜5％ <![CDATA[CuAl2O4 catalyst]]> 8.8％ 11.1％ <![CDATA[NiAl2O4 catalyst]]> ＜5％ ＜5％ <![CDATA[CoAl2O4 catalyst]]> 10.5％ 17.0％ <![CDATA[MgAl2O4 catalyst]]> ＜5％ ＜5％

[0088] As can be seen from Table 1, the silver-containing divalent metal oxide catalysts and trivalent metal oxide catalysts alone, as well as the silver-free spinel structure ABi2O4 catalysts and AAl2O4 catalysts (A is divalent metal Zn, Cu, Ni, Co, Mg in sequence), have low purification efficiency for hydrogen and carbon monoxide in simulated thermal runaway exhaust gas at room temperature, and cannot promptly eliminate the health hazards and explosion risks caused by the gases generated when the lithium-ion battery thermal runaway.

[0089] The silver-containing ABi2O4 catalysts obtained in Examples 1 to 5 (where A is a divalent metal such as Zn, Cu, Ni, Co, or Mg) and the silver-containing AAl2O4 catalysts obtained in Examples 6 to 10 (where A is a divalent metal such as Zn, Cu, Ni, Co, or Mg) were tested for purification efficiency of thermal runaway simulated exhaust gas. The test method was the same as that of the comparative example, and the test results are shown in Table 2.

[0090] Table 2

[0091] Catalyst type Hydrogen purification efficiency (%) Carbon monoxide purification efficiency (%) <![CDATA[Silver-containing ZnBi2O4 catalyst]]> 91.2％ 93.1％ <![CDATA[Silver-containing CuBi2O4 catalyst]]> 95.4％ 96.9％ <![CDATA[Silver-containing NiBi2O4 catalyst]]> 83.8％ 85.6％ <![CDATA[Silver-containing CoBi2O4 catalyst]]> 84.3％ 81.1％ <![CDATA[Silver-containing MgBi2O4 catalyst]]> 78.1％ 82.5％ <![CDATA[Silver-containing ZnAl2O4 catalyst]]> 87.7％ 91.4％ <![CDATA[Silver-containing CuAl2O4 catalyst]]> 85.5％ 87.8％ <![CDATA[Silver-containing NiAl2O4 catalyst]]> 74.1％ 81.9％ <![CDATA[Silver-containing CoAl2O4 catalyst]]> 83.3％ 85.1％ <![CDATA[Silver-containing MgAl2O4 catalyst]]> 71.8％ 78.3％

[0092] As can be seen from Table 2, the silver-containing ABi2O4 catalysts obtained in Examples 1 to 5 (where A is a divalent metal such as Zn, Cu, Ni, Co, or Mg, in sequence) and the silver-containing AAl2O4 catalysts obtained in Examples 6 to 10 (where A is a divalent metal such as Zn, Cu, Ni, Co, or Mg, in sequence) achieved purification efficiencies exceeding 70% for hydrogen and carbon monoxide in thermal runaway exhaust gas at room temperature in the presence of carbon dioxide. The silver-containing CuBi2O4 catalyst achieved a hydrogen purification efficiency of 95.4% and a carbon monoxide purification efficiency of 96.9% at room temperature, respectively. Compared to the silver-free spinel catalysts obtained in Comparative Examples 8 to 17, after loading a certain amount of elemental silver, the catalysts fully utilize the advantages of silver's low Fermi level, high active site density, and strong stability. Combining these with the spinel catalysts achieves synergistic enhancement of catalyst performance through the steric effect. These catalysts can efficiently catalyze hydrogen and carbon monoxide in thermal runaway exhaust gas at room temperature, demonstrating practical application prospects.

[0093] The silver-containing ZnAlBiO4 catalyst obtained in Example 11 and the silver-containing ZnAlBiO4 catalyst on the honeycomb ceramic support obtained in Example 12 were tested for purification efficiency of thermal runaway simulated exhaust gas. The test space velocity of the silver-containing ZnAlBiO4 catalyst was 20000h -1 The test space velocity of silver-containing ZnAlBiO4 catalyst on honeycomb ceramic carrier is 10000h -1 The other test methods are the same as those of the comparative example. The test results of the above catalysts and the test results of the silver-containing ZnBi2O4 catalyst obtained in Example 1, the silver-containing CuBi2O4 catalyst obtained in Example 2, and the silver-containing ZnAl2O4 catalyst obtained in Example 6 are summarized in Table 3.

[0094] Table 3

[0095]

[0096] As shown in Table 3, with the same silver loading, the silver-containing ZnAlBiO4 catalyst obtained in Example 11, compared to the silver-containing ZnBi2O4 catalyst obtained in Example 1 and the silver-containing ZnAl2O4 catalyst obtained in Example 6, changes the trivalent metals in the spinel from separate Bi and separate Al to an equal mixture of Bi and Al. Due to lattice distortion and steric effects, the catalyst's purification efficiency for hydrogen and carbon monoxide in thermal runaway exhaust gas is further improved, reaching 98.8% and 98.9%, respectively. Compared to the silver-containing CuBi2O4 catalyst obtained in Example 2, the silver-containing ZnAlBiO4 catalyst obtained in Example 11 not only has further improved catalytic performance, but also has Zn and Al at less than one-third the price of Cu and Bi, which facilitates cost reduction and increased efficiency.

[0097] The silver-containing CuBi2O4 catalyst obtained in Example 2 and the silver-containing ZnAlBiO4 catalyst obtained in Example 11 both have excellent performance. Figure 1 As shown, it can be seen from the scanning electron microscope image that the silver-containing CuBi2O4 catalyst obtained in Example 2 and the silver-containing ZnAlBiO4 catalyst obtained in Example 11 have good dispersion, and the elemental silver supported on the catalyst is uniformly precipitated on the catalyst surface in the form of nanorods. The stability and dispersibility of the elemental silver in the silver-containing ZnAlBiO4 catalyst obtained in Example 11 are more excellent.

