A method of producing manganese dioxide active in the oxidation of carbon monoxide

 

(57) Abstract:

The invention relates to inorganic chemistry and can be used in particular for the preparation of the catalyst used for purification of gas mixtures of carbon monoxide in the systems of collective and individual protection of respiratory organs and the emissions of industrial enterprises, for purification of exhaust gases of internal combustion engines, as well as for other industrial and environmental purposes. Method for obtaining manganese dioxide active in the oxidation of carbon monoxide, comprising adding potassium permanganate solution with a concentration of 15 to 20 wt.% to a solution of manganese sulfate with a concentration of 20 to 25 wt.% under stirring, filtering and washing of the final product. The proposed method can significantly improve the performance of process equipment while maintaining high level of catalytic activity of manganese dioxide in the oxidation of carbon monoxide. table 1.

The invention relates to inorganic chemistry and can be used in particular for the preparation of the catalyst used for purification of gas mixtures of carbon monoxide in the systems of collective and individual is its combustion, as well as for other industrial and environmental purposes.

A method of obtaining manganese dioxide, comprising the reaction of manganate with carbonate of an alkali metal and NaHCO3in the ratio 6:4 - 0:10 or (NH4)2CO3and NH4HCO3in the ratio of 9.6:0.4 to 0:10 in aqueous solution at 20 - 90oC, the heating is obtained a crystalline precipitate of manganese dioxide at 280 - 400oC in an atmosphere containing 10 to 80 vol.% water vapor, processing of manganese dioxide with concentrated nitric acid and subsequent heating to a temperature of 160 - 300oC (patent Germany N 2051917 from 22.10.70, class C 01 G 45/02).

The disadvantage of this method is the complexity of the technological process of obtaining manganese dioxide, caused by the necessity of heating a crystalline precipitate of manganese dioxide at 280 - 400oC in an atmosphere of water vapor, the subsequent processing of manganese dioxide with concentrated nitric acid and additional heat treatment of manganese dioxide at 160 - 300oC.

Also known is a method of obtaining manganese dioxide, including the interaction of a solution containing 44,6 g chetyrehletnego manganese sulfate in 500 ml of water and 50 ml of koncentrira for 20 min, filtering and washing the precipitate obtained (patent UK N 1315374 from 20.04.70, class C 01 G 45/02).

The disadvantage of this method is the low catalytic activity of the obtained manganese dioxide in the oxidation of carbon monoxide.

Closest to the proposed technical substance and the number of matching characteristics is a method of obtaining manganese dioxide comprising adding 200 ml of 5% potassium permanganate solution to 250 ml of a 5% solution of manganese sulfate at 50 - 60oC under stirring for 2 hours, the Mixture is left for 2 h, then placed it on the day in a warm place. The precipitation is filtered off, washed with water to remove sulfate ions and dried for 8 to 10 h at 110 - 120oC (Karyakin Y. C. Pure chemical reagents. Guidance for the preparation of inorganic drugs. M-L: State. ).technology. ed. chem. literature, 1947, S. 324).

The disadvantage of this method is the low productivity of the process equipment caused by small concentrations of the reacting substances.

The aim of the invention is to increase the productivity of the process equipment while maintaining at a high level Catalytica way including adding potassium permanganate solution to a solution of manganese sulfate with stirring, filtering and washing of the final product.

The difference of the proposed method against known is that solutions of potassium permanganate and manganese sulfate take with a concentration of 15 to 20 and 20 to 25 wt.% respectively.

The method is as follows.

To 1 l of a solution containing manganese sulfate in the amount of 20 - 25 wt. % add 1 l of a solution containing potassium permanganate in the amount of 15 to 20 wt.% at 50 - 60oC under stirring for 2 hours the Mixture was kept at this temperature for 2 h, and then another day at 40 - 50oC. the precipitate of manganese dioxide was filtered, washed from sulfate ions with hot water at 60 - 70oC, dried at 110 - 120oC for 8 to 10 hours the Dried precipitate is pressed at a pressure of 100 ATM., crushed, sieved fraction of 0.5 - 1.0 mm and dried at 170oC for 3 hours the Catalytic activity of the obtained manganese dioxide in the oxidation of carbon monoxide was 6.5 to 7.9%; catalytic activity of the manganese dioxide obtained by a known method amounted to 7.3, and 7.1

Example 1. In a reactor equipped with a mixing and Aut heat. When the temperature reached 50oC include stirring for 2 h, add 1 l of a solution containing potassium permanganate in the amount of 15 wt.%. The mixture was kept at this temperature for 2 h, and then another day at 45oC. the precipitate of manganese dioxide was filtered, washed from sulfate ions with hot water at 60oC, dried at 110oC within 8 hours of the Dried precipitate is pressed at a pressure of 100 ATM., crushed, sieved fraction of 0.5 - 1.0 mm and dried at 170oC for 3 hours the Catalytic activity of the obtained manganese dioxide in the oxidation of carbon monoxide amounted to 7.3.

Example 2. A process as in example 1, except for concentrations of manganese sulfate and potassium permanganate, which amounted to 25 and 20 wt.% respectively. The catalytic activity of the obtained manganese dioxide in the oxidation of carbon monoxide was 7.1.

The results of the study of the influence of the concentration of manganese sulfate and potassium permanganate on the performance of the process equipment shown in the table.

As follows from the data shown in the table, the best performance of the process equipment is observed when the solutions of SEO manganese less than 20 wt.% and the concentration of potassium permanganate is less than 15 wt.% reduces the productivity of the process equipment, and the increase in the concentration of sulphate of manganese above 25 wt.% and the concentration of potassium permanganate is higher than 20 wt. % impossible, because when the temperature holding process, the solubility of manganese sulfate and potassium permanganate is such that when these concentrations are almost saturated solutions of these substances.

The essence of the proposed method is as follows.

Improving the performance of process equipment while maintaining high level of catalytic activity of manganese dioxide in the oxidation of carbon monoxide when using solutions of manganese sulfate and potassium permanganate concentrations of 20 to 25 and 15 to 20 wt.% accordingly, due to the following reason. The use of reagents with the specified concentrations (proposed method) leads to the fact that in the same amount of technological device enters the reaction much more reactant than in the case of solutions of manganese sulfate and potassium permanganate with concentrations of 5 wt.% (known way). This leads to a more finished product in the amount of technological apparatus, since the reagents rachabane. Since the other parameters of the reaction (temperature and duration add potassium permanganate solution to a solution of sulphate of manganese) remain unchanged, the catalytic activity of the obtained manganese dioxide in the oxidation of carbon monoxide remains at a sufficiently high level.

Thus, the proposed method can significantly improve the performance of process equipment while maintaining high level of catalytic activity of manganese dioxide in the oxidation of carbon monoxide.

From the above it follows that each of the signs stated together to a greater or lesser impact on the achievement of this goal, namely: to increase the productivity of the process equipment while maintaining high level of catalytic activity of manganese dioxide in the oxidation of carbon monoxide, and the entirety is sufficient to characterize the claimed technical solution.

A method of producing manganese dioxide active in the oxidation of carbon monoxide, comprising adding a solution of potassium permanganate to the solution of manganese sulfate with stirring, filtering and washing the final p wt.% and 20 - 25 wt.% respectively.

 

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