KR101083307B1 - V2o6 based catalyst - Google Patents

Abstract

The present invention relates to an vanadium pentoxide catalyst. The disclosed vanadium pentoxide-based catalyst of the present invention is a honeycomb type catalyst carrying vanadium pentoxide with titanium dioxide as a carrier to remove nitrogen oxides. In order to adsorb and remove the term trioxide and promote the oxidation reaction of elemental mercury, the total amount of catalyst raw materials is added. It contains 0.1 to 1.0% by weight of alkaline earth metal chlorides by weight. The vanadium pentoxide-based catalyst of the present invention can remove the term trioxide and promote the oxidation of elemental mercury while maintaining the nitrogen oxide removal activity.

Description

Ivanadium pentoxide-based catalyst {V2O6 BASED CATALYST}

The present invention relates to an vanadium pentoxide-based catalyst, and relates to an vanadium pentoxide-based catalyst for removing nitrogen oxide using ammonia as a reducing agent.

In general, nitrogen oxides (NO _X ) are produced by the reaction of nitrogen and oxygen in the combustion air that is oxidized or oversupplied in the fuel in a high temperature combustion facility, and the atmosphere causing photochemical smog and acid rain when discharged to the atmosphere. It is a pollutant.

In order to remove nitrogen oxides during the combustion process, selective catalytic reduction (SCR) is widely used to decompose and remove nitrogen oxides into nitrogen and water with ammonia as a reducing agent in the presence of a catalyst. In the selective catalytic reduction technology, various catalysts such as noble metals and metal oxides have been proposed. Among them, vanadium pentoxide-based catalysts are known to be excellent. In order to actually apply the catalyst used in the selective catalytic reduction technology in a power plant, it is manufactured and used in the form of honeycomb to reduce the pressure loss generated in the catalyst bed.

Such selective catalytic reduction techniques have been disclosed in US Pat. No. 4,164,546, US Pat. No. 4,106,286, US Pat. No. 4,572,110, Korean Patent 314,758, Korean Patent 295,370, and Korean Patent 523,511.

On the other hand, most of the mercury generated by coal combustion exists in the form of elemental mercury, which is difficult to remove due to insoluble properties. In addition, the elemental mercury discharged from the power plant remains in the atmosphere to create a harmful environment for the human body is being managed intensively, a lot of research to remove the elemental mercury in the developed countries, including the United States.

Among the techniques for removing mercury, the technique of removing elemental mercury using an adsorbent such as activated carbon has difficulty in field application due to high cost. Also, Korea Patent No. As 765 405 disclosed in the conventional pentoxide was added to the oil-in-water power station ash vanadium catalyst after changing the source sosueun the sanhwasueun technique to remove in a wet desulfurization system is high mercury removal efficiency, while dioxide (SO ₂ ) There is a problem of promoting the oxidation reaction.

In Korea, vanadium pentoxide-based catalysts are installed and used mainly in SCR facilities using flue gas denitrification technology, which is attracting attention not only for its existing denitrification capacity but also for its oxidative reactivity with respect to mercury emissions from power plants, which are being regulated around the world. . However, the elemental mercury oxidation capacity of the vanadium pentoxide catalyst under SCR conditions is not so high due to competition with the denitrification reaction.

Therefore, in the application of vanadium pentoxide-based catalysts to heavy oil and coal-fired power plants, it is required to develop new technologies capable of adsorbing sulfur trioxide (SO ₃ ) in the exhaust gas components and promoting the oxidation reaction of elemental mercury.

The present invention has been made in accordance with the above-described requirements, and an object thereof is to provide an vanadium pentoxide-based catalyst which promotes the oxidation reaction of elemental mercury by adsorbing alkaline earth metal chlorides to an vanadium pentoxide-based catalyst and adsorbs sulfur trioxide.

The vanadium pentoxide-based catalyst of the present invention is a honeycomb type catalyst in which vanadium pentoxide is supported on titanium dioxide as a carrier to remove nitrogen oxides, and the total amount of catalyst raw materials is added to adsorb and remove the term trioxide and promote the oxidation reaction of elemental mercury. It contains 0.1 to 1.0% by weight of alkaline earth metal chlorides by weight.

Here, the alkaline earth metal chloride includes any one of magnesium, calcium and strontium.

In addition, the titanium dioxide is preferably 50 to 53% by weight based on the total weight of the catalyst raw material.

