A carbon monoxide catalytic combustion catalyst and a method for preparing the same

Abstract

The present application relates to the technical field of industrial waste gas treatment, in particular to a carbon monoxide catalytic combustion catalyst and a preparation method thereof, 1, a sol-gel method is used to prepare a Co, Zr and Ce solid solution, a certain molar proportion of a complexing agent is added to metal salt dissolved in deionized water, the pH of the solution is adjusted, and stirring is performed under the condition of a 60 DEG C water bath until a viscous gel is obtained, and then drying, calcination and grinding are performed to obtain the solid solution; 2, an active metal is loaded, a certain amount of at least one nitrate salt of Cu, Mn, La and Mg is dissolved in deionized water, and the solid solution carrier is loaded on the nitrate salt by an equal-volume impregnation method, and then drying and calcination are performed to obtain a loaded catalyst; 3, the loaded catalyst is placed in a 5% water vapor environment and aged at 700 DEG C for 10 hours to obtain a final catalyst. The catalyst has high activity and stability for carbon monoxide, and has very low activity for low-carbon alkanes such as methane, and can be used for removing a small amount of carbon monoxide in low-carbon alkanes by catalytic combustion, and has certain industrial application prospects.

Description

Technical Field

[0001] This invention relates to the field of industrial waste gas treatment technology, and in particular to a carbon monoxide catalytic combustion catalyst and its preparation method. Background Technology

[0002] Low-concentration coal mine gas refers to gas with a methane content of less than 30%. Its resource utilization presents certain technical challenges, but direct dilution and emission would lead to the greenhouse effect and ozone layer depletion. Regenerative thermal oxidation (RTO) is an effective technology for fully utilizing low-concentration coal mine gas while significantly reducing greenhouse gas emissions.

[0003] However, a small amount of carbon monoxide is inevitably generated during the regenerative thermal oxidation process for treating low-concentration coal mine gas, posing a significant threat to the environment and human health. In the presence of a catalyst, fully utilizing the heat generated during regenerative oxidation to convert carbon monoxide into carbon dioxide is a feasible approach. Developing highly active carbon monoxide catalytic combustion catalysts is crucial for this technology.

[0004] Chinese patent CN109569678 B discloses a carbon monoxide catalytic combustion catalyst that exhibits uniform dispersion, high catalytic efficiency, resistance to sintering, and good stability. This catalyst is a noble metal catalyst, using phosphate-modified alumina as a support and alkali metal oxides as forming aids. This catalyst is suitable for CO removal under medium to low concentration, high flow rate, and low or high temperature conditions.

[0005] Chinese patent CN106540754 B discloses a catalytic combustion catalyst using ceramic fiber as a support. This catalyst employs acid-treated ceramic fiber as the support and precious metals as the active component. The coating and active component are loaded onto the ceramic fiber support using an impregnation method. This catalyst possesses advantages such as a robust coating, good hydrothermal stability, and high-temperature resistance. It can be used for the catalytic combustion removal of various waste gases, including methane, VOCs, H2, and CO.

[0006] The catalysts mentioned above exhibit strong catalytic activity and have certain application prospects. However, all of these catalysts use precious metals, and their large-scale application is limited due to the high price and susceptibility to poisoning associated with precious metals.

[0007] Developing inexpensive catalysts with high activity, long lifespan, and suitability for the catalytic combustion of CO in industrial waste gases is an effective way to reduce CO pollution in the atmosphere. Summary of the Invention

[0008] The purpose of this invention is to provide a carbon monoxide catalytic combustion catalyst and its preparation method, so as to solve the problems mentioned in the background art.

[0009] The method for preparing the catalyst involved in this invention includes the following steps:

[0010] (1) Preparation of Co, Zr and Ce solid solutions by sol-gel method: a certain amount of metal salts were weighed and dissolved in deionized water, a certain molar ratio of complexing agent was added, the pH of the sol-gel solution was adjusted, and the solution was stirred in a water bath at 60°C until it became a viscous gel. After drying, calcining and grinding, Co, Zr and Ce solid solution carriers were obtained.

[0011] (2) Loading of active metals: a certain amount of at least one nitrate of Cu, Mn, La and Mg is weighed and dissolved in deionized water, loaded onto a solid solution support by an equal volume impregnation method, and then dried and calcined to obtain the loaded catalyst.

