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

 

(57) Abstract:

The potassium permanganate solution is added to a solution of manganese sulfate with stirring. The final product is treated by electrodialysis. The method allows to obtain manganese dioxide, far beyond the known catalytic activity in the oxidation of carbon monoxide. table 1.

The invention relates to the field of 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.

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 concentrated nitric acid, 31 g of finely ground permanganate potassium with constant stirring reagents for 20 minutes, filtering and washing the precipitate obtained (U.S. Pat. UK N 1315374 from 20.04.70,, CL C 01 G 45/02).

Lack of isvisit.

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 a temperature of 50-60oC under stirring for 2 hours. The mixture is left for 2 hours, 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 8-10 hours at a temperature of 110-120oC (Y. C. Karjakin Clean chemicals. Guidance for the preparation of inorganic drugs. M-L, 1947 State.). technology.ed.chem.literature S. 324).

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

The claimed invention is directed to the solution of the following problem - the increase of catalytic activity of manganese dioxide in the oxidation of carbon monoxide, which is achieved by the proposed method comprising adding a solution of potassium permanganate to the solution of manganese sulfate with stirring, filtering and washing of the final product.

The difference between the proposals is Alisa.

The method is as follows.

To 250 ml of a 5% solution of sulphate of manganese add 200 ml of 5% potassium permanganate solution at a temperature of 50-60oC under stirring for 2 hours. The mixture is left for 2 hours, then placed it on the day in a warm place. The precipitation is filtered off, washed with water to remove sulfate ions, is loaded into the camera electrodialyzer and process for 10-15 hours at a potential gradient of 50-300/see After processing manganese dioxide is dried at a temperature of 110-120oC for 8-10 hours. The dried precipitate is pressed at a pressure of 100 ATM, crushed, sieved fraction of 0.5-1.0 mm and dried at a temperature of 170oC for 3 hours. The catalytic activity of the obtained manganese dioxide in the oxidation of carbon monoxide was 11.7 to 12.5, the catalytic activity of the manganese dioxide obtained by a known method, was 6.5 to 7.9.

Example 1

Take 200 ml of 5% potassium permanganate solution and add it to 250 ml of a 5% solution of manganese sulfate at a temperature of 50oC under stirring for 2 hours. The mixture is left for 2 hours, then placed it on the day in a warm place. The precipitation is filtered off, proof when the potential gradient of 50 in/see After processing of manganese dioxide is dried at a temperature of 110oC for 8 hours. The dried precipitate is pressed at a pressure of 100 ATM, crushed, sieved fraction of 0.5-1.0 mm and dried at a temperature of 170oC for 3 hours. The catalytic activity of the obtained manganese dioxide in the oxidation of carbon monoxide was 11.9.

Example 2

A process as in example 1, except for the gradient of the potential, which amounted to 150 in/see the Catalytic activity of the obtained manganese dioxide in the oxidation of carbon monoxide was 11.9.

Example 3

A process as in example 1, except for the gradient of the potential, which amounted to 300 in/see the Catalytic activity of the obtained manganese dioxide in the oxidation of carbon monoxide was 12.3.

The study of the influence of the potential gradient on the catalytic activity of the manganese dioxide in the oxidation of carbon monoxide is shown in the table (see the end of the description)

Catalytic activity (A) was calculated by the formula:

< / BR>
where v is the specific speed gas flow, 0,32 l/mins2;

the time of appearance after layer of oxide of carbon with a concentration of 0.1 Co;

s is the cross - sectional area of 3.14 cm2
M - molecular weight of carbon monoxide, 28 g/mol;

V - volume of sample, 7.9 cm3.

As follows from the data shown in the table, the highest catalytic activity of the manganese dioxide in the oxidation of carbon monoxide observed in the processing of manganese dioxide by electrodialysis.

The essence of the method consists in the following.

The increase of catalytic activity in the oxidation of carbon monoxide in the processing of manganese dioxide by electrodialysis is likely caused by the following reason. In the process of obtaining manganese dioxide, which runs for a long time (more than a day), on the surface of the formed particles of manganese dioxide is adsorbed a significant amount of sulfate ions, which are known to be a strong catalyst poison for oxide systems in the oxidation of carbon monoxide. Obviously, the washing water does not completely remove sulfate ions from the surface of the particles of manganese dioxide and therefore there is a partial poisoning of the catalytic centers. However, processing of manganese dioxide by electrodialysis leads to almost complete removal of sulfate ions from the surface of the particles dioxide organzational activity in the oxidation of carbon monoxide.

Thus, the proposed method allows to obtain manganese dioxide significantly superior to known catalytic activity in the oxidation of carbon monoxide.

Obtained by the proposed method manganese dioxide will give the possibility to produce a catalyst that will enable more efficient treatment of gas mixtures of carbon monoxide in the systems of collective and individual protection of respiratory organs and industrial emissions, the exhaust gases of internal combustion engines and so on; and giving a real opportunity to effectively solve a wide range of environmental and technological problems.

From the above it follows that each of the signs stated together to a greater or lesser extent affect the solution of the problem, namely to increase the catalytic activity of the 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 of the final

 

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FIELD: electrochemical engineering.

SUBSTANCE: invention relates to electrochemical treatment of electrolyte solutions and electrodialysis methods, and, in particular, deionization methods. Method of electrodialysis desalting of an electrolyte solution comprises introducing solution into space between ion-selective membranes, applying direct current electric field, and conducting process to final concentration, while simultaneously measuring imposed process parameters, including current and voltage values, followed by calculating therefrom electric resistance of electrodialyzer and adjusting an electrical parameter. The latter is electric resistance of solution, for which part of dialyzate or concentrate is recycled to the process beginning. Direct current electric field originates from rectifier with external feeding voltametric characteristic.

EFFECT: prevented excessive current density above its allowed value, which would lead to concentration polarization and formation of sparingly soluble precipitates on the membrane surfaces; and increased operational reliability.

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