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 increase the stability of the catalytic elements to destructive tension in the longitudinal and transverse compression after thermal Cycling as a catalyst mass is proposed to use composition comprising, in wt.%: sludge 45 - 55, clay 31 to 35, ferrous sulfate (P) heptahydrate 9 - 12, ammonia water (25%) 4 - 6, polyethylene glycol of 1 to 2. As a result, the stability of the catalytic elements to destructive stress in compression is increased by 45% to 70%, while the transverse - 20 - 25%. table 1.

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

The known method for the catalytic purification of exhaust gases from nitrogen oxides at elevated temperatures with the restoration of the oxide is the active component in the form of waste industrial production tails wet enrichment or flotation tailings underground mines, binder, such as clay, and various adjuvants (coal, peat, sawdust). The disadvantage of this known method is relatively low degree of purification of exhaust gases from nitrogen oxides.

Closest to the claimed us the 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. The disadvantages of this known method, taken as a prototype, is the low degree of purification of exhaust gases from nitrogen oxides and relatively low mechanical stability of the catalyst used here to destructive stress at compression after thermal Cycling.

The declared objective is achieved by the fact that in the known method for the catalytic purification of exhaust gases from nitrogen oxides at an elevated temperature by reduction of nitrogen oxides with ammonia as the catalyst use composition comprising the active ingredient in the form of industrial waste and binder - clay, as an active ingredient use sewage sludge thermal power plants generated during the washing of boilers and catalyst mass additionally contains iron sulfate (II), ammonia water and glycol in the following ratio of ingredients (wt.%):

Sludge - 45-55

Clay - 31-35

Ferrous sulfate heptahydrate (P) - 9-12

Ammonia water (25%) - 4-6

The glycol - 1-2

The use of the proposed method is increased stability of the catalyst used here to destructive stress in compression 45-70%, while cross - 20-25% compared with the same for the prototype method, the direct consequence of which is the preservation of its high catalytic activity over a longer period of operation than in the case of using the prototype method.

RA is vosstanovleniya of nitrogen oxides by ammonia, where the catalyst mass would be used in the composition of the named higher quality set of ingredients, the literature has not been described. This fact allows us to assume that we declare our object corresponds to the first criterial feature of the invention is a novelty. In addition, knowledge of the aggregate properties of the prototype method and characteristics make changes, namely the introduction of the catalyst mass of sewage sludge thermal power plants, iron sulfate (II) ammonia water and glycol is not possible to predict the observed result of such changes positive effect, namely increased stability of the catalyst used here to breaking stress in compression after thermal Cycling (periodic heating and cooling of the catalyst). Therefore, the essence of the proposed facility is not obvious from the currently known in this technical field level, and this automatically means that the claimed us technical solution corresponds to the second criterion characteristic of the invention, an inventive step. Finally, the proposed method provides only minor mods its industrial implementation of the use of any additional expensive processing equipment. In this regard, there is every reason to believe that the claimed object and corresponds to the third criterion characteristic of the invention and industrial applicability.

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:

training components,

preparation of a catalyst mass (bag components),

forming elements,

drying,

the annealing.

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 a mesh size of 0.1-0.5 mm Preparation of a catalyst mass is carried out in the mixer, where the first load sludge, clay, iron sulfate (II) heptahydrate and stirred for one hour. Then in the mixer pour 25% aqueous ammonia solution, polyethylene glycol (PEG) and stirred its contents until a homogeneous catalyst mass. In conclusion, the obtained mass before forming, water is added in an amount of 10 wt.% of the total amount of the mixture.

The catalyst mass is formed into pellets, tablets, flat is the temperature value of 25-30oC to a residual moisture content of 4-5% and annealed at a temperature of 500oC for 2 h with a forced air supply to the furnace annealing.

Example 2

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

Sludge - 45

Clay - 35

Sulphate of iron (II) heptahydrate - 12

Ammonia water - 6

PEG-9 - 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 0,1 about. %, the oxygen content in the gas is 5% vol. the volumetric ratio of ammonia/oxides of nitrogen is 1.0, the velocity of the gas in the channel of the catalyst - 0.6 m/s, the contact time of 0.11 sec, 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 tubes having a length of 70 mm with a channel of square cross section 6x6 mm, the Content of nitrogen oxides in the exhaust gas before and after the reactor was determined spectrometrically by well-known methods.

Data on the degree of purification of exhaust gases from nitrogen oxides using a catalyst of the above composition are presented in table. It contains the values of the strength of the catalytic elements in prodemu voltage before and after thermal Cycling was carried out by us in accordance with the method developed the all-Union heat engineering Institute (VTI) of the Ministry of energy in 1988.

