A catalyst for treating excessive ozone in a civil aviation passenger cabin air and a preparation method thereof

Abstract

The application discloses a kind of catalysts for treating excessive ozone in civil aviation passenger cabin air and a preparation method thereof.The catalyst comprises a carrier and a coating.The carrier is an aluminum honeycomb carrier.The coating contains cerium-zirconium modified alumina, transition metal oxide, noble metal platinum or palladium, and the content of platinum or palladium is 1-5 wt.%.The catalyst of the application can be used to treat excessive ozone in civil aviation passenger cabin air.The aluminum honeycomb carrier designed and manufactured has the characteristics of light weight, greatly reducing the load of the aircraft.Cerium-zirconium modified alumina used in the catalyst is a porous material with high specific surface area, which can better disperse noble metal on its surface and improve the utilization rate of noble metal.The addition of transition metal produces a synergistic effect with noble metal, improving the activity and service life of the catalyst.The preparation method of the application is simple, easy to operate and easy to form industrialization.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of catalyst for treating excessive ozone in civil aviation passenger cabin air and its preparation method, which is suitable for treating ozone-containing waste gas or excessive ozone concentration gas in limited space, especially treating excessive ozone in civil aviation passenger cabin air. BACKGROUND

[0002] Safe ozone concentration level is not only the basis of high-quality environment in aircraft passenger cabin, but also the focus of domestic and foreign civil aviation authorities. Ozone is a gas with special odor, which is chemically active. It not only has a certain impact on the health of the passengers on the plane, but also can react with other substances in the passenger cabin to produce secondary pollution, so its concentration level must be strictly controlled.

[0003] The current control method of ozone concentration in civil aviation cabin mainly includes adsorption method and thermal catalytic decomposition method. The adsorption method uses the large specific surface area and rich pore structure of activated carbon, which has strong adsorption of air pollutants. After the ozone-containing air flows through the activated carbon, the ozone molecules on the surface of the activated carbon are adsorbed, thereby achieving the purpose of removing ozone. This method has good effect on removing ozone, but the activated carbon adsorption device has limited adsorption capacity and is prone to spontaneous combustion after use, which may even cause explosion. This makes the filter have short service life and high maintenance cost, so it has not been widely used on the plane.

[0004] CN107875536 A discloses a recycling process of oxygen circulation regeneration system in a rescue cabin, which gradually converts the carbon dioxide exhaled by the personnel seeking refuge into oxygen for recycling. In the process, the adsorbent material uses solid amine or molecular sieve to effectively adsorb carbon dioxide. Thermal catalytic technology is to decompose ozone into oxygen under the action of catalyst by heating. The working temperature reaches 200℃ or above to produce good removal effect. This method can be applied and popularized when removing a small amount of ozone in the air of civil aviation passenger cabin.

[0005] CN111377522 A discloses a preparation method of catalyst for ozone catalytic wet oxidation treatment of wastewater. The catalyst is a supported catalyst, wherein the active component is a transition metal or a noble metal, and the carrier is one or more of activated carbon, molecular sieve and oxide. The transition metal is one or more of Fe, Co, Ni, Cu, Zn and Mn, preferably one or more of Fe, Cu and Mn. The noble metal is one or more of Pt, Pd, Ru, Rh and Ir, preferably Pt and / or Ru.

[0006] In the application of ozone oxidation technology, CN113578323 A discloses a method for preparing a metal-modified foam ceramic ozone catalyst, which addresses the problems of high pressure drop, high flow resistance, and the significant influence of bed height on transport performance in applications. By using foam ceramic as a catalyst support, the reaction fluid passes through the pores of the foam ceramic after being coated with the catalyst, which greatly improves the conversion efficiency and reaction rate. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a catalyst for treating excessive ozone in civil aviation cabin air and its preparation method. It can be used to treat ozone-containing waste gas or gas with excessive ozone concentration in a confined space, especially for treating excessive ozone in civil aviation cabin air. It has the characteristics of simple preparation method, easy operation, and easy industrialization.

[0008] To address the issue of safely and efficiently treating excessive ozone levels in passenger cabins, this invention provides a catalyst comprising: an aluminum honeycomb carrier and a catalyst coating formulation. The catalyst coating amount is 80–100 g / L, and the coating material is cerium-zirconium modified alumina loaded with noble metals and transition metal oxides, with the noble metal content ranging from 1% to 5%. The catalyst carrier is primarily made of lightweight aluminum foil, rolled into a honeycomb carrier according to size requirements, with a carrier diameter of 200–250 mm, a height of 20–30 mm, and a pore size of 260–440 mesh. Four or eight metal skeletons are added inside the aluminum honeycomb carrier to increase its mechanical strength.

