The catalyst for selective reduction of nitrogen oxides by methane

 

(57) Abstract:

The invention relates to heterogeneous catalysts for selective reduction of nitrogen oxides by hydrocarbons and can be used in the production of exhaust gases containing hydrocarbons with low molecular weight ( hasenson stations, gas plants, power plants and so on) the Objective of the invention is the creation of catalyst for selective reduction of nitrogen oxides in wet and dry environments while reducing cost and simplifying cooking, which is solved by using a catalyst for selective reduction of nitrogen oxides containing as a carrier of montmorillonite in the amount of 85 to 95 wt. % used both in natural and in the protonated form, and cobalt in an amount of 5 to 5 wt. %. The proposed catalyst in comparison with the prototype increases the conversion of NO from 30 to 80 % both in dry and in humid atmosphere, simplifies production and reduces the cost of up to 3 - 5 $/kg 1 h. p. F.-ly, 1 table.

The invention relates to heterogeneous catalysts for selective reduction of nitrogen oxides by hydrocarbons, which can be used in the production of exhaust gases containing hydrocarbons with low molecule the reduction of nitrogen oxides by hydrocarbons, containing 4, 2 wt. gallium and 95.8 wt. zeolite ZSM-5 in the H form, synthesized by an ion exchange method [1]

The disadvantages of the catalyst are high cost (20 60 $/kg), the complexity of manufacturing (ion exchange at 80oC 24 h) and lower conversion in the presence of water vapor (from 40% in dry atmosphere to 13% in the presence of 2% water vapor).

A known catalyst for selective reduction of nitrogen oxides by hydrocarbons containing 4 wt. iron and 96 wt. zeolite ZSM-5 (Si/Al 14) in the H form, synthesized by the method of ion exchange. The disadvantages are its high cost (20 60 $/kg), the complexity of manufacturing (ion exchange at 80oC 24 h) and lower conversion in the presence of water vapor (from 30% in dry atmosphere to 12% in the presence of water vapor) [2]

Closest to the present invention is a catalyst containing 4 wt. cobalt and 96 wt. zeolite ZSM-5 (Si/Al 14) in the H form.

The disadvantages of the catalyst are high cost (20 60 $/kg), the complexity of manufacturing (ion exchange at 80oC 24 h) and lower conversion in the presence of water vapor (from 53% in dry atmosphere to 28% in the presence of water vapor) [3]

The task of the invention is the creation of a catalyst for selective reduction of nitrogen oxides in wet and dry environments is izlagaemogo catalyst for selective reduction of nitrogen oxides, which contains as a carrier of montmorillonite in the amount of 85 to 95 wt. and cobalt in an amount of 5 to 15 wt.

When the content of co is less than 5 wt. and more than 15 wt. the catalyst and reduces its activity.

Montmorillonite can be used as a carrier as a natural part of My[(Al2-yMgySi4O10(OH)2]nH2O. Preferably the use of montmorillonite in the H form of the composition of Hy[(Al2-yMgySi4O10(OH)2]nH2O.

View deposits of natural montmorillonite has no effect on the activity and stability of catalysts.

The proposed catalyst is illustrated by the following examples.

Example 1. of 4.75 g (95 wt.) shredded natural montmorillonite impregnated with 10 ml of a solution of nitrate of cobalt (11) containing 1,23 g Co(NO3)26H2O (5 wt.), is evaporated to dryness with constant stirring on a water bath. Dried at 100oC for 3 h, and calcined at 500oC 5 o'clock

After the catalyst was omitted stream of dry and wet (1% H2O) gas of the following composition: NO concentration of 300 ppm, CH4- 400 ppm, O215 16% rest of the nitrogen, with about the
NO(): = (Co-C)/Co100% ,

where Co input NO concentration, ppm;

C NO concentration at the outlet of the reactor, ppm.

Example 2. 4.5 g (90 wt.) shredded natural montmorillonite impregnated with 10 ml of a solution of nitrate of cobalt (11) containing 2,47 g Co(NO3)26H2O (10 wt.). Next, similarly to example 1.

Example 3. of 4.25 g (85 wt.) shredded natural montmorillonite impregnated with 10 ml of a solution of nitrate of cobalt (11) containing 3,70 g Co(NO3)26H2O (15 wt.). Next, similarly to example 1.

Example 4. of 4.75 g (95 wt.) montmorillonite in the H form is impregnated with 6 to 8 ml of a solution of nitrate of cobalt (11) containing 1,23 g Co(NO3)26H2O (5 wt.). Next, similarly to example 1.

Example 5. 4.5 g (90 wt.) montmorillonite in the H form impregnated with 10 ml of a solution of nitrate of cobalt (11) containing 2,47 g Co(NO3)26H2O (10 wt. ). Next, similarly to example 1.

Example 6. of 4.25 g (85 wt.) montmorillonite in the H form impregnated with 10 ml of a solution of nitrate of cobalt (11) containing 3,70 g Co(NO3)26H2O (15 wt. ). Next, similarly to example 1.

Example 7. Zeolite H-DCM-1122 (SiO2/Al2O330) 5 g subjected to ion exchange of 0.5 M rest the th currency repeated at 50 80oC. the Sample was washed with 20-fold amount of bidistilled water. Was dried in air at 20 - 25oC during the day (prototype).

The results of the tests of the catalysts shown in the table.

The catalytic activity of catalysts for selective reduction of nitrogen oxides on the basis of natural and H-shaped montmorillonite.

Thus, the proposed catalyst in comparison with prototypes increases the conversion of NO from 30 to 80% both in dry and in humid atmosphere, simplifies production and reduces the cost to 3 5 $/kg

Sources of information taken into account in the examination

1. Y. Li, P. J. Battavio, J. N. Armor, J. Catal. 142, 561 571, 1993.

2. US Patent 5149512 A; Y. Li, J. N. Armor. B 01 J 8/00, 1992.

3. Y. Li, J. N. Armor. J. Catal. 145, 1 9, 1994.

1. The catalyst for selective reduction of nitrogen oxides by methane containing cobalt on silica-alumina carrier, characterized by the fact that he as the carrier contains montmorillonite in the following ratio, wt.

Cobalt 5 15

Montmorillonite Else

2. The catalyst p. 1, characterized in that it contains montmorillonite in the protonated form.

 

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