Example 3

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

Sludge - 49

Clay and 33.5

Sulphate of iron (II) heptahydrate - 11

Ammonia water - 5

PEG-9 - 1,5

Example 4

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

Sludge - 55

Clay - 31

Sulphate of iron (II) heptahydrate - 9

Ammonia water - 4

PEG-9 - 1

Example 5

Spend as example 2, but for the preparation of the catalyst take the next starting number of components, wt.%:

Sludge - 50

Clay - 30

Sulphate of iron (II) - 12

Ammonia water - 6

PEG-9 - 2

Example 6 (comparative)

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

Sludge - 45

Clay - 38

Sulphate of iron (II) heptahydrate - 9

Ammonia water - 6

PEG-9 - 2

Example 7 (comparative)

Carried out as example 2, but for the preparation of the catalyst using the following ratio of components, wt.%:

Perform as example 2, but for the manufacture of the catalyst using the following composition of the catalyst mass, in wt.%:

Sludge - 60

Clay - 23

Sulphate of iron (II) heptahydrate - 9

Ammonia water - 6

PEG-9 - 2

Example 9 (comparative)

Implement as example 2, but for the preparation of the catalyst take the following ingredients, wt.%:

Sludge - 35

Clay - 45

Sulphate of iron (II) heptahydrate - 12

Ammonia water - 6

PEG-9 - 2

Example 10 (comparative)

Spend as example 2, but for the preparation of the catalyst take the starting number of components, wt.%:

Sludge - 49

Clay - 29

Sulphate of iron (II) heptahydrate - 12

Ammonia water - 8

PEG-9 - 2

Example 11 (comparative)

Perform as example 2, but using the following ratio of ingredients, wt.%:

Sludge - 49,5

Clay - 29,5

Sulphate of iron (II) heptahydrate - 12

Ammonia water - 6

PEG-9 - 3

Example 12 (comparative)

Perform as example 5, but instead of PEG-9 used PEG-4 the next part of the catalyst mass, in wt.%:

Sludge - 50

Clay - 30

Sulphate of iron (II) heptahydrate - 12

Ammonia water - 6

PEG-4 - 2

Example 13 (fucking weight in wt.%:

Sludge - 50

Clay - 30

Sulphate of iron (II) heptahydrate - 12

Ammonia water - 6

PEG-35 - 2

Example 14 (comparative prototype)

Prepare the catalyst mass, as in example 2, but as an active component of the catalyst used, the slag formed in the process of gasification and hydrolysis of heavy petroleum products, calcined at 500oC and washed from the carbon black, the following number of components in wt.%:

Slag - 50

Clay - 30

Sulphate of iron (II) heptahydrate - 12

Ammonia water - 6

PEG-9 - 2

Example 15 (comparative prototype)

Perform as example 14, but for the manufacture of the catalyst take the following ratio of components, wt.%:

Slag - 45

Clay - 35

Sulphate of iron (II) heptahydrate - 12

Ammonia water - 6

PEG-9 - 2

Example 16 (comparative prototype)

Perform as example 14, the following composition of the catalyst mass, in wt.%:

Slag - 49

Clay and 33.5

Sulphate of iron (II) heptahydrate - 11

Ammonia water - 5

PEG-9 - 1,5

As clearly seen from the table data, the use of the claimed our way catalytic purification of exhaust gases from nitrogen oxides with the prototype [2] (cf. examples 2-5, 14-16). Draws attention to the fact that in case declare our object strength used in the catalyst after thermal Cycling increases as compared to that before thermal Cycling, while in the case of the prototype method the strength of the catalyst under longitudinal compression, however, falls. The degree of purification of exhaust gases using the proposed method compared with the same for the prototype method remains almost unchanged or even slightly increased. At the same time, it should be noted that the claimed us limits the number of ingredients in the catalyst mass are significant and go beyond these limits leads either to reduce the resistance to destructive voltage after thermal Cycling, or to reduce the degree of purification of exhaust gases from nitrogen oxides (cf. examples 2-5 and 6-11). At the same time, the molecular weight of the polyethylene glycol used to prepare the catalyst mass has almost no influence on either his strength or degree of purification of exhaust gases from nitrogen oxides (cf. example 5 and examples 12, 13).

Method for catalytic purification of exhaust gases from nitrogen oxides at elevated temperatures pic is NT in the form of industrial waste, and clay, characterized in that, as an active ingredient use sewage sludge thermal power plants generated during the washing of the boiler, and the catalyst additionally contains iron sulfate (II), ammonia water and glycol in the following ratio of ingredients, wt.%:

Sludge - 45 - 55

Clay - 31 - 35

Sulphate of iron (II) heptahydrate - 9 - 12

Ammonia water (25%) 4 to 6

The glycol - 1 - 2P

 

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