KR20200057155A - Tungsten/titania-based composite oxide carrier and method for manufacturing the same, nox removal catalyst using the carrier, and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a method for preparing a vanadium/tungsten/titania-based denitrification catalyst, which provides improved thermal durability to the catalyst provided at the end portion of an exhaust gas treatment device of various emitting sources using a diesel engine in order to remove gaseous nitrogen oxides, against high-temperature heat energy caused by abnormal ignition occurring during a DPF regeneration process in the device. More particularly, the present invention provides a method which includes: allowing an additive/tungsten/titania composite oxide carrier used as a carrier for preparing the catalyst for enhancing thermal durability to be bound in such a manner that a Ti-O-Me binding structure may be formed; and supporting vanadium as an active metal in the carrier. Then, silica and titania as additives are bound to the carrier to produce a Ti-O-Si species, which has a binding structure having enhanced thermal durability, through an impregnation process. In this manner, it is possible to inhibit a decrease in specific surface area of the catalyst under high-temperature heat energy, to suppress phase transfer of titania and aggregation of vanadium so that crystallization may be reduced, and to inhibit formation of a Ti-V-O species lost into titania due to vanadium sintering. In addition, the specific surface area of the carrier having optimized thermal durability is controlled by adjusting firing temperature, and the structural species of vanadium as an active metal is formed into polymeric V. Thus, it is possible to enhance SCR reaction activity, and to provide a catalyst having excellent thermal stability and denitrification efficiency by supporting additives enhancing thermal durability, when preparing a vanadium/tungsten/titania-based catalyst.

Description

Tungsten / Titania-based composite oxide carrier and its manufacturing method, denitration catalyst using the carrier and its manufacturing method {TUNGSTEN / TITANIA-BASED COMPOSITE OXIDE CARRIER AND METHOD FOR MANUFACTURING THE SAME, NOX REMOVAL CATALYST USING THE CARRIER, AND MANUFACTURING METHOD THEREOF}

The present invention is equipped with a flue gas treatment device for treating nitrogen oxides generated from various emission sources such as diesel engines, and a method for manufacturing a denitrification catalyst for a selective catalytic reduction (SCR) mechanism for converting nitrogen oxides into nitrogen and moisture and a method for manufacturing the same The present invention also relates to a tungsten / titania-based composite oxide carrier used for such a denitration catalyst and a method for manufacturing the same.

Diesel engines using diesel fuel as the main energy source are applied to various emission sources. For example, diesel engines are applied to fixed pollution sources such as engines and emergency generators used in mobile pollution sources such as agricultural equipment, industrial equipment, and ships, as well as diesel vehicles (passenger cars and large vehicles). Nitrogen oxide, one of the air pollutants, is discharged from the diesel engine application. Nitrogen oxides cause problems such as global warming, visible obstruction, and acid rain, and have recently been known to act as secondary pollutants that form ultrafine dust. Due to this, various technologies exist for removing nitrogen oxides generated from pollutants such as diesel engines, but selective catalytic reduction (SCR) is advantageous in terms of economic, technical, and stability, and is most widely used, mainly titania or tungsten / Vatadium / titania-based or vanadium / tungsten / titania denitration catalysts based on titania composite oxide carriers and applied with vanadium as active metals are common commercial catalysts.

In the case of a fixed pollutant source using a diesel engine, the operating conditions in which the catalyst must treat exhaust gas are relatively stable. For example, the flow rate, reaction temperature, space velocity, etc. of the exhaust gas treatment device equipped with the catalyst are kept constant. On the other hand, in the case of a mobile pollutant using a diesel engine, a complex automotive catalyst system is applied to treat various pollutants generated from diesel fuel. Four types of systems are applied to these mobile pollutants, DOC, DPF, SCR, and AOC, respectively, but they are not stable due to the operating conditions of the diesel engine in the mobile pollutant. In particular, in the case of SCR catalysts, in order to remove HC, CO, and soot contained in the exhaust gas, an oxidation reaction is generated and controlled by DOC and DPF in the front end. As it rises, it has a high temperature thermal effect on the SCR catalyst at the rear stage.

Typically, the denitrification efficiency of the vanadium / titania or vanadium / tungsten / titania denitration catalyst is reduced by thermal energy, and the cause can be explained by several examples. First, in the vanadium / titania constituting the catalyst, the specific surface area of the entire catalyst is reduced by sintering due to thermal energy. Second, the reduction of the specific surface area is that the crystallinity of titania increases as the crystallinity is sintered in an anatase, resulting in loss of function due to a phase transition phenomenon that is converted into a rutile phase. Third, ammonia is oxidized at a reaction temperature of 400 ° C. or higher to promote oxidation of the active metal vanadium, and accordingly, the amount of ammonia as a reducing agent participating in the reaction decreases, thereby reducing the activity of total denitrification efficiency. Fourth, high thermal energy causes sintering of vanadium itself, which is the active metal in the catalyst, and vanadium causes a substitution reaction with the internal material of titania having a crystal lattice due to subsequent thermal energy, which is lost inside the catalyst, thereby causing the reaction activity of the catalyst surface It is to lose points. For this reason, in the case of a vanadium / titania-based or vanadium / tungsten / titania-based SCR catalyst, it is urgent to develop a catalyst with improved thermal durability regardless of operating conditions, and to gradually increase emission regulations by using a separate additive. Need to be satisfied.

Most of the vanadium / tungsten / titania catalysts mainly used as SCR catalysts to date are catalysts prepared by adding silica in the form of tungsten or SiO ₂ as an additive to improve the thermal durability of the initial vanadium / titania catalyst. However, these catalysts also had a denitrification function deteriorated by high-temperature thermal energy. To solve this, the catalyst was prepared by lowering the supported content of vanadium as an active metal and increasing the coating amount on a support such as honeycomb. This technique can be explained in relation to the surface density of the vanadium / titania catalyst, and examples thereof are Korean Patent Registration No. 10-1629483 and Non-Patent Document 1 (Applied Catalysis A: General, 499, pp. 1-12, 2015). ). According to this, the specific surface density of the vanadium supported on the titania support can be controlled according to the carrier and the content of vanadium supported. The lower the vanadium loading content, the lower the value for this optimum value, but the specific surface area of titania, which is the carrier, is reduced by thermal energy, and the surface density again approaches the optimum value. However, in the case of such a technique, the denitrification efficiency may be improved as the usage period increases, but since the coating amount on the support is high, ΔP may increase in the process in the entire diesel engine, and there is a high possibility of catalyst desorption. Accordingly, as a recent research trend, studies are being conducted to minimize the reduction in specific surface area by controlling the vanadium loading content to have the thermal durability of the catalyst.

