KR102504656B1 - Selective catalytic reduction catalysts comprising nitrogen doped titanium dioxide support and method of preparing same - Google Patents

Abstract

The present invention relates to a support comprising nitrogen-doped titanium dioxide (N doped TiO ₂ , N-TiO ₂ ); and an active material supported on the support and containing a metal oxide. The selective reduction catalyst and method for preparing the same of the present invention use a support containing nitrogen-doped titanium dioxide (N-TiO ₂ ) to prevent aggregation of catalytically active materials and improve dispersibility of active materials, resulting in high nitrogen efficiency. It has the effect of removing oxides.

Description

Selective reduction catalyst comprising nitrogen-doped titanium dioxide support and method for preparing the same

The present invention relates to a selective reduction catalyst and a method for preparing the same, and more particularly, by using a support containing nitrogen-doped titanium dioxide (N-TiO ₂ ) to prevent aggregation of catalytically active materials, thereby reducing active materials It relates to a selective reduction catalyst that can remove nitrogen oxides with high efficiency by improving acidity and a method for preparing the same.

Nitrogen oxides (NOx) are nitrogen dioxide, nitrous oxide, and nitrous oxide, which are generated during the combustion process in stationary emission sources such as power plants and various industrial boilers, and are discharged into the atmosphere, thereby causing photochemical smog and acid rain.

Among technologies for removing nitrogen oxides, currently the most widely commercialized technologies are the SCR (Selective Catalytic Reduction) method, which removes nitrogen oxides by reducing them to harmless water and nitrogen on a catalyst using ammonia as a reducing agent, and the high-temperature area without using a catalyst There is a SNCR (Selective Non Catalytic Reduction) method that reduces nitrogen oxides by converting them into nitrogen and water vapor using only a reducing agent (typically, ammonia).

The SCR method injects ammonia or a hydrocarbon reducing agent into the exhaust gas discharged from a fixed emission source, mixes the exhaust gas and the reducing agent, and then passes through a catalyst to reduce nitrogen oxides to water and nitrogen to remove nitrogen oxides. This SCR method removes nitrogen oxides. Although it is very effective in removing nitrogen oxides, the denitrification effect may be greatly reduced in operating conditions outside the proper temperature range, for example, in low-load operation where the exhaust gas temperature is low.

As concerns about fine dust rapidly increase, such as the recent launch of the Pan-National Countermeasures Committee for fine dust, interest in research to reduce nitrogen oxide, one of the representative precursors of secondary fine dust, is increasing. Therefore, it is necessary to develop a catalyst with higher efficiency in order to comply with recently strengthened nitrogen oxide emission regulations.

In addition, since the catalytic reaction is a surface reaction, it is necessary to develop a technology capable of preventing aggregation of the catalytically active material because high efficiency can be achieved even with a low content when the catalytic reaction point is increased by nanodispersing the active materials.

An object of the present invention is to prevent aggregation of catalytic active materials by using a support containing nitrogen-doped titanium dioxide (N-TiO ₂ ), thereby improving the dispersibility of the active materials to remove nitrogen oxides with high efficiency. A selective reduction catalyst and a method for preparing the same are provided.

According to one aspect of the present invention, a support comprising nitrogen-doped titanium dioxide (N doped TiO ₂ , N-TiO ₂ ); and an active material supported on the support and containing a metal oxide.

The support is porous titanium dioxide; and the nitrogen-doped titanium dioxide formed on the surface of the porous titanium dioxide.

The nitrogen-doped titanium dioxide may be formed on a surface adjacent to the outside of the porous titanium dioxide.

The nitrogen-doped titanium dioxide may be additionally formed on a surface adjacent to pores of the porous titanium dioxide.

The nitrogen-doped titanium dioxide may be formed by replacing nitrogen (N) with oxygen (O) of titanium dioxide (TiO ₂ ) or invading a lattice defect of titanium dioxide.

The metal oxide may include vanadium oxide and tungsten oxide.

