KR20240031839A - De-nox catalyst having high durability for sulfur dioxide, manufacturing method of the same, and process for elimination of nitrogen oxides using the same - Google Patents

Abstract

In the denitrification catalyst for removing nitrogen oxides with high durability of sulfur dioxide of the present invention, the manufacturing method thereof, and the method for removing nitrogen oxides using the same, the denitrification catalyst is a selective catalytic reduction using an ammonia reducing agent to remove nitrogen oxides contained in exhaust gas ( It is a quaternary denitrification catalyst consisting of vanadium-molybdenum-antimony-titania applied to selective catalytic reduction (SCR) reaction. Antimony, molybdenum, and vanadium are supported on a titania carrier, and a complex oxide (V _{2 )} of molybdenum and vanadium is supported. It exists in the form of MoO ₈ ).

Description

Denitrification catalyst for removing nitrogen oxides with high durability of sulfur dioxide, manufacturing method thereof, and method for removing nitrogen oxides using the same }

The present invention relates to a denitrification catalyst for removing nitrogen oxides with high sulfur dioxide durability, a method of manufacturing the same, and a method of removing nitrogen oxides using the same.

Recently, nitrogen oxides (NOx) are known to be major air pollutants generated from industrial boilers, thermal power plants, and waste incineration facilities, causing ultrafine dust precursors, photochemical smog, ozone layer destruction, and global warming. Accordingly, various methods for removing nitrogen oxides are being researched and developed, and among these, selective catalytic reduction (hereinafter referred to as “SCR”) technology is widely used. This SCR is a technology in which ammonia, a reducing agent, and nitrogen oxides react on a catalyst to selectively decompose into nitrogen and water.

Denitrification catalysts that can be applied to the SCR reaction using ammonia as a reducing agent can be manufactured in various ways. A variety of catalysts have been proposed, ranging from noble metal catalysts to basic metal catalysts, and it is known that the interaction between the supported active material and the carrier has a significant impact on the denitrification performance. Specifically, vanadium-tungsten-titania and vanadium-molybdenum-titania catalysts, which are commercial catalysts widely used in SCR recently, are reported to exhibit excellent denitrification efficiency at 300 to 400°C.

However, the catalysts commercialized to date have the problem that SCR reaction is difficult at temperatures below 300°C due to low activation energy.

Currently, in Korea, there is increasing interest in applying the SCR process to improve denitrification efficiency as a clean facility for exhaust gases from steel mill sintering plants, cement manufacturing processes, and chemical processes. When using a vanadium-based commercial catalyst (vanadium-tungsten-titania) in the process of applying the existing SCR process to the above application, a process that requires raising the temperature to maintain the temperature of 300 to 400 ℃ is required. Therefore, a catalyst that shows excellent efficiency in a low temperature range below 300°C, which is the temperature of the space where the SCR process can be applied without additional heating of the exhaust gas, is required. In addition, the above process requires a low-temperature SCR catalyst that can be operated for a long time even in exhaust gas conditions containing sulfur dioxide (SO ₂ ) generated during combustion of fossil fuels. A side reaction occurs when sulfur dioxide is present in the exhaust gas, and in this case, sulfur dioxide is oxidized to sulfur trioxide (SO ₃ ) through a catalyst surface oxidation reaction. Sulfur trioxide reacts with ammonia, a reducing agent, and moisture contained in exhaust gas to form the following ammonium sulfate salts (NH ₄ HSO ₄ and (NH ₄ ) ₂ SO ₄ ). This reaction progresses faster as the temperature decreases, and not only does it deposit on the catalyst surface and block the active site, reducing catalyst performance, but also causes corrosion of the lower device and inner walls. In order to suppress the formation of ammonium sulfate salt in the denitrification catalyst layer, sulfur dioxide is removed in the front-end desulfurization facility, but moisture is supplied to improve desulfurization efficiency. At this time, the exhaust gas temperature rapidly decreases, deteriorating the back-end denitrification performance. As an alternative to this, a process to reheat the exhaust gas using a duct burner is required. Considering the generation of secondary pollutants from the fuel used during reheating and the reduction in energy efficiency, this method is not desirable. In addition, even if sulfur dioxide is removed considering economic and environmental regulations, it is difficult to remove 100%, and some sulfur dioxide (several tens of ppm) is present in the exhaust gas, causing deterioration of denitrification catalyst performance. Therefore, a denitrification catalyst that exhibits high efficiency at temperatures below 300°C and has excellent durability against sulfur dioxide is required. Hereinafter, we will look at the technical details of prior literature related to denitrification catalysts applied to the SCR system.

In "Korean Patent No. 10-1426601" (hereinafter referred to as "Prior Art 1") and "Applied Surface Science, 481 (2019) 1167-1177" (hereinafter referred to as "Prior Art 2"), vanadium oxide- A denitrification catalyst consisting of molybdenum oxide and titanium oxide is disclosed. In particular, in order to suppress the formation of ammonium sulfate salt when sulfur dioxide is contained in the exhaust gas, molybdenum oxide contains hexavalent molybdenum (Mo ⁶⁺ ) with an oxidation value of at least 150 atoms/cm ³ and titanium oxide contains trivalent titanium (Ti ³⁺ ). The atomic ratio (Ti ³⁺ /(Ti ⁴⁺ + Ti ³⁺ )) is up to 0.3, and the precursor of titania oxide is non-crystalline metatitanic acid (TiO ₂ ·xH ₂ O).

In "Applied Catalysis A, General 570 (2019) 42-50" (hereinafter referred to as "Prior Art 3"), the denitrification catalyst consisting of vanadium oxide-molybdenum oxide-titanium oxide is polymeric vanadate due to the addition of molybdenum. and a study on the characteristics of improved durability against sulfur dioxide from the enhancement of the Brønsted acid site.

In "Chemical Engineering Journal 294 (2016) 264-272" (hereinafter referred to as "Prior Art 4"), a denitrification catalyst consisting of vanadium oxide-molybdenum oxide-titanium oxide coated on cordierite ceramic honeycomb manufactured by impregnation method. The crystallization and redox properties of vanadium oxide were changed by controlling the amount of active species according to the Mo/V ratio. As the Mo/V ratio was changed from 2 to 8, improved performance exceeded 80% at 350-450°C, and at a Mo/V ratio of 8, durability against sulfur oxides and moisture was partially improved. .

"Catalysis Communications 46 (2014) 90-93" (hereinafter referred to as "Prior Art 5") shows improved denitrification performance by adding molybdenum oxide to cerium oxide-titanium oxide, and especially suppresses the adsorption of sulfur oxide and moisture. This shows research results that improved durability. It is reported that the addition of molybdenum oxide promotes denitrification performance by the formation of Brønsted acid sites and crystallization of cerium oxide.

As described above, current research on catalysts for nitrogen oxide removal improves low-temperature nitrogen oxide removal rate by adding molybdenum to vanadium/titania as in prior art 1 to 3, improves catalytic performance by improving resistance to sulfur dioxide, or improves catalyst performance. , As in prior art 4, research is focused on improving the crystallization and redox ability of oxides by coating vanadium/titania on cordierite ceramic honeycomb, or improving acid site formation and denitrification performance by adding molybdenum to ceria/titania. It is being achieved.