Next, examples of the catalyst having the thermal durability enhanced carrier or vanadium / carrier and a method for manufacturing the same are disclosed in Korean Patent Publication Nos. 10-2006-0132894, 10-2007-0122453, 10-2013-003817, etc. There is this. First, Korean Patent Publication No. 10-2006-0132894 discloses a method for manufacturing nanostructured particles having a high specific surface area and thermal stability, and adding a stabilizing agent to improve thermal stability. It is characterized by time thermal stability. In this case, the nano-structured metal oxide particles using oxo-anionic species selected from the group consisting of phosphate, silicate, aluminate, tungstate, molybdate, polytungstate and poly molybdate as stabilizers To form a zirconia-silica composition. However, in the case of a carrier using a nanostructured material, there is no content regarding thermal durability and binding with titania (TiO ₂ ) in an SCR reaction using vanadium, which is an active metal, and pH and autoclave are used to aggregate bonds between precursors and precursors. Due to the coprecipitation method, the manufacturing method has a rather difficult limitation. In addition, in the analytical method, BET, XRD, and FE-TEM were used to confirm the specific surface area reduction rate, particle size, and crystallinity, but as described later, one of the features of the present invention was to have thermal durability by forming a specific crystal structure in the catalyst. The cause is not explicitly explained or disclosed.

Next, Korean Patent Publication No. 10-2007-0122453 discloses the formation of silica-titania composite oxide particles produced by a vapor phase method, and controls the content of titania to produce a specific surface area of 100 m ² / g or less. It is characterized by controlling the Ti-Si ratio. In the case of the disclosed patent, a gas phase method was used for the production of a composite oxide of silica and titania, and the flow rate ratio, combustion time, combustion temperature and combustion atmosphere using silicon tetrachloride and titanium tetrachloride gas introduced into the combustion burner are used. Control to derive a constant Ti-Si ratio. However, in the case of the disclosed patent, although the thermal durability was partially improved by preparing a Ti-Si composite oxide, ultimately, the use of the final composite oxide is to be used as an external additive for an electrophotographic toner, and application of various precursors is disclosed. In addition, the gas phase method disclosed as a manufacturing method has a great difference when compared with a co-precipitation method or an impregnation method commonly employed in catalyst production.

Next, Republic of Korea Patent Publication No. 10-2013-0038178 relates to a composition and a process for producing a silica-stabilized anatase titania, small nanoparticles using various types of silicates, silica, further including tungsten and vanadia It is disclosed to form a catalyst support material in the form. Specifically, in the case of the disclosed patent, various types of silicates and silica are supported on a tungsten / titania carrier to improve thermal stability with respect to a vanadium / tungsten / titania denitration catalyst, but the supported content of SiO _2, the supported content of W and the specific surface area In addition to the minimum value, vanadium is supported to form a catalyst that minimizes the change in denitrification efficiency in the SCR reaction. As the type of Si precursor used, tetra ammonium silicate, tetraethyl ortho silicate, silicon halide, silicon alkoxide, silicon organic compound, fluoric silicate, alkali silicate solution, and silicic acid were used to bond with titania, of which Si precursor was tetra ammonium Optimized with silicate and silicic acid. Changes in SCR denitrification efficiency through the prepared optimal carrier were compared before / after heat treatment at 325 ° C. However, the disclosed patent, unlike the present invention as described below, was prepared Si-Ti carrier using a co-precipitation method that requires a pH control and autoclave, washing process for the produced material, and also for the used Si precursor There is no mention of dimethoxy dimethylsilane (DMDMS, C ₄ H ₁₂ O ₂ Si), which is one of Si precursors and comparison between precursors that can be optimized during manufacturing by impregnation, and also the structure in which Si used is formed by bonding with TiO ₂ There is no reference to species, and only ²⁹ Si-MASNMR analysis is mentioned in which structural analysis can only discriminate the number of bonds between Si-Si. In addition, in the published patent, comparison of the reaction activity before and after heat treatment at 350 ° C. is a section with excellent reaction activity, which is a rather difficult temperature range to compare the thermal durability enhancement of the catalyst, and discloses the effects of additives other than Si. It is not.

In addition, an example of a denitration catalyst having improved thermal durability according to loading of an additive in a vanadium / tungsten / titania-based catalyst composition used for nitrogen oxide removal is Non-Patent Document 2 (Applied Catalysis B Environmental, 60, pp. 173-179, 2005). According to this, the titania precursor and silica sol were mixed in a molar ratio to prepare a composite oxide carrier having a titania / silica composition using a co-precipitation method, and then a denitration catalyst was prepared by supporting vanadium as an active metal. The prepared titania / silica composite oxide carrier measured the specific surface area after heating at a heat treatment temperature of 550-750 ° C, and showed that as the silica molar ratio increased, the size of the specific surface area maintained according to the heat treatment temperature increased. However, when the denitrification efficiency was compared by heat treatment after loading vanadium on the composite oxide carrier, the activity was deteriorated. Oxidation of vanadium was observed through the XPS analysis rather than the analysis of the binding between titania and silica, and NH ₃ -TPD and reactants. The analysis of the reaction characteristics from the concentration of the gas has been mainly described, and ultimately, as described later, it does not mention a bonding structure that affects one of the characteristics of the present invention, thermal durability.

Next, another example of a denitration catalyst having improved thermal durability according to loading of an additive in a vanadium / tungsten / titania-based catalyst composition used for nitrogen oxide removal is Non-Patent Document 3 (Journal of Alloys and Compounds, 408-412, pp. 1108-1112, 2006), Non-Patent Document 4 (Catalysis Today, 184, pp. 227-236, 2012). According to this, an active metal vanadium is supported on 'DT58' TiO ₂ , which is one of the existing commercial titanias, to compare the thermal durability effect in the SCR reaction. In the case of DT58, it is a silica / tungsten / titania oxide composition prepared in advance from a titania manufacturer. In the above study, vanadium / is obtained through additives such as La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Er, Yb, etc. The effect of improving the thermal durability of the silica / tungsten / titania catalyst was studied. The role of silica in the catalyst inhibited the conversion of titania anatase to rutile and inhibited crystallization of tungsten. When Tb, one of the rare earth metals as an additive, was used, the reaction activity was increased after heat treatment, but the initial activity was very low. However, these studies also show that vanadium, which reacts by thermal energy through XRD and H ₂ -TPR analysis, is found through analysis rather than by promoting thermal durability due to a specific crystal structure formed by the binding between titania and an additive. Studies have been conducted to improve the reaction activity and thermal durability by the structural species TbVO ₄ .

