Composite oxides are widely used as catalysts in modern chemical industry because of their excellent oxidation/reduction properties, high mechanical strength and good thermal stability. Among them, perovskite compound oxide is particularly eye-catching. Since the 1950s, perovskite-type composite oxides have been used in catalytic combustion, photocatalysis, fuel cells and metals
Air cell, environmental catalysis, catalytic hydrogenation, catalytic cracking and so on have been widely used and studied. At present, there are many methods used to synthesize perovskite, such as coprecipitation method, sol-gel method, solid phase method, hydrothermal method and so on. However, the specific surface area of perovskite prepared by these methods is small, and the application prospect of perovskite composite oxide is limited due to its low specific surface area. The template method is used to prepare porous metal oxide materials. Perovskite composite oxide has excellent thermal stability, REDOX performance, oxygen mobility and electron ion conductivity due to its special composition and structure. In recent years, it has attracted extensive attention in the field of catalyst.
3. Composite transition metal oxides with perovskite structure have attracted wide attention in the field of catalytic combustion of vocs in recent years due to their low price, high catalytic activity and good thermal stability. However, the perovskite-type oxide catalysts prepared by traditional methods have small surface area, and their catalytic activity is greatly limited, which hinders their commercial application to a certain extent. Therefore, it is one of the research focuses of perovskite oxide catalysts to increase specific surface area and catalytic activity by appropriate preparation method.
The invention provides a preparation method and application of aluminum air electrode catalyst material lanthanum manganate with cubic particle accumulation structure. The cubic particle stacking structure of the invention has the advantages of simple preparation process, low price, high catalytic activity and good thermal stability.
The invention provides a preparation method for lanthanum manganate, including the following steps:
Step 1: Mix lanthanum nitrate and manganese nitrate evenly according to the molar ratio of 1:1, then add citric acid and dissolve in deionized water and anhydrous ethanol to prepare a solution;
Step 2. Add the activated carbon template to the solution of Step 1 to form a mixed solution;
Step 3. Ultrasound the mixed solution in Step 2 for 60min and then stand for 12h;
Step 4. Put the obtained polymer in the oven at 60℃ to dry for 12h;
Step 5. The sample obtained in Step 4 was calcined in Muffle furnace at 350℃ for 3h, and then calcined at 650 ~ 750℃ for 1 ~ 3h to remove the activated carbon template, and the cubic dense structure lanthanum manganate was obtained.
In the above preparation methods, the templates of lanthanum nitrate, manganese nitrate, citric acid, deionized water, ethanol and activated carbon are 5mmol, 5mmol, 10mmol, 5ml, 15ml and 0.1 ~ 0.3g, respectively.
12. In the above preparation methods, lanthanum nitrate and manganese nitrate in step 1 are la(no3)3·
6h2o and mn(no3)2.
The invention also provides the application of lanthanum manganate prepared by the above-mentioned preparation method. The cubic particle accumulation structure lanthanum manganate and acetylene black are mixed as the catalytic layer of air electrode according to the mass ratio of 6:4, and the working electrode with the length of 4cm and the width of 3cm is pressed. The aluminum plate is used as the negative electrode, and the electrolyte uses 6mol/l koh solution to form the aluminum air battery in the organic glass frame. The method of preparing cubic particle accumulation structure lanthanum manganate is simple, easy to operate and convenient for large-scale production. The produced cubic particle accumulation structure lanthanum manganate can expand the selection of aluminum air electrode catalyst and develop new metals.