However, for the production of low-temperature, high-activity and high-durability denitrification catalysts, research on methods to improve nitrogen oxide removal activity and sulfur dioxide durability below 300°C by improving notable active sites and oxidation states of active ingredients at low temperatures is being conducted. It is still insufficient. Considering this situation, it can be said that research and development on methods that can actually improve the activity and durability of catalysts in a complex manner are required.

The problem to be solved by the present invention is to provide a denitrification catalyst that exhibits excellent removal activity of nitrogen oxides (NOx) and improved durability against sulfur dioxide in a low temperature range of 300 ° C. or lower.

Another problem to be solved by the present invention is to provide a method for producing the denitrification catalyst.

Another problem to be solved by the present invention is to provide a method for removing nitrogen oxides using the method for producing the denitrification catalyst.

The denitrification catalyst according to the concept of the present invention for achieving the above problem is a vanadium-molybdenum-antioxidant applied to a selective catalytic reduction (SCR) reaction using an ammonia reducing agent to remove nitrogen oxides contained in exhaust gas. It is a quaternary nitrogen denitrification catalyst made of mony-titania, in which antimony, molybdenum, and vanadium are supported on a titania carrier, and exists in the form of a complex oxide (V ₂ MoO ₈ ) in which molybdenum and vanadium are combined.

The method for producing a denitrification catalyst according to the concept of the present invention to achieve the above other problems is to remove nitrogen oxides contained in exhaust gas by using vanadium applied to a selective catalytic reduction (SCR) reaction using an ammonia reducing agent. - A method of producing a quaternary denitrification catalyst consisting of molybdenum-antimony-titania, comprising dissolving 0.5 to 5% by weight of antimony in the form of a precursor in a solvent relative to 100 parts by weight of the catalyst to prepare an aqueous antimony solution, catalyst Preparing a molybdenum aqueous solution by dissolving 0.5 to 10% by weight of molybdenum in the form of a precursor in a solvent relative to 100 parts by weight, dissolving 1 to 5% by weight of vanadium in the form of a precursor in a solvent relative to 100 parts by weight of the catalyst to prepare an aqueous vanadium solution. Preparing a slurry by mixing the prepared aqueous solution of antimony, molybdenum, and vanadium with a titanium oxide carrier, drying the slurry, and then calcining at 300 to 700° C. to produce vanadium-molybdenum-antimony-titania. It includes preparing a catalyst.

The method of removing nitrogen oxides according to the concept of the present invention for achieving the above-mentioned another problem is a method of removing nitrogen oxides from exhaust gas using the denitrification catalyst, wherein the denitrification catalyst is used to remove nitrogen oxides from exhaust gas containing ammonia and nitrogen oxides or ammonia. , allow exhaust gases containing nitrogen oxides and sulfur dioxide to pass through.

According to embodiments of the present invention, the vanadium oxidation rate of the denitrification catalyst is adjusted to adjust the ratio of vanadium (V ⁴⁺ + V ³⁺ ), which corresponds to the sum of tetravalent and trivalent oxidation to the total vanadium among vanadium oxides, to 25. A catalyst that exhibits excellent nitrogen oxide removal efficiency even in the low temperature range of 300°C or lower by maintaining the ratio of molybdenum (Mo ⁶⁺ ), whose oxidation to the total molybdenum among molybdenum oxides is the sum of the hexavalent values, at more than 80%. can be provided.

In addition, it is possible to provide a denitrification catalyst for removing nitrogen oxides that has excellent durability against sulfur dioxide (SO ₂ ) contained in exhaust gas.

Figure 1 shows the ammonia reducing agent of catalysts prepared according to Comparative Preparation Example 1, Comparative Preparation Example 2, Comparative Preparation Example 4, Preparation Example 2, and Comparative Preparation Example 9 in order to evaluate the denitrification performance of the denitrification catalyst according to the present invention. This is a graph showing the results of the denitrification performance evaluation.
Figure 2 is a graph showing the results of evaluating the denitrification performance of the catalysts prepared according to Comparative Preparation Examples 3 to 6 using an ammonia reducing agent in relation to the denitrification performance of the denitrification catalyst of the present invention.
Figure 3 is a graph showing the results of evaluating the denitrification performance of the catalysts prepared according to Preparation Examples 1 to 4 using an ammonia reducing agent to evaluate the denitrification performance of the denitrification catalyst of the present invention.
Figure 4 is a graph showing the results of evaluating the denitrification performance using a reducing agent at 220°C for catalysts prepared according to Comparative Preparation Examples 3 to 6 and Preparation Examples 1 to 4 to evaluate the denitrification performance of the denitrification catalyst of the present invention. am.
Figure 5 is a graph showing the results of evaluating the denitrification performance of the catalysts prepared according to Preparation Example 2 and Preparation Examples 5 to 7 using an ammonia reducing agent to evaluate the denitrification performance of the denitrification catalyst of the present invention.
Figure 6 is a graph showing the results of evaluating the denitrification performance of the catalysts prepared according to Preparation Example 2 and Preparation Examples 8 to 12 using an ammonia reducing agent to evaluate the denitrification performance of the denitrification catalyst of the present invention.
Figure 7 shows sulfur dioxide injection of catalysts prepared according to Comparative Preparation Example 1, Comparative Preparation Example 2, Comparative Preparation Example 4, Preparation Example 2, and Comparative Preparation Example 9 to evaluate the durability of the denitrification catalyst of the present invention against sulfur dioxide. This is a graph showing the results of evaluating denitrification performance using an ammonia reducing agent over time.
Figure 8 shows the This is a graph showing (X-ray diffraction pattern, XRD pattern).
Figure 9 shows the electron diffraction analysis pattern (selected area electron) of catalysts prepared according to Preparation Example 2, Comparative Preparation Example 4, Comparative Preparation Example 7, and Comparative Preparation Example 8 in relation to the electron diffraction analysis pattern of the denitrification catalyst of the present invention. This is a graph showing diffraction patterns (SAED patterns).
Figure 10 shows the total amount of molybdenum oxide using This is a graph showing the ratio of molybdenum (Mo ⁶⁺ ) whose oxidation to molybdenum corresponds to the sum of hexavalent values.
Figure 11 shows catalysts prepared according to Comparative Preparation Example 1, Comparative Preparation Example 2, Comparative Preparation Example 4, and Preparation Examples 1 to 4 to confirm the type and distribution of vanadium oxide formed on the surface of the denitrification catalyst of the present invention. This is a graph showing the ratio of vanadium (V ⁴⁺ + V ³⁺ ) whose oxidation to the total vanadium corresponds to the sum of tetravalent and trivalent vanadium oxides using XPS.
Figure 12 shows the oxidation of all vanadium of catalysts prepared according to Comparative Preparation Example 2 and Preparation Examples 1 to 4 in order to confirm the nitrogen oxide removal efficiency for vanadium oxide distribution according to the molybdenum content contained in the denitrification catalyst of the present invention. This is a graph showing the correlation between the denitrification performance at 220 and 200°C according to the ratio of vanadium (V ⁴⁺ + V ³⁺ ), which is the sum of tetravalent and trivalent vanadium (V 4+ + V 3+ ).
Figure 13 shows the sulfur dioxide adsorption of catalysts prepared according to Comparative Preparation Example 1, Comparative Preparation Example 2, Comparative Preparation Example 4, Preparation Example 2, and Comparative Preparation Example 9 in relation to the sulfur dioxide adsorption amount and durability of the denitrification catalyst of the present invention. This is _a graph showing the correlation with _the arrival time of

Hereinafter, with reference to the attached drawings, the present invention will be described in detail so that those skilled in the art can easily practice it.

