KR102469119B1 - Phosphorylated Metal Vanadate Catalysts for Nitrogen oxides Reduction - Google Patents

Abstract

According to one aspect of the present invention, an active point containing at least one of metal vanadate salts represented by [Formula 1], [Formula 2], [Formula 3] or [Formula 4]; and a carrier on which the active point is supported. A catalyst for nitrogen oxide reduction in which a portion of metal vanadate is functionalized with H _{3 -A} PO ₄ ^A- (A = 1, 2 or 3) is provided.
[Formula 1]
(RM)VO ₄ (RM is at least one selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu)
[Formula 2]
La V ₃ O ₉
[Formula 3]
(TM) V _X O _5+X (X is 1, 2 or 3; TM is one or more selected from the group consisting of Mn, Co, Ni and Cu)
[Formula 4]
FeVO ₄ or Fe ₂ V ₄ O ₁₃

Description

Phosphorylated Metal Vanadate Catalysts for Nitrogen oxides Reduction

The present invention relates to a metal vanadate catalyst for nitrogen oxide reduction functionalized with H _{3 -A} PO ₄ ^A- (A = 1, 2 or 3), and specifically, a rare earth metal vanadium as an active site in a support. Nitrogen oxides including rare-earth metal vanadate or transition metal vanadate, wherein a part of the active site is functionalized with H _3-A PO ₄ ^A- (A = 1, 2, or 3) It relates to a heterogeneous catalyst for reduction and a method for preparing the same.

The selective catalytic reduction of NO _X (SCR), which converts nitrogen oxides (NO _X ) and ammonia (NH ₃ ), which are one of the main causes of recent secondary fine dust formation, with high efficiency and stability, is It proceeds through (1) and (2).

4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O . (One)

2NO ₂ + 4NH ₃ + O ₂ → 3N ₂ + 6H ₂ O . (2)

Improvements in the performance, stability, and durability of the above-mentioned SCR process can be achieved through improvement of the surface characteristics of commercial catalysts applied to the SCR process. For example, a representative commercial catalyst applied to the SCR process of power plants, sintering plants, low- and high-speed ships, and cement factories is vanadium oxide-WO ₃ /TiO ₂ (vanadium oxide (V oxide) is V ₂ O ₃ , VO ₂ , V ₂ O ₅ is one or more species selected from). One of the methodologies for improving the surface properties of commercial catalysts can be structural modification of vanadium oxide (V oxide) applied as an active site of commercial catalysts. Specifically, metal vanadate formed by chemical fusion between vanadium oxide and a rare-earth metal (RM) or transition metal (TM) oxide serves as an active site for the SCR reaction. may be desirable. More specifically, metal vanadate is a composite oxide of vanadium and a rare earth metal or transition metal, which is a requirement for improving the active point of vanadium oxide included in the commercial catalyst 1) of the active point of the catalyst during the SCR reaction due to its low melting point. Congregation phenomenon, 2) relatively weak redox cycling trait, 3) relatively small amount of Brφnsted acid site or Lewis acid site, 4) NH ₃ /NO The decrease in SCR reaction efficiency per unit time due to the weak interaction between _X and the acid site or the strong interaction between H ₂ O and the acid site, 5) Absence of fast SCR reaction at low temperature (reaction equation (3)), 6) Lack of durability against catalyst surface poisoning of SO ₂ contained in exhaust gas, 7) Ammonium sulfate (ammonium sulfate) formed during the SCR reaction based on a series of chemical reactions shown in equations (4) to (6) Insufficient durability against catalyst surface poisoning from sulfate, (NH ₄ ) ₂ SO ₄ , AS), ammonium bisulfate ((NH ₄ ) HSO ₄ , ABS), 8) Alkali metals contained in exhaust gas Poor durability against poisoning of catalyst surface of (alkali-metal)-based compound, 9) one of poor durability due to lack of vanadium oxide active site or structural stability of support against hydrothermal aging can solve the problem.

Specifically, in the case of (TM)V _X O _5+X (X= 1, 2, or 3; TM= Mn, Co, Ni, or Cu) or FeVO ₄ /Fe ₂ V ₄ O ₁₃ , a transition metal vanadate, In the case of (RM)VO ₄ (RM= La, Ce, Nd, Sm, Gd, Tb or Er), which is a rare earth metal vanadate and can be improved by one or more of the above bundles 1-7 compared to the catalyst, the above 8 At least one of -9 bundles can be improved, and LaV ₃ O ₉ , which is a rare earth metal vanadate, can be improved at least one of bundles 1 to 9 above.

NO + NO ₂ + 2NH ₃ → 2N ₂ + 3H ₂ O . (3)

SO ₂ + ½ O ₂ → SO ₃ … (4)

SO ₃ + 2NH ₃ + H ₂ O → (NH ₄ ) ₂ SO ₄ … (5)

SO ₃ + NH ₃ + H ₂ O → (NH ₄ )HSO ₄ … (6)

However, in spite of the various advantages that the above-mentioned metal vanadates provide as an active site of the SCR catalyst, the examples reported so far are that the catalyst prepared by dispersing the metal vanadate in the support is 1) applied as it is to the SCR reaction, or 2) It is limited to application after functionalization with SO _B ^2- (B = 3 or 4).

Domestic registered patent 10-2187494

The present invention has been proposed to further improve/maximize the advantages of the metal vanadate as an active site for SCR catalysts provided by the metal vanadate, and the surface of the metal vanadate to H _3-A PO ₄ ^A- (A = 1, 2 or 3) The purpose is to further improve the SCR reaction performance / durability of the catalyst by functionalization. Specifically, preparation of heterogeneous catalysts containing at least one of rare-earth metal vanadate or transition metal vanadate crystal phases as an SCR catalyst active site and some of the active sites as H ₃ Its purpose is to provide a technique for functionalization using _-A PO ₄ ^A- . In addition, the present invention includes oxides of Groups 15 and 16 elements as cocatalysts on the surface of a metal vanadate catalyst functionalized (phosphorylated) with H _3-A PO ₄ ^A- , thereby improving acid character and redox characteristics. (redox cycling feature), poisons (H ₂ O, SO ₂ , AS/ABS, alkali-metal) and degradation (hydro-thermal aging) improved resistance (resistance) of the method for producing a heterogeneous catalyst for SCR reaction intended to provide However, these tasks are exemplary, and the scope of the present invention is not limited thereby.

According to one aspect of the present invention for solving the above problems, an active point containing at least one of metal vanadate salts represented by [Formula 1], [Formula 2], [Formula 3] or [Formula 4]; and a support on which the active point is supported, wherein a portion of the active point is functionalized with H _3-A PO ₄ ^A- (A = 1, 2 or 3), and a catalyst for nitrogen oxide reduction is provided.

[Formula 1]

(RM)VO ₄ (RM is at least one selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu)

[Formula 2]

La V ₃ O ₉

[Formula 3]

(TM) V _X O _5+X (X is 1, 2 or 3; TM is at least one selected from the group consisting of Mn, Co, Ni and Cu)

[Formula 4]

FeVO ₄ or Fe ₂ V ₄ O ₁₃

According to one embodiment of the present invention, a promoter that is an oxide of a group 15 or group 16 element may be further included in the carrier, and the promoter is 10 ^-5 wt% to 50wt% compared to the carrier. may have a composition range of

According to an embodiment of the present invention, the group 15 or group 16 elements include nitrogen (N), phosphorus (P), sulfur (S), arsenic (As), selenium (Se), antimony (Sb), tel It may be any one selected from the group consisting of rurium (Te), bismuth (Bi), polonium (Po), moscobium (Mc), and livermorium (Lv), or a combination thereof.