[0009] The specific surface area of ​​the cerium-zirconium modified alumina is 180 m². 2 The cerium-zirconium solid solution has a mass percentage content of 15-40% and a cerium-zirconium molar ratio of 1:1 to 10:1. The transition metal oxide in the coating material is one or more of iron, cobalt, manganese, and copper oxides, with a mass percentage content of 8-20%.

[0010] Accordingly, the present invention also provides a method for preparing a catalyst, comprising the steps of:

[0011] (1) Carrier pretreatment: Soak the carrier in a certain concentration of nitric acid for 20-45 minutes, where the concentration of nitric acid is 10%. After soaking, take it out, rinse it with deionized water, and dry it for later use.

[0012] (2) Preparation of cerium-zirconium modified alumina: Weigh a certain amount of alumina and add water and stir. Weigh a certain amount of cerium nitrate and zirconium nitrate, dissolve them in water, and add them to the alumina at a rate of 10-20 mL / min. After the addition is complete, stir for 4-6 h, then adjust the pH to 8-9 with ammonia water and continue stirring for 4 h. Dry at 120-150℃ for 8 h and then calcine at 600℃ for 1-2 h to obtain cerium-zirconium modified alumina.

[0013] (3) Preparation of transition metal oxide coating material: a certain amount of cerium-zirconium modified alumina is weighed and stirred with water. A certain amount of transition metal nitrate is weighed and dissolved with water, and is added to the cerium-zirconium modified alumina at a rate of 10-20 mL / min. After the dropwise addition is completed, stirring is continued for 4-6 h, and then the pH is adjusted to 7-8 with barium hydroxide, and stirring is continued for 2 h. After drying at 120-150°C, calcination is carried out at 600°C for 1-2 h to obtain the transition metal oxide coating material.

[0014] (4) Preparation of noble metal slurry: a certain amount of transition metal oxide coating material is weighed and stirred with water. A platinum nitrate or palladium nitrate solution is added to the transition metal oxide coating material at a rate of 5-20 mL / min. After the dropwise addition is completed, stirring is continued for 2-4 h, and a certain amount of aluminum colloid is added, and stirring is continued for 30 min to obtain the transition metal oxide coating material slurry.

[0015] (5) Carrier coating: the corresponding mass of noble metal slurry is applied to the end face of the carrier, and the slurry is uniformly coated in the carrier channel by using the positive pressure method. Drying is carried out at 120-150°C for 2-4 h, and the carrier is calcined at 550-600°C for 1-2 h to obtain the finished catalyst.

[0016] Compared with the prior art, the technical scheme of the present application has the following advantages:

[0017] The aluminum honeycomb carrier designed and manufactured in the catalyst of the present application has the characteristic of light mass, which greatly reduces the load of the aircraft, and can also be applied in scenarios where the loading mass is limited. The cerium-zirconium modified alumina used in the catalyst is a high specific surface area porous material, which can better disperse the noble metal on its surface and improve the utilization rate of the noble metal. The addition of transition metals produces a synergistic effect with the noble metal, improving the activity and service life of the catalyst. The preparation method of the present application is simple, easy to operate, and easy to form industrialization. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The figure is a schematic diagram of the appearance of the catalyst, wherein the diameter of the catalyst carrier is 200-250 mm, the height is 20-30 mm, and the number of holes is 260-440 mesh. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present application, a more comprehensive description of the present application will be provided below. However, the present application can be realized in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0021] Example 1

[0022] In this embodiment, the carrier is an aluminum honeycomb carrier with a size of Φ208-22mm / 300 mesh and a volume of 0.7476L. The coating material loading is 100g / L.

[0023] In this embodiment, the coating material is cerium-zirconium modified alumina loaded with noble metal and transition metal oxides, the noble metal is palladium with a content of 2%, and the transition metal is manganese with an oxide content of 10%.

[0024] The preparation method of the catalyst comprises the following steps:

[0025] (1) Carrier pretreatment: immerse the carrier in nitric acid with a concentration of 8% for 30 minutes, then take it out, rinse it with deionized water, and dry it for later use.

[0026] (2) Preparation of cerium-zirconium modified alumina: weigh 160g of alumina and add 300g of water to stir. Weigh 66.0g of cerium nitrate and 65.2g of zirconium nitrate, dissolve them in water, and add them to the alumina at a rate of 10mL / min. After the dropwise addition is complete, stir for 6h, then adjust the pH to 8 with ammonia water and continue stirring for 4h. After drying at 120℃ for 8h, calcine at 600℃ for 2h to obtain cerium-zirconium modified alumina.