Next, another example of a denitration catalyst having improved thermal durability according to the loading of an additive in a vanadium / tungsten / titania-based catalyst composition used for nitrogen oxide removal is Non-Patent Document 5 (Chinese Journal of Catalysis, 37, pp. 1340) -1346, 2016). According to this, a commercially available TiO ₂ composed of a conventional tungsten / titania, silica / tungsten / titania oxide composition, DT52, DT58 was loaded with active metal vanadium to conduct a thermal durability study in the denitrification reaction. When comparing the two catalysts, XRD, Raman, and H ₂ -TPR were analyzed to compare the thermal durability to thermal energy at high temperature. As a result, it was studied that the silica / tungsten / titania composition had thermal durability. Specifically, it is mentioned that thermal durability is reduced due to the formation of a Ti-VO solid solution. However, in the analysis of Raman and H ₂ -TPR, the Ti-VO structure according to presence / absence was mentioned indirectly through a reference, and it is judged that accurate interpretation is difficult because the crystalline vanadia species and the peak position overlap. Although studies on the thermal durability of denitrification catalysts have recently been conducted and many studies have been conducted and refer to the causes through analysis, it is insufficient to mention the decisive improvement factor in denitrification catalysts with improved thermal durability.

From the above-mentioned prior arts, there are active researches to improve the thermal durability to maintain the properties and denitrification efficiency of the downstream SCR catalyst during abnormal ignition due to DPF regeneration in the diesel engine in relation to the denitration catalyst for removing gaseous nitrogen oxides. . Among them, research into various materials such as silica as an additive material has been conducted to date, but the catalyst has improved thermal durability in the process of maintaining the properties of the catalyst such as specific surface area, bonding structure, vanadium oxidation value, denitrification efficiency, etc. from high temperature thermal energy Research on the effect of the determinants of the factors is negligible. In addition, in the case of the catalyst having improved thermal durability, a co-precipitation method has been mainly used to induce the binding of an additive and a carrier, and it exhibits a disadvantage of low initial efficiency. It is necessary to develop a catalyst.

For this reason, ultimately, there is a need for a method of manufacturing a vanadium / additive / tungsten / titania catalyst capable of exhibiting optimum denitration efficiency by controlling vanadium surface density from control of specific surface area according to thermal durability and firing temperature.

Republic of Korea Registered Patent No. 10-1629483 Republic of Korea Patent Publication No. 10-2006-0132894 Republic of Korea Patent Publication No. 10-2007-0122453 Republic of Korea Patent Publication No. 10-2013-0126837

Non-Patent Document 1 (Applied Catalysis A: General, 499, pp. 1-12, 2015) Non-Patent Document 2 (Applied Catalysis B Environmental, 60, pp. 173-179, 2005) Non-Patent Document 3 (Journal of Alloys and Compounds, 408-412, pp. 1108-1112, 2006) Non-Patent Document 4 (Catalysis Today, 184, pp. 227-236, 2012) Non-Patent Document 5 (Chinese Journal of Catalysis, 37, pp. 1340-1346, 2016)

The present invention is excellent in thermal durability, and the denitrification efficiency at a high temperature and a low temperature is maintained tungsten / titasia-based composite oxide carrier and a manufacturing method thereof, and a denitration catalyst using vanadium as an active metal using the composite oxide carrier, and It is to provide the manufacturing method.

The present inventors, in the process of researching and developing a catalyst related to the above solution, after preparing silica / tungsten / titania composite oxide carrier by supporting silica as an additive (Me; Additive metal) on an existing commercial tungsten / titania carrier Denitrification catalyst is prepared by supporting vanadium on the carrier as an active metal. In this case, by controlling the precursor type and content of the additive, the amount of active metal supported, the supporting method and detailed process conditions, a Me-O-Ti binding structure species, which is a form combined with TiO ₂ in a composite oxide carrier, is formed. On the other hand, as a deactivation factor of the denitration catalyst due to high thermal energy, the specific surface area is reduced and the phase transition to a rutile species of anatase species, the crystallinity due to the change in vanadium oxidation, and the sintering of vanadium itself into the titania crystal lattice By confirming that the denitrification activity point is effectively suppressed by the substitution of Ti-VO structural species and the loss of vanadium into the catalyst, thermal durability is enhanced and excellent denitrification efficiency can be exhibited at high temperature as well as at low temperature. The invention has been reached. The gist of the present invention based on transplantation and knowledge related to the above-described problem is as follows.

(1) A composite oxide carrier comprising 5 to 8 parts by weight of tungsten and 1 to 5 parts by weight of silica with respect to 100 parts by weight of titania, and the bonding structure of Si-O-Ti is 70% or more of the total silica structure.

(2) A composite oxide carrier, characterized in that it is prepared by carrying a tungsten precursor and a silica precursor to contain 5 to 8 parts by weight of tungsten and 1 to 5 parts by weight of silica relative to 100 parts by weight of titania, and then firing at 500 to 650 ° C. Manufacturing method.

(3) The silica precursor is dimetho dimethylsilane (DMDMS, Dimethoxy dimethylsilane, C ₄ H ₁₂ O ₂ Si) characterized in that the composite oxide carrier production method of (2).

(4) The tungsten precursor is ammonium metatungstate ((NH ₄ ) 10H ₂ (W ₂ O ₇ ) ₆ ), characterized in that the composite oxide carrier production method of (2).

(5) The method for preparing a composite oxide carrier of (2), wherein the tungsten precursor or silica precursor is a soluble compound.

(6) A denitration catalyst comprising 2 to 5 parts by weight of vanadium with respect to 100 parts by weight of the composite oxide carrier according to (1).

(7) The denitration catalyst of (6), wherein the vanadium structural species has a polymeric V structure.