According to one embodiment of the present invention, the support may include any one of carbon (C), Al ₂ O ₃ , MgO, ZrO ₂ , CeO ₂ , TiO ₂ and SiO ₂ .

According to an embodiment of the present invention, the rare earth metal vanadate represented by [Formula 1] or [Formula 2] or the transition metal vanadate represented by [Formula 3] or [Formula 4] is the carrier 100 It may include 10 ^-4 to 50 parts by weight compared to parts by weight.

According to one embodiment of the present invention, the carrier may have a porous structure.

According to another aspect of the present invention, a method for preparing a catalyst for nitrogen oxide reduction is provided.

According to an embodiment of the present invention, the manufacturing method includes mixing a vanadium precursor solution and a rare earth metal (or transition metal) precursor solution; Injecting a material constituting the carrier into the mixed solution; And one or more of the metal vanadates represented by [Formula 1], [Formula 2], [Formula 3] or [Formula 4] are active points on the support by obtaining a solid from the mixed solution and performing calcination. Preparing a catalyst supported by; Functionalizing a part of the surface of the prepared catalyst by using one or more of phosphorylation groups (H ₂ PO ₄ ^- , HPO ₄ ^2- or PO ₄ ^3- ).

[Formula 1]

(RM)VO ₄ (RM is at least one selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu)

[Formula 2]

La V ₃ O ₉

[Formula 3]

(TM) V _X O _5+X (X is 1, 2 or 3; TM is at least one selected from the group consisting of Mn, Co, Ni and Cu)

[Formula 4]

FeVO ₄ or Fe ₂ V ₄ O ₁₃

According to one embodiment of the present invention, the functionalization with a phosphorylation group may be performed by a reactive gas containing PH ₃ and O ₂ .

According to one embodiment of the present invention, the reaction gas may have a concentration of PH ₃ and O ₂ ranging from 10 ppm to 10 ⁵ ppm.

According to one embodiment of the present invention, the flow rate (flow rate) is 10 ^-5 mL min ^-1 to 10 ⁵ mL min ^-1 , the pressure has a range of 10 ^-5 bar to 10 ⁵ bar, 100 ℃ to 800 ℃ It can be carried out for 0.1 hour to 24 hours at a temperature range of ℃.

According to one embodiment of the present invention, the step of functionalization with a phosphorylation group includes the steps of stirring and drying the synthesis solvent and the catalyst; and flowing a processing gas containing PH ₃ and O ₂ to the surface of the catalyst, wherein the synthesis solvent includes phosphoric acid (H ₃ PO ₄ ); organic phosphoric acid compounds such as ammonium phosphate ((NH ₄ ) ₃ PO ₄ ), diammonium phosphate ((NH ₄ ) ₂ HPO ₄ ), and ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ); or dimethyl phosphite ((CH ₃ O) ₂ HPO), diethyl phosphite ((C ₂ H ₅ O) ₂ HPO), trimethyl phosphite ((CH ₃ O) ₃ P), triethyl phosphite ((C ₂ H ₅ O) ₃ P), triisopropyl phosphite ((C ₃ H ₇ ) ₃ P), triphenyl phosphite ((C ₆ H ₅ O) ₃ P); organic phosphoric acid compounds; have.

According to one embodiment of the present invention, the concentration of the phosphorus precursor contained in the synthesis solvent may have a range of 10 ^-5 mol L ^-1 to 1 mol L ^-1 .

According to one embodiment of the present invention, the stirring may be performed for 0.1 hour to 24 hours.

According to one embodiment of the present invention, in the step of flowing the processing gas to the surface of the catalyst, the concentration of O ₂ in the processing gas may have a range of 10 ⁻⁵ vol% to 50 vol%.
According to one embodiment of the present invention, the step of flowing the processing gas containing PH ₃ and O ₂ to the surface of the catalyst after stirring and drying the synthesis solvent and the catalyst, the temperature range of 100 ℃ to 800 ℃ It may be performed for 0.1 hour to 24 hours.

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According to one aspect of the present invention for solving the above problems, 1) rare earth metals (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) or To prepare a catalyst in which one or more of metal vanadates, which are complex oxides based on the chemical bond of transition metal (Mn, Co, Ni, and Fe) oxides and vanadium (V) oxide, are applied as an active point, 2 ) by applying an oxide of a group 15 or 16 element as a cocatalyst, or 3) functionalizing (phosphorylating) a part of the catalyst surface with H _3-A PO ₄ ^A- (A= 1, 2 or 3) to operate SCR In the process, a catalyst surface with high NO _X conversion and high N ₂ selectivity can be realized. In addition, through functionalization of the catalyst surface using a phosphorylation group, 1) inducing favorable interactions between the metal vanadate active site surface and NO _X , NH ₃ and H ₂ O, 2) improving redox characteristics, 3) Poisoning (SO ₂ , AS, ABS, and alkali-metal) or hydro-thermal aging that may occur during the SCR reaction can improve durability. Based on these advantages, there is an effect of dramatically improving the performance and lifespan of the SCR heterogeneous catalyst. However, these tasks are illustrative, and the scope of the present invention is not limited thereby.

1 is a result of observing the catalysts prepared in Examples 1 to 6 of the present invention using a scanning electron microscope (SEM).
2 is a result of observing the catalysts prepared in Examples 1 to 6 of the present invention with a high resolution transmission electron microscope (HRTEM).
3 is a graph showing selected area electron diffraction patterns (SAED patterns) of the catalysts prepared in Examples 1 to 6 of the present invention.
4 is a graph showing X-ray photo-electron spectroscopy results in the P 2p _3/2 region of the catalysts prepared in Examples 1 to 6 of the present invention.
5 is a result of observing the catalysts prepared in Examples 7 to 10 of the present invention using a scanning electron microscope (SEM).
6 is a result of observing the catalysts prepared in Examples 7 to 10 of the present invention with a high resolution transmission electron microscope (HRTEM).
7 is a graph showing selected area electron diffraction patterns (SAED patterns) of the catalysts prepared in Examples 7 to 10 of the present invention.
8 is a graph showing X-ray photo-electron spectroscopy results in the P 2p _3/2 region of the catalysts prepared in Examples 7 to 10 of the present invention.
9 to 12 are graphs showing SCR performance analysis results of catalysts prepared in Examples and Comparative Examples of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The detailed description of the present invention which follows refers to the accompanying drawings which illustrate, by way of illustration, specific embodiments in which the present invention may be practiced. These embodiments are described in sufficient detail to enable one skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in one embodiment in another embodiment without departing from the spirit and scope of the invention. Additionally, it should be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. Accordingly, the detailed description set forth below is not to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all equivalents as claimed by those claims. Like reference numerals in the drawings indicate the same or similar functions throughout various aspects and may be exaggerated for convenience.

Hereinafter, preferred 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 practice the present invention.

An SCR catalyst according to an embodiment of the present invention includes an active site, which is a region where reactants are adsorbed and products are desorbed after the reaction occurs, and a support supporting the active site.