The selective reduction catalyst may include 0.1 to 10 parts by weight of the vanadium oxide based on 100 parts by weight of the support; 1 to 10 parts by weight of the tungsten oxide; may include.

The form of the selective reduction catalyst may include any one form selected from the group consisting of powder, honeycomb, plate, corrugated shape, and granule.

The selective reduction catalyst may be porous having pores.

The pore size of the selective reduction catalyst may be 5 to 20 nm.

The particle size of the selective reduction catalyst may be 10 to 50 nm.

The selective reduction catalyst may be used to remove nitrogen oxides (NOx).

According to another aspect of the present invention, (a) preparing a support solution including a support including nitrogen-doped titanium dioxide (N doped TiO ₂ , N-TiO ₂ ); (b) preparing a precursor solution containing a metal oxide precursor; (c) preparing a mixed solution by mixing the support solution and the precursor solution and irradiating with ultrasonic waves; and (d) preparing the selective reduction catalyst by stirring and drying the mixed solution; It provides a method for producing a selective reduction catalyst comprising a.

Step (a) is (a-1) preparing a solution containing titanium dioxide (TiO ₂ ) and a nitrogen precursor; (a-2) preparing a support containing nitrogen-doped titanium dioxide (N-TiO ₂ ) by drying and heat-treating the solution; and (a-3) preparing the support solution by mixing the support with water.

The nitrogen precursor may include at least one selected from the group consisting of urea (CH ₄ N ₂ O), ammonium nitrate (NH ₄ NO ₃ ), ammonium hydroxide (NH ₄ OH), and ammonia (NH ₃ ).

The metal oxide precursor may include a vanadium oxide precursor and a tungsten oxide precursor.

The vanadium oxide precursor is ammonium metavanadate (NH ₄ VO ₃ ), vanadyl sulfate (VOSO ₄ ), vanadyl oxalate (VOC ₂ O ₄ xH ₂ O) and vanadyl acetylacetonate [VO(acac) ₂ ] may include one or more selected from the group consisting of.

The tungsten oxide precursor is ammonium metatungstate hydrate (Ammonium metatungstate, (NH ₄ ) ₆ H ₂ W ₁₂ O ₄ 0 xH ₂ O), ammonium tungstate (Ammonium tungstate, (NH ₄ ) ₁₀ H ₂ (W ₂ O) ₇ ) ₆ ) Ammoniumparatungstate hydrate (Ammoniumparatungstate, (NH ₄ ) ₁₀ (H ₂ W ₁₂ O ₄₂ )·4H ₂ O) and tungsten oxide (WO ₃ ) includes at least one selected from the group consisting of can do.

Step (b) is (b-1) preparing a first precursor solution containing the vanadium oxide precursor; and (b-2) preparing a second precursor solution containing the tungsten oxide precursor; can include

In step (b-1), the first precursor solution is selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, serveric acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid and terephthalic acid It may further include one or more selected from.

The selective reduction catalyst and method for preparing the same of the present invention uses a nitrogen-doped titanium dioxide (N-TiO ₂ ) support to prevent aggregation of catalytic active materials and improve dispersibility of active materials to remove nitrogen oxides with high efficiency. There are effects that can be done.

In addition, the present invention can expect commercialization as formability and strength are guaranteed even in the case of scale-up by utilizing conventional titanium dioxide (TiO ₂ ).

In addition, regardless of the shape of the catalyst, the present invention can be used in place of conventional titanium dioxide (TiO ₂ ) in honeycomb, plate, and corrugated forms, and supports catalytic active materials of various compositions. and can utilize it.

1 is an XPS surface analysis graph of supports according to Example 1 and Comparative Example 1.
Figure 2 is a UV-Visible analysis result of the support according to Example 1 and Comparative Example 1.
3a to 3c are analysis results of bonding changes of O 1s, N 1s, and Ti 2p on the surfaces of the supports according to Example 1 and Comparative Example 1.
4 is an evaluation result of nitrogen oxide removal characteristics of catalysts according to Examples 2 to 4 and Comparative Example 2.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

However, the following description is not intended to limit the present invention to specific embodiments, and in describing the present invention, if it is determined that the detailed description of related known technologies may obscure the gist of the present invention, the detailed description will be omitted. .