The method for manufacturing a denitrification catalyst for nitrogen oxide removal according to the present invention exhibits excellent nitrogen oxide removal efficiency in a low temperature range of 300°C or lower by controlling the oxidation value of vanadium and molybdenum through the addition of antimony and excellent durability against sulfur dioxide. A denitrification catalyst having

The denitrification catalyst can be named ‘vanadium-molybdenum-antimony-titania catalyst’.

Specifically, the vanadium-molybdenum-antimony-titania catalyst can be manufactured by supporting vanadium, molybdenum, and antimony on titania, drying and calcining them. In other words, the physical properties of the vanadium-molybdenum-antimony-titania catalyst can be artificially changed through the addition of a co-catalyst (antimony) to maximize the activity of the catalyst that selectively converts nitrogen oxides and its durability against sulfur dioxide.

At this time, the added molybdenum can be added in different amounts from 1 to 7 wt% by weight of the catalyst to produce the catalyst.

In this case, by adding a cocatalyst, the ratio of vanadium (V ⁴⁺ + V ³⁺ ), which corresponds to the sum of tetravalent and trivalent oxidation of all vanadium in vanadium oxide, is adjusted to 25% or more, and the total oxidation of vanadium in molybdenum oxide is adjusted to 25% or more. The ratio of molybdenum (Mo ⁶⁺ ), which corresponds to the sum of the hexavalent oxidation of molybdenum, can be adjusted to 80% or more.

In addition, when manufacturing a vanadium-molybdenum-antimony-titania catalyst using an impregnation method, the catalyst can be manufactured by changing the method and order of supporting each material, followed by drying and heat treatment.

In addition, the vanadium content as the main catalyst can be added in different amounts from 1 to 5 wt% by weight of the catalyst to produce a vanadium-molybdenum-antimony-titania catalyst.

Here, XPS (X-ray photoelectron spectroscopy) analysis is used as a means to analyze the oxidation state of the supported vanadium. According to XPS analysis, the characteristic peaks of each element present on the catalyst surface are separated based on the unique binding energy of the oxide containing that element, and the type and distribution of the oxide present on the catalyst surface. The ratio can be analyzed, and each fit can be separated by the Gaussian-Lorentzian method. Therefore, according to the You can check it.

Below, based on the above-described information, the manufacturing method of vanadium-molybdenum-antimony-titania and vanadium-molybdenum-titania catalysts will be described in detail.

The vanadium-molybdenum-antimony-titania catalyst is manufactured by introducing antimony, molybdenum, and vanadium precursors into a titania carrier to prepare a mixed slurry, then drying and calcining the mixed slurry. The vanadium-molybdenum-titania catalyst is manufactured by introducing molybdenum and vanadium precursors into a titania carrier to prepare a mixed slurry, then drying and calcining the mixed slurry.

The titania carrier may be amorphous titanic acids _{( TiO}

In addition, the vanadium precursor may be ammonium metavanadate (NH ₄ VO ₃ ) or vanadium oxytrichloride (VOCl ₃ ), and is contained in an amount of 0.5 to 10.0% by weight, preferably 1.0 to 5.0% by weight, based on the titania carrier. It can be. If the vanadium content is less than 1.0% by weight, the effect of removing nitrogen oxides may be insufficient, and if it exceeds 5.0% by weight, the efficiency compared to the increase in content may not be satisfactory.

Meanwhile, the molybdenum precursor can be introduced into the titania carrier as a cocatalyst using a wet impregnation method. In the present invention, the molybdenum precursor is ammonium molybdate ((NH ₄ ) ₂ MoO ₄ ), ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O), and molybdic acid (H ₂ MoO ₄ ). Any one selected from the group consisting of can be used, and there is no particular limitation, but it is preferable to use ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O). The content of molybdenum may be 0.5 to 10% by weight, preferably 3% by weight, based on the catalyst.

Meanwhile, the antimony precursor can be introduced into the titania carrier as a cocatalyst using a wet impregnation method. The antimony precursor may be any one selected from the group consisting of antimony trichloride (SbCl ₃ ) and antimony acetate (Sb(CH ₃ COO) ₃ ), and is not particularly limited, but may include antimony acetate (Sb(CH ₃ COO) ) It is desirable to use ₃ ). The content of antimony may be 0.5 to 5% by weight, preferably 2% by weight, based on the catalyst.

As a method for producing a vanadium-molybdenum-antimony-titania catalyst, first, an antimony precursor equivalent to 2% by weight of antimony is dissolved in acetic acid (CH ₃ COOH) to prepare an aqueous antimony solution. At this time, antimony acetate (Sb(CH ₃ COO) ₃ ) is used as a precursor of antimony. Next, a molybdenum precursor equivalent to 3% by weight of molybdenum is dissolved in distilled water to prepare a molybdenum aqueous solution. At this time, ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O) is used as a precursor for molybdenum. Then, a vanadium precursor equivalent to 2% by weight of vanadium is dissolved in distilled water to prepare a vanadium aqueous solution. At this time, ammonium metavanadate (NH ₄ VO ₃ ) is used as a precursor for vanadium. Afterwards, the aqueous antimony solution, the aqueous molybdenum solution, and the aqueous vanadium solution are mixed with titania, stirred into a slurry state, dried, and then dried using a dryer for more than a day to remove the remaining moisture contained in the catalyst micropores. Heat treatment is performed on the sample for which the drying process has been completed under an air atmosphere. That is, production of a vanadium-molybdenum-antimony-titania catalyst using titania as a carrier and using 2% by weight of an aqueous antimony solution, 3% by weight of molybdenum aqueous solution, and 2% by weight of vanadium aqueous solution. carry out.

As a method for producing a vanadium-molybdenum-titania catalyst, a molybdenum precursor equivalent to 3% by weight of molybdenum is first dissolved in distilled water to prepare a molybdenum aqueous solution. At this time, ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O) is used as a precursor for molybdenum. Then, a vanadium precursor equivalent to 2% by weight of vanadium is dissolved in distilled water to prepare a vanadium aqueous solution. At this time, ammonium metavanadate (NH ₄ VO ₃ ) is used as a precursor for vanadium. Afterwards, the molybdenum aqueous solution and the vanadium aqueous solution are mixed with titania, stirred to form a slurry, dried, and then dried using a dryer for more than a day to remove the remaining moisture contained in the catalyst micropores. Heat treatment is performed on the sample for which the drying process has been completed under an air atmosphere. That is, a vanadium-molybdenum-titania catalyst is produced based on the above-described method using titania as a carrier, a 3% by weight aqueous molybdenum solution, and a 2% by weight aqueous vanadium solution.