Catalysts for nitrogen oxide reduction according to an embodiment of the present invention are tetragonal (CeVO ₄ , NdVO ₄ , SmVO ₄ , GdVO ₄ , TbVO ₄ and ErVO ₄ ) represented by the following [Formula 1] rare earth metal vanadate may be included as an active point.

[Formula 1]

(RM)VO ₄ (RM is at least one selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu)

The nitrogen oxide reduction catalysts of the present invention activate at least one selected from tetragonal or monoclinic lanthanum vanadate (LaVO ₄ ) represented by the above [Formula 1] It may be included as a point, or lanthanum vanadate (LaV ₃ O ₉ ) on a monoclinic represented by the following [Formula 2] may be included as an active point.

[Formula 2]

La V ₃ O ₉

Catalysts for reducing nitrogen oxides according to embodiments of the present invention are anorthic (NiV ₂ O ₆ ) phase, monoclinic (Ni ₂ V ₂ O ₇ ) phase, and orthorombiic phase represented by the following [Formula 3]: (orthorhombic; Ni ₃ V ₂ O ₈ ) phase nickel vanadate may be included as an active site.

[Formula 3]

(TM) V _X O _5+X (X is 1, 2 or 3; TM is one or more selected from Mn, Co, Ni or Cu)

Catalysts for reducing nitrogen oxides of the present invention activate iron vanadate on triclinic (FeVO ₄ ) or monoclinic (Fe ₂ V ₄ O ₁₃ ) represented by the following [Formula 4] points can be included.

[Formula 4]

FeVO ₄ or Fe ₂ V ₄ O ₁₃

Catalysts for nitrogen oxide reduction according to embodiments of the present invention are characterized in that some of the catalyst surfaces are functionalized using one or more of phosphorylation groups (H ₂ PO ₄ ^- , HPO ₄ ^2- or PO ₄ ^3- ). However, it is characterized in that it is functionalized without damaging the above-described crystal structure (crystal system).

According to embodiments of the present invention, the active site functionalized with the phosphorylation groups is composed of substantially only metal vanadate. For example, 90% by weight or more of the material constituting the active site may be composed of metal vanadate. It preferably contains 95% by weight or more, more preferably 99% by weight or more, and the balance may be composed of unavoidable materials that may be generated in the manufacturing process.

Unlike the case where conventional SCR catalysts include rare earth metal oxides or transition metal oxides as cocatalysts that increase thermal stability at high temperatures and performance at low and high temperatures, in the embodiment of the present invention, metal vanadate is applied as an active site, By functionalizing some of these surfaces with phosphorylation groups (H _3-A PO ₄ ^A- ; A = 1, 2 or 3), catalyst surfaces with high _NOx conversion and high N ₂ selectivity during SCR operation can be realized. .

In addition, the examples in which a part of the surface of the metal vanadate active point of the present invention is functionalized with phosphorylation groups have excellent SCR catalytic properties compared to the comparative examples consisting only of the surface of the metal vanadate active point, but are poisoned by SO ₂ It can minimize and exhibit excellent resistance to poisons (H ₂ O/SO ₂ /AS/ABS).

The metal vanadate active site in which a part of the surface is functionalized with phosphorylation groups according to the above-described embodiment of the present invention can be prepared by various methods. For example, a physical mixing method such as hydrothermal synthesis, solvothermal synthesis, mechano-chemical method (ball-milling), or non-templated or templated synthesis method. templated synthesis), water impregnation method or dry impregnation method (wet or dry impregnation method), and thermal decomposition method (thermal decomposition method using metal-V based complex).

These vanadate active points may be dispersed in a porous carrier to be described later, and may have a diameter (maximum diameter) of 0.1 nm to 500 μm. In this case, the metal vanadate may have a composition range of 10 ^-4 to 50 parts by weight based on 100 parts by weight of the carrier.

The catalyst for nitrogen oxide reduction according to the embodiment of the present invention described above may further include a promoter (promoter). The active site of the catalyst for reducing nitrogen oxides needs to block the adsorption of sulfur dioxide (SO ₂ ) contained in flue gas or show low performance in the oxidation reaction of sulfur dioxide (SO ₂ ). Ammonia (NH ₃ ) applied as a reducing agent reacts with sulfur trioxide (SO ₃ ) according to the following chemical equations (4) to (6) to form ammonium sulfate-based poisons (ammonium sulfate or ammonium bisulfate) on the catalyst surface. After precipitating, ammonium sulfate can be irreversibly adsorbed on the active site of the catalyst at a low temperature of 300°C or lower. Ammonium sulfate adsorbed on the catalyst surface can reduce the SCR activity per unit time of the catalyst by interfering with the adsorption of nitrogen oxides (NO _X ) and ammonia, a reducing agent. In addition, sulfur trioxide (SO ₃ ) formed by oxidation of sulfur dioxide combines with water vapor contained in flue gas to generate sulfuric acid (H ₂ SO ₄ ) and may cause a problem of corroding the system at the end of the SCR process.

SO ₂ + 1/2 O ₂ → SO _{3 . . .} (4)

SO ₃ + 2NH ₃ + H ₂ O → (NH ₄ ) ₂ SO _{4 …} (5)

SO ₃ + NH ₃ + H ₂ O→ (NH ₄ )HSO _{4 …} (6)

The promoter may play a role of improving resistance to poisoning of the catalyst surface by poisoning substances such as sulfur dioxide (SO ₂ ) or ammonium sulfate, which may occur during the SCR reaction. For example, the promoter can reduce the binding energy between sulfur dioxide (SO ₂ ) and the surface of the catalyst. Due to this, it is also possible to minimize the oxidation reaction of sulfur dioxide (SO ₂ ) (reaction formula 4) that may occur during the low-temperature SCR reaction. In addition, sulfur dioxide and ammonia react to minimize the amount of ammonium sulfate (AS, Reaction Formula 5) or ammonium bisulfate (ABS, Reaction Formula 6) adsorbed on the catalyst surface, thereby poisoning the catalyst surface and reducing the SCR activity per unit time of the catalyst. can prevent In addition, the promoter may be added as a component of the catalyst surface capable of decomposing the above-described AS and ABS at low temperatures.

The promoter includes an oxide of a group 15 or group 16 element. The Group 15 or Group 16 elements include nitrogen (N), phosphorus (P), sulfur (S), arsenic (As), selenium (Se), antimony (Sb), tellurium (Te), bismuth (Bi), It may be at least one or a combination thereof selected from the group consisting of polonium (Po), moscobium (Mc), and livermorium (Lv). The promoter may include 10 ^-5 to 50 parts by weight, preferably 5 parts by weight or less, and more preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the carrier.

The supporter serves to disperse and support the metal vanadate and the promoter. The active site of the catalyst must have high redox characteristics for smooth adsorption and conversion of nitrogen oxides (NO _X ). At this time, when the catalyst is prepared by supporting the vanadate on an appropriate support, highly reactive oxygen (O ₂ ) species present in the support can be smoothly supplied to the active point. That is, the oxidation-reduction characteristics of the catalyst can be improved. At the same time, when the vanadate is prepared in a highly dispersed form in the support, the catalyst efficiency can be further improved. Therefore, it is possible to prepare a catalyst for reducing nitrogen oxides, including a carrier having characteristics capable of providing the above environment.