In addition, the vanadium pentoxide is preferably 0.1 to 1.0% by weight based on the total weight of the catalyst raw material.

Since the vanadium pentoxide-based catalyst of the present invention can be prepared by adding a small amount of alkaline earth metal chloride to a vanadium pentoxide denitrification catalyst which is widely used for commercial use, it maintains the nitrogen oxide removal activity without additional equipment, Can remove and promote the oxidation of elemental mercury.

In addition, since the alkaline earth metal chloride contained in the vanadium pentoxide-based catalyst of the present invention can utilize HCl generated in the process of adsorbing trioxide to promote the oxidation reaction of elemental mercury, elemental mercury can be oxidized without additional injection of oxidizing gas. There is an effect that can be easily applied to the site without additional equipment for mercury removal in the power plant.

The vanadium pentoxide-based catalyst of the present invention is a honeycomb catalyst extruded to remove nitrogen oxides using ammonia as a reducing agent, and includes titanium dioxide, vanadium pentoxide, alkaline earth metal chlorides, and other additives.

The titanium dioxide (TiO ₂ ) is used as a carrier of the catalyst, it is preferably 50 to 53% by weight based on the total weight of the catalyst raw material.

The vanadium pentoxide (V ₂ O ₅ ) is an active material, it is preferably 0.1 to 1.0% by weight, more preferably 0.5% by weight based on the total weight of the catalyst raw material.

The alkaline earth metal chloride includes magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), beryllium (Be), and the like. For example, the alkaline earth metal chloride may be magnesium chloride, calcium chloride, strontium chloride. The alkaline earth metal chloride is 0.05 to 0.5% by weight, more preferably 0.1 to 1.0% by weight.

The other additives may be kaolin, starch, silica sol, methylcellulose, nitric acid, water and the like.

Hereinafter, preferred embodiments and test examples of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. However, these are provided only for describing the present invention in detail, and the scope of the present invention is not limited thereto.

Example 1-7 Preparation of Ivanadium Pentaoxide-based Honeycomb Catalyst Added with Alkaline Earth Metal Chloride

In order to support vanadium pentoxide (V ₂ O ₅ ), which is an active substance, in titanium dioxide (TiO ₂ ) used as a carrier of the catalyst, 0.1N ammonium vanadate (N ₄₎ in accordance with the amount of vanadium pentoxide to be supported VO ₃ ) is dissolved in distilled water and oxalic acid is added so that the pH of the aqueous solution is 2.4 to 3.0, and then heated to about 60 ~ 70 ℃.

Titanium dioxide was added to the aqueous solution, followed by mixing for 2 hours or more, the water was evaporated in a vacuum evaporator, dried at a temperature of 100 ° C. for at least 12 hours, and calcined under an air atmosphere for 5 hours.

In this embodiment, the honeycomb catalyst has a titanium dioxide content of 50 to 53% by weight based on the total combined weight of the catalyst raw materials, including 0.1 to 1.0% by weight of alkaline earth metal chlorides, 5% by weight of kaolin, 3% by weight of starch, Additives such as 6% by weight of silica sol, 3% by weight of methyl cellulose, 0.5% by weight of nitric acid, and 28.5 to 32.4% by weight of water are mixed.

The mixture is thoroughly mixed by kneading process, and the kneaded product is extruded for honeycomb molding, dried for 72 hours under constant temperature and humidity conditions (105 ° C, 95% relative humidity) and A honeycomb catalyst according to the present embodiment is prepared by baking for 5 hours at 500 ° C.

Example catalyst Titanium dioxide Ivanadium pentoxide
Magnesium chloride
(One) Calcium chloride
(2) Strontium Chloride (3) One SCR_MC00 52.00 0.5 0.0 0.0 0.0 2 SCR_MC01 51.98 0.5 0.1 0.1 0.1 3 SCR_MC03 51.96 0.5 0.3 0.3 0.3 4 SCR_MC05 51.94 0.5 0.5 0.5 0.5 5 SCR_MC07 51.92 0.5 0.7 0.7 0.7 6 SCR_MC10 51.90 0.5 1.0 1.0 1.0 7 Commercial SCR -

Table 1 shows the compounding ratio of the catalyst prepared in Examples 1 to 6 by weight, and 51.90 to 52.00% by weight of titanium dioxide was loaded with 0.5% by weight of vanadium pentoxide. Alkaline earth metal chlorides such as magnesium chloride (1), calcium chloride (2) and strontium chloride (3) are added at a ratio of 0.1 to 1.0% by weight. Example 7 is for a comparative experiment, and prepared a honeycomb-type vanadium pentoxide-based commercial catalyst having the same shape as in Examples 1 to 6.