Terms used herein are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, operation, component, or combination thereof described in the specification, but one or more other features or It should be understood that the presence or addition of numbers, steps, operations, components, or combinations thereof is not precluded.

Also, terms including ordinal numbers such as first and second to be used below may be used to describe various components, but the components are not limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention.

In addition, when a component is referred to as being “formed” or “layered” on another component, it may be formed or laminated directly on the front or one side of the surface of the other component, but intermediate It should be understood that other components may be further present.

Hereinafter, the selective reduction catalyst of the present invention will be described in detail. However, this is presented as an example, and the present invention is not limited thereby, and the present invention is only defined by the scope of the claims to be described later.

The present invention relates to a support comprising nitrogen-doped titanium dioxide (N doped TiO ₂ , N-TiO ₂ ); and an active material supported on the support and containing a metal oxide.

The support is porous titanium dioxide; and the nitrogen-doped titanium dioxide formed on the surface of the porous titanium dioxide.

The nitrogen-doped titanium dioxide may be formed on a surface adjacent to the outside of the porous titanium dioxide.

The nitrogen-doped titanium dioxide may be additionally formed on a surface adjacent to pores of the porous titanium dioxide.

The nitrogen-doped titanium dioxide may be formed by replacing nitrogen (N) with oxygen (O) of titanium dioxide (TiO ₂ ) or invading a lattice defect of titanium dioxide.

The nitrogen-doped titanium dioxide (N-TiO ₂ ) may have a micropore area (T-plot) of 3 to 15 m ² /g, preferably 8 to 11 m ² /g, showing pores of 2 nm or less. there is.

As the nitrogen-doped titanium dioxide (N-TiO ₂ ) provides an anchoring site through a high specific surface area and surface non-metal doping, catalytically active materials can be dispersed, which serves to suppress not only the main catalyst but also catalytic side reactions. Catalytic activity enhancement can be expected through the dispersion of cocatalysts.

The metal oxide may include vanadium oxide and tungsten oxide.

The vanadium oxide may be a main catalyst and the tungsten oxide may be a cocatalyst.

The selective reduction catalyst may include 0.1 to 10 parts by weight of the vanadium oxide based on 100 parts by weight of the support; 1 to 10 parts by weight of the tungsten oxide; preferably, 0.1 to 5 parts by weight of the vanadium oxide; 3 to 7 parts by weight of the tungsten oxide; may include.

With respect to 100 parts by weight of the support, if the vanadium oxide is less than 0.1 parts by weight, it is not preferable because high denitrification efficiency cannot be achieved due to the low content, and if it is greater than 10 parts by weight, SO ₂ is oxidized to SO ₃ in a high temperature region, or , which is undesirable because it causes various side reactions such as oxidizing ammonia used as a reducing agent and generating NOx.

With respect to 100 parts by weight of the support, if the tungsten oxide is less than 0.1 parts by weight, the structure and thermal stability cannot be secured due to the insufficient amount of the active material in the catalyst, thereby narrowing the active temperature range and lowering the activity. However, if it exceeds 10 parts by weight, agglomeration of the powder may occur due to a high content, and a side reaction of the catalyst may be caused at a high temperature, which is not preferable.

The form of the selective reduction catalyst may include any one form selected from the group consisting of powder, honeycomb, plate, corrugated shape, and granule.

The selective reduction catalyst may be porous having pores.

The selective reduction catalyst may have a micropore area (T-plot) of 3 to 15 m ² /g, preferably 5 to 11 m ² /g, showing pores of 2 nm or less.

The pore size of the selective reduction catalyst may be 5 to 20 nm.