Considering the conversion rate and energy efficiency for nitrogen oxides, the heat treatment process is performed in a gas atmosphere containing nitrogen and oxygen at a temperature of 300 to 700°C for 1 to 8 hours, preferably at a temperature of 500°C for 5 hours. This heat treatment process can be performed in various known types of furnaces, such as tube-type furnaces, convection-type furnaces, and grate-type furnaces, and is not particularly limited.

In addition, the vanadium-molybdenum-antimony-titania catalyst according to the present invention is processed in the form of particles or monoliths with a small amount of binder, or is manufactured in the form of plates, slates, pellets, etc., or is applied to a support processed in such forms. It can be used by coating.

In addition, in practical application, the vanadium-molybdenum-antimony-titania catalyst according to the present invention is used by coating structures such as metal plates, metal fibers, ceramic filters, honeycombs, and glass pipes, air purifiers, interior decorations, interior and exterior materials, wallpaper, etc. It is also possible to use it at the rear end of industrial processes where exhaust gas containing sulfur dioxide is generated.

Above, the vanadium-molybdenum-antimony-titania catalyst for nitrogen oxide removal in low temperature ranges has been described. Hereinafter, specific examples of the method for producing the denitrification catalyst of the present invention will be described with reference to the drawings.

Manufacturing Example 1

In the production of a vanadium-molybdenum-antimony-titania catalyst for nitrogen oxide removal, antimony acetate (Sb(CH ₃ COO) ₃ ) is measured to be 2% Sb by weight based on the weight of the catalyst and then dissolved in acetic acid (CH ₃ COOH). to prepare an aqueous antimony solution. Subsequently, ammonium heptamolybdate ((NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O) was weighed to obtain 1% Mo by weight based on the weight of the catalyst, and then dissolved in distilled water heated to 60°C or higher to prepare a molybdenum aqueous solution. Manufactured. Subsequently, ammonium metavanadate (NH ₄ VO ₃ ) was quantified to have 2% V by weight based on the weight of the catalyst and then dissolved in distilled water heated to 60°C or higher to prepare an aqueous vanadium solution. In this case, in order to increase the solubility of ammonium metavanadate, oxalic acid ((COOH) ₂ , an amount equivalent to a vanadium molar ratio of 1:1) is added while stirring little by little until the pH of the vanadium aqueous solution reaches 2.5. After mixing the prepared aqueous solution of antimony, molybdenum, and vanadium with titania to form a slurry, moisture was removed using a vacuum rotary evaporator, and then dried in a dryer at 103°C for more than a day to completely remove the moisture contained in the micropores. Dry. Afterwards, “2V1MoSbTi” was manufactured by firing in an air atmosphere at a temperature of 500°C for 5 hours in a convection furnace.

Production example 2

“2V3MoSbTi” was prepared in the same manner as in Preparation Example 1, except that in the process of preparing the molybdenum aqueous solution in Preparation Example 1, the molybdenum content was 3% by weight Mo based on the weight of the catalyst.

Production example 3

“2V5MoSbTi” was prepared in the same manner as in Preparation Example 1, except that in the process of preparing the molybdenum aqueous solution in Preparation Example 1, the molybdenum content was 5% by weight Mo based on the weight of the catalyst.

Production example 4

“2V7MoSbTi” was prepared in the same manner as in Preparation Example 1, except that in the process of preparing the molybdenum aqueous solution in Preparation Example 1, the molybdenum content was 7% by weight Mo based on the weight of the catalyst.

Production example 5

In the antimony addition process of Preparation Example 2, the prepared antimony aqueous solution and titania were mixed to form a slurry, moisture was removed using a vacuum rotary evaporator, and then the moisture contained in the micropores was removed at 103°C. After being sufficiently dried in a dryer for more than a day, antimony-titania is produced by firing in an air atmosphere at a temperature of 200° C. for 5 hours in a convection type furnace. Afterwards, “2V3MoSbTi” was prepared in the same manner as in Preparation Example 2 by mixing the prepared molybdenum and vanadium aqueous solution with antimony-titania.

Production example 6

In the molybdenum addition process of Preparation Example 2, the prepared molybdenum aqueous solution and titania were mixed to form a slurry, moisture was removed using a vacuum rotary evaporator, and then in a dryer at 103°C to completely remove moisture contained in micropores. After sufficiently drying for more than a day, molybdenum-titania is produced by firing in an air atmosphere at a temperature of 200° C. in a convection furnace for 5 hours. Afterwards, “2VSb3MoTi” was prepared in the same manner as in Preparation Example 2 by mixing the prepared antimony and vanadium aqueous solution with molybdenum-titania.

Production example 7

In the antimony addition process of Preparation Example 2, the prepared antimony aqueous solution and titania were mixed to form a slurry, moisture was removed using a vacuum rotary evaporator, and then the moisture contained in the micropores was removed at 103°C. After being sufficiently dried in a dryer for more than a day, antimony-titania is produced by firing in an air atmosphere at a temperature of 500° C. for 5 hours in a convection furnace. Afterwards, “2V3MoSbTi” was prepared in the same manner as in Preparation Example 2 by mixing the prepared molybdenum and vanadium aqueous solution with antimony-titania.

Production example 8

“1V3MoSbTi” was prepared in the same manner as Preparation Example 2, except that in the vanadium addition process of Preparation Example 2, a vanadium aqueous solution was prepared using a vanadium content of 1% by weight based on the weight of the catalyst.

Production example 9

“1.5V3MoSbTi” was prepared in the same manner as Preparation Example 2, except that in the vanadium addition process of Preparation Example 2, a vanadium aqueous solution was prepared using a vanadium content of 1.5% by weight based on the weight of the catalyst.

Production example 10

“3V3MoSbTi” was prepared in the same manner as Preparation Example 2, except that in the vanadium addition process of Preparation Example 2, a vanadium aqueous solution was prepared using a vanadium content of 3% by weight based on the weight of the catalyst.

Production example 11

“4V3MoSbTi” was prepared in the same manner as Preparation Example 2, except that in the vanadium addition process of Preparation Example 2, a vanadium aqueous solution was prepared using a vanadium content of 4% by weight based on the weight of the catalyst.

Production example 12

“5V3MoSbTi” was prepared in the same manner as Preparation Example 2, except that in the vanadium addition process of Preparation Example 2, a vanadium aqueous solution was prepared using a vanadium content of 5% by weight based on the weight of the catalyst.

Comparative Manufacturing Example 1

In the production of a vanadium-titania catalyst for nitrogen oxide removal, ammonium metavanadate (NH ₄ VO ₃ ) is metered to 2% V by weight based on the weight of the catalyst, and then dissolved in distilled water heated to 60°C or higher to prepare an aqueous vanadium solution. did. In this case, in order to increase the solubility of ammonium metavanadate, oxalic acid ((COOH) ₂ , an amount equivalent to a vanadium molar ratio of 1:1) is added while stirring little by little until the pH of the vanadium aqueous solution reaches 2.5. The prepared aqueous solution of vanadium and titania are mixed to form a slurry, the moisture is removed using a vacuum rotary evaporator, and the slurry is thoroughly dried in a dryer at 103°C for more than a day to completely remove the moisture contained in the micropores. Afterwards, “2VTi” was manufactured by firing in an air atmosphere at a temperature of 500°C for 5 hours in a convection furnace.