The carrier may include carbon (C) or a metal oxide. The metal oxide may be any one selected from Al ₂ O ₃ , MgO, ZrO ₂ , CeO ₂ , TiO ₂ and SiO ₂ .

A catalyst for nitrogen oxide reduction according to an embodiment of the present invention may be composed of a morphology having a large surface area. The wider the surface area, the faster the adsorption of nitrogen oxide or ammonia, which is a reactant, and the higher the reaction rate, thereby increasing the efficiency of nitrogen oxide (NO _X ) reduction. In order to secure such a large surface area, the catalyst may have a porous structure. For example, a porous structure with a large surface area can be implemented by configuring the carrier as an agglomerate obtained by calcining a powder material.

The catalyst for nitrogen oxide reduction according to an embodiment of the present invention may be functionalized by phosphorylating its surface. Phosphorylation treatment according to the present invention means functionalization of the catalyst with H _3-A PO ₄ ^A- (A=1, 2 or 3). In the present specification, “functionalization” may refer to a process of improving catalyst performance by increasing the number of active sites of the catalyst or improving properties such as adsorption of reactants and catalysts. For example, when the catalyst for nitrogen oxide reduction according to the present invention is phosphorylated and functionalized with H _3-A PO ₄ ^A- , a catalyst surface that is advantageous for adsorption and conversion of nitrogen oxides can be realized, and new active sites are formed. You may.

Characteristics of Brφnsted acid sites inherent in H _3-A PO ₄ ^A- species bound to metal species on the surface through phosphorylation treatment of the catalyst surface and functionalization by H ₃ -A PO ₄ ^A- can be adjusted. Specifically, among the H _3-A PO ₄ ^A- species present on the catalyst surface, H ₂ PO ₄ ^- has a greater amount of adsorbing ammonia (NH ₃ ), a reducing agent, compared to HPO ₄ ^2- and PO ₄ ^3- can provide a Brφnsted acid site of The SCR reaction performance of the catalyst may be influenced by the distribution of the H ₂ PO ₄ ^- , HPO ₄ ^2- and PO ₄ ^3- on the catalyst surface.

At this time, the phosphorylation treatment of the present invention may be performed by a reactive gas containing PH ₃ and O ₂ . And, the reactive gas has a concentration of PH ₃ and O ₂ in the range of 10 ppm to 10 ⁵ ppm, a flow rate of 10 ^-5 mL min ^-1 to 10 ⁵ mL min ^-1 , and a pressure of 10 ^-5 bar to 10 ⁵ bar. And, the phosphorylation treatment may be performed for 0.1 hour to 24 hours at a temperature range of 100 ℃ to 800 ℃.

In addition, the phosphorylation treatment according to an embodiment of the present invention is phosphoric acid (phosphoric acid, H ₃ PO ₄ ), ammonium phosphate ((NH ₄ ) ₃ PO ₄ ), ammonium phosphate bibasic, (NH ₄ ) ₂ HPO ₄ ), ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ), dimethyl phosphite ((CH ₃ O) ₂ HPO), diethyl phosphite ((C ₂ H ₅ O) ₂ HPO), trimethyl phosphite ((CH ₃ O) ₃ P), triethyl phosphite (C ₂ H ₅ O) ₃ P), triisopropyl phosphite (C ₃ H ₇ ) ₃ P), triphenyl phosphite Phosphoric acid such as triphenyl phosphite ((C ₆ H ₅ O) ₃ P), organic phosphate, organic phosphite, etc., and a synthetic solvent containing a phosphorus precursor and catalyst are stirred and dried. , it can be carried out by flowing the processing gas to the surface of the catalyst at a predetermined flow rate/pressure/temperature for a specific period of time.

And the concentration of the phosphorus precursor contained in the synthesis solvent is in the range of 10 ^-5 mol L ^-1 to 1 mol L ^-1 , but may be stirred for 0.1 hour to 24 hours, and the concentration of O ₂ in the treatment gas is 10 ^- It may range from ⁵ vol% to 50 vol%. And, the phosphorylation treatment may be performed for 0.1 hour to 24 hours at a temperature range of 100 ℃ to 800 ℃.

When the conditions for phosphorylating the catalyst are less than the above range, the H _{3 -A} PO ₄ ^A- functionalization effect of the catalyst may be insufficient. In addition, when the above range is exceeded, the oxidation-reduction characteristics of the catalyst surface are increased during the SCR reaction by excessive functionalization of the surface of the support or NO ₂ production efficiency for fast SCR reaction of Equation (3) below Oxygen species (O _α ) that enhance the can be extinguished. Therefore, the phosphorylation treatment of the catalyst can be carried out within the range of the conditions described above.

NO + NO ₂ + 2NH ₃ → 2N ₂ + 3H ₂ O . (3)

The catalyst surface modified by phosphorylation includes H _3-A PO ₄ ^A- (A = 1, 2 or 3) functional groups having the characteristics of a Bronsted acid site, which are ammonia (NH ₃ ) to react with H _3-A PO ₄ ^A— … NH ₃ form additional species. That is, the functionalized catalyst by phosphorylation treatment according to the present invention can increase the number of Bronsted acid sites compared to the non-functionalized catalyst. In addition, the catalyst modified by functionalization using H ₃ -A PO ₄ ^A- can increase the oxidation/reduction characteristics compared to the non-functionalized catalyst by additionally forming 'metal-H _3-A PO ₄ ^A- ' species. have. In addition, the 'metal-H _{3 -A} PO ₄ ^A- ' species can improve the production efficiency of NO ₂ for the fast SCR reaction of Equation (3).

That is, H _3-A PO ₄ ^A- (A = 1, 2 or 3) Depending on functionalization (phosphorylation) conditions, the number of acid sites is adjusted, or reactants (NO _X and NH ₃ )/poisoning agents (AS and ABS) ) and the binding strength can be adjusted. On the other hand, when the structure/type of metal vanadate active sites favorable to the SCR reaction is changed, 1) a catalyst for improving the NO _X turnover cycle efficiency and the NO oxidation efficiency desirable for the fast SCR reaction The number/strength of Roensted acid sites can be varied, and 2) the number/strength of Lewis acid sites unsaturated with multiple coordinating bonds can be varied.

Hereinafter, a method for preparing a catalyst for nitrogen oxide reduction according to an embodiment of the present invention will be described.

First, a vanadium precursor solution and a rare earth metal (or transition metal) precursor solution are prepared, and then a mixed solution is prepared by mixing them. After sufficiently stirring the mixed solution, hydrothermal synthesis or dehydration is performed to obtain a solid, followed by calcination to prepare a catalyst for reducing nitrogen oxides in which metal vanadate is dispersed.

At this time, the type of compound (oxalic acid or ethylenediaminetetraacetic acid) capable of coordinating with vanadium ion (V ⁵⁺ ) is diversified, or the pH of the mixed solution is adjusted to disperse active points of metal vanadate having various crystal phases on the support. can make it

In the above-described preparation method, a promoter may be formed in the catalyst by using a support added to the mixed solution as a group 15 or group 16 element incorporated therein. For example, a carrier mixed with a promoter can be prepared by mixing powder of a material constituting the carrier with a solution in which a compound of a group 15 or group 16 element is dissolved, followed by stirring and dehydration and calcining.

