The catalyst for purification of gases from nitrogen oxides

 

(57) Abstract:

The invention relates to catalysts for the protection of the environment from the toxic emissions of nitrogen oxides and can be used in power, chemical, metallurgical and other industries, with exhaust gases containing nitrogen oxides. The objective of the invention is the development of a catalyst for cleaning of gases from nitrogen oxides with high mechanical strength, maintaining high catalytic activity and a partial or complete replacement of toxic and expensive vanadium component on the copper containing component. The problem is solved by using a catalyst containing a carrier, comprising titanium dioxide containing at least one active component selected from the group of compounds of vanadium, copper, and tremolite or wollastonite, or their mixture with the following content of components in the catalyst, wt.% the content of compounds V and/or Cu in terms of metal: V no more than 1; Cu not more than 2; Tremolite and/or wollastonite 2 - 12; the Rest of the Media. 7 C.p. f-crystals, 1 table.

The invention relates to catalysts for the protection of the environment from the toxic emissions of nitrogen and can be used in power, chemical, tx2">

As the active components of the catalysts used in the process of selective catalytic reduction (SCR) of nitrogen oxides by ammonia, use the oxides of vanadium, copper, iron, manganese, tungsten, molybdenum, Nickel, titanium and their various combinations.

One of the problems encountered in the design of catalysts SLE is the improvement of life through the creation of catalytic systems with high specific catalytic activity and high mechanical strength. The problem is the selection of catalytic systems with partial or complete replacement of toxic and expensive of vanadium compounds.

Known catalyst with high mechanical strength for the process of SLE, including solid-based media aerosoles and refractory clay and alternately deposited layers of titanium oxide and vanadium oxide [1].

The disadvantages of this catalyst is a complex technology layer-by-layer deposition of titanium oxide and vanadium, disposal of wastewater, and the impossibility of its use in gas emissions, containing large quantities of soot and dust due to abrasion of the active catalyst layer.

Known catalyst, vkluchau - 500 μm at a mass ratio of such agent and clay 4,5 - 1:1 [2].

The disadvantage of this catalyst is the reduction of mechanical strength in environments containing moisture due to the swelling of clay.

The known method of increasing the mechanical strength of the catalyst by introducing into the composition of extractable mass aluminosilicate, mullite-siliceous fibers [3]. In the composition of the catalyst include titanium oxide and another oxide such as vanadium, molybdenum and/or tungsten and inorganic fiber, and the gaps between the fibers are filled with the specified catalytic composition. The ratio by weight of the catalytic composition and the fiber is not less than 3.

The disadvantage of this catalyst is the dilution of the active component and, therefore, decrease the activity of the catalyst, as well as the limited possibility of preparation of catalysts of different geometry.

Closest to the invention to the technical essence and the achieved result is a catalyst containing at least 1 to 3 wt.% from the group of oxides of Cu, Ni, Co and V, 7 - 8 wt.% WO315 wt.% clay, the rest of the media on the basis of titanium dioxide. The catalyst was prepared in the form of blocks Anirut vitreous lining-based glaze. Additionally, before the front layer of the catalyst install metal grille, stamped according to the dimensions of the cross section of the unit of catalyst. Specific surface area of the obtained catalyst 10 - 150 m2/g with a pore volume of 0.2 - 0.6 cm3/, the Degree of conversion of NOxat 350 - 380oC does not exceed 89% [4].

The disadvantages of this catalyst are very energy intensive method of its preparation and multistage.

The objective of the invention is the development of a catalyst for cleaning of gases from nitrogen oxides with high mechanical strength while maintaining high catalytic activity.

The problem is solved by using the catalyst containing the medium consisting of titanium dioxide containing at least one active component selected from the group of compounds of vanadium, copper, and tremolite and/or wollastonite in the following content of components in the catalyst, wt.%:

The content of compounds V and/or Cu in terms of metal

V - No more than 1

Cu is Not more than 2

Tremolite and/or wollastonite - 2 - 12

Media - Rest

The catalyst has the following composition, wt.%:

The content of compounds V in terms of metal

V - 0.16 wt.%:

The content of compounds of Cu, calculated on the metal

Cu is 0.2 - 2

Tremolite and/or wollastonite - 2 - 12

Media - Rest

The catalyst has the following composition, wt.%:

The content of compounds V and Cu is 0.2 - 1

Tremolite and/or wollastonite - 2 - 12

Media - Rest

The catalyst may further contain an oxide of tungsten in an amount of not more than 10 wt. % fiber - not more than 5 wt.%, clay is not more than 10 wt.%.

To obtain the catalyst used thermostable fibrous material is wollastonite or tremolite, showing a reinforcing effect, which leads to a hardening catalyst, and contributing to an increase in the share of transport macropores larger than . The wollastonite mineral from the class of chain silicates of the formula [CaSiO3]n, formed by the metamorphism of limestone. Tremolite is a mineral from the class of chain silicates group monoclinic amphiboles, the formula [Ca3Mg5[Si4O11](OH)2]n.

The proposed catalyst has a high mechanical strength and high catalytic activity in comparison with the known solution.