[0027] (3) Preparation of transition metal oxide coating material: weigh 135g of cerium-zirconium modified alumina and add water to stir. Weigh 61.7g of manganese nitrate solution and dilute it with water, then add it to the cerium-zirconium modified alumina at a rate of 20mL / min. After the dropwise addition is complete, stir for 5h, then adjust the pH to 8 with barium hydroxide and continue stirring for 2h. After drying at 120℃, calcine at 600℃ for 2h to obtain the transition metal oxide coating material.

[0028] (4) Preparation of noble metal slurry: weigh 100g of manganese-containing coating material and add water to stir. Weigh 2g of Pd-containing palladium nitrate solution and add it to the manganese-containing coating material at a rate of 10mL / min. After the dropwise addition is complete, stir for 4h, then add 30g of aluminum paste and continue stirring for 30min until the slurry is uniform. The transition metal oxide coating material slurry is obtained.

[0029] (5) Carrier coating: The noble metal slurry is given to the carrier end face, and the slurry is uniformly coated in the carrier channel by using the positive pressure method until the dry weight of the coating material is 75 g. The coated carrier is dried at 120 °C for 4 h and calcined at 550 °C for 1 h to obtain catalyst product A.

[0030] Example 2

[0031] Example 2 differs from the catalyst prepared in Example 1 only in the type of noble metal, and the specific preparation method comprises the following steps:

[0032] (1) Carrier pretreatment: The carrier is soaked in nitric acid with a concentration of 8% for 30 min. After soaking, it is taken out, washed with deionized water, and dried for use.

[0033] (2) Preparation of cerium-zirconium modified alumina: 160 g of alumina is weighed and stirred with 300 g of water. 66.0 g of cerium nitrate and 65.2 g of zirconium nitrate are weighed and dissolved in water, and then added to the alumina at a rate of 10 mL / min. After the dropwise addition is completed, stirring is continued for 6 h, and then the pH is adjusted to 8 with ammonia water, and stirring is continued for 4 h. After drying at 120 °C for 8 h, calcination is carried out at 600 °C for 2 h to obtain cerium-zirconium modified alumina.

[0034] (3) Preparation of transition metal oxide coating material: 135 g of cerium-zirconium modified alumina is weighed and stirred with water. 61.7 g of manganese nitrate solution is weighed and diluted with water, and then added to the cerium-zirconium modified alumina at a rate of 20 mL / min. After the dropwise addition is completed, stirring is continued for 5 h, and then the pH is adjusted to 7 with barium hydroxide, and stirring is continued for 2 h. After drying at 120 °C, calcination is carried out at 600 °C for 2 h to obtain the transition metal oxide coating material.

[0035] (4) Preparation of noble metal slurry: 100 g of manganese-containing coating material is weighed and stirred with water. 2 g of platinum-containing platinum nitrate solution is weighed and added to the manganese-containing coating material at a rate of 10 mL / min. After the dropwise addition is completed, stirring is continued for 4 h, and 30 g of aluminum paste is added, and stirring is continued for 30 min until the slurry is uniform. The transition metal oxide coating slurry is obtained.

[0036] (5) Carrier coating: The noble metal slurry is given to the carrier end face, and the slurry is uniformly coated in the carrier channel by using the positive pressure method until the dry weight of the coating material is 75 g. The coated carrier is dried at 120 °C for 4 h and calcined at 550 °C for 1 h to obtain catalyst product A.

[0037] Example 3

[0038] Example 3 differs from the catalyst prepared in Example 1 only in the content of noble metal, and the specific preparation method comprises the following steps:

[0039] (1) Carrier pretreatment: the carrier was soaked in nitric acid with a concentration of 8% for 30 min, then taken out, washed with deionized water, and dried for use.

[0040] (2) Preparation of cerium-zirconium modified alumina: 160 g of alumina was weighed and stirred with 300 g of water. 66.0 g of cerium nitrate and 65.2 g of zirconium nitrate were dissolved in water and added to the alumina at a rate of 10 mL / min. After the addition was completed, stirring was continued for 6 h. Then the pH was adjusted to 9 with ammonia water, and stirring was continued for 4 h. After drying at 120°C for 8 h, calcination was carried out at 600°C for 2 h to obtain cerium-zirconium modified alumina.

[0041] (3) Preparation of transition metal oxide coating material: 135 g of cerium-zirconium modified alumina was weighed and stirred with water. 61.7 g of manganese nitrate solution was diluted with water and added to the cerium-zirconium modified alumina at a rate of 20 mL / min. After the addition was completed, stirring was continued for 5 h. Then the pH was adjusted to 8 with barium hydroxide, and stirring was continued for 2 h. After drying at 120°C, calcination was carried out at 600°C for 2 h to obtain the transition metal oxide coating material.