< Test Example  1-7> NOx removal rate measurement

The catalyst prepared according to Examples 1 to 7 was mounted in a honeycomb type catalytic reactor, and a mixed gas similar to the exhaust gas composition in the actual combustion system was injected at a flow rate of 10 L per minute. Here, the mixed gas is composed of oxygen concentration 3.0%, nitrogen oxide 100ppm, sulfur dioxide 300ppm, ammonia 100ppm, trioxide about 10ppn and the balance gas nitrogen. The reaction temperature was elevated at intervals of 50 ° C. from 300 ° C. to 400 ° C.

Table 2 shows the nitrogen oxide removal rate (%) according to the reaction temperature, and the concentration of nitrogen oxide was measured using a non-dispersive infrared method.

Test Example
catalyst
NOx removal rate (%) 300 ° C 350 ℃ 400 ° C (One) (2) (3) (One) (2) (3) (One) (2) (3) One SCR_MC00 85.0 85.0 85.0 87.0 87.0 87.0 84.5 84.5 84.5 2 SCR_MC01 85.5 84.5 85.0 87.5 87.0 87.0 87.0 84.5 84.5 3 SCR_MC03 86.5 85.5 86.0 88.0 87.0 87.0 88.0 87.5 87.0 4 SCR_MC05 87.5 86.5 87.0 89.0 88.0 87.5 87.0 87.7 87.5 5 SCR_MC07 87.5 87.0 87.0 90.0 88.5 88.0 87.0 87.8 87.3 6 SCR_MC10 88.5 87.5 87.5 91.5 89.5 90.5 88.0 87.5 87.2 7 Commercial SCR 85.0 85.0 85.0 89.0 89.0 89.0 88.5 88.5 88.5

Referring to Table 2, the removal rate of nitrogen oxides of more than 87% in the SCR_MC01, SCR_MC03, SCR_MC05, SCR_MC07, SCR_MC10 catalyst of 0.1 to 1.0% by weight alkaline earth metal chloride based on the reaction temperature 350 ℃.

< Test Example  8-14> sulfur trioxide ( SO ₃ ) Adsorption removal rate measurement

In the catalyst prepared according to Examples 1-7 and Test Example 1-7 under the conditions of using the CCD (Controlled Condenstion Method) method to change the concentration of trioxide (SO ₃ ) by the catalyst at about 400 ℃ while maintaining the reaction temperature of the catalyst One hour was collected by condensation with sulfuric acid (H ₂ SO ₄ ) and measured by ion chromatography.

Table 3 shows the removal rate of the trioxide according to the catalyst according to Examples 1-7 and the conditions of Test Examples 1-7.

Test Example catalyst SO ₃ removal rate (%) 8        SCR_MC00 -5.5
9

SCR_MC01
(One) 15.5 (2) 13.2 (3) 12.5
10

SCR_MC03
(One) 25.5 (2) 22.5 (3) 23.5
11

SCR_MC05
(One) 30.0 (2) 27.5 (3) 28.7
12

SCR_MC07
(One) 32.5 (2) 28.7 (3) 29.5
13

SCR_MC10
(One) 55.5 (2) 50.5 (3) 52.3 14 Commercial SCR -5.0

As shown in Table 3, the removal rate of sulfur trioxide of SCR_MC01, SCR_MC03, SCR_MC05, SCR_MC07, and SCR_MC10 catalyst to which 0.1-1.0 wt% of alkaline earth metal chloride was added was more than 10%, which was much higher than that of a commercial SCR catalyst. The negative value of the sulfur trioxide adsorption removal rate of the commercial SCR catalyst in Table 3 is a result of the oxidation of the catalyst to increase the concentration of sulfur trioxide.