[0012] (3) Catalyst aging: The loaded catalyst is placed in a 5% water vapor environment and aged at 700℃ for 10 hours to obtain the final catalyst.

[0013] Preferably, the molar ratio of Co, Zr, and Ce in the solid solution is 1:(0.1–0.5):(0.1–0.5). The ratio of the total molar amount of metal to the complexing agent is 1:(0.5–2).

[0014] Preferably, the pH of the sol-gel solution is adjusted using 1M / L sodium hydroxide or hydrochloric acid, controlling the pH range to 3–9, with a preferred pH range of 4–6.

[0015] Preferably, the complexing agent is one of citric acid, polyethylene glycol, or polyvinylpyrrolidone, which has multiple active components.

[0016] Preferably, the active metal element is at least one of Cu, Mn, La, and Mg.

[0017] Preferably, the molar ratio of the active metal elements Cu, Mn, La, and Mg is 1:(0-2):(0-0.5):(0-1.5):(0-1), and the total metal loading is 10wt% to 30wt%, preferably 12wt% to 38wt%.

[0018] Preferably, the concentration of water vapor during the high-temperature aging process of the catalyst is 1% to 10%, and more preferably 5%.

[0019] Preferably, the aging temperature of the catalyst is 500℃~900℃, and more preferably 600℃~700℃.

[0020] The present invention also provides a carbon monoxide catalytic combustion catalyst obtained according to the preparation method described above.

[0021] The catalyst involved in this invention exhibits high activity and stability for carbon monoxide, while having extremely low activity for low-carbon alkanes such as methane. This catalyst can be used to remove small amounts of carbon monoxide from low-carbon alkanes by catalytic combustion. It has a long service life, a wide range of raw material sources, and low price, and has certain prospects for industrial application. Detailed Implementation

[0022] The technical solution will be clearly and completely described below through embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The catalyst of the present invention is prepared by the following method:

[0024] Example 1

[0025] 18.2 g of cobalt nitrate, 16.3 g of cerium nitrate, and 16.9 g of zirconium nitrate were weighed and dissolved in 500 ml of deionized water. After stirring for 10 min, 23.1 g of citric acid was added. The pH of the solution was adjusted to 4–6 by adding 1 M / L sodium hydroxide. The solution was placed in a water bath and stirred at 60 °C until it reached a gel-like state. After drying at 80 °C, it was calcined in a muffle furnace at 500 °C for 4 h. After cooling, it was ground to obtain a powdered support. 2.15 g of manganese nitrate and 0.93 g of lanthanum nitrate were weighed and dissolved in 4.35 g of deionized water. An equal volume of this solution was impregnated onto 10 g of the above support. After drying at 80 °C, it was calcined at 500 °C. The above catalyst was then treated under 5% steam at 700 °C for 10 h to obtain the final catalyst.

[0026] Example 2

[0027] 2.15g of manganese nitrate, 0.93g of lanthanum nitrate, and 0.47g of titanium nitrate were weighed and dissolved in 4.35g of deionized water. The solution was then impregnated onto 10g of the support from Example 1 by an equal volume. After drying at 80°C, the solution was calcined at 500°C. The catalyst was then treated at 700°C for 10 hours under 5% steam to obtain the final catalyst.

[0028] Example 3

[0029] 0.93 g of lanthanum nitrate and 0.47 g of titanium nitrate were dissolved in 4.35 g of deionized water, and the mixture was impregnated onto 10 g of the support from Example 1 by equal volume. After drying at 80 °C, the catalyst was calcined at 500 °C. The catalyst was then treated at 700 °C for 10 h under 5% steam to obtain the final catalyst.

[0030] Comparative Example 1

[0031] Weigh 18.2g of cobalt nitrate, 16.3g of cerium nitrate, and 16.9g of zirconium nitrate, dissolve them in 500ml of deionized water, stir for 10min, and then add 23.1g of citric acid. Add 1M / L sodium hydroxide to adjust the pH of the solution to 4-6. Place the solution in a water bath and stir at 60℃ until it becomes gel-like. Dry it at 80℃, then calcine it in a muffle furnace at 500℃ for 4h. After cooling, grind it to obtain a powder carrier. Weigh 2.15g of manganese nitrate and 0.93g of lanthanum nitrate, dissolve them in 4.35g of deionized water, and impregnate 10g of the above carrier with an equal volume. Dry it at 80℃ and then calcine it at 500℃.