After the catalyst is prepared, a H _{3 -A} PO ₄ ^A- functionalization step may be added to improve the catalyst properties. The H _3-A PO ₄ ^A- functionalization can be performed by introducing/exposing a process gas containing PH ₃ and O ₂ to the surface of the catalyst at a predetermined flow rate/pressure/temperature for a specific time. Table 1 below shows a range of conditions for H _{3 -A} PO ₄ ^A- functionalization.

PH ₃ content
(ppm) O ₂ content
(vol%) exposure time
(h) processing temperature
(℃) 10 to 10 ⁵ 10 ^-5 to 90 0.1 to 24 200 to 800

In introducing and exposing the treatment gas containing PH ₃ and O ₂ to the surface of the catalyst, the H _{3 -A} PO ₄ ^A- functionalization conditions are 200°C temperature, 0.1 hour, 10 ppm PH ₃ , or 10 ^-5 In the case of less than vol% of oxygen (O ₂ ), the effect of H _3-A PO ₄ ^A- functionalization on the catalyst surface may be insignificant. On the other hand, when the temperature of 800 ℃ or 24 hours, 10 ⁵ ppm of PH ₃ , or 90 vol% of oxygen (O ₂ ) exceeds, the surface of the carrier is excessively functionalized with H _3-A PO ₄ ^A- , resulting in an SCR reaction. Oxygen (O _α ) species that increase the activity of may be extinguished. Thus, H _3-A PO ₄ ^A- functionalization of the catalyst surface can be carried out between the above conditions.

In addition, for H _3-A PO ₄ ^A- functionalization, phosphoric acid (H ₃ PO ₄ ), ammonium phosphate (NH ₄ ) ₃ PO ₄ ), ammonium phosphate bibasic (NH 4 ) ₄ ) ₂ HPO ₄ ), ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ), dimethyl phosphite ((CH ₃ O) ₂ HPO), diethyl phosphite (C ₂ H ₅ O) ₂ HPO), trimethyl phosphite (CH ₃ O) ₃ P), triethyl phosphite (C ₂ H ₅ O) ₃ P), triisopropyl phosphite, (C ₃ H ₇ ) ₃ P), phosphoric acid such as triphenyl phosphite (C ₆ H ₅ O) ₃ P), organic phosphate or organic phosphite, etc. It can be carried out by stirring and drying the synthetic solvent containing the phosphorus precursor and the catalyst, and then injecting and exposing the processing gas to the surface of the catalyst at a predetermined flow rate/pressure/temperature for a specific time. Table 2 below shows a range of conditions for H _{3 -A} PO ₄ ^A- functionalization.

phosphorus precursor concentration
(mol L ^-1 ) stirring time
(h) O ₂ content
(vol %) exposure time
(h) processing temperature
(℃) 10 ^-5 to 1 0.1 to 24 10 ^-5 to 50 0.1 to 24 100 to 800

After stirring and drying the synthetic solvent containing the phosphorus precursor and the catalyst, injecting and exposing the processing gas, the H _3-A PO ₄ ^A- functionalization condition is 10 ^-5 mol L ^-1 of the phosphorus precursor, stirring for 0.1h time, 10 ^-5 vol% of oxygen (O ₂ ), 0.1 h exposure time, and less than 100 °C temperature, the effect of H _{3 -A} PO ₄ ^A- functionalization on the catalyst surface may be insignificant. On the other hand, 1 mol L ^-1 of the phosphorus precursor, 24h stirring time, 50vol% of oxygen (O ₂ ), 24h exposure time, when the temperature exceeds 800 ℃, the surface of the support is excessively H _3-A PO ₄ ^A- Oxygen (O _α ) species that are functionalized to increase the activity of the SCR reaction can be eliminated. Thus, H _3-A PO ₄ ^A- functionalization of the catalyst surface can be carried out between the above conditions.

Hereinafter, embodiments for better understanding of the present invention will be described. However, the following examples are only for helping understanding of the present invention, and the embodiments of the present invention are not limited to only the following examples.

Comparative Example 1-6: Preparation of Ce, Nd, Sm, Gd, Tb and Er Catalysts

3.93 mmol of rare earth metal precursor (Ce ₍ NO ₃ ) ₃ 6H ₂ O for Ce; Nd _{(NO 3 ) 3 6H 2 O} ) for Nd; Sm(NO ₃ ) ₃ 6H ₂ O for Sm; Gd(NO ₃ ) ₃ 6H ₂ O for Gd; Tb(NO ₃ ) ₃ 5H ₂ O for Tb; 60mL of distilled water in which Er(NO ₃ ) ₃ .5H ₂ O for Er) was dissolved was added and stirred. Then, anatase TiO ₂ powder (support; 9.25 g for Ce; 9.23 g for Nd; 9.21 g for Sm; 9.18 g for Gd; 9.18 g for Tb; 9.14 g for Er) was added to the mixed solution, and the pH While maintaining at 8, stir at room temperature for 4 hours. The prepared mixed solution is dehydrated and dried. Finally, the dried synthetic intermediate is calcined at 500° C. for 5 hours. Catalysts were prepared according to the above conditions, and they were respectively Ce (Comparative Example 1), Nd (Comparative Example 2), Sm (Comparative Example 3), Gd (Comparative Example 4), Tb (Comparative Example 5) and Er (Comparative Example). Example 6).

Example 1-6: Preparation of Ce-P, Nd-P, Sm-P, Gd-P, Tb-P and Er-P catalysts

3 g of the catalysts of Comparative Examples 1 to 6 were added to 250 mL of distilled water in which 2.25 mmol of (NH ₄ ) ₂ HPO ₄ was dissolved, and stirred at room temperature for 18 hours. After dehydrating and drying the prepared mixed solution, calcination is performed at 500° C. for 1 hour. Catalysts were prepared according to the above conditions, and these were respectively Ce-P (Example 1), Nd-P (Example 2), Sm-P (Example 3), Gd-P (Example 4), Tb- They were named P (Example 5) and Er-P (Example 6).

Comparative Example 7-9: Ni _One , Ni ₂ and Ni ₃ Preparation of Catalysts

60 mL of nickel precursor (Ni(NO ₃ ) ₂ 6H ₂ O of 0.98 mmol for Ni ₁ ; 1.96 mmol for Ni ₂ ; 2.94 mmol for Ni ₃ ) dissolved in 140 mL of distilled water in which 1.96 mmol of NH ₄ VO ₃ was dissolved. of distilled water was added and stirred. Then, anatase TiO ₂ powder (support; 4.84g for Ni ₁ ; 4.78g for Ni ₂ ; 4.73g for Ni ₃ ) was added to the mixed solution, and the mixture was stirred at room temperature for 4 hours. The prepared mixed solution is dehydrated and dried. Finally, the dried synthetic intermediate is calcined at 500° C. for 5 hours. Catalysts were prepared according to the above conditions, and were named as Ni ₁ (Comparative Example 7), Ni ₂ (Comparative Example 8) and Ni ₃ (Comparative Example 9), respectively.

Examples 7-9: Ni _One -P, Ni ₂ -P and Ni ₃ Preparation of -P catalysts

3 g of the catalysts of Comparative Examples 1 to 6 were added to 200 mL of distilled water in which 0.44 mmol of (NH ₄ ) ₂ HPO ₄ was dissolved, and stirred at room temperature for 18 hours. After dehydrating and drying the prepared mixed solution, calcination is performed at 500° C. for 1 hour. Catalysts were prepared according to the above conditions, and were named as Ni ₁ -P (Example 7), Ni ₂ -P (Example 8) and Ni ₃ -P (Example 9), respectively.