The particle size of the selective reduction catalyst may be 10 to 50 nm.

The selective reduction catalyst may be used to remove nitrogen oxides (NOx).

The activation temperature of the selective reduction catalyst may be 150 to 450 °C, preferably 250 to 400 °C.

The selective reduction catalyst is used to discharge nitrogen oxides (e.g. NO, NO ₂ , etc., commonly known as _NOx , acid rain, photochemical smog, etc. in) It is a denitration catalyst that can convert N ₂ and H ₂ O into harmless substances.

Hereinafter, the method for preparing the selective reduction catalyst of the present invention will be described in detail.

First, nitrogen doped titanium dioxide (N doped TiO ₂ , N-TiO ₂ ) Prepare a support solution comprising a support comprising (step a).

Step (a) is (a-1) preparing a solution containing titanium dioxide (TiO ₂ ) and a nitrogen precursor; (a-2) preparing a support containing nitrogen-doped titanium dioxide (N-TiO ₂ ) by drying and heat-treating the solution; and (a-3) preparing the support solution by mixing the support with water.

The drying in step (a-2) may be rotary evaporation, and the solvent may be evaporated through the drying.

The heat treatment of step (a-2) may be performed in a nitrogen (N ₂ ) atmosphere.

The nitrogen precursor may include at least one selected from the group consisting of urea (CH ₄ N ₂ O), ammonium nitrate (NH ₄ NO ₃ ), ammonium hydroxide (NH ₄ OH), and ammonia (NH ₃ ).

Next, a precursor solution containing a metal oxide precursor is prepared (step b).

The metal oxide precursor may include a vanadium oxide precursor and a tungsten oxide precursor.

The vanadium oxide precursor is ammonium metavanadate (NH ₄ VO ₃ ), vanadyl sulfate (VOSO ₄ ), vanadyl oxalate (VOC ₂ O ₄ xH ₂ O) and vanadyl acetylacetonate [VO(acac) ₂ ] may include one or more selected from the group consisting of, and preferably may include ammonium metavanadate (NH ₄ VO ₃ ).

The tungsten oxide precursor is ammonium metatungstate hydrate (Ammonium metatungstate, (NH ₄ ) ₆ H ₂ W ₁₂ O ₄ 0 xH ₂ O), ammonium tungstate (Ammonium tungstate, (NH ₄ ) ₁₀ H ₂ (W ₂ O) ₇ ) ₆ ) Ammoniumparatungstate hydrate (Ammoniumparatungstate, (NH ₄ ) ₁₀ (H ₂ W ₁₂ O ₄₂ )·4H ₂ O) and tungsten oxide (WO ₃ ) includes at least one selected from the group consisting of and preferably include ammonium metatungstate hydrate ((NH ₄ ) ₆ H ₂ W ₁₂ O ₄ 0·xH ₂ O).

Step (b) is (b-1) preparing a first precursor solution containing the vanadium oxide precursor; and (b-2) preparing a second precursor solution containing the tungsten oxide precursor; can include

In step (b-1), the first precursor solution is selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, serveric acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid and terephthalic acid It may further include one or more selected from.

Next, the support solution and the precursor solution are mixed and ultrasonically irradiated to prepare a mixed solution (step c).

The ultrasonic irradiation of step (c) may be performed for 0.5 to 3 hours.

Finally, the mixed solution is stirred and dried to prepare the selective reduction catalyst (step d).

The drying of step (d) may be performed at a temperature of 50 to 100 ° C. for 0.5 to 5 hours, the drying may be rotary evaporation, and the solvent may be evaporated through the drying.

After step (d), step (e) of heat-treating the selective reduction catalyst; may further include.

The heat treatment of step (d) may be performed at a temperature of 300 to 600 °C for 0.5 to 5 hours.

[Example]

Hereinafter, a preferred embodiment of the present invention will be described. However, this is for illustrative purposes and the scope of the present invention is not limited thereby.

