Method for catalytic purification of exhaust gases from nitrogen oxides

 

(57) Abstract:

Use: in the treatment of various gaseous emissions from industrial production and disposal of industrial waste and can be implemented in the energy, chemical, engineering and other industries. The invention is: to improve the degree of purification of exhaust gases as a catalyst is proposed to use a composition containing the ingredients in the following ratio, wt.%: sludge 45 - 85; clay 13 - 35; fuel oil 2 - 20. As a result, the degree of purification of exhaust gases from nitrogen oxides is increased by 20 - 25%. table 1.

The invention relates to the field of purification of various gaseous emissions from industrial production and disposal of industrial waste and can be implemented in the energy, chemical, engineering and other industries.

The known method for the catalytic purification of exhaust gases from nitrogen oxides at an elevated temperature with the reduction of nitrogen oxides to elemental nitrogen by ammonia, which is used as a catalyst composition comprising an active component in the form of industrial waste proizvodeno, and different adjuvants (coal, peat, sawdust) [1] . The disadvantage of this known method is relatively low degree of purification of exhaust gases from nitric oxide.

Closest to the claimed object on the totality of symptoms and the achieved technical effect is way catalytic purification of exhaust gases from nitrogen oxides at an elevated temperature by reduction of nitrogen oxides with ammonia to elemental nitrogen, which is used as a catalyst composition comprising an active component in the form of waste industrial production slag generated in the processes of gasification and pyrolysis of heavy oil, proclivity at 350-750oC after washing the carbon black, and binder, in particular clay, cement or lime [2] . The disadvantage of this known method is used as a prototype, is also low degree of purification of exhaust gases from nitrogen oxides.

The purpose of the invention is to increase the degree of purification of exhaust gases from nitric oxide, while maintaining a sufficiently high tensile strength of the catalyst for combustion.

This objective is achieved in that in the known method [2] cataletto nitrogen ammonia using a catalyst, containing the active ingredient in the form of waste industrial production and binder - clay, as an active ingredient use sewage sludge thermal power plants generated during the washing of the boiler, and the catalyst additionally contains oil in the following ratio of ingredients, wt.%:

Sludge - 45-85

Clay - 13-35

Oil - 2-20

The result of using the proposed method, the degree of purification of exhaust gases from nitrogen oxides is increased as compared to that for the prototype method by 20-25%.

Declare on the subject of the invention, a method of catalytic purification of exhaust gases is illustrated by the following examples.

Example 1 (preparation of catalyst). The technological process of preparation of the catalyst for purification of exhaust gases from nitrogen oxides includes the following stages: preparation of components; preparation of a catalyst mass (bag components); forming elements of the catalyst; drying the catalyst; activation of the catalyst.

For the preparation of components of the sewage sludge and clay is subjected to drying at a temperature of 60-85oC to a residual moisture content of 3-5%, then crushed and sieved through a sieve with the components and mix them for 20-30 minutes Then in the mixer pour the oil and water (20% by weight of other components) and stirred the contents of the mixer to obtain a homogeneous mass.

The catalyst is formed into pellets, tablets, flat or corrugated sheets, cell blocks, or other form elements. After forming the catalyst is dried at a temperature of 18-25oC and a relative humidity of 80-85% to a residual moisture content of 2-4%. Then it is subjected to activation by annealing at a temperature of 500oC for 2 h In the activation process in the annealing furnace serving the air force.

Example 2. Prepare the inventive catalyst according to the technology described in example 1 using the following amounts of ingredients, wt.%:

Sludge - 85

Clay - 13

Oil - 2

Method implemented in a quartz reactor with a diameter of 35 mm and a length of 300 mm under the following conditions: concentration of NOx at the inlet of the reactor to 0.1 vol.%; the oxygen content in the gas of 5 vol.%; the volumetric ratio of ammonia/oxides of nitrogen and 1.0; the velocity of the gas in the channel of the catalyst of 0.6 mm/s; the contact time of 0.1 s; the temperature of the gas 250-400oC; the carrier gas is air. Testing of the catalyst is carried out on a cell element in the form of a tube length 70 mm square channel section 66 mm

Data on the degree of purification of exhaust gases from nitrogen oxides using a catalyst of the composition given in the table. There are the values for the tensile strength of the catalyst in compression. Tensile strength was determined on the device MP-20 by the method of [4].

Example 3. Carried out as example 2, but for the preparation of the catalyst charge, the following quantities of ingredients, wt.%:

Sludge - 55

Clay - 25

The oil - 10

Example 4. Perform as example 2, but for the preparation of the catalyst take the following starting components, wt.%:

Sludge - 45

Clay - 35

Oil - 20

Example 5 (comparative). Spend as example 2, but for the preparation of the catalyst take the next starting number of ingredients, wt.%:

Sludge - 80

Clay - 10

The oil - 10

Example 6 (comparative). Perform as example 2, but for the preparation of the catalyst take the next starting number of ingredients, wt.%:

Sludge - 55

Clay - 20

Oil - 25

Example 7 (comparative). Carried out as example 2, but for the preparation of the catalyst take the next starting number of ingredients, wt.%:

Sludge - 30

Clay - 50

Oil - 20

Example 8 (compare the slag, formed in the processes of gasification and hydrolysis of heavy petroleum products, calcined at 500oC and washed from the carbon black, the following amount, wt.%:

Slag - 85

Clay - 13

Oil - 2

Example 9 (comparative prototype [2]). Prepared as example 8, in the following ratio, wt.%:

Slag - 55

Clay - 25

The oil - 10

Example 10 (comparative prototype [2]). Perform as example 8, but for the preparation of the catalyst take the following number of components, wt.%:

Slag - 45

Clay - 35

Oil - 20

As can be seen from the data presented in the table, the catalysts made according to examples 5 and 6 and having in its composition, respectively, less than 13% clay and more than 25% of the oil, provide a relatively high degree of exhaust gases from nitrogen oxides, but do not have the necessary mechanical strength. The minimum compressive strength for catalysts is 20 MPa. The catalyst made according to example 7, containing less than 45% sludge, provides a low degree of purification of exhaust gases from nitric oxide.

Samples of the catalyst on the basis of the slag formed during gasification and pyrolysis of heavy oil, anal is up to 20-25% less flue gases from nitrogen oxides compared with later (see examples 2 and 3, 3 and 9, 4 and 10).

Method for catalytic purification of exhaust gases from nitrogen oxides at elevated temperatures with the use of ammonia and the use of a catalyst containing an active component in the form of waste industrial production and clay, characterized in that as the active component using sewage sludge thermal power plants generated during the washing of the boiler, and the catalyst additionally contains oil in the following ratio, wt.%:

Sludge - 45 - 85

Clay - 13 - 35

Oil - 2 - 20h

 

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