Comparative Example 10: Ni _One -Preparation of Sb catalyst

100mL of an acetic acid solution (acetic acid) in which 12.32mmol of Sb(CH ₃ COO) ₃ was dissolved was added to 250ml of distilled water to which 48.5g of TiO ₂ was added, and after stirring and dehydration, it was calcined at 500°C for 5 hours. ) treatment to prepare a TiO ₂ carrier (Sb/TiO ₂ ) incorporating 3 wt% of Sb. Sb/TiO ₂ was used, but after preparing a catalyst under the same conditions as in Comparative Example 7, it was named Ni ₁ -Sb of Comparative Example 10.

Example 10: Ni _One -Preparation of Sb-P catalyst

3 g of the catalyst of Comparative Example 10 was added to 200 mL of distilled water in which 0.44 mmol of (NH ₄ ) ₂ HPO ₄ was dissolved, and stirred at room temperature for 18 hours. After dehydrating and drying the prepared mixed solution, calcination is performed at 500° C. for 1 hour. The catalyst of Example 10 was prepared according to the above conditions, and it was named Ni ₁ -Sb-P.

Experimental Example 1: Characterization of Catalysts

The surface morphology of the catalysts prepared in Examples 1 to 6 was analyzed using scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM), and The results are shown in FIGS. 1 and 2, respectively.

Referring to FIGS. 1 and _{2, it can be confirmed that the prepared catalysts constitute a porous carrier of TiO 2 agglomerate} having a particle size (maximum diameter) of several hundred nanometers to several hundred micrometers, respectively. there was.

In order to confirm the degree of porosity of the catalysts corresponding to Examples 1 to 6, N ₂ physisorption experiments were performed to measure the BET surface area and BJH pore volume. In addition, components of the catalysts prepared in Examples 1 to 6 were analyzed using X-ray fluorescence (XRF). Table 3 shows the measurement results.

BET surface area BJH pore volume V content (wt.%) RM/V (molar ratio) P/(RM+V)
(molar ratio) Example 1 68.8 m ² g ^-1 0.3 cm ³ g ^-1 1.9 (± 0.1) 1.0 (± 0.1) 0.5 (± 0.1) Example 2 72.1 m ² g ^-1 0.2 cm ³ g ^-1 2.0 (± 0.1) 1.0 (± 0.2) 0.5 (± 0.1) Example 3 73.7 m ² g ^-1 0.3 cm ³ g ^-1 2.0 (± 0.1) 1.0 (± 0.1) 0.5 (± 0.1) Example 4 70.7 m ² g ^-1 0.3 cm ³ g ^-1 2.0 (± 0.1) 1.0 (± 0.1) 0.5 (± 0.1) Example 5 66.2 m ² g ^-1 0.3 cm ³ g ^-1 2.0 (± 0.1) 1.0 (± 0.1) 0.5 (± 0.1) Example 6 68.2 m ² g ^-1 0.3 cm ³ g ^-1 2.0 (± 0.1) 1.0 (± 0.1) 0.6 (± 0.1)

From the BET surface area and BJH pore volume results, it was confirmed that the catalysts prepared in Examples 1 to 6 had a porous structure. In addition, the V content of the catalysts was almost the same as 2wt% based on the total weight of the catalyst.

It was found that the molar ratios of RM/V of the catalysts of Examples 1 to 6 had values close to 1, which is a theoretical molar ratio. Through this, it was confirmed that the RMVO ₄ on the surfaces of the catalysts of Examples 1 to 6 were successfully dispersed in the porous TiO ₂ carrier. In addition, it was found that the molar ratios of P/(RM+V) of the catalysts of Examples 1 to 6 had almost the same values of about 0.5. This means that the functionalization of the catalyst surfaces of Examples 1 to 6 by H _3-A PO ₄ ^A- proceeded to a similar extent.

Crystal structures of the catalysts of Examples 1 to 6 were analyzed using a selected area electron diffraction pattern (SAED pattern), and the results are shown in FIG. 3 .

Referring to FIG. 3, in the case of the catalyst of Example 1, (1 0 3) and (1 0 1) crystal planes of tetragonal CeVO ₄ were observed, and in the case of the catalyst of Example ₂ , (1 0 3) of (1 0 3), (1 0 1) crystal planes were observed. In addition, in the case of the catalyst of Example 3, (1 0 3) and (1 0 1) crystal planes of tetragonal SmVO ₄ were observed, and in the case of the catalyst of Example 4, (1 0 3) and (1 0 1) of tetragonal GdVO ₄ were observed. ) crystal planes were observed. Also, (1 0 3) and (1 0 1) crystal planes of tetragonal TbVO ₄ were observed in the case of the catalyst of Example 5, and (1 0 3) and (1 0 1) of tetragonal ErVO ₄ in the case of the catalyst of Example 6. ) crystal planes were observed. In addition, all of Examples 1 to 6 have a tetragonal crystal structure, which means a TiO ₂ support, and the crystal faces corresponding to the anatase phase of TiO ₂ (1 1 2), (2 2 0), ( 2 1 1) or (1 0 1).

As shown in FIG. 3 , in Examples 1 to 6, patterns of materials other than rare earth metal vanadate, for example, vanadium oxide or rare earth metal oxide, were not observed. That is, in Examples 1 to 6 of the present invention, it can be confirmed that vanadium oxide and rare earth metal oxide constitute one composite oxide (rare earth metal vanadate), and that vanadium oxide and rare earth metal oxide exist separately and are not mixed. can

The H _3-A PO ₄ ^A- functional group distribution on the catalyst surfaces of Examples 1 to 6 was analyzed in the 2P _3/2 region using X-ray photo-electron spectroscopy, and the results are shown in FIG. did It can be seen that the catalyst surfaces of Examples 1 to 6 are functionalized with H ₂ PO ₄ ^- , HPO ₄ ^2- or PO ₄ ^3- . Importantly, it can be seen that the relative content of the H ₂ PO ₄ ^- functional group increases in the order of Tb-P~Er~P < Sm-P < Nd-P < Gd-P < Ce-P, which indicates that the catalyst surface It means that the number of Bronsted acids present in increases in the order of Tb-P~Er~P < Sm-P < Nd-P < Gd-P < Ce-P.

The surface morphology of the catalysts prepared in Examples 7 to 10 was analyzed using scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The results are shown in FIGS. 5 and 6, respectively.

Referring to FIGS. 5 and 6, it can be confirmed that TiO ₂ aggregates (TiO ₂ agglomerate) having a particle size (maximum diameter) of several hundred nanometers to several hundred micrometers constitute a porous carrier in the prepared catalysts. there was.

In order to confirm the porosity of the catalysts corresponding to Examples 7 to 10, N ₂ physisorption experiments were performed to measure the BET surface area and BJH pore volume. In addition, components of the catalysts prepared in Examples 7 to 10 were analyzed using X-ray fluorescence (XRF). Table 4 shows the measurement results.