(8) The denitration catalyst of (6), wherein the denitration catalyst has a specific surface area of 70.0 m ² / g or more.

(9) A denitration catalyst production method characterized by being prepared by carrying a vanadium precursor so that it is 2 to 5 parts by weight of vanadium with respect to 100 parts by weight of the composite oxide carrier according to (1) above, and then calcining at 500 to 600 ° C.

(10) A method for preparing a denitration catalyst according to (9), wherein the vanadium precursor is ammonium metavanadate (NH ₄ VO ₃ ).

(11) The method for preparing a denitration catalyst according to (9), wherein the vanadium precursor is a soluble compound.

Vanadium / tungsten / titania catalysts, which are mainly used in SCR systems mounted for the treatment of nitrogen oxides in diesel engine exhaust gas, have been deactivated by high temperature heat energy from non-idealization occurring during the regeneration process of the shear DPF. In the case of the denitration catalyst according to the present invention, when silica is added as an additive (Me), a silica / tungsten / titania composite oxide carrier having improved thermal durability is formed by forming a bonding structure of Me-O-Ti, and when supporting an active metal By controlling the heat treatment temperature, it is possible to manufacture a catalyst dispersed in a polymeric V structure that exhibits excellent denitrification efficiency at a low temperature of 300 ° C. or less in a vanadium structure by controlling a specific surface area and a supported amount of the carrier.

That is, the present invention maximizes thermal durability by forming a Ti-O-Si type structural species by first combining titania (TiO ₂ ) as an additive silica, thereby reducing specific denitrification efficiency by thermal energy. Decreased phenomenon, titania anatase phase transition to rutile, vanadium oxidation increases crystallinity due to change, and vanadium self-sintering causes a substitution reaction to form Ti-VO species inside the titania crystal lattice, where vanadium disappears into the catalyst By controlling the phenomenon that the active point is reduced, it is possible to maximize structural stability against high temperature thermal energy. Denitrification efficiency at high and low temperatures may be improved by controlling the sintering temperature of the vanadium by controlling the firing temperature on the composite oxide carrier having the maximum thermal durability.

1 is a graph showing the results of measuring the denitrification efficiency before and after the heat treatment of the catalysts prepared according to Preparation Example 1 and Comparative Preparation Examples 1 to 3 according to the present invention, in order to evaluate the activity of the denitration catalyst.
Figure 2 is a graph showing the results of measuring the pore distribution before and after heat treatment of the catalysts prepared according to Preparation Examples 1 and Comparative Preparation Examples 1 to 3 according to the present invention, in order to evaluate the pore distribution of the denitration catalyst.
3 is XPS (X-ray photoelectron spectroscopic) before and after heat treatment of the catalysts prepared according to Preparation Examples 1 and Comparative Preparation Examples 1 to 3 according to the present invention, in order to confirm the binding form and ratio of silica and titania in the denitration catalyst. ) Graph showing Si _2P analysis results. Figure 4 is to confirm the formation of the combustion product CO _{2 in} the course of the carrier firing, Preparation Example 1 and Comparative Preparation Examples 1 to 3 according to the present invention without firing the carrier until drying only in a drying oven (105 ℃) O ₂ -TPO (Temperature Programmed Oxidation) graph showing analysis results.
Figure 5 shows the results of XRD (X-ray diffraction) analysis before and after heat treatment of the catalysts prepared according to Preparation Example 1 and Comparative Preparation Examples 1 to 3 according to the present invention to confirm changes in titania and vanadium structural species. graph.
FIG. 6 is an analysis of H ₂ -TPR (Hydrogen-Temperature Programmed Reduction) before and after heat treatment of the catalysts prepared according to Preparation Examples 1 and 3 and Comparative Preparation Examples 1 to 3 according to the present invention, in order to confirm changes in reduction characteristics of the denitration catalyst. Graph showing results.
Figure 7 shows the denitration efficiency before and after the heat treatment of the catalysts prepared according to Preparation Examples 1 and 3 to 3 to 3 according to the present invention, in order to evaluate NH ₃ -SCR activity according to a method for preparing a denitration catalyst. Graph showing measured results.
FIG. 8 shows XPS before and after heat treatment of catalysts prepared according to Preparation Example 7 and Preparation Examples 3-1 to 3-3 according to the present invention, in order to confirm the binding form and ratio of silica and titania in a denitration catalyst. ray photoelectron spectroscopic) Graph showing Si _2P analysis results.
Figure 9 is before the heat treatment of the catalyst prepared according to Preparation Example 1, Preparation Examples 3-1 to 3-3 according to the present invention, in order to confirm the vanadium structural species controlled according to the manufacturing conditions of the active metal vanadium in the denitration catalyst Graph showing results of Raman spectroscopy analysis after /.

Hereinafter, the present invention will be described in detail. The present invention relates to a composite oxide carrier and a method for manufacturing the same, and relates to a denitration catalyst useful for removing nitrogen oxides by supporting an active metal on such a composite oxide carrier and a method for manufacturing the same, hereinafter sequentially described.

The composite oxide carrier is based on tungsten / titania and is characterized by comprising silica. The composite oxide carrier is prepared by supporting a tungsten precursor and a silica precursor to contain 5 to 8 parts by weight of tungsten and 1 to 5 parts by weight of silica relative to 100 parts by weight of titania, followed by firing at a predetermined temperature, and combined with titania at a specific silica precursor. It is characterized by having a Si-O-Ti bonding structure of 70% or more of the total Si ratio.

As the tungsten precursor, ammonium metatungstate ((NH ₄ ) 10H ₂ (W ₂ O ₇ ) ₆ ) can be advantageously applied, and if the content is less than 5 parts by weight based on 100 parts by weight of titania, the denitration efficiency of the catalyst is reduced. It is not preferable, and more than 8 parts by weight is also undesirable because the denitrification efficiency is rather lowered.

Dimetho dimethylsilane (DMDMS, Dimethoxy dimethylsilane, C ₄ H ₁₂ O ₂ Si) as the silica precursor is the only of the various silica precursors to form a Si-O-Ti structural species that improves thermal durability through bonding with titania, If the content is less than 1 part by weight based on 100 parts by weight of titania, the effect of promoting thermal durability is reduced, and if it is more than 5 parts by weight, denitrification efficiency is lowered, which is not preferable.