Comparative Manufacturing Example 2

In the production of a vanadium-antimony-titania catalyst for nitrogen oxide removal, antimony acetate (Sb(CH ₃ COO) ₃ ) is metered to 2% Sb by weight based on the weight of the catalyst, and then dissolved in acetic acid (CH 3 COOH) to produce antimony acetate (Sb(CH ₃ COO) 3 ). Prepare an aqueous solution of Moni. Subsequently, ammonium metavanadate (NH ₄ VO ₃ ) was quantified to have 2% V by weight based on the weight of the catalyst and then dissolved in distilled water heated to 60°C or higher to prepare an aqueous vanadium solution. In this case, in order to increase the solubility of ammonium metavanadate, oxalic acid ((COOH) ₂ , an amount equivalent to a vanadium molar ratio of 1:1) is added while stirring little by little until the pH of the vanadium aqueous solution reaches 2.5. After mixing the prepared aqueous solution of antimony and vanadium with titania to form a slurry, moisture is removed using a vacuum rotary evaporator, and then thoroughly dried in a dryer at 103°C for more than a day to completely remove moisture contained in micropores. . Afterwards, “2VSbTi” was manufactured by firing in an air atmosphere at a temperature of 500°C for 5 hours in a convection furnace.

Comparative Manufacturing Example 3

In the production of a vanadium-molybdenum-titania catalyst for nitrogen oxide removal, ammonium heptamolybdate ((NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O) was metered to 1% Mo by weight based on the weight of the catalyst and then heated at 60°C. An aqueous molybdenum solution was prepared by dissolving in distilled water heated as described above. Subsequently, ammonium metavanadate (NH ₄ VO ₃ ) was quantified to have 2% V by weight based on the weight of the catalyst and then dissolved in distilled water heated to 60°C or higher to prepare an aqueous vanadium solution. In this case, in order to increase the solubility of ammonium metavanadate, oxalic acid ((COOH) ₂ , an amount equivalent to a vanadium molar ratio of 1:1) is added while stirring little by little until the pH of the vanadium aqueous solution reaches 2.5. After mixing the prepared molybdenum and vanadium aqueous solution with titania to form a slurry, moisture is removed using a vacuum rotary evaporator, and then sufficiently dried in a dryer at 103°C for more than a day to completely remove moisture contained in micropores. Afterwards, “2V1MoTi” was manufactured by firing in an air atmosphere at a temperature of 500°C for 5 hours in a convection furnace.

Comparative Manufacturing Example 4

“2V3MoTi” was prepared in the same manner as Comparative Preparation Example 3, except that in the molybdenum addition process of Comparative Preparation Example 3, a molybdenum aqueous solution was prepared using a molybdenum content of 3% by weight based on the weight of the catalyst.

Comparative Manufacturing Example 5

“2V5MoTi” was prepared in the same manner as Comparative Preparation Example 3, except that in the molybdenum addition process of Comparative Preparation Example 3, a molybdenum aqueous solution was prepared using a molybdenum content of 5% by weight based on the weight of the catalyst.

Comparative Manufacturing Example 6

“2V7MoTi” was prepared in the same manner as in Comparative Preparation Example 3, except that in the molybdenum addition process of Comparative Preparation Example 3, a molybdenum aqueous solution was prepared using a molybdenum content of 7% by weight based on the weight of the catalyst.

Comparative Manufacturing Example 7

In the process of adding antimony, molybdenum, and vanadium in Preparation Example 2, except that an aqueous solution of antimony, molybdenum, and vanadium was prepared using 10, 15, and 10% by weight of antimony, molybdenum, and vanadium, respectively, based on the weight of the catalyst. , “10V15Mo10SbTi” was manufactured in the same manner as Preparation Example 2.

Comparative Manufacturing Example 8

"In the same manner as Comparative Preparation Example 3, except that in the molybdenum and vanadium addition process of Comparative Preparation Example 3, molybdenum and vanadium aqueous solutions were prepared using molybdenum and vanadium contents of 15 and 10% by weight, respectively, based on the weight of the catalyst." 10V15MoTi" was prepared.

Comparative Manufacturing Example 9

In the production of a vanadium-tungsten-titania catalyst for nitrogen oxide removal, ammonium metatungstate ((NH ₄ ) ₆ H ₂ W ₁₂ O ₄₀ ) is weighed to 5% by weight based on the weight of the catalyst, and then heated to 60°C or higher in distilled water. An aqueous tungsten solution was prepared by dissolving in . Subsequently, ammonium metavanadate (NH ₄ VO ₃ ) as a vanadium precursor was weighed to 2% by weight based on the weight of the catalyst and then dissolved in distilled water heated to 60°C or higher to prepare an aqueous vanadium precursor solution. In this case, in order to increase the solubility of ammonium metavanadate, oxalic acid (corresponding to a 1:1 molar ratio of vanadium) is added while stirring little by little until the pH of the vanadium aqueous solution reaches 2.5. The prepared aqueous solution of tungsten and vanadium is mixed with titania to form a slurry. After removing moisture using a vacuum rotary evaporator, the slurry is sufficiently dried in a dryer at 103°C for more than a day to completely remove moisture contained in micropores. Finally, “2V5WTi” was prepared by firing in an air atmosphere at a temperature of 500°C for 5 hours in a convection furnace.

The catalyst composition according to the Preparation Example and Comparative Preparation Example described above is shown in [Table 1] below.

division vanadium
Content (wt%) molybdenum
Content (wt%) antimony
Content (wt%) note catalyst Manufacturing Example 1 2 One 2 - 2V1MoSbTi Production example 2 2 3 2 - 2V3MoSbTi Production example 3 2 5 2 - 2V5MoSbTi Production example 4 2 7 2 - 2V7MoSbTi Production example 5 2 3 2 Mix antimony with titania, heat treat at 200 degrees, then deposit vanadium and molybdenum 2V3MoSbTi Production example 6 2 3 2 Molybdenum mixed with titania, heat treated at 200 degrees, vanadium and antimony deposited 2VSb3MoTi Production example 7 2 3 2 Mix antimony with titania, heat treat at 500 degrees, then deposit vanadium and molybdenum 2V3MoSbTi Production example 8 One 3 2 - 1V3MoSbTi Production example 9 1.5 3 2 - 1.5V3MoSbTi Production example 10 3 3 2 - 3V3MoSbTi Production example 11 4 3 2 - 4V3MoSbTi Production example 12 5 3 2 - 5V3MoSbTi Comparative Manufacturing Example 1 2 - - - 2VTi Comparative Manufacturing Example 2 2 - 2 - 2VSbTi Comparative Manufacturing Example 3 2 One - - 2V1MoTi Comparative Manufacturing Example 4 2 3 - - 2V3MoTi Comparative Manufacturing Example 5 2 5 - - 2V5MoTi Comparative Manufacturing Example 6 2 7 - - 2V7MoTi Comparative Manufacturing Example 7 10 15 10 - 10V15Mo10SbTi Comparative Manufacturing Example 8 10 15 - - 10V15MoTi Comparative Manufacturing Example 9 2 - - Contains 5 wt% tungsten 2V5WTi

Example 1

In order to confirm the nitrogen oxide removal efficiency in preparing the catalyst of the present invention, the catalysts prepared according to Comparative Preparation Example 1, Comparative Preparation Example 2, Comparative Preparation Example 4, Preparation Example 2, and Comparative Preparation Example 9 were tested at a space velocity of 60,000 hr ^-1. To evaluate the SCR reaction characteristics under the conditions, the conversion rate of NOx was measured, and the results are shown in Figure 1 below. The experimental conditions and measurement methods are as follows, and are the same in Examples 2 to 4 described later.

