RU2156164C2 - Carbon monoxide oxidation catalyst - Google Patents

Abstract

FIELD: carbon monoxide oxidation catalysts applicable in cleaning gases from carbon monoxide. SUBSTANCE: new catalyst includes manganese dioxide and lead dioxide, and is distinguished by the fact that it presents anode slime formed on lead anode in electrolytic reduction of zinc from acid sulfate solutions preliminarily washed from electrolyte and dried, and containing, wt. %: manganese dioxide above 50; lead dioxide up to 15; silver oxide up to 0.15; the balance, additives. EFFECT: higher separation efficiency of exhaust gases from ecologically hazardous components, high process economic efficiency. 6 tbl

Description

 The invention relates to the field of gas purification from environmentally hazardous components and can be used for purification of exhaust gases of an internal combustion engine, for the neutralization of exhaust gases from industrial enterprises, thermal power plants, asphalt concrete plants and other technological industries and aggregates containing carbon monoxide.

 Cement-based copper-manganese and zinc-copper-chromium catalysts are known [Kuznetsov I.E., Shmat K.I., Kuznetsov S.I. Equipment for sanitary cleaning of gases. Kiev. Technique, 1989, p. 236]. The disadvantages of the catalyst are the relatively high cost and complexity of manufacture.

 The closest technical solution is a catalyst for purification of exhaust gas containing carbon monoxide, which is a mixture of oxide or oxides of manganese and oxide or oxides of lead [SU 450388, 30.11.74, 01 J 23/34]. The disadvantage of the catalyst is the need for its manufacture, the cost of materials and production.

 The objective of the invention is the use of a by-product of electrochemical metal reduction from an aqueous electrolyte solution as an inexpensive and effective catalyst for the oxidation of carbon monoxide.

 The technical result that can be achieved by carrying out the invention consists in a high degree of purification of the exhaust gases from environmentally hazardous components while at the same time being economical.

This technical result is achieved by the fact that in the known catalyst for the oxidation of carbon monoxide, including manganese dioxide and lead dioxide, an anode slurry is used that is formed on a lead anode during electrolytic reduction of zinc from acidic sulfate solutions, previously washed from the electrolyte and dried, containing, wt.% :
Manganese dioxide - More than 50,
Lead dioxide - Up to 15,
Silver oxide - Up to 0.15,
Impurities - The rest,
The essence of the catalytic effect of the anode sludge is that when it is formed in the electrochemical process of anodic oxidation of the components of the sludge, chemical and structural transformations occur, leading to the formation of compounds with an effective catalytic effect in the oxidation of carbon monoxide.

 Examples of practical application.

 As the catalyst used anode sludge formed on a lead anode during electrolytic reduction of zinc from acidic sulfate solutions, composition, wt.%: Manganese dioxide 53.9; lead dioxide 15; silver oxide 0.06; impurities - the rest. Preliminarily, the anode sludge was washed from the remaining electrolyte and dried in air for 3 days.

 To generate carbon monoxide, a furnace was used in which wood-particle material was burned during incomplete combustion of fuel. From the furnace, the resulting gas mixture was passed through an absorption flask with concentrated sulfuric acid, then through a flask - an absorber with a 10% aqueous solution of NaOH, through a spray trap with glass balls and collected in a rubber chamber, from where the gas mixture passed through a U-shaped glass tube with a diameter of 15 mm with a catalyst, which was placed in a sand bath with electric heating. The gas mixture was monitored for the content of carbon monoxide by an AFA-121 gas analyzer at the entrance to the U-shaped tube (before the catalyst) and at the exit from it (after the catalyst). The temperature in the sand bath (external temperature), the catalyst, and the purified gas exiting the tube were controlled using a mercury thermometer.

 Anode sludge powder was placed in a U-shaped tube through which the gas to be cleaned was passed. The gas speed was controlled so that the gas and powder created a "fluidized bed" in one of the elbows of the tube and thus created the maximum possible contact between the surface of the catalyst and the gas to be cleaned. Due to the high density of the powder and the low velocity of the gas stream, the ablation of the catalyst is negligible and was controlled by a filter filled with glass wool.

 Tables 1-4 give the results of gas purification from carbon monoxide for various operating conditions of the catalyst.

 Example 1 (table 1).

When the catalyst was dried at 80 ^o C for 45 minutes, the content of the main component of manganese dioxide increased to 54.89 wt.%.

 From the data of table 1 it follows that the best indicators are obtained under the conditions given in table. A.

 During the 3.6 hours of catalyst operation, its weight decreased by 12.59%, mainly due to the removal of gaseous components, while the content of manganese dioxide increased to 62.80 wt.%.

 Example 2 (table 2).

 The catalyst was dried analogously to example 1, at the same time, the catalyst and gas were reacted at a lower temperature than in example 1.

From the data of table 2 it follows that at temperatures of the catalyst more than 100 ^o C and gas more than 50 ^o C the degree of purification of gas from CO exceeds 50%.

 Within 1 hour of operation of the catalyst, its weight decreases by 9.63%, while the content of manganese dioxide increases to 60.74 wt.%.

 Example 3 (table 3).

When calcining the catalyst at 300 ^o C for 30 minutes, the content of manganese dioxide increased to 58.02 wt.%.

From the data of table 3 it follows that at a catalyst temperature of 190 ^o C the degree of purification of gas from CO was 79%.

 During 0.93 hours of operation of the catalyst, its weight decreases by 1.48%, while the content of manganese dioxide increases to 58.89 wt.%.

 Example 4 (table 4).

The catalyst was calcined at 500 ^o C for 25 minutes, while the content of manganese dioxide increased to 59.87 wt.%.

 From the data of table 4 it follows that the best indicators are obtained under the conditions given in table. B.

 During 1.62 hours of operation of the catalyst, its weight decreased by 0.01 wt.%, While the content of manganese dioxide increased to 59.88 wt.%.

The experimental data indicate that at a catalyst temperature of more than 100 ^o C the degree of gas purification from CO exceeds 50%, with increasing catalyst temperature the degree of gas purification from CO increases and at a temperature of 250 ^o C reaches 90-97% at a gas flow rate of 0, 35-0.50 dm ³ / min.

Preliminary calcination of the catalyst to 500 ^o C does not change the activity of the catalyst.

 The content of the main components of the anode sludge is in the range, wt. %: manganese dioxide 50-90, lead dioxide up to 15, silver oxide up to 0.15, moisture and impurities - the rest.

 Compared with the prototype, the use of anode sludge, a by-product of electrochemical metal reduction from an aqueous electrolyte solution, as an inexpensive and effective catalyst for the oxidation of carbon monoxide does not require additional costs for its manufacture. If necessary, the anode sludge is easily pressed into tablets.

Claims (1)

A carbon monoxide oxidation catalyst comprising manganese dioxide and lead dioxide, characterized in that the catalyst is an anode slurry formed on a lead anode during electrolytic reduction of zinc from acidic aqueous sulfate solutions, previously washed from the electrolyte and dried, containing, wt.%:
Manganese Dioxide - Over 50
Lead dioxide - Up to 15
Silver Oxide - Up to 0.15
Impurities - Rest

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