BET surface area BJH pore volume V content (wt.%) Ni/V (molar ratio) P/(Ni+V)
(molar ratio) Example 7 71.0 m ² g ^-1 0.3 cm ³ g ^-1 2.0 (± 0.1) 0.4 (± 0.1) 0.2 (± 0.1) Example 8 71.3 m ² g ^-1 0.3 cm ³ g ^-1 2.0 (± 0.1) 0.9 (± 0.1) 0.2 (± 0.1) Example 9 74.1 m ² g ^-1 0.3 cm ³ g ^-1 2.0 (± 0.1) 1.5 (± 0.1) 0.2 (± 0.1) Example 10 82.0 m ² g ^-1 0.3 cm ³ g ^-1 2.0 (± 0.1) 0.5 (± 0.1) 0.2 (± 0.1)

From the BET surface area and BJH pore volume results, it was confirmed that the catalysts prepared in Examples 7 to 10 had a porous structure. In addition, the V content of the catalysts was almost the same as 2wt% based on the total weight of the catalyst.

The molar ratios of Ni/V of the catalysts of Examples 7 to 10 are theoretical molar ratios of 0.5 (Example 7; NiV ₂ O ₆ ), 1 (Example 8; Ni ₂ V ₂ O ₇ ), It was found to have values close to 1.5 (Example 9; Ni ₃ V ₂ O ₈ ) and 0.5 (Example 10; NiV ₂ O ₆ ). Through this, it was confirmed that nickel vanadate salts were successfully dispersed in the porous TiO ₂ carrier on the surfaces of the catalysts of Examples 7 to 10. In addition, it was found that the molar ratios of P/(Ni+V) of the catalysts of Examples 7 to 10 had almost the same values of about 0.2. This means that the functionalization of the catalyst surfaces of Examples 7 to 10 by H _3-A PO ₄ ^A- proceeded to a similar extent.

Crystal structures of the catalysts of Examples 7 to 10 were analyzed using a selected area electron diffraction pattern (SAED pattern), and the results are shown in FIG. 7 .

Referring to FIG. 7, in the case of the catalyst of Example ₇ , (-1 ₁ 0), (1 1 0), (0 2 0), (0 1 1), (0 2 1) and (1 -2 1) crystal planes were observed, and in the case of the catalyst of Example 8, (-1 1 1), (0 0 2), (1 1 1), (-2 1 2) of monoclinic Ni ₂ V ₂ O ₇ ) and (1 3 0) crystal planes were observed, and in the case of the catalyst of Example 9, (0 2 0), (0 2 1) and (1 1 2) crystal planes of orthorhombic Ni ₃ V ₂ O ₈ were observed. Example 10 In the case of a catalyst, the (-1 0 1), (0 2 1), (1 -2 1) and (-1 _-2 1) crystal planes of anorthic NiV ₂ O ₆ or ( ₄ 0 0) crystal faces were observed. In addition, Examples 7 to 10 all show crystal planes (1 0 1) and (0 0 4) corresponding to the anatase phase of TiO ₂ having a tetragonal crystal structure, which means a TiO ₂ support. was

As shown in FIG. 7, in Examples 7 to 10, patterns of materials other than nickel vanadate, for example, vanadium oxide or nickel oxide, were not observed. That is, in Examples 7 to 10 of the present invention, it can be confirmed that vanadium oxide and nickel oxide constitute one composite oxide (nickel vanadate), and vanadium oxide and nickel oxide are separately present and not mixed.

The H _3-A PO ₄ ^A- functional group distribution on the catalyst surfaces of Examples 7 to 10 was analyzed in the 2P _3/2 region using X-ray photo-electron spectroscopy, and the results are shown in FIG. did It can be seen that the catalyst surfaces of Examples 7 to 10 are functionalized with H ₂ PO ₄ ^- , HPO ₄ ^2- or PO ₄ ^3- . Importantly, the relative content of H ₂ PO ₄ ^- functional groups is Ni ₃ -P (34.2%) < Ni ₂ -P (38.5%) < Ni ₁ -P (45.3%) < Ni ₁ -Sb-P (66.1%). ), which indicates that the number of Bronsted acids present on the catalyst surface increases in the order of Ni ₃ -P < Ni ₂ -P < Ni ₁ -P < Ni ₁ -Sb-P it means.

Hereinafter, the SCR performance analysis results of the catalysts according to Examples 1 to 10 and Comparative Examples 1 to 10 of the present invention will be described with reference to FIGS. 9 to 12 .

Experimental Example 2: Performance analysis of SCR reaction (1)

The performance of the SCR process was measured using the catalysts of Examples 1 to 6 and Comparative Examples 1 to 6. Performance of the catalysts described above at a space velocity of 60,000 ^{hr -1} under a reaction fluid containing 800 ppm NO _x , 800 ppm NH ₃ , 3 vol % O ₂ , 6 vol % H ₂ O and N ₂ as an inert gas. was measured, and FIG. 9 shows the NO _x conversion result. All catalysts exhibited 100% nitrogen selectivity in the temperature range of 150°C-400°C. On the other hand, referring to FIG. 6, the catalysts of Examples 2 to 6 functionalized with H _{3 -A} PO ₄ ^A- were not functionalized with H 3-A PO ₄ ^A- and were not functionalized with the catalysts of Comparative Examples 2 to 6. It can be seen that higher NO _X values are shown at 150 ° C - 400 ° C compared to This means that the functionalization of rare earth metal vanadate with H _3-A PO ₄ ^A- is effective in increasing the number of Bronsted acids for adsorption of NH ₃ , and the “metal-H _3-A PO ₄ ^A- ” bond This means that it is effective in enhancing the redox characteristics of the catalyst surface. On the other hand, the catalyst of Example ₁ containing _{CeVO 4} functionalized with H _{3 -A} PO ₄ ^A- was 150 ° ^C- It can be seen that at 400 ℃ shows a smaller NO _X value. This means that it is important to select a rare earth metal vanadate active site to improve SCR performance by H _{3 -A} PO ₄ ^A- functionalization.

FIG. 10 shows NO _X conversion rates at 250° C. and 350° C. of the catalysts of Examples 1 to 6 obtained in FIG. 9 . In the case of rare earth metal vanadate active sites, when functionalized with H _3-A PO ₄ ^A- , it can be seen that CeVO ₄ and GdVO ₄ are most preferred for improving SCR performance. This is consistent with the results of X-ray photo-electron spectroscopy in the 2P _3/2 region of the catalysts of Examples 1 to 6. Specifically, when functionalization of rare earth metal oxides with H _3-A PO ₄ ^A- , CeVO ₄ and GdVO ₄ have more H ₂ PO ₄ ^- (Brønsted acid) compared to TbVO ₄ , NdVO ₄ , SmVO ₄ and ErVO ₄ . ) functional group, a larger amount of NH ₃ can be adsorbed per unit time during the SCR reaction, and a more favorable surface environment for the reaction of the adsorbed NH ₃ and NO _X is created.

Experimental Example 3: Performance analysis of SCR reaction (2)

The performance of the SCR process was measured using the catalysts of Examples 7 to 10 and Comparative Examples 7 to 10. Performance of the catalysts described above at a space velocity of 60,000 ^{hr -1} under a reaction fluid containing 800 ppm NO _x , 800 ppm NH ₃ , 3 vol % O ₂ , 6 vol % H ₂ O and N ₂ as an inert gas. was measured, and FIG. 11 shows the NO _x conversion result. All catalysts exhibited 100% nitrogen selectivity in the temperature range of 150°C-400°C. On the other hand, referring to FIG. 11, the catalysts of Examples 7 to 10 functionalized with H ₃ -A PO ₄ ^A- were not functionalized with H _3-A PO ₄ ^A- and were not functionalized with the catalysts of Comparative Examples 7 to 10. It can be seen that higher NO _X values are shown at 150 ° C - 400 ° C compared to This means that functionalization of nickel (transition metal) vanadate with H _3-A PO ₄ ^A- is effective in increasing the number of Bronsted acids for adsorption of NH ₃ , and “metal (nickel or vanadium)-H _{3 -A} PO ₄ ^A- means that the "bonding is effective in enhancing the redox properties of the catalyst surface.