[Experimental conditions]

The gas injected into the catalytic reactor is in an air atmosphere with a gaseous nitrogen oxide concentration of 800 ppm, oxygen 3%, moisture 6 vol.%, inflow rate of 500 cc/min, space velocity of 60,000 hr ^-1 , and test temperature range of 180~400. The experiment was conducted at ℃. For reference, space velocity is an indicator of the amount of target gas that the catalyst can process, and is expressed as the volume ratio of the catalyst to the total gas flow rate.

[measurement method]

The gas phase nitrogen oxide conversion rate was calculated according to [Equation 1] below. In addition, the nitrogen conversion rate is calculated by measuring the concentration of nitrogen oxides generated when the injected gaseous nitrogen oxides are unreacted using a non-dispersive infrared gas analyzer (ZKJ-2, Fuji Electric Co.). Additionally, the concentration of gaseous ammonia was measured using a detector tube to measure NH ₃ slip that occurs due to unreacted gaseous ammonia injected as a reducing agent.

[Equation 1]

Looking at the nitrogen oxide removal rates of Comparative Preparation Example 1, Comparative Preparation Example 2, Comparative Preparation Example 4, Preparation Example 2, and Comparative Preparation Example 9' from FIG. 1, antimony or/and molybdenum and tungsten were added to Comparative Preparation Example 1 (2VTi). By adding this, the overall low-temperature denitrification efficiency improvement effect can be confirmed. In particular, it can be seen that when the catalyst was prepared by supporting antimony, molybdenum, and vanadium on titania in Preparation Example 2 (2V3MoSbTi), it showed a better nitrogen oxide conversion rate in the temperature range of 200 to 250 ° C.

Example 2

Based on the results in Example 1, an experiment was conducted to determine the effect of adding various amounts of molybdenum on the nitrogen oxide conversion rate, and the results are shown in Figures 2 to 4 below. The experimental conditions were carried out in the same manner as in Example 1 described above, and the catalysts used were Comparative Preparation Examples 3 to 6 and Preparation Examples 1 to 4 depending on the molybdenum content.

From Figure 2, like the nitrogen oxide removal rates of Comparative Preparation Examples 3 to 6 (2VxMoTi), different nitrogen oxide removal performance was shown as the content of added molybdenum was changed. In particular, it can be seen that the catalyst prepared by supporting 3% by weight of molybdenum based on the catalyst of Comparative Preparation Example 4 (2V3MoTi) shows a better nitrogen oxide conversion rate in the temperature range of 200 to 250°C among the 2VxMoTi catalysts.

From Figure 3, as shown in the nitrogen oxide removal rates of Preparation Examples 1 to 4 (2VxMoSbTi), different nitrogen oxide removal performance was shown as the content of added molybdenum was changed. In particular, it can be seen that the catalyst prepared by supporting 3% by weight of molybdenum based on the catalyst of Preparation Example 2 (2V3MoSbTi) shows the best nitrogen oxide conversion rate in the temperature range of 200 to 250°C among the 2VxMoSbTi catalysts.

From Figure 4, the nitrogen oxide removal rates at 220°C of Comparative Preparation Examples 3 to 6 (2VxMoTi) and Preparation Examples 1 to 4 (2VxMoSbTi) can be confirmed. It can be seen that the catalysts of Preparation Example 1 (2V1MoSbTi) and Preparation Example 2 (2V3MoSbTi) containing antimony exhibit excellent nitrogen oxide conversion rates at 220°C. On the other hand, the catalysts of Preparation Example 3 (2V5MoSbTi) and Preparation Example 4 (2V7MoSbTi) show lower nitrogen oxide conversion rates than Comparative Preparation Example 5 (2V5MoTi) and Comparative Preparation Example 6 (2V7MoTi). In particular, it can be seen that the catalyst prepared by supporting 2% by weight of antimony and 3% by weight of molybdenum based on the catalyst of Preparation Example 2 (2V3MoSbTi) shows the best nitrogen oxide conversion rate at 220°C.

Example 3

Based on the results in Examples 1 and 2, an experiment was conducted to determine the effect of the order and method of metal support on the nitrogen oxide conversion rate by preparing it on a vanadium-molybdenum-antimony-titania catalyst through various supporting methods using an impregnation method. did. The experimental conditions were carried out in the same manner as in Example 1 described above, and the catalyst used was Preparation Example 2 and Preparation Examples 5 to 7, which were prepared according to the metal loading sequence and method on a vanadium-molybdenum-antimony-titania catalyst. .

From Figure 5, it can be seen that differences in nitrogen oxide conversion activity efficiency occur in the vanadium-molybdenum-antimony-titania catalysts of Preparation Example 2 and Preparation Examples 5 to 7 depending on the metal loading order and method. Preparation Example 5, in which an antimony precursor was mixed with titania, dried, and then fired at 200°C to support vanadium and molybdenum precursors; Preparation Example 6, in which a molybdenum precursor was mixed with titania, dried, and fired at 200°C to support vanadium and antimony precursors; And in the case of Preparation Example 7, in which an antimony precursor was mixed with titania, dried, and then fired at 500°C to support vanadium and molybdenum precursors, a similar level of nitrogen oxide conversion was shown. In particular, it can be seen that Preparation Example 2, in which antimony, molybdenum, and vanadium precursors are supported on titania, exhibits the best nitrogen oxide conversion rate in the temperature range of 200 to 250°C. The manufacturing method corresponding to Preparation Example 2 is significant in that the catalyst can be manufactured through a simple manufacturing process by reducing the heat treatment process to one when manufacturing the catalyst.

Example 4

Based on the results in Example 3, an experiment was performed to determine the effect of adding various amounts of vanadium on the nitrogen oxide conversion rate in the vanadium-molybdenum-antimony-titania catalyst. The experimental conditions were carried out in the same manner as in Example 1 described above, and the catalysts used were Preparation Example 2 and Preparation Examples 8 to 12 depending on the vanadium content.

From Figure 6, it can be seen that as the vanadium content increases from 1% by weight (Preparation Example 8) to 3% by weight (Preparation Example 10), the nitrogen oxide conversion rate increases in the temperature range of 180 to 250°C. Meanwhile, the catalyst with a vanadium content of 4% by weight (Preparation Example 11) showed a low-temperature nitrogen oxide conversion rate similar to that of the catalyst with a vanadium content of 3% by weight (Preparation Example 10). On the other hand, the catalyst with a vanadium content of 5% by weight (Preparation Example 12) shows a low-temperature nitrogen oxide conversion rate that decreases as the vanadium content increases.