Only the silica precursor added to the composite oxide carrier simultaneously forms Si-O-Ti bond structure species in the carrier. In this case, in order to have thermal durability of the catalyst, the Si-O-Ti structure species is 70 based on the total silica added. %.

In the composite oxide carrier according to the present invention, the silica loading is characterized by being carried out by an impregnation method, in which case the firing temperature is preferably 500 to 650 ° C. If the firing temperature is less than 500 ° C, the thermal durability is reduced, which is undesirable, and if it exceeds 650 ° C, the Si-O-Ti ratio is less than 70%, which is undesirable.

According to the present invention, by adding the silica and calcining at a predetermined temperature, the composite oxide is enhanced in structural durability at a high temperature, that is, thermal durability, by the Ti-O-Si bonding structure species formed in the composite oxide carrier. That is, by the action of the binding structure species of the above-mentioned additive, the specific surface area reduction of the catalyst is suppressed, the phase transition from the anatase of the carrier titania to rutile is suppressed, and the crystallinity increases due to the change in oxidation of the active metal vanadium and Vanadium self-sintering causes a substitution reaction, and the formation of a Ti-VO species suppresses the loss of the active point due to the disappearance of vanadium into the catalyst.

The denitration catalyst according to the present invention is prepared by carrying a vanadium precursor so as to have 2.0 to 5.0 parts by weight of vanadium with respect to 100 parts by weight of the above-mentioned composite oxide carrier in order to have optimum reaction activity, followed by firing at a predetermined temperature. The vanadium acts as an active metal of the denitration catalyst, and as its precursor material, ammonium metavanadate (NH ₄ VO ₃ ) can be advantageously applied. When the content of vanadium is less than 2 parts by weight based on 100 parts by weight of the composite oxide carrier, the denitrification efficiency is decreased, and if it is more than 5.0 parts by weight, the crystallinity of the active metal vanadium increases, which is not preferable.

In addition, the denitrification catalyst is prepared with a specific surface area of about 170.0 to 100.0 m ² / g when vanadium is supported and fired, and it is preferable to maintain about 70.0 m ² / g or more to maintain a desired catalytic activity even after heat treatment. Do. The factors influencing the specific surface area are firing or heat treatment temperatures, and thus control of the firing or heat treatment temperature is important for controlling the specific surface area.

On the other hand, the precursor for each of tungsten and silica added during the production of the composite oxide carrier, and the precursor for vanadium as an active metal may be a soluble compound. The soluble compound means a compound that is completely dissolved in distilled water used as a solvent in the catalyst manufacturing method impregnation method in the present invention, and is not volatilized when preparing a carrier by stirring with titania.

As described above, in the case of the denitration catalyst according to the present invention, thermal durability is maximized by forming a Ti-O-Si type structural species by first binding titania (TiO ₂ ) as an additive silica, thereby denitrifying by thermal energy. A decrease in specific surface area of denitrification catalyst, a factor that decreases efficiency, phase transition to rutile on titania anatase, crystallinity due to change in vanadium oxidation, and substitution reaction due to sintering of vanadium itself, forming Ti-VO species to activate By controlling the phenomenon in which the point is reduced, it is possible to maximize the structural stability against high temperature thermal energy, and by controlling the firing temperature of the composite oxide carrier that maximizes the thermal durability, the structural species of vanadium is controlled to improve the denitrification efficiency at high and low temperatures. Can be enhanced. When the denitration catalyst of the present invention is applied to an ammonia-based selective catalytic reduction system for controlling nitrogen oxides generated in various emission sources using a diesel engine, thermal durability and denitrification efficiency at high and low temperatures are much better than conventional catalysts. Do.

The denitration catalyst according to the present invention is provided in the form of a powder, or formed into various bulk shapes such as honeycomb, slate or pellets by itself, or provided on a surface of a metal, ceramic plate, fiber, filter or honeycomb structure. It can be used by coating.

Hereinafter, the present invention will be described in more detail based on preferred examples and experimental examples of the present invention. However, the technical spirit of the present invention is not limited to or limited thereto, and may be variously implemented by a person skilled in the art.

How to measure

The conversion rate of gaseous nitrogen oxide was calculated according to [Equation 1] below. The concentration of NO that is unreacted and discharged at the rear end of the catalyst layer was measured by a non-dispersive infrared gas analyzer (ZKJ-2, Fuji Electric Co.), and in the case of N ₂ O, it was calculated by measuring with Ultramat6 (Siemens Co.), and ammonia. The concentration of was measured with a detection tube (3M, 3La, 3L, GASTEC Co.).

Manufacturing example  One

The SCR catalyst used for nitrogen oxide control according to the present invention is composed of an active metal serving as a main catalyst, a material added to improve the thermal durability of the catalyst, and a support or a carrier that accommodates the additive.

Dimetho dimethylsilane (DMDMS, Dimethoxy dimethylsilane, C ₄ H ₁₂ O ₂ Si) to prepare silica / tungsten / titania as a composite oxide carrier (hereinafter abbreviated as 'carrier') before carrying vanadium. ) Was dissolved by quantitatively dissolving to 5.0 parts by weight based on 100 parts by weight of titania, and then an aqueous silica solution was prepared. After mixing the prepared silica precursor aqueous solution and tungsten / titania in a slurry form and drying it using a vacuum rotary evaporator, 24 in a 105 ^o C dryer to completely remove residual impurities contained in the fine pores. It was dried sufficiently for more than an hour. Since then the occupant at a temperature of 10 ^o C at a heating rate of 100 / min ^o C to 500 ^o C in the interval in a square and then fired in an air atmosphere for 4 hours to prepare a silica / tungsten oxide / titania carrier.

Subsequently, ammonium metavanadate (NH ₄ VO ₃ ) was used as a vanadium precursor and quantified to be 2.0 parts by weight based on 100 parts by weight based on the weight of the previously prepared silica / tungsten / titania carrier to prepare it by wet impregnation. . In this case, the catalysts corresponding to the respective manufacturing examples are referred to as 'Fresh catalyst' in the first firing process after vanadium loading and 'Aging catalyst' in the case of the catalyst subjected to the second heat treatment process (600 ℃ -10 hours, air atmosphere). I named it. In the case of the first heat treatment, the process of firing after supporting the general active metal was referred to as the first heat treatment, and in the case of the second heat treatment, the thermal durability related to the denitration catalyst of the present invention was promoted to artificially confirm the temperature. It means that higher thermal energy (600 ℃ -10 hours) is added.