The process of preparation of catalysts includes the following stages:

the IDA tungsten, clay and fiberglass;

the addition of an aqueous solution of salts of copper and/or vanadium;

prolonged stirring the mix with the addition of an organic plasticizer and water;

extrusion or molding catalyst weight;

the crop has wilted, drying and calcination.

In the preparation of the catalysts used powders of wollastonite and tremolite natural origin with a particle size of 60 to 100 μm.

Characteristics of the catalysts, the results are given in the table. The content of active components Cu and/or V is given in terms of the metal, since according to physico-chemical studies of the catalysts there are no pure phase of oxides or sulfates of copper and vanadium.

In examples 1 to 4 using TiO2(anatase modification), obtained by vapor-phase hydrolysis of titanium chloride, with a specific surface area of 15 m2/g and a pore volume of 0.34 ml/year

Example 1. In the Z-shaped mixer mix 9,38 kg TiO2, 0.5 kg WO3, then add a solution of sulphate of vanadyl (0,298 kg VOSO43H2O 1.5 l of water), to produce the desired molding properties is poured a solution of polyethylene oxide (PEO) [0,1 kg per 1 l H2O]. The components are thoroughly peremeshivanii ekstragiruyut model fine mesh blocks with a diameter of 10 mm, the size of channel 1,2 x 1, a 2 mm, a wall thickness of 0.4 mm, the blocks section 24 mm, duct size 6 x 6 mm, wall thickness 1.5 mm, rings with an external diameter of 6 mm and an inner diameter of 2 mm to determine the mechanical strength. On the vacuum screw press is extracted blocks of honeycomb structure in the form of a prism of square section 75 x 75 mm or 150 x 150 mm, pipe size 2 x 2 mm, 5.6 x 5.6 mm, wall thickness 0.8 to 1.4 mm, the block length of 150 - 500 mm Catalyst provalivajut, dried and calcined in air with a gradual rise of temperature up to 500oC and forced circulation of coolant along the canals, maintained at 500oC for 4 h

Example 2. In the Z-shaped mixer mix 8,68 kg TiO2, 1 kg WO3, 0.2 kg of tremolite, then add a solution of sulphate of vanadyl (0,298 kg VOSO43H2O 1.5 l of water), add a solution of polyethylene oxide (0.1 kg WTE 0,96 l H2O). Next, similarly to example 1.

Example 3. In the Z-shaped mixer mix 8,58 kg TiO20.1 kg WO3, 1.2 kg of tremolite, add a solution of sulphate of vanadyl (2,298 kg VOSO43H2O 1.5 l of water), add a solution of polyethylene oxide (0.1 kg WTE 0,96 l H2O). Next, similarly to example 1.

Example 4. In the Z-shaped mixer UB>2O 1.5 l of water), add a solution of polyethylene oxide (0.09 kg 0.74 l H2O). Next, similarly to example 1.

Example 5. For the preparation of the catalyst used media containing mainly TiO2(anatase) obtained by hydrolysis of titanyl sulphate, with a specific surface area of 132 m2/g and a pore volume of 0.42 ml/g

In the Z-shaped mixer mix, a total of 8.74 kg TiO2, 1 kg of wollastonite, add a solution of nitrate of copper (0,759 kg Cu(NO3)23H2O), add a solution of polyethylene oxide (0.1 kg PEO 1.3 l H2O). Next, similarly to example 1.

In examples 6 to 7, 9, 10 using media containing mainly TiO2(anatase), obtained by hydrolysis of titanium chloride, with a specific surface area of 190 - 200 m2/g, pore volume of 0.5 - 0.6 ml/g, different content of V as an impurity. To prepare the catalysts in examples 8, 11 use the media containing mainly TiO2(anatase) obtained by hydrolysis of titanyl sulphate, with a specific surface area 74 m2/g and a pore volume of 0.36 ml/year

Example 6. In the Z-shaped mixer mix 8,83 kg media on the basis of TiO2with the vanadium content of 0.34 wt.%, 0.9 kg of tremolite, add a solution of copper sulfate (0,427 kg CuSO4

Example 7. In the Z-shaped mixer mix 8.1 kg media on the basis of TiO2with the content of vanadium 0,86 wt.%, 1 kg of tungsten oxide, 0.9 kg of tremolite, add a solution of polyethylene oxide (0.1 kg PEO 3.6 l H2O). Next, similarly to example 1.

Example 8. In the Z-shaped mixer mix 7.96 kg media on the basis of TiO21 kg of tungsten, 0.9 kg of tremolite, add a solution of nitrate of copper (0,416 kg Cu(NO3)23H2O 1.3 l H2O), add a solution of poliatilenaksida (0.1 kg per 1 l H2O). Next, similarly to example 1.

Example 9. In the Z-shaped mixer is mixed with 8.05 kg media on the basis of TiO2with the vanadium content of 0.37 wt.%, 0.5 kg of tremolite, 1 kg of clay, poured a copper sulfate solution (0,699 CuSO45H2O 2.5 l H2O), add a solution of polyethylene oxide (0.1 kg per 1 l H2O). Next, similarly to example 1.