[0042] (4) Preparation of noble metal slurry: 100 g of manganese-containing coating material was weighed and stirred with water. 1 g of palladium nitrate solution containing 1 g of Pd was added to the manganese-containing coating material at a rate of 10 mL / min. After the addition was completed, stirring was continued for 4 h. Then 30 g of aluminum paste was added, and stirring was continued for 30 min until the slurry was uniform in state. The transition metal oxide coating material slurry was obtained.

[0043] (5) Carrier coating: the noble metal slurry was applied to the end face of the carrier, and the slurry was uniformly coated in the carrier channel by using the positive pressure method until the dry weight of the coating material was 75 g. The coated carrier was dried at 120°C for 4 h and calcined at 550°C for 1 h to obtain the finished catalyst C.

[0044] Example 4

[0045] Example 4 differs from the catalyst prepared in Example 1 only in the type and content of noble metal. The specific preparation method includes the following steps:

[0046] (1) Carrier pretreatment: the carrier was soaked in nitric acid with a concentration of 8% for 30 min, then taken out, washed with deionized water, and dried for use.

[0047] (2) Preparation of cerium-zirconium modified alumina: 160 g of alumina was weighed and stirred with 300 g of water. 66.0 g of cerium nitrate and 65.2 g of zirconium nitrate were dissolved in water and added to the alumina at a rate of 10 mL / min. After the addition was completed, stirring was continued for 6 h. Then the pH was adjusted to 9 with ammonia water, and stirring was continued for 4 h. After drying at 120°C for 8 h, calcination was carried out at 600°C for 2 h to obtain cerium-zirconium modified alumina.

[0048] (3) Preparation of transition metal oxide coating material: 135 g of cerium-zirconium modified alumina was weighed and stirred with water. 61.7 g of manganese nitrate solution was weighed and diluted with water, and was added to the cerium-zirconium modified alumina at a rate of 20 mL / min. After the dropwise addition was completed, stirring was continued for 5 h, and then the pH was adjusted to 7 with barium hydroxide, and stirring was continued for 2 h. After drying at 120°C, calcination was performed at 600°C for 2 h to obtain the transition metal oxide coating material.

[0049] (4) Preparation of noble metal slurry: 100 g of the manganese-containing coating material was weighed and stirred with water. 1 g of palladium nitrate solution containing 1 g of Pd and 1 g of platinum nitrate solution containing 1 g of Pt were weighed and added to the manganese-containing coating material at a rate of 10 mL / min. After the dropwise addition was completed, stirring was continued for 4 h, and 30 g of alumina sol was added, and stirring was continued for 30 min until the slurry was uniform in state to obtain the transition metal oxide coating material slurry.

[0050] (5) Carrier coating: The noble metal slurry was applied to the end face of the carrier, and the slurry was uniformly coated in the carrier channel using a positive pressure method until the dry weight of the coating material was 75 g. The coated carrier was dried at 120°C for 4 h and calcined at 550°C for 1 h to obtain catalyst product D.

[0051] Example 5

[0052] Example 5 differs from the catalyst prepared in Example 4 only in the type of transition metal, and the specific preparation method includes the following steps:

[0053] (1) Carrier pretreatment: The carrier was soaked in nitric acid of a certain concentration for 30 min, and the concentration of the nitric acid was 8%. After the soaking was completed, the carrier was removed and rinsed with deionized water, and then dried for use.

[0054] (2) Preparation of cerium-zirconium modified alumina: 160 g of alumina was weighed and stirred with 300 g of water. 66.0 g of cerium nitrate and 65.2 g of zirconium nitrate were weighed and dissolved in water, and were added to the alumina at a rate of 10 mL / min. After the dropwise addition was completed, stirring was continued for 6 h, and then the pH was adjusted to 9 with ammonia water, and stirring was continued for 4 h. After drying at 120°C for 8 h, calcination was performed at 600°C for 2 h to obtain the cerium-zirconium modified alumina.

[0055] (3) Preparation of transition metal oxide coating material: 135 g of cerium-zirconium modified alumina was weighed and stirred with water. 50.2 g of manganese nitrate solution and 8.5 g of copper nitrate were weighed and dissolved in water, and were added to the cerium-zirconium modified alumina at a rate of 20 mL / min. After the dropwise addition was completed, stirring was continued for 5 h, and then the pH was adjusted to 8 with barium hydroxide, and stirring was continued for 2 h. After drying at 120°C, calcination was performed at 600°C for 2 h to obtain the transition metal oxide coating material.