Manufacturing example  2

When the silica precursor in Preparation Example 1 is supported on tungsten / titania, ammonium metatungstate ((NH ₄ ) 10H ₂ (W ₂ O ₇ ) ₆ ) as a tungsten oxide precursor is set to 8.0 parts by weight based on 100 parts by weight of titania. It is prepared by dissolving in a fixed amount to prepare an aqueous solution, and then supporting it with an aqueous silica solution to prepare it by wet impregnation. Since then the occupant at a temperature of 10 ^o C / min 100 ^o C intervals in the 200 ~ 800 ^o C at a temperature rising speed in a square and then fired in an air atmosphere for 4 hours, was prepared according to the silica / tungsten oxide / titania carrier to the sintering temperature . Also, silica / tungsten / titania according to the firing temperature The carrier Named Preparation Examples 2-1 to 2-7 and summarized in [Table 1] below.

division Additive Parts by weight Active substance precursor Heat treatment temperature and time Preparation Example 2-1 Silica 5 Dimetho dimethylsilane 200 ℃ -4 hours tungsten 8 Ammonium metatungstate Manufacturing example
2-2 Silica 5 Dimetho dimethylsilane 300 ℃ -4 hours tungsten 8 Ammonium metatungstate Manufacturing example
2-3 Silica 5 Dimetho dimethylsilane 400 ℃ -4 hours tungsten 8 Ammonium metatungstate Manufacturing example
2-4 Silica 5 Dimetho dimethylsilane 500 ℃ -4 hours tungsten 8 Ammonium metatungstate Manufacturing example
2-5 Silica 5 Dimetho dimethylsilane 600 ℃ -4 hours tungsten 8 Ammonium metatungstate Manufacturing example
2-6 Silica 5 Dimetho dimethylsilane 700 ℃ -4 hours tungsten 8 Ammonium metatungstate Manufacturing example
2-7 Silica 5 Dimetho dimethylsilane 800 ℃ -4 hours tungsten 8 Ammonium metatungstate

Manufacturing example  3

When preparing the silica / tungsten / titania carrier in Preparation Example 2 , the temperature was raised to a temperature of 600 to 700 ^o C at 50 ^o C intervals with respect to the firing temperature, and then fired in an air atmosphere for 4 hours to fire the silica / tungsten / titania carrier. Prepare according to temperature.

Subsequently, ammonium metavanadate (NH ₄ VO ₃ ) was used as a vanadium precursor and quantified to be 2.0 parts by weight based on 100 parts by weight based on the weight of the previously prepared silica / tungsten / titania carrier to prepare it by wet impregnation. . Also, silica / tungsten / titania according to the firing temperature The catalyst supporting vanadium on the carrier was named in Preparation Examples 3-1 to 3- 3 and summarized in [Table 2] below.

division Additive Parts by weight Active substance precursor Heat treatment temperature and time Active metal
(Parts by weight) Preparation Example 3-1 Silica 5 Dimetho dimethylsilane 600 ℃ -4 hours vanadium
(2) tungsten 8 Ammonium metatungstate Manufacturing example
3-2 Silica 5 Dimetho dimethylsilane 650 ℃ -4 hours vanadium
(2) tungsten 8 Ammonium metatungstate Manufacturing example
3-3 Silica 5 Dimetho dimethylsilane 700 ℃ -4 hours vanadium
(2) tungsten 8 Ammonium metatungstate

Manufacturing example  4

100 parts by weight based on the weight of the previously prepared silica / tungsten / titania carrier using ammonium metavanadate (NH ₄ VO ₃ ) as a vanadium precursor to the silica / tungsten / titania carrier prepared according to the firing temperature in Preparation Example 4. It was quantified to a standard 2.5 to 4.0 parts by weight, and was prepared by wet impregnation. In addition, the catalytic group prepared according to the vanadium loading content on the silica / tungsten / titania carrier according to the calcination temperature was referred to as the Preparation Examples 4-1 to 4-4 groups and summarized in [Table 3] below.

division Additive Parts by weight Active substance precursor Heat treatment temperature and time Active metal
(Parts by weight) Production Example 4-1 group Silica 5 Dimetho dimethylsilane 500 ℃ -4 hours vanadium
(2.0 ~ 6.0) tungsten 8 Ammonium metatungstate Manufacturing example
4-2 group Silica 5 Dimetho dimethylsilane 600 ℃ -4 hours vanadium
(2.0 ~ 4.0) tungsten 8 Ammonium metatungstate Manufacturing example
4-3 group Silica 5 Dimetho dimethylsilane 650 ℃ -4 hours vanadium
(2.0 ~ 4.0) tungsten 8 Ammonium metatungstate Manufacturing example
4-4 groups Silica 5 Dimetho dimethylsilane 700 ℃ -4 hours vanadium
(2.0 ~ 4.0) tungsten 8 Ammonium metatungstate

Comparative manufacturing example  One

Unlike Preparation Example 1, a tungsten / titania carrier was used without using a silica precursor. As a tungsten precursor, ammonium metatungstate ((NH ₄ ) 10H ₂ (W ₂ O ₇ ) ₆ ) is used to quantify and dissolve to 8.0 parts by weight based on 100 parts by weight of titania, and then prepared in a tungsten aqueous solution, followed by wet impregnation do. Thereafter, ammonium metavanadate (NH ₄ VO ₃ ) as a vanadium oxide precursor was quantified to be 2.0 parts by weight based on 100 parts by weight of a silica / tungsten / titania carrier prepared as a vanadium precursor, and was prepared by wet impregnation. Subsequently, in the same manner as in Production Example 1, the temperature was increased to 500 ° C. and calcined in an air atmosphere for 4 hours to prepare a vanadium / tungsten / titania catalyst.

Comparative manufacturing example  2

Unlike Preparation Example 1, colloidal silica (LUDOX, Colloid SiO ₂ , 30 wt.% Suspension in H ₂ O) was used as a silica precursor when preparing a silica / tungsten / titania carrier, and the silica precursor was 5.0 based on 100 parts by weight of titania. After dissolving it by quantification so as to be added by weight, it was prepared in the form of an aqueous silica solution, and then heated to a temperature of 500 ° C in the same manner as in Preparation Example 1, and calcined in an air atmosphere for 4 hours to prepare a silica / tungsten / titania carrier. Thereafter, an aqueous solution of vanadium is supported on the prepared carrier to prepare it by wet impregnation.