[0098] The X-ray diffraction analysis of the silver-containing CuBi2O4 catalyst obtained in Example 2 and the silver-containing ZnAlBiO4 catalyst obtained in Example 11 is detailed in Figure 2 As shown, from the X-ray diffraction pattern, it can be seen that the three strong peaks of the silver-containing CuBi2O4 catalyst obtained in Example 2 and the silver-containing ZnAlBiO4 catalyst obtained in Example 11 are relatively obvious, indicating that the crystallinity of the catalyst is good and the crystal form is stable, and obvious diffraction peaks of Ag element appear at 2θ of 38.1°, 44.2°, and 64.4°, and the diffraction peak intensity is obvious. The silver-containing CuBi2O4 catalyst corresponds well to the standard card JCPDS (42-0344) in the spectrum library, proving that the prepared crystal is a tetragonal spinel CuBi2O4. Since the silver-containing ZnAlBiO4 catalyst is half co-doped with trivalent metal elements, no matching standard spectrum is retrieved in the spectrum library. Combined with the calculation formula of the interplanar spacing, it can be calculated that the ZnAlBiO4 crystal structure is a tetragonal structure, which is consistent with the spinel structure. It is speculated that the lattice distortion further enhances the catalytic activity of the catalyst.

[0099] The silver-containing ZnAlBiO4 catalyst on a honeycomb ceramic support obtained in Example 12 exhibits lower overall wind resistance than the silver-containing ZnAlBiO4 catalyst obtained in Example 11, enhancing contact between the catalyst and exhaust gas and facilitating practical application. Furthermore, the honeycomb ceramic support contains less active components of the catalyst, and even with only a doubling of the space velocity, it can still achieve a purification efficiency of over 99% for hydrogen and carbon monoxide in thermal runaway exhaust gas. The silver-containing ZnAlBiO4 catalyst on a honeycomb ceramic support obtained in Example 12 can be directly used in industrial applications.

Claims

1. A method for preparing a room-temperature oxidation catalyst for hydrogen and carbon monoxide generated by battery thermal runaway, characterized in that: The following steps are involved: S1. Dissolve a divalent metal nitrate and a trivalent metal nitrate in a precursor sol at a stoichiometric ratio of 1:2 according to the spinel AB2O4 structure, heat and stir until a gel is formed, and then dry to obtain a spinel precursor xerogel, wherein A is a divalent metal and B is a trivalent metal. The precursor sol is composed of a hydroxyl donor and an acidic regulator, the volume ratio of the hydroxyl donor to the acidic regulator is 1:(0.2-1), and the weight ratio of the precursor sol to the nitrate is (4-10):1; the divalent metal nitrate is Zn(NO3)2·6H2O, Cu(NO 3) one of 2·3H2O, Ni(NO3)2·6H2O, Co(NO3)2·6H2O, and Mg(NO3)2·6H2O; the trivalent metal nitrate is at least one of Bi(NO3)3·5H2O and Al(NO3)3·9H2O; wherein the temperature for heating and stirring is 40-70°C, the drying temperature is 100-140°C, and the drying time is 2-4 hours; the hydroxyl donor is at least one of ethanol, ethylene glycol, glycerol, and isopropyl alcohol; and the acidity regulator is at least one of citric acid and oxalic acid; S2. The spinel precursor xerogel and silver nitrate were ball-milled and sintered to obtain a silver-containing AB2O4 composite catalyst; S3. A silver-containing AB2O4 composite catalyst is mixed with silica sol and oxalic acid and ball-milled to obtain a catalyst slurry. A cordierite honeycomb ceramic support is then uniformly impregnated with the catalyst slurry and calcined to obtain a cordierite honeycomb ceramic support-supported silver-containing AB2O4 composite catalyst. The weight ratio of the silver-containing AB2O4 composite catalyst, silica sol and oxalic acid in the catalyst slurry is 1:(5-20):(1-10), the silica sol concentration is 5-20%, the ball-milling time is 1-4 hours, the calcination temperature is 200-600°C, and the calcination time is 1-4 hours. The cordierite honeycomb ceramic support is impregnated with the catalyst slurry multiple times and calcined to obtain a cordierite honeycomb ceramic support-supported silver-containing AB2O4 composite catalyst having an active component content of 10-30%.

2. The method for preparing a room-temperature oxidation catalyst for hydrogen and carbon monoxide generated by battery thermal runaway according to claim 1, characterized in that: In step S2, the molar ratio of divalent metal nitrate to silver nitrate is (5-15):1, the sintering temperature is 500-800° C., and the sintering time is 2-8 hours.

3. The method for preparing a room-temperature oxidation catalyst for hydrogen and carbon monoxide generated by battery thermal runaway according to claim 1, characterized in that: In the steps S1-S3, the heating rates of the heating, stirring, drying, sintering and burning processes are all 5-10°C / min.

4. The method for preparing a room-temperature oxidation catalyst for hydrogen and carbon monoxide generated by battery thermal runaway according to claim 1, characterized in that: In the steps S2-S3, a planetary ball mill is used for ball milling, the grinding balls are made of alumina or zirconia ceramic balls, the grinding balls have a diameter of 5mm-10mm, the ball-to-material ratio is 5-20:1, and the rotation speed is 100-900 rpm.

5. A room-temperature oxidation catalyst for hydrogen and carbon monoxide generated by thermal runaway of a battery, prepared by the preparation method according to any one of claims 1 to 4.

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