[Preparation of support]

Example 1: Preparation of titanium dioxide doped with nitrogen

10 g of TiO ₂ powder was added to a 2M solution of urea, stirred for 1 hour, dried by rotary evaporation at 70°C for 30 minutes at 50 mbar, and then dried at 70°C for 30 minutes at 0 mbar to dry the solvent. Rotary evaporation was performed. Next, nitrogen-doped titanium dioxide (N-TiO ₂ ) was prepared by heat treatment in a N ₂ atmosphere (500 cc/min) for 1 hour at a temperature of 500 °C.

[Preparation of Selective Reduction Catalyst]

Example 2: 2V5W/N-TiO ₂ manufacture of

4.65 g of N-TiO ₂ prepared according to Example 1 was dispersed in 100 ml of distilled water and stirred for 30 minutes to prepare a support solution.

Subsequently, 0.30 g of oxalic acid (Sigma-Aldrich) and 0.13 g (2wt%) of ammonium metavanadate (NH ₄ VO ₃ , Sigma-Aldrich) were added to 50 ml of distilled water and heated to 60 ° C. A first precursor solution was prepared by stirring for 30 minutes.

Next, 0.27 g (5wt%) of ammonium metatungstate hydrate (Ammonium metatungstate, (NH ₄ ) ₆ H ₂ W ₁₂ O ₄ 0·xH ₂ O, Sigma-Aldrich) was dissolved in 50 ml distilled water, followed by 30 A second precursor solution was prepared by stirring for a minute.

Next, after mixing the support solution and the first and second precursor solutions, ultrasonic dispersion was performed for 1 hour, followed by stirring at 60 °C for 2 hours. In addition, after rotary evaporation at 70 ° C. for 1 hour at 50-0 mbar to evaporate the solvent, the catalyst in powder form was recovered, and heat treatment was performed at 500 ° C. for 2 hours (heating rate 5 ° C. / min). Selective reduction catalyst ( 2V5W/N-TiO ₂ ) was prepared.

Example 3: 4V5W/N-TiO ₂ manufacture of

In Example 2, instead of using 0.13 g (2wt%) of ammonium metavanadate (NH ₄ VO ₃ , Sigma-Aldrich), 0.26 g (4wt%) of ammonium metavanadate (Ammonium metavanadate, NH ₄ A selective reduction catalyst (4V5W/N-TiO ₂ ) was prepared in the same manner as in Example 2, except for using VO ₃ , Sigma-Aldrich).

Example 4: 0.5V5W/N-TiO ₂ manufacture of

In Example 2, instead of using 0.13 g (2wt%) of ammonium metavanadate (NH ₄ VO ₃ , Sigma-Aldrich), 0.03 g (0.5wt%) of ammonium metavanadate (Ammonium metavanadate, NH A selective reduction catalyst (0.5V5W/N-TiO ₂ ) was prepared in the same manner as in Example 2, except that ₄ VO ₃ , Sigma-Aldrich) was used.

[Preparation of support]

Comparative Example 1: Conventional Titanium Dioxide

Titanium dioxide (TiO ₂ , CristalACTiV DT-51) purchased from TRONOX was prepared.

[Preparation of Selective Reduction Catalyst]

Comparative Example 2: 2V5W/TiO ₂ manufacture of

In Example 2, instead of using 4.65 g of N-TiO ₂ prepared according to Example 1, 4.65 g of TiO ₂ according to Comparative Example 1 was used as a selective reduction catalyst in the same manner as in Example 2. (2V5W/TiO ₂ ) was prepared.