[0032] The catalytic combustion activity of the catalysts involved in Examples 1, 2, 3, and Comparative Example 1 was evaluated in a fixed-bed reactor. Specific evaluation conditions were as follows: 200 mg of catalyst was weighed into the fixed-bed reactor, and a mixture of 0.5% carbon monoxide and air was introduced into the reactor at a flow rate of 200 ml / min. Starting from 25 °C, the concentration of carbon monoxide in the reactor tail gas was tested at different temperatures using a programmed temperature rise method, and the temperature at which the carbon monoxide conversion rate reached 99% was recorded. The catalyst evaluation results (carbon monoxide) are shown in Table 1.

[0033] Table 1

[0034] catalyst T99(℃) Example 1 90.3 Example 2 76.4 Example 3 88.2 Comparative Example 1 91.2

[0035] Catalyst activity evaluation (methane)

[0036] The methane catalytic combustion activity of the catalysts involved in Example 1 and Comparative Example 1 was evaluated in a fixed-bed reactor. The specific evaluation conditions were as follows: 200 mg of catalyst was weighed into the fixed-bed reactor, and a mixture of 1% methane and air was introduced into the reactor at a flow rate of 100 ml / min. The methane conversion rate of the catalyst was recorded at 400 °C. The catalyst activity evaluation results are shown in Table 2.

[0037] Table 2

[0038] catalyst Methane conversion rate at 400℃ Example 1 1.2 Comparative Example 1 13.5

[0039] Catalyst thermal stability test

[0040] The catalysts involved in Example 1 and Comparative Example 1 were heat-treated in air at 800°C for 10 hours. The catalytic combustion activity of the catalysts for carbon monoxide was evaluated under the same conditions. The temperature at which the carbon monoxide conversion rate reached 99% was recorded. The catalyst activity after heat treatment is shown in Table 3.

[0041] Table 3

[0042] catalyst T99(℃) Example 1 90.9 Comparative Example 1 132.5

[0043] Table 1 shows that the catalyst exhibits high catalytic activity for carbon monoxide. Tables 2 and 3 show that the activity for methane decreases significantly after steam aging, while the thermal stability of the catalyst increases significantly.

[0044] The preparation method of this invention can significantly improve the catalytic activity and thermal stability of the catalyst for carbon monoxide, while exhibiting extremely low activity towards low-carbon alkanes such as methane. This catalyst can be used for the removal of trace amounts of carbon monoxide from low-carbon alkanes via catalytic combustion, and has promising industrial application prospects.

[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a carbon monoxide catalytic combustion catalyst, characterized in that, Includes the following steps: (1) Preparation of Co, Zr and Ce solid solutions by sol-gel method: a certain amount of metal salts were weighed and dissolved in deionized water, a certain molar ratio of complexing agent was added, the pH of the sol-gel solution was adjusted, and the solution was stirred in a water bath at 60°C until it became a viscous gel. After drying, calcining and grinding, Co, Zr and Ce solid solution carriers were obtained. (2) Loading of active metals: Manganese nitrate and lanthanum nitrate were weighed in a weight ratio of 2.15:0.93 and dissolved in deionized water. The total loading of metals was 10wt% to 30wt%. The metals were loaded onto the solid solution support by the equal volume impregnation method. After drying and calcination, the loaded catalyst was obtained. (3) Catalyst aging: The loaded catalyst is placed in a 5% water vapor environment and aged at 700℃ for 10 hours to obtain the final catalyst.

2. The method for preparing a carbon monoxide catalytic combustion catalyst according to claim 1, characterized in that, The molar ratio of Co, Zr, and Ce in the solid solution is 1:(0.1–0.5):(0.1–0.5); the ratio of the total molar amount of metal to the complexing agent is 1:(0.5–2).

3. The method for preparing a carbon monoxide catalytic combustion catalyst according to claim 1, characterized in that, The pH of the sol-gel solution is adjusted using 1M / L sodium hydroxide or hydrochloric acid, controlling the pH range to 3–9.

4. The method for preparing a carbon monoxide catalytic combustion catalyst according to claim 1, characterized in that, The complexing agent is one or more of citric acid, polyethylene glycol, and polyvinylpyrrolidone.

5. A carbon monoxide catalytic combustion catalyst obtained by the preparation method according to any one of claims 1 to 4.