[0056] (4) Preparation of noble metal slurry: 100 g of the manganese-containing coating material was weighed and stirred with water. 1 g of palladium nitrate solution containing Pd and 1 g of platinum nitrate solution containing Pt were weighed and added to the manganese-containing coating material at a rate of 10 mL / min. After the dropwise addition was completed, the mixture was stirred for 4 h. Then, 30 g of aluminum paste was added, and the mixture was continuously stirred for 30 min until the slurry was uniform in state. Thus, a transition metal oxide coating material slurry was obtained.

[0057] (5) Carrier coating: The noble metal slurry was applied to the end face of the carrier, and the slurry was uniformly coated in the carrier channel by using a positive pressure method until the dry weight of the coating material was 75 g. The coated carrier was dried at 120℃ for 4 h and calcined at 550℃ for 1 h to obtain catalyst product E.

[0058] Performance test

[0059] The catalyst samples of Examples 1 to 5 were sequentially numbered as A to E, and the performance of the samples A to E was tested to detect the ozone decomposition efficiency of the catalysts. The test conditions were as follows: reaction space velocity 40000 / h, reaction temperature RT-200℃, ozone concentration 1000 ppm, and balance gas air. The test results are shown in Table 1.

[0060] Table 1: Performance test results of the first to fifth examples

[0061]

[0062] As can be seen from Table 1, the catalyst samples A to E obtained in Examples 1 to 5 all have the ability to catalytically decompose ozone, and the high-palladium catalyst represented by A and the composite oxide catalyst represented by E have better activity than the catalysts of the other examples.

[0063] In summary, the catalyst prepared by the present application can effectively reduce the ozone concentration in the gas, and can be popularized when treating ozone-containing waste gas or when the ozone concentration in the gas in a limited space exceeds the standard.

Claims

1. A catalyst for treating excessive ozone in civil aviation cabin air, the catalyst comprising a carrier and a coating, characterized in that: The catalyst is supported on an aluminum honeycomb carrier with a size of Φ208-22mm / 300 mesh and a volume of 0.7476L. The coating material loading is 100g / L. The catalyst coating contains cerium-zirconium modified alumina, transition metal oxides, and the noble metals platinum and palladium. The preparation method of the catalyst includes: (1) Carrier pretreatment: The carrier is soaked in nitric acid of a certain concentration for 30 minutes, where the concentration of nitric acid is 8%. After soaking, the carrier is taken out, rinsed with deionized water, dried and ready for use. (2) Preparation of cerium-zirconium modified alumina: Weigh 160g of alumina and add 300g of water and stir; Weigh 66.0g of cerium nitrate and 65.2g of zirconium nitrate and dissolve them in water, and add them to the alumina at a rate of 10mL / min. After the addition is complete, stir for 6h, then adjust the pH to 9 with ammonia water and continue stirring for 4h; Dry at 120℃ for 8h and calcine at 600℃ for 2h to obtain cerium-zirconium modified alumina; (3) Preparation of transition metal oxide coating material: Weigh 135g of cerium-zirconium modified alumina and add water and stir; weigh 50.2g of manganese nitrate solution and 8.5g of copper nitrate, dilute and dissolve them with water, and add them to the cerium-zirconium modified alumina at a rate of 20mL / min. After the addition is completed, stir for 5h, then adjust the pH to 8 with barium hydroxide and continue stirring for 2h; dry at 120℃ and calcine at 600℃ for 2h to obtain transition metal oxide coating material; (4) Preparation of precious metal slurry: Weigh 100g of transition metal oxide coating material and add water and stir; weigh palladium nitrate solution containing 1gPd and platinum nitrate solution containing 1gPt, and add them to the transition metal oxide coating material at a rate of 10mL / min. After the addition is completed, stir for 4h, add 30g of aluminum glue, and continue stirring for 30min until the slurry is uniform, and obtain precious metal slurry; (5) Carrier coating: Apply precious metal slurry to the end face of the carrier and use positive pressure method to uniformly coat the slurry into the pores of the carrier until the dry weight of the coating material is 75g; dry the coated carrier at 120℃ for 4h and calcine at 550℃ for 1h to obtain the catalyst product.

2. The catalyst for treating excessive ozone in civil aviation cabin air according to claim 1, characterized in that: The aluminum honeycomb carrier has several metal skeletons inside to increase the carrier's mechanical strength.

3. The catalyst for treating excessive ozone in civil aviation cabin air according to claim 2, characterized in that: The metal frame consists of 4 or 8 components.

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