Comparative manufacturing example  3

Unlike Preparation Example 1, when preparing a silica / tungsten / titania carrier, tetraethyl orthosilicate (TEOS, Tetraethyl orthosilicate, C ₈ H ₂ O ₄ Si) was used as a silica precursor, and the silica precursor was based on 100 parts by weight of titania. After dissolving by quantification to 5.0 parts by weight to prepare a silica aqueous solution, the temperature was raised to 500 ° C. in the same manner as in Preparation Example 1, and calcined in an air atmosphere for 4 hours to prepare a silica / tungsten / titania carrier. Thereafter, an aqueous solution of vanadium is supported on the prepared carrier to prepare it by wet impregnation.

Comparative manufacturing example  4

When preparing the tungsten / titania carrier in Comparative Preparation Example 1, ammonium metatungstate ((NH ₄ ) 10H ₂ (W ₂ O ₇ ) ₆ ) was used as a tungsten precursor to quantify and dissolve so as to be 8.0 parts by weight based on 100 parts by weight of titania. It is prepared in a tungsten aqueous solution and then prepared by a wet impregnation method. Since then the occupant at a temperature of ^{10 o C / min 200 ~ 800} o C to 100 ^o C at a temperature rising rate in the interval in a square and then fired in an air atmosphere for 4 hours, was prepared according to the sintering temperature of the tungsten oxide / titania carrier. In addition, the tungsten / titania carrier according to the firing temperature was named Comparative Production Example 4-1 and was prepared until Comparative Production Example 4-7 and summarized in Table 4 below.

division Additive Parts by weight Active substance precursor Heat treatment temperature and time compare
Preparation Example 4-1 tungsten 8 Ammonium metatungstate 200 ℃ -4 hours compare
Manufacturing example
4-2 tungsten 8 Ammonium metatungstate 300 ℃ -4 hours Comparative manufacturing example
4-3 tungsten 8 Ammonium metatungstate 400 ℃ -4 hours Comparative manufacturing example
4-4 tungsten 8 Ammonium metatungstate 500 ℃ -4 hours Comparative manufacturing example
4-5 tungsten 8 Ammonium metatungstate 600 ℃ -4 hours Comparative manufacturing example
4-6 tungsten 8 Ammonium metatungstate 700 ℃ -4 hours Comparative manufacturing example
4-7 tungsten 8 Ammonium metatungstate 800 ℃ -4 hours

Comparative manufacturing example  5

When preparing the silica / tungsten / titania carrier in Comparative Preparation Example 2, colloidal silica (LUDOX, Colloid SiO ₂ , 30 wt.% Suspension in H ₂ O) was used as a silica precursor to quantify to 5.0 parts by weight based on 100 parts by weight of titania. Dissolved and prepared in the form of an aqueous silica solution, followed by wet impregnation. Since then in a square at a heating rate of 10 ^o C / min temperature increase to a temperature of 100 ^o C intervals in the 200 ~ 800 ^o C and then fired in an air atmosphere for 4 hours to produce along the silica / tungsten oxide / titania carrier to the sintering temperature . In addition, the silica / tungsten / titania carrier according to the firing temperature was named Comparative Production Example 5-1 and prepared until Comparative Production Example 5-7 and summarized in [Table 5] below.

division Additive Parts by weight Active substance precursor Heat treatment temperature and time compare
Manufacturing example
5-1 Silica 5 Colloidal silica 200 ℃ -4 hours tungsten 8 Ammonium metatungstate compare
Manufacturing example
5-2 Silica 5 Colloidal silica 300 ℃ -4 hours tungsten 8 Ammonium metatungstate compare
Manufacturing example
5-3 Silica 5 Colloidal silica 400 ℃ -4 hours tungsten 8 Ammonium metatungstate compare
Manufacturing example
5-4 Silica 5 Colloidal silica 500 ℃ -4 hours tungsten 8 Ammonium metatungstate compare
Manufacturing example
5-5 Silica 5 Colloidal silica 600 ℃ -4 hours tungsten 8 Ammonium metatungstate compare
Manufacturing example
5-6 Silica 5 Colloidal silica 700 ℃ -4 hours tungsten 8 Ammonium metatungstate compare
Manufacturing example
5-7 Silica 5 Colloidal silica 800 ℃ -4 hours tungsten 8 Ammonium metatungstate

Comparative manufacturing example  6

Compared using the preparation 3, tetraethyl ortho silicate _{(TEOS, Tetraethyl orthosilicate, C 8} H 2 O 4 Si) as a silica precursor in the manufacture of silica / tungsten oxide / titania carrier in the amount to be added 5.0 parts by weight to titania 100 parts by weight based on Dissolved and prepared in the form of an aqueous silica solution, followed by wet impregnation. Since then in a square at a heating rate of 10 ^o C / min temperature increase to a temperature of 100 ^o C intervals in the 200 ~ 800 ^o C and then fired in an air atmosphere for 4 hours to produce along the silica / tungsten oxide / titania carrier to the sintering temperature . In addition, the silica / tungsten / titania carrier according to the calcination temperature was named Comparative Production Example 6-1 and prepared until Comparative Production Example 6-7 and summarized in [Table 6] below.

division Additive Parts by weight Active substance precursor Heat treatment temperature and time compare
Manufacturing example
6-1 Silica 5 Tetraethyl
Orthosilicate 200 ℃ -4 hours tungsten 8 Tetraethyl
Orthosilicate compare
Manufacturing example
6-2 Silica 5 Tetraethyl
Orthosilicate 300 ℃ -4 hours tungsten 8 Ammonium metatungstate compare
Manufacturing example
6-3 Silica 5 Tetraethyl
Orthosilicate 400 ℃ -4 hours tungsten 8 Ammonium metatungstate compare
Manufacturing example
6-4 Silica 5 Tetraethyl
Orthosilicate 500 ℃ -4 hours tungsten 8 Ammonium metatungstate compare
Manufacturing example
6-5 Silica 5 Tetraethyl
Orthosilicate 600 ℃ -4 hours tungsten 8 Ammonium metatungstate compare
Manufacturing example
6-6 Silica 5 Tetraethyl
Orthosilicate 700 ℃ -4 hours tungsten 8 Ammonium metatungstate compare
Manufacturing example
6-7 Silica 5 Tetraethyl
Orthosilicate 800 ℃ -4 hours tungsten 8 Ammonium metatungstate

Comparative manufacturing example  7

The silica precursor prepared with dimetho dimethylsilane (DMDMS, Dimethoxy dimethylsilane, C ₄ H ₁₂ O ₂ Si) was prepared by using the composite oxide carrier used in Preparation Examples 1 to 3 with silica / tungsten / titania To compare the thermal durability, based on the weight of a commercial carrier containing silica and tungsten, using ammonium metavanadate (NH ₄ VO ₃ ) as a vanadium precursor to 'DT58', a silica / tungsten / titania oxide composition prepared in advance from the manufacturer. It was quantified to be 2.0 parts by weight based on 100 parts by weight, and was prepared by wet impregnation .