Conditions for Examples 2 to 4 and Comparative Example 2 are shown in Table 1 below.

catalyst active substance main catalyst co-catalyst support vanadium precursor tungsten precursor V ₂ O ₅ WO ₃ Example 2
(2V5W/N-TiO ₂ ) NH ₄ VO ₃ (NH ₄ ) ₆ H ₂ W ₁₂ O ₄ 0 xH ₂ O 2wt% 5wt% N—TiO ₂
(93wt%) Example 3 (4V5W/N-TiO ₂ ) NH ₄ VO ₃ (NH ₄ ) ₆ H ₂ W ₁₂ O ₄ 0 xH ₂ O 4wt% 5wt% N—TiO ₂ (91 wt %) Example 4 (0.5V5W/N-TiO ₂ ) NH ₄ VO ₃ (NH ₄ ) ₆ H ₂ W ₁₂ O ₄ 0 xH ₂ O 0.5wt% 5wt% N—TiO ₂ (94.5 wt %) Comparative Example 2 (2V5W/TiO ₂ ) NH ₄ VO ₃ (NH ₄ ) ₆ H ₂ W ₁₂ O ₄ 0 xH ₂ O 2wt% 5wt% TiO ₂ (93 wt %)

[Test Example]

Test Example 1: Surface Analysis and Optical Characteristic Analysis of Support

1 is an XPS surface analysis graph of supports according to Example 1 and Comparative Example 1, and FIG. 2 is a UV-Visible analysis result of supports according to Example 1 and Comparative Example 1. XPS (X-ray photoelectron spectroscopy, Thermo, K Alpha+) analysis was performed on the surface of Examples 1 and 2 by irradiating Al Kα with X-rays.

According to FIG. 1, N-TiO ₂ (Example 1) in which a nitrogen functional group was imparted to TiO ₂ powder using Urea showed a distinct yellow color as can be seen in the picture inserted in FIG. 1. In addition, as a result of analyzing the surface components through XPS analysis, the N-TiO ₂ powder (Example 1) showed a high Nitrogen content of 17.89 at%, and a distinct N1s peak appeared.

In addition, according to FIG. 2, the conventional TiO ₂ powder (Comparative Example 1) is absorbed only at a wavelength of 400 nm or less, whereas the N-TiO ₂ powder (Example 1) shows light absorption at 600 nm or less, and the active wavelength range It was found that this was expanded.

Test Example 2: Bonding structure change analysis

3a to 3c are analysis results of bonding changes of O 1s, N 1s, and Ti 2p on the surfaces of the supports according to Example 1 and Comparative Example 1.

According to FIGS. 3a to 3c, O1s first reduced the surface oxygen content of N-TiO ₂ (Example 1) to 7.25 at% as Nitrogen replaced the oxygen site of TiO ₂ (Comparative Example 1). O _ads are oxygen or OH-groups adsorbed on the surface of TiO ₂ , and N-TiO ₂ (Example 1) has a reduced peak due to the generation of substitutional O-Ti-N or interstitial Ti-NO in the lattice. . In addition, N 1s is formed by dividing into Ti-NO (interstitial nitrogen, Ni) and O-Ti-N (substituted nitrogen, Ns), and these nitrogen functional groups act as anchoring sites to disperse active substances more stably than oxygen groups. can make it In all of FIGS. 3a to 3c, it can be seen that the lattice structure is changed as the nitrogen is doped and shifted to a lower binding energy as a whole.

Test Example 4: Analysis of Pore Characteristics

The pore characteristics of Examples 1 to 4 and Comparative Examples 1 and 2 were analyzed using ASAP 2010 (Micrometritics Co., USA), and the results are shown in Table 2 below.

catalyst BET Surface Area
(m ² /g) T-plot Micropore Area
(m ² /g) Pore Volume
(cm ³ /g) Pore Size
(nm) Crystal Size
(nm)* Comparative Example 1 TiO ₂ 87.83 6.59 0.29 13.46 18.9 Example 1 N—TiO ₂ 84.39 9.57 0.27 13.46 18.9 Comparative Example 2 2V5W/TiO ₂ 75.48 1.64 0.28 14.18 19.7 Example 2 2V5W/N-TiO ₂ 80.03 8.21 0.27 12.90 19.2 Example 3 4V5W/N-TiO ₂ 71.14 8.54 0.26 14.24 19.5 Example 4 0.5V5W/N-TiO ₂ 77.91 6.87 0.28 13.77 19.3

* Crystal size was calculated by the Scherrer equation.