Example 5

In order to confirm the effect of sulfur dioxide on catalyst durability in the production of the catalyst of the present invention, sulfur dioxide was removed during the nitrogen oxide removal reaction for Comparative Preparation Example 1, Comparative Preparation Example 2, Comparative Preparation Example 4, Preparation Example 2, and Comparative Preparation Example 9. A durability test for sulfur dioxide of the catalyst was performed by injection, and the test conditions were as follows.

[Experimental conditions]

The gas injected into the catalytic reactor is in an air atmosphere, with a gaseous nitrogen oxide concentration of 250 ppm, an injected ammonia/nitrogen oxide ratio of 0.98, oxygen 15 vol%, moisture 6 vol%, inflow rate 500 cc/min, space velocity 30,000 hr ^{- 1} , the experiment temperature range was 220℃. The sulfur dioxide durability test measures the nitrogen oxide removal performance that changes per reaction time by injecting moisture and sulfur dioxide during the denitrification reaction of the catalyst prepared by the catalyst preparation method described above.

Referring to the results in FIG. 7, Preparation Example 2 (2V3MoSbTi) showed the best durability against sulfur dioxide. In the selective catalytic reduction reaction for Comparative Preparation Example 1 (2VTi), Comparative Preparation Example 9 (2V5WTi), Comparative Preparation Example 2 (2VSbTi), Comparative Preparation Example 4 (2V3MoTi), and Preparation Example 2 (2V3MoSbTi), 6 vol% As moisture and 75 ppm of sulfur dioxide are injected, the time required for the nitrogen oxide removal rate to decrease to 85% of the initial performance due to catalyst deactivation is 132, 165, 240, 833, and 1130 hours, respectively. Preparation Example 2 (2V3MoSbTi) shows further improved sulfur dioxide resistance due to the addition of antimony and molybdenum.

Example 6

The crystal structures of Preparation Example 2 (2V3Mo2SbTi), Comparative Preparation Example 4 (2V3MoTi), Comparative Preparation Example 7 (10V15Mo10SbTi), and Comparative Preparation Example 8 (10V15MoTi) were analyzed using an X-ray diffractomer. and the resulting X-ray diffraction patterns (XRD patterns) were shown. Referring to FIG. 8, in both Preparation Example 2 (2V3Mo2SbTi) and Comparative Preparation Example 4 (2V3MoTi), only crystal planes of anatase phase having a tetragonal crystal structure, indicating a titania carrier, were observed, whereas crystalline surfaces of the anatase phase were observed. No peaks for metal oxides were observed. This is interpreted to be because the size or content of the metal oxide crystal particles dispersed in the carrier is too small to perform X-ray diffraction analysis. Therefore, an In Comparative Preparation Example 7 (10V15Mo10SbTi), peaks corresponding to V ₂ MoO ₈ and Sb ₂ O ₅ were observed. Meanwhile, in Comparative Preparation Example 8 (10V15MoTi), peaks corresponding to V ₂ O ₅ , V ₂ MoO ₈ and MoO ₃ were observed, and in particular, the peak corresponding to V ₂ MoO ₈ was observed to be very small. From the above results, it was confirmed that vanadium oxide and molybdenum oxide exist as V ₂ MoO ₈ types in VMoSbTi, but mostly as V ₂ O ₅ and MoO ₃ in VMoTi.

For a clearer crystalline analysis of the metal oxide, the selected area electron diffraction pattern of Preparation Example 2 (2V3Mo2SbTi), Comparative Preparation Example 4 (2V3MoTi), Comparative Preparation Example 7 (10V15Mo10SbTi), and Comparative Preparation Example 8 (10V15MoTi) was used. , SAED pattern) was used for analysis. Referring to Figure 9, Preparation Example 2 (2V3Mo2SbTi) and Comparative Preparation Example 7 (10V15Mo10SbTi) show circular rings corresponding to anatase TiO ₂ , V ₂ MoO ₈ , and SbVO ₄ crystal planes. On the other hand, in Comparative Preparation Example 4 (2V3MoTi) and Comparative Preparation Example 8 (10V15MoTi), circular rings corresponding to anatase TiO ₂ , V ₂ O ₅ , MoO ₃ and V ₂ MoO ₈ crystal planes were observed.

As shown in the X-ray diffraction analysis and electron diffraction pattern results, most of the vanadium oxide of VMoSbTi exists in the V ₂ MoO ₈ structure and the partial presence of the SbVO ₄ structure was confirmed. On the other hand, the structure of the main vanadium oxide constituting VMoTi was V ₂ O ₅ , and molybdenum oxide was confirmed to exist in the MoO ₃ structure (V ₂ O ₅ structure and V ₂ MoO ₈ structure were observed). It shows that the structure of vanadium oxide was converted from V ₂ O ₅ to V ₂ MoO ₈ as Sb was added to VMoTi.

Example 7

The XPS results of Mo 3d were analyzed for the catalysts prepared according to Comparative Preparation Example 4 and Preparation Examples 1 to 4 and separated by the Gaussian-Lorentzia method, and the oxidation of all molybdenum present on the catalyst surface corresponds to the sum of the hexavalent values. The ratio of molybdenum (Mo ⁶⁺ ) is shown. Referring to the results of FIG. 10, Comparative Preparation Example 4 (2V3MoTi) was 62.5%, Preparation Example 1 (2V1MoSbTi) was 81.8%, Preparation Example 2 (2V3MoSbTi) was 83.3%, Preparation Example 3 (2V5MoSbTi) was 84.6%, and Preparation Example 3 (2V5MoSbTi) was 84.6%. Example 4 (2V7MoSbTi) shows a Mo ⁶⁺ ratio of 83.4%. 2V3MoTi, which does not contain antimony, shows a relatively low Mo ⁶⁺ ratio of 62.5%, while 2VxMoSbTi, which contains antimony, shows a high ratio of 81.8 to 84.6%.

Next, the XPS analysis results of V 2p were separated for the catalysts prepared according to Comparative Preparation Example 1, Comparative Preparation Example 2, Comparative Preparation Example 4, and Preparation Examples 1 to 4 using the same method as the XPS analysis described above, and the The type and distribution ratio of vanadium oxide present are shown. Referring to the results of FIG. 11, the ratio of vanadium (V ⁴⁺ + V ³⁺ ) whose oxidation to the total vanadium in the vanadium oxide corresponds to the sum of tetravalence and trivalence is Preparation Example 2 (2V3MoSbTi; 33.3%) > Preparation Example 1 (2V1MoSbTi; 29.7%) > Comparative Preparation Example 4 (2V3MoTi; 25.7%) > Comparative Preparation Example 2 (2VSbTi; 21.7%) > Comparative Preparation Example 1 (2VTi; 20.1%) > Preparation Example 3 (2V5MoSbTi; 18.0%) ) > Shows the sequence of Preparation Example 4 (2V7MoSbTi; 14.3%). Based on the ratio of vanadium (V ⁴⁺ + V ³⁺ ), the oxidation value for the total vanadium according to the molybdenum content (0, 1, 3, 5, and 7 wt%) for the 2VxMoSbTi catalyst is the sum of tetravalent and trivalent The correlation between the ratio of vanadium (V ⁴⁺ + V ³⁺ ) and the nitrogen oxide conversion rate was shown. Referring to the results of FIG. 12, as the ratio of vanadium (V ⁴⁺ + V ³⁺ ), which corresponds to the sum of tetravalent and trivalent oxidation of all vanadium, increases, the low-temperature nitrogen oxide conversion rate at 220 and 200 ° C increases. You can check that.