Example 10. In the Z-shaped mixer mix of 7.25 kg media on the basis of TiO2with the content of vanadium 0.22 wt.%, 1 kg of oxide of tungsten, 0.5 kg of Thermolite, 0.7 kg of clay, 0.5 kg of molito-silica fibers, adding a solution of copper sulfate (0,078 kg CuSO45H2O 2.5 l H2O). Next, similarly to example 1.

Example 11. In the Z-shaped mixer mix 8,08 kg wear is that copper (0,350 kg CuSO45H2O in 1 liter of H2O), add a solution of polyethylene oxide (0.1 kg per 1.5 l H2O). Next, similarly to example 1.

Example 12. D Z-shaped mixer mix 9,07 kg media on the basis of TiO2, 0.9 kg of tremolite, adding a solution of sulphate of vanadyl (kg 0,067 VOSO43H2O 1.5 l of water), add a solution of polyethylene oxide (0.1 kg in 1 l of H2O). Next, similarly to example 1.

Example 13. In Z-obrazana mixer mix 9,05 kg media on the basis of TiO2, 0.9 kg of tremolite, add a solution of copper sulfate (0,078 kg CuSO45H2O 1.1 l H2O), add a solution of polyethylene oxide (0.1 kg per 1 l H2O). Next, similarly to example 1.

Example 14 (the prototype). Simultaneously mixed catalyst components: 2 weight. including metavanadate ammonium, 8 mass. hours of parabolicamara ammonium, 100 wt. including titanium oxide, 15 wt. including clay, 2 wt. hours of polyethylene oxide, 20 wt. hours of polyethylene glycol and 50 wt. parts of water. Next, similarly to example 1.

The catalytic properties of the catalyst samples studied by running the installation using the gas mixture of the composition of NOxto 0.05%, NH3) - 0,05 about. %, O2to 0.5 vol.%. Volumetric gas flow rate is equal to 27000 h-1. Analysis of the gas mixture OS is BR>
.

Testing of the catalyst is carried out in the temperature range of 225 - 400oC.

To determine the mechanical strength mass ekstragiruyut in the form of rings high, equal to the outside diameter, which are then subjected to compressive crush strength in the transverse direction. The essence of the method consists in the measurement of the efforts of the destruction of the ring between two parallel plates. The biggest strength of the catalyst is expressed in kilograms per square centimeter and are calculated according to the formula

,

where

N - indicator device in divisions;

A calibration coefficient, kg/del;

S is the cross sectional area of ring catalyst, cm2.

The porous structure was determined by the method of mercury porometry on the device Porosiger-9300.

As follows from the above examples, the optimum content of tremolite and/or wollastonite is in the range of 2 to 12 wt.% (examples 1-3). The content of tremolite and/or wollastonite less than 2 wt.% not enough to achieve high mechanical strength. The increase in the content of more than 12 wt.% significantly degrades the plastic properties of the moldable mass, the introduction of tremolite and/or wollastonite in catalyst mass to ensure the substance of the catalyst without the use of an optical fiber, clay and expensive organic plasticizers (example 5). However, the use of tremolite and wollastonite increases the share of transport macropores (>maintain high mechanical strength (for example, 2).

It is possible to make active solid catalyst with a low content of active ingredient (examples 10, 13 and 14) and partial or complete replacement of expensive toxic compounds vanadium to copper-containing compounds (examples 4, 5, 7, 9 and 10).

Thus, the present invention can find application in the energy, chemical, metallurgical and other industries, with the exhaust gases, in which resides the oxides of nitrogen.

1. The catalyst for purification of gases from nitrogen oxides-based media, including titanium dioxide containing at least one active component selected from the group of compounds of vanadium, copper, characterized in that it additionally contains tremolite and/or wollastonite in the following content of components in the catalyst, wt.%:

The content of compounds V and/or Cu in terms of the metal V - Not more than 1

Cu is Not more than 2

Tremolite and/or wollastonite - 2,0 - 12,0

Media - Rest

2. The catalyst p. 1, etal V - 0,16 - 1,0

Tremolite and/or wollastonite - 2,0 - 12,0

Media - Rest

3. The catalyst p. 1, characterized in that the content of the components is, wt.%:

The content of compounds of Cu, calculated on the metal Cu - 0,2 - 2,0

Tremolite and/or wollastonite - 2,0 - 12,0

Media - Rest

4. The catalyst p. 1, characterized in that the content of the components is, wt.%:

The content of compounds V and Cu in terms of the metal V - 0,16 - 0,5

Cu - 0,2 - 1,0

Tremolite and/or wollastonite - 2,0 - 12,0

Media - Rest

5. The catalyst PP.1 to 4, characterized in that it further contains an oxide of tungsten in an amount of not more than 10 wt.%.

6. The catalyst PP.1 to 5, characterized in that it further comprises a glass fiber in an amount of not more than 5 wt.%.

7. The catalyst PP.1 - 6, characterized in that it further comprises a clay in an amount of not more than 10 wt.%.

8. The catalyst PP.1 to 7, characterized in that the proportion of macropores with a size of more than 10,000 is not less than 23%.

 

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