According to Table 2, as nitrogen was doped, the specific surface area of N-TiO ₂ (Example 1) was reduced by about 3.5 m ² /g compared to TiO ₂ (Comparative Example 1). In addition, when the active material was supported on N-TiO ₂ (Example 1), a relatively high specific surface area was maintained overall, and N-TiO ₂ (Example 1) showed many micropores of 2 nm or less. As a result, aggregation of the active material can be prevented, and dispersibility of the active material can be improved.

In addition, when a powder type SCR catalyst was prepared by supporting vanadium and tungsten, 2V5W/TiO ₂ (Comparative Example 2) showed a BET specific surface area of 75.48 m ² /g, whereas 2V5W/N-TiO ₂ (Example 2) showed a relatively high specific surface area of 80.03 m ² /g, and the micropore area showing pores of 2 nm or less also showed a high value for the catalysts according to Examples 2 to 3 including the N-TiO ₂ support. there was. Since the catalytic reaction is a surface reaction, the specific surface area of the catalyst is directly related to the denitrification efficiency. In general, as the specific surface area increases, the dispersion of the active ingredient improves, and the increase in active points is directly related to high properties.

Test Example 5: Analysis of nitrogen oxide removal characteristics

4 is an evaluation result of nitrogen oxide removal characteristics of catalysts according to Examples 2 to 4 and Comparative Example 2. In order to confirm the nitrogen oxide removal characteristics of the catalysts according to Examples 2 to 4 and Comparative Example 2, O ₂ 5%, NO 300 ppm, NH ₃ 300 ppm, N ₂ balance gas flow at a total flow of 500 sccm, GHSV Evaluation was performed under the condition of 60,000 h ^-1 (solid line in Fig. 4). In addition, 300 ppm of SO ₂ was added and flowed for evaluation (dotted line in FIG. 4).

According to FIG. 4, the nitrogen oxide removal efficiency of the 2V5W/N-TiO ₂ (Example 2) catalyst is higher than that of 2V5W/TiO ₂ (Comparative Example 2), particularly in the temperature range of 250 to 400 °C. It was found to exhibit high efficiencies close to . In addition, when the content of _the active material increases, the activity may decrease due to particle aggregation. , Accordingly, it was found that the 4V5W/N-TiO ₂ (Example 3) catalyst exhibits high nitrogen oxide reduction efficiency over the entire temperature range. This can improve the dispersibility of catalytically active materials based on the nitrogen anchoring site on the surface of N-TiO ₂ , and as there are a large number of micropores, the specific surface area of the synthesized catalyst can be improved to disperse acid points. An SCR catalyst with high NOx reduction characteristics could be prepared.

The scope of the present invention is indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be interpreted as being included in the scope of the present invention. do.

Claims (19)