Example 8

Based on the results in Example 5, Comparative Preparation Example 1 (2VTi), Comparative Preparation Example 2 (2VSbTi), and The sulfur dioxide adsorption amount of the catalysts prepared according to Comparative Preparation Example 4 (2V3MoTi), Preparation Example 2 (2V3MoSbTi), and Comparative Preparation Example 9 (2V5WTi) was measured, and the results are shown in Table 2 below.

[measurement method]

Analysis was performed using Micromeritics' AutoChem II-2920 chemisorption analyzer and Hiden's HPR20m mass spectrometer. The experimental method is to install 0.1 g of catalyst in the reaction device, inject 1% sulfur dioxide gas at a temperature of 220°C, adsorb for 1 hour, and then inject argon gas for 1 hour to exclude physically adsorbed sulfur dioxide. Afterwards, the reactor was heated from 220°C to 1000°C at a rate of 10°C/min, and the gas desorbed at the rear was measured using a mass spectrum analyzer. After measuring the intensity of sulfur dioxide (m/e, molecular weight = 64) that desorbs as the temperature rises, integrate to calculate the area, calculate the adsorption amount of each catalyst through a standardized calculation process, and present the results. It was.

division Arrival time (hr)
X _NOx /X _NOx,initial Sulfur dioxide adsorption amount
(μmol _SO2 g ^-One _CAT ) Comparative Manufacturing Example 1 132 167.1 Comparative Manufacturing Example 2 240 58.3 Comparative Manufacturing Example 4 833 24.0 Production example 2 1130 7.0 Comparative Manufacturing Example 9 165 63.7

Referring to the results in [Table 2], each catalyst shows a different sulfur dioxide adsorption amount, and the sulfur dioxide adsorption amount is Comparative Preparation Example 1 (2VTi; 167.1 μmol _SO2 g ^-1 _CAT ) > Comparative Preparation Example 9 (2V5WTi; 63.7 μmol) _SO2 g ^-1 _CAT ) > Comparative Preparation Example 2 (2VSbTi; 58.3 μmol _SO2 g ^-1 _CAT ) > Comparative Preparation Example 4 (2V3MoTi; 24.0 μmol _SO2 g ^-1 _CAT ) > Preparation Example 2 (2V3MoSbTi; 7.0 μmol _SO2 g ^{- 1} _CAT ) indicates the order. Next, based on the above results, the correlation between sulfur dioxide adsorption amount and catalyst durability was investigated.

Referring to the results of FIG. 13, Comparative Preparation Example 1 (2VTi), Comparative Preparation Example 2 (2VSbTi), Comparative Preparation Example 4 (2V3MoTi), Preparation Example 2 (2V3MoSbTi), and Comparative Preparation Example 9 (2V5WTi) As the amount of sulfur dioxide adsorption measured from the catalysts decreases, durability due to sulfur dioxide injection in the denitrification reaction tends to increase. In particular, in the case of Preparation Example 2 (2V3MoSbTi), the sulfur dioxide adsorption amount was the lowest at 7.0 μmol _SO2 g ^-1 _CAT , and as a result of the durability test, the time required to reduce the initial performance to 85% (X _NOx /X _NOx,initial = 0.85 ) was confirmed as the longest at 1130 hours.

Above, embodiments of the present invention have been described with reference to the attached drawings, but those skilled in the art will understand that the present invention can be implemented in other specific forms without changing its technical idea or essential features. You will understand that it exists. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive.

Claims (10)

A quaternary denitrification catalyst consisting of vanadium-molybdenum-antimony-titania applied to a selective catalytic reduction (SCR) reaction using an ammonia reducing agent to remove nitrogen oxides contained in exhaust gas,
A denitrification catalyst in which antimony, molybdenum, and vanadium are supported on a titania carrier, and exists in the form of a complex oxide (V ₂ MoO ₈ ) in which molybdenum and vanadium are combined. According to claim 1,
A denitrification catalyst, characterized in that vanadium (V ⁴⁺ + V ³⁺ ), which exists in the form of the complex oxide and whose oxidation corresponds to the sum of tetravalence and trivalence, is more than 25% of the total vanadium. According to claim 1,
A denitrification catalyst, characterized in that molybdenum (Mo ⁶⁺ ), which exists in the form of the complex oxide and whose oxidation value corresponds to the sum of hexavalence, is more than 80% of the total molybdenum. According to claim 1,
The denitrification catalyst is a catalyst characterized in that it is processed into any one shape selected from the group consisting of particle shape, plate shape, corrugate shape, pellet shape, spherical shape, and honeycomb shape. A method of producing a quaternary denitrification catalyst consisting of vanadium-molybdenum-antimony-titania applied to a selective catalytic reduction (SCR) reaction using an ammonia reducing agent to remove nitrogen oxides contained in exhaust gas,
Preparing an aqueous antimony solution by dissolving 0.5 to 5% by weight of antimony in precursor form in a solvent based on 100 parts by weight of catalyst;
Preparing a molybdenum aqueous solution by dissolving 0.5 to 10% by weight of molybdenum in precursor form in a solvent based on 100 parts by weight of catalyst;
Preparing an aqueous vanadium solution by dissolving 1 to 5% by weight of vanadium in precursor form in a solvent based on 100 parts by weight of catalyst;
Preparing a slurry by mixing the prepared aqueous solution of antimony, molybdenum, and vanadium with a titanium oxide carrier; and
A method for producing a denitrification catalyst comprising drying the slurry and calcining it at 300 to 700° C. to produce a vanadium-molybdenum-antimony-titania catalyst. According to claim 5,
The molybdenum precursor is ammonium molybdate ((NH ₄ ) ₂ MoO ₄ ), ammonium molybdate tetrahydrate ((NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O), and molybdic acid (H ₂ MoO ₄ ). A method for producing a vanadium-molybdenum-antimony-titania catalyst for removing nitrogen oxides, characterized in that it is one or more selected from the group consisting of. According to claim 5,
The antimony precursor is antimony trichloride (SbCl ₃ ) or antimony acetate (Sb(CH ₃ COO) ₃ ). According to claim 5,
The vanadium precursor is ammonium metavanadate (NH ₄ VO ₃ ) or vanadium oxytrichloride (VOCl ₃ ). According to claim 5,
The titania carrier is a denitrifying agent comprising amorphous titanic acids _{( TiO} Method for producing catalyst. A method of removing nitrogen oxides from exhaust gas using the denitrification catalyst according to any one of claims 1 to 4, wherein the denitrification catalyst removes exhaust gas containing ammonia and nitrogen oxides or exhaust gas containing ammonia, nitrogen oxides, and sulfur dioxide. A method of removing nitrogen oxides that allows them to pass through.