< Test Example  15-21> HCL  Free of elemental mercury Oxidation rate (%)

Under the conditions of the catalysts prepared in Examples 1-7 and Test Examples 1-7, 50 μg / m3 of elemental mercury generated through the elemental mercury generator without the addition of HCl as the catalytic oxidizer was diluted and supplied with nitrogen as a balance gas. The elemental mercury and mercury oxide concentrations before and after the passage of the reactor were measured using a mercury type analyzer (Mercury / DM-6B, Nippon Instruments Corporation) while maintaining the reaction temperature at 350 ° C.

Test Example catalyst Elemental mercury oxidation rate (%) 15        SCR_MC00 0.5
16

SCR_MC01
(One) 3.5 (2) 2.7 (3) 3.3
17

SCR_MC03
(One) 10.0 (2) 9.5 (3) 8.7
18

SCR_MC05
(One) 25.0 (2) 22.5 (3) 21.7
19

SCR_MC07
(One) 37.5 (2) 33.5 (3) 36.1
20

SCR_MC10
(One) 55.0 (2) 51.3 (3) 53.9 21        Commercial SCR 0.0

As shown in Table 4, in the case of commercially available SCR catalysts, almost no oxidation occurs, the oxidation rate of elemental mercury increases as the weight% of the alkaline earth metal chloride added increases, and SCR_MC10 to which 1.0 weight% of alkaline earth metal chloride is added. In the case of the catalyst, the oxidation rate of elemental mercury was 50% or more, which was superior to that of a commercial SCR catalyst.

< Test Example  22-28> HCL  Of elemental mercury Oxidation rate (%)

To the catalyst prepared in Examples 1 to 7 and the conditions of Test Examples 1 to 7, 20 ppm of HCl as a catalytic oxidant was added, and 50 μg / m 3 of elemental mercury generated through the elemental mercury generator was diluted and supplied with nitrogen as a balance gas. The concentration of elemental mercury and mercury oxide before and after the passage of the reactor was measured using a mercury type analyzer (Mercury / DM-6B, Nippon Instruments Corporation) while maintaining the reaction temperature at 350 ° C.

Test Example catalyst Elemental mercury oxidation rate (%) 15        SCR_MC00 28.5
16

SCR_MC01
(One) 37.5 (2) 35.5 (3) 37.0
17

SCR_MC03
(One) 45.5 (2) 43.3 (3) 43.7
18

SCR_MC05
(One) 65.5 (2) 55.7 (3) 63.2
19

SCR_MC07
(One) 78.7 (2) 75.7 (3) 77.3
20

SCR_MC10
(One) 91.2 (2) 90.3 (3) 90.5 21        Commercial SCR 30.5

As shown in Table 5, the elemental mercury oxidation rate was 30% in the commercial SCR catalyst, while the oxidation rate of elemental mercury was superior to 90% or more in the SCR_MC10 catalyst to which 1.0 wt% of alkaline earth metal chloride was added.

Alkaline earth metal chlorides, for example, magnesium chloride (MgCl ₂ ) is the reaction scheme to remove the sulfur trioxide (SO ₃ ) by the reaction scheme, as shown in Scheme 1.

Referring to Scheme 1, HCl is generated while magnesium chloride adsorbs the trioxide. HCL can promote the oxidation reaction of elemental mercury, which is shown in Scheme 2.

Most of the mercury generated by coal combustion is in the form of elemental mercury. Elemental mercury is difficult to remove due to insolubility, while water-soluble mercury oxide can be easily removed from the wet flue gas desulfurization ratio of a power plant.

Although the detailed description of the present invention described above has been described with reference to a preferred embodiment of the present invention, a person skilled in the art without departing from the spirit and scope of the present invention described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (4)

As a honeycomb catalyst which carries vanadium pentoxide as a carrier to remove nitrogen oxides, In order to adsorb and remove the trioxide port and promote the oxidation reaction of elemental mercury, it contains 0.1 to 1.0% by weight of alkaline earth metal chloride based on the total weight of the catalyst raw material, Ivanadium pentoxide-based catalyst comprising kaolin, starch, silica sol, methylcellulose, nitric acid and water. The method of claim 1, wherein the alkaline earth metal chloride, Ivanadium pentoxide-based catalyst comprising any one of magnesium, calcium and strontium. The method of claim 1, The titanium dioxide is vanadium pentoxide-based catalyst is 50 to 53% by weight based on the total weight of the catalyst raw material. The method of claim 1, The vanadium pentoxide is an vanadium pentoxide-based catalyst of 0.1 to 1.0% by weight based on the total weight of the catalyst raw materials.