(a) preparing a support solution including a support including nitrogen-doped titanium dioxide (N doped TiO ₂ , N-TiO ₂ );
(b) preparing a precursor solution containing a metal oxide precursor;
(c) preparing a mixed solution by mixing the support solution and the precursor solution and irradiating with ultrasonic waves; and
(d) preparing a selective reduction catalyst by stirring and drying the mixed solution; including,
The selective reduction catalyst
a support including the nitrogen-doped titanium dioxide (N doped TiO ₂ , N-TiO ₂ ); and
A method for producing a selective reduction catalyst comprising a; active material supported on the support and containing a metal oxide. According to claim 1,
the support
porous titanium dioxide; and
Method for producing a selective reduction catalyst comprising the nitrogen-doped titanium dioxide formed on the surface of the porous titanium dioxide. According to claim 2,
Method for producing a selective reduction catalyst, characterized in that the nitrogen-doped titanium dioxide is formed on the surface adjacent to the outside of the porous titanium dioxide. According to claim 3,
Method for producing a selective reduction catalyst, characterized in that the nitrogen-doped titanium dioxide is additionally formed on the surface adjacent to the pores of the porous titanium dioxide. According to claim 1,
The nitrogen-doped titanium dioxide is a method for producing a selective reduction catalyst, characterized in that nitrogen (N) is substituted with oxygen (O) of titanium dioxide (TiO ₂ ) or formed by invading a lattice defect of titanium dioxide. . According to claim 1,
The method for producing a selective reduction catalyst, characterized in that the metal oxide comprises vanadium oxide (V ₂ O ₅ ) and tungsten oxide (WO ₃ ). According to claim 6,
The selective reduction catalyst
With respect to 100 parts by weight of the support,
0.1 to 10 parts by weight of the vanadium oxide; and
Method for producing a selective reduction catalyst comprising 1 to 10 parts by weight of the tungsten oxide. According to claim 1,
Selective reduction characterized in that the form of the selective reduction catalyst includes any one form selected from the group consisting of powder, honeycomb, plate, corrugated shape and granule Method for preparing a catalyst. According to claim 1,
The method for producing a selective reduction catalyst, characterized in that the selective reduction catalyst is porous having pores. According to claim 9,
Method for producing a selective reduction catalyst, characterized in that the pore size of the selective reduction catalyst is 5 to 20 nm. According to claim 1,
Method for producing a selective reduction catalyst, characterized in that the particle size of the selective reduction catalyst is 10 to 50 nm. According to claim 1,
Method for producing a selective reduction catalyst, characterized in that the selective reduction catalyst is used for removing nitrogen oxides. According to claim 1,
step (a)
(a-1) preparing a solution containing titanium dioxide (TiO ₂ ) and a nitrogen precursor;
(a-2) preparing a support containing nitrogen-doped titanium dioxide (N-TiO ₂ ) by drying and heat-treating the solution; and
(a-3) preparing the support solution by mixing the support with water; a method for producing a selective reduction catalyst comprising the. According to claim 13,
The nitrogen precursor comprises at least one selected from the group consisting of urea (CH ₄ N ₂ O), ammonium nitrate (NH ₄ NO ₃ ), ammonium hydroxide (NH ₄ OH) and ammonia (NH ₃ ). Method for preparing a selective reduction catalyst. According to claim 1,
The method for producing a selective reduction catalyst, characterized in that the metal oxide precursor comprises a vanadium oxide precursor and a tungsten oxide precursor. According to claim 15,
The vanadium oxide precursor is ammonium metavanadate (NH ₄ VO ₃ ), vanadyl sulfate (VOSO ₄ ), vanadyl oxalate (VOC ₂ O ₄ xH ₂ O) and vanadyl acetylacetonate [VO(acac) ₂ ] Method for producing a selective reduction catalyst, characterized in that it comprises at least one selected from the group consisting of. According to claim 15,
The tungsten oxide precursor is ammonium metatungstate hydrate (Ammonium metatungstate, (NH ₄ ) ₆ H ₂ W ₁₂ O ₄ 0 xH ₂ O), ammonium tungstate (Ammonium tungstate, (NH ₄ ) ₁₀ H ₂ (W ₂ O) ₇ ) ₆ ) Ammoniumparatungstate hydrate (Ammoniumparatungstate, (NH ₄ ) ₁₀ (H ₂ W ₁₂ O ₄₂ )·4H ₂ O) and tungsten oxide (WO ₃ ) includes at least one selected from the group consisting of Method for producing a selective reduction catalyst, characterized in that for. According to claim 15,
step (b)
(b-1) preparing a first precursor solution containing the vanadium oxide precursor; and
(b-2) preparing a second precursor solution containing the tungsten oxide precursor; Method for producing a selective reduction catalyst comprising a. According to claim 18,
In step (b-1), the first precursor solution is selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, serveric acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid and terephthalic acid Method for producing a selective reduction catalyst, characterized in that it further comprises at least one selected from.

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