In addition, when comparing the SCR performance of Examples 7 to 9, it was found that the catalyst of Example 7 showed the most improved SCR performance. This means that functionalization by H _3-A PO ₄ ^A- is more effective for NiV ₂ O ₆ compared to Ni ₂ V ₂ O ₇ and Ni ₃ V ₂ O ₈ , and SCR by H _3-A PO ₄ ^A- functionalization This means that the preferred selection of the transition metal vanadate active point/crystal phase is important for performance improvement.

In addition, when comparing the performances of Example 7 and Example 10, it can be seen that the catalyst of Example 10 containing Sb as a cocatalyst exhibits increased SCR performance compared to the catalyst of Example 7 containing no Sb as a cocatalyst. This means that the cocatalyst, Sb oxide, is favorable for enhancing the acidity or redox properties of the catalyst surface.

Experimental Example 4: Performance analysis of SCR reaction (3)

The performance of the SCR process was measured using the catalysts of Example 7, Example 10, Comparative Example 7, and Comparative Example 10. At a space velocity of 60,000 ^{hr -1} , a reaction comprising 800 ppm NO _x , 800 ppm NH ₃ , 500 ppm SO ₂ , 3 vol % O ₂ , 6 vol % H ₂ O and the inert gas N ₂ The performance of the catalysts described above was measured under a fluid, and the NO _x conversion results are shown in FIG. 12 . All catalysts exhibited 100% nitrogen selectivity in the temperature range of 150°C-400°C. On the other hand, referring to FIG. 12, it can be seen that the catalyst of Example 7 functionalized with H _{3 -A} PO ₄ ^A- showed higher NO _X values at 150°C-400°C compared to the catalyst of Comparative Example 7 without functionalization. have. This means that functionalization of NiV ₂ O ₆ by H _3-A PO ₄ ^A- enhances resistance to SO ₂ , a poisoning species supplied during the SCR reaction, or AS/ABS, a poisoning species generated. In addition, referring to FIG. 12, it can be seen that the catalyst of Example 10 functionalized with H _3-A PO ₄ ^A- showed NO _X values similar to those of the unfunctionalized catalysts of Comparative Example 10 at 150°C-400°C. have. This means that a Bronsted acid site having the characteristics of SO ₃ ^2- /SO ₄ ^2- was additionally formed on the catalyst surface of Comparative Example 10 by SO ₂ /O ₂ , and the H _3-A PO ₄ ^A presented in the present invention ^- means that can exhibit Brønsted acid properties similar to SO ₃ ^2- /SO ₄ ^2- and resistance to SO ₂ /AS/ABS.

In addition, when comparing the performances of Example 7 and Example 10, it can be seen that the catalyst of Example 10 containing Sb as a cocatalyst exhibits increased SCR performance compared to the catalyst of Example 7 containing no Sb as a cocatalyst. This means that the cocatalyst, Sb oxide, is favorable for further improvement of resistance to SO ₂ /AS/ABS poisoning species on the catalyst surface.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

Claims (16)

an active point containing at least one of metal vanadates represented by [Formula 1] or [Formula 3]; and
Including; a carrier on which the active point is supported,
A catalyst for nitrogen oxide reduction in which some of the active sites are functionalized with H _{3 -A} PO ₄ ^A- (A = 1, 2 or 3).
[Formula 1]
(RM)VO ₄ (RM is at least one selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu)
[Formula 3]
(Ni) _X V ₂ O _5+X (X is 1, 2 or 3) According to claim 1,
Catalyst for nitrogen oxide reduction, further comprising a promoter that is an oxide of a Group 15 or Group 16 element in the support. According to claim 2,
The promoter has a composition range of 10 ^-5 wt% to 50wt% compared to the carrier, nitrogen oxide reduction catalyst. According to claim 2,
The group 15 or group 16 element,
Nitrogen (N), Phosphorus (P), Sulfur (S), Arsenic (As), Selenium (Se), Antimony (Sb), Tellurium (Te), Bismuth (Bi), Polonium (Po), Moscobium ( Mc) and any one selected from the group consisting of liver morium (Lv), or a combination thereof, a catalyst for reducing nitrogen oxides. According to claim 1,
The support is carbon (C), Al ₂ O ₃ , MgO, ZrO ₂ , CeO ₂ , TiO ₂ and SiO ₂ containing any one of, nitrogen oxide reduction catalyst. According to claim 1,
The rare earth metal vanadate represented by [Chemical Formula 1] or the transition metal vanadate represented by [Chemical Formula 3] comprises 10 ^-4 to 50 parts by weight based on 100 parts by weight of the carrier. A catalyst for reducing nitrogen oxides. According to claim 1,
The support is a catalyst for nitrogen oxide reduction that has a porous structure. mixing a vanadium precursor solution and a rare earth metal or transition metal precursor solution;
Injecting a material constituting the carrier into the mixed solution;
A solid material was obtained from the mixed solution and calcined to prepare a catalyst having at least one of a rare earth metal vanadate represented by [Formula 1] or a transition metal vanadate represented by [Formula 3] supported on a support doing; and
Functionalizing a portion of the prepared catalyst with a phosphorylation group (H _3-A PO ₄ ^A- ) (A = 1, 2 or 3); method for producing a catalyst for reducing nitrogen oxides, including.
[Formula 1]
(RM)VO ₄ (RM is at least one selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu)
[Formula 3]
(Ni) _X V ₂ O _5+X (X is 1, 2 or 3) delete delete delete According to claim 8,
The step of functionalization with a phosphorylation group,
Stirring and drying the synthetic solvent and the catalyst,
The synthetic solvent,
phosphoric acid (H ₃ PO ₄ );
organic phosphates such as ammonium phosphate ((NH ₄ ) ₃ PO ₄ ), diammonium phosphate ((NH ₄ ) ₂ HPO ₄ ), and ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ); or
Dimethyl phosphite ((CH ₃ O) ₂ HPO), diethyl phosphite ((C ₂ H ₅ O) ₂ HPO), trimethyl phosphite ((CH ₃ O) ₃ P), triethyl phosphite ((C ₂ organic phosphites such as H ₅ O) ₃ P), triisopropyl phosphite ((C ₃ H ₇ ) ₃ P), and triphenyl phosphite ((C ₆ H ₅ O) ₃ P); Method for producing a catalyst for reducing nitrogen oxides comprising: According to claim 12,
Method for producing a catalyst for nitrogen oxide reduction, characterized in that the concentration of the phosphorus precursor contained in the synthesis solvent has a range of 10 ^-5 mol L ^-1 to 1 mol L ^-1 . According to claim 12,
The stirring step is performed for 0.1 hour to 24 hours,
A method for preparing a catalyst for nitrogen oxide reduction. delete delete

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