RU2198027C2 - Carbon monoxide oxidation catalyst - Google Patents

Abstract

FIELD: oxidation catalysts. SUBSTANCE: catalyst, containing, up to wt. %: lead oxides, 45; manganese oxides, 15; silver oxides, 7; cobalt oxides, 5; and lead, manganese, silver, and cobalt compounds the balance, constitutes anodic slime formed on lead anode during electrolytic reduction of cobalt from acidic sulfate solutions, which is preliminarily washed from electrolyte and then dried. EFFECT: reduced expenses on starting materials. 2 tbl, 3 ex

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 of 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 cobalt from acidic sulfate solutions, previously washed from the electrolyte and dried and containing, wt.% :
Lead oxides - Up to 45
Manganese Oxides - Up to 15
Silver Oxides - Up to 7
Cobalt Oxides - Up to 5
Compounds of Manganese, Lead, Silver, Cobalt - Else.

 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.

 Anode sludge formed on a lead anode during electrolytic reduction of cobalt from acidic sulfate solutions containing an admixture of manganese was used as a catalyst. Preliminarily, the anode sludge was washed from the remaining electrolyte and dried in air to constant weight.

 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 an absorber flask with a 10% aqueous NaOH solution, through a spray trap with glass balls, it was collected in a rubber chamber, from where the gas mixture passed through six consecutively connected U-shaped glass tubes with a diameter 15 mm with a catalyst, which were 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 monitored 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.

 In the table. 1 given mass, g, k phase composition of the anode sludge according to x-ray phase analysis.

 From the data table. 1 it follows that the anode sludge contains oxides of manganese, lead, cobalt and silver, as well as their compounds, in particular polypermanganites, in which metals are in various oxidation states, which is typical for catalysts of this type.

In the table. 2 shows the results of gas purification from carbon monoxide for various operating conditions of the catalyst in the form of a dependence of the degree of gas purification from CO, in wt.%, Of carbon monoxide removed in relation to the initial amount, on temperatures, ^o С, catalyst and gas, and time, sec.

 Example 1 (table. 2).

The catalytic oxidation of carbon monoxide was carried out at a catalyst temperature of 80 ^o C and a gas of 22 ^o C.

 From the data table. 2, it follows that during 6 s the gas is 22.7% purified from CO.

 Example 2 (table. 2).

The catalytic oxidation of carbon monoxide was carried out at a catalyst temperature of 150 ^o C and a gas of 28 ^o C.

 From the data table. 2 it follows that during 6 s the gas is 36.3% purified from CO.

 Example 3 (table. 2).

The catalytic oxidation of carbon monoxide was carried out at temperatures of the catalyst 200 ^o C and gas 30 ^o C.

 From the data table. 2 it follows that for a time of 6 s the gas is purified from CO by 45.5%.

Experimental data indicate that at a catalyst temperature of more than 200 ^o With the degree of gas purification from CO exceeds 50%.

With increasing temperature of the catalyst and the contact time of the catalyst and the gas to be purified, the degree of gas purification from CO increases and at a temperature of 300 - 350 ^o C can reach 90-97% at a gas flow rate of 0.35-0.50 dm ³ / min.

 Compared with the prototype, the use of anode sludge, a by-product of the electrochemical reduction of metal 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 cobalt from acid sulfate solutions, previously washed from the electrolyte and dried, containing, wt.%:
Lead oxides - Up to 45
Manganese Oxides - Up to 15
Silver Oxides - Up to 7
Cobalt Oxides - Up to 5
Compounds of Lead, Manganese, Silver, Cobalt -

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