Example  One

In the production of vanadium / silica / tungsten / titania-based catalyst for removing gaseous nitrogen oxide according to the present invention, denitrification efficiency evaluation according to the precursor type of silica as an additive and nitrogen oxide removal activity of vanadium / tungsten / titania catalyst, which is the main commercial catalyst composition In order to evaluate, the nitrogen oxide removal rates of the fresh catalyst and the aging catalyst were measured at 200 to 500 ^° C. in the reaction temperature range for Preparation Example 1 and Comparative Preparation Examples 1 to 3. In this case, the nitrogen oxide concentration was 800 ppm, the nitrogen oxide / ammonia was 1: 1, the oxygen concentration was 10%, and the moisture was 6 vol.%, And the space velocity was measured at 150,000 h ^{- 1} . The experimental results are shown in [Fig. 1-a], [Fig. 1-b], and [Fig. 1-c].

As a result, in the case of the catalysts of Preparation Examples 1 to 3 and Comparative Preparation Examples 1 to 3, the silica precursor was used as dimesso dimethylsilane (DMDMS, Dimethoxy dimethylsilane, C ₄ H ₁₂ O ₂ Si) in the entire temperature range in [Fig. 1-a]. Example 1 and the conventional commercial catalyst composition of vanadium / tungsten / titania Comparative Preparation Example 1 and silica precursor colloidal silica (LUDOX, Colloid SiO ₂ , 30 wt.% Suspension in H ₂ O) and tetra ethyl orthosilicate (TEOS, Tetraethyl orthosilicate) , C ₈ H ₂ O ₄ Si) prepared in Comparative Examples 2 and 3 catalysts prepared with dimetho dimethylsilane (DMDMS, Dimethoxy dimethylsilane, C ₄ H ₁₂ O ₂ Si) in fresh catalyst and aging catalyst before / after heat treatment Except for Example 1, the remaining catalysts exhibited a characteristic in which the reaction activity was lowered in the reaction temperature section, and in the case of Preparation Example 1, the activity reduction rate was the lowest at a high temperature, and the reaction activity was enhanced at a low temperature.

In order to compare this more clearly, the reaction activity before and after heat treatment in the high temperature region (500 ° C) and the low temperature region (250 ° C) showing the largest reaction activity is shown in [Fig. 1-b] and [Fig. 1-c]. Did. In the case of a high temperature reaction temperature of 500 ° C, the reaction activity was reduced in all catalysts, but in the case of Production Example 1, a decrease rate of -6% was observed, whereas in Comparative Production Example 1 -13.2% and in Comparative Production Example 2 -10.25% , Comparative Production Example 3 showed a reduction rate of 10% or more with a reduction rate of -20.5%. Next, in the case of Preparation Example 1 at a low reaction temperature of 250 ° C, the reaction activity was increased to 29.82%, whereas Comparative Production Example 1 was -21.25%, Comparative Production Example 2 was -11.75%, and Comparative Production Example 3 Silver showed a decrease rate of 10% or more with a decrease rate of -14.5%.

Through this, the catalyst prepared through the silica / tungsten / titania carrier used as Preparation Example 1 using the silica precursor as dimetho dimethylsilane (C ₄ H ₁₂ O ₂ Si) reduced the denitrification efficiency at high / low temperature It was confirmed that this was the smallest. This confirmed that the SCR denitrification efficiency was stable by promoting thermal durability from structural stability due to the combination of titania and silica in the case of a catalyst prepared through a silica / tungsten-titania carrier using DMDMS.

Example  2

When preparing a vanadium / silica / tungsten / titania catalyst, the effect of enhancing the thermal durability of the carrier can be obtained through the combination of silica and titania before vanadium is supported. In order to confirm this more clearly, Comparative Example 4 (W / TiO ₂ ) prepared from a tungsten / titania carrier that does not support vanadium and silica, which are active metals, and silica / tungsten / titania carrier are prepared according to precursor types. 2 (DMDMS), Comparative Preparation Example 5 (Colloid), Comparative Preparation Example 6 (TEOS) measuring the specific surface area of each of the carriers prepared at 100 ° C intervals up to a heat treatment temperature of 200 to 800 ° C to obtain a change value according to temperature It was compared to [Table 7].

As a result, it was confirmed that in the case of only TiO ₂ without additives such as tungsten and silica, as the heat treatment temperature increased, the size of the specific surface area decreased significantly. On the other hand, in Production Example 2 and Comparative Production Examples 4 to 6, it was confirmed that the property of maintaining a specific surface area of about 240 m ² / g even when the heat treatment temperature up to 300 ° C was increased. Subsequently, at a heat treatment temperature of 400 ° C. or higher, a specific surface area of 200 m ² / g or less was observed for the carriers of Comparative Preparation Examples 4 to 6, but a high specific surface area of 233.07 m ² / g was maintained for Production Example 2. In addition, as the heat treatment temperature increased to 800 ° C., the carriers except Production Example 2 showed a specific surface area lower than 100 m ² / g up to 600 ° C., and Production Example 2 maintained a high specific surface area of 159.62 m ² / g. Showed. At 700 and 800 ℃ heat treatment temperature, all the carriers showed a specific surface area below 100 m ² / g, but Production Example 2 showed 97.951 m ² / g and 55.476 m ² / g at each temperature, and the ratio changed according to the thermal energy. Excellent thermal durability against surface area was confirmed.

Next, the specific surface areas before and after the heat treatment of the catalysts prepared by supporting the active metal vanadium through the carriers were prepared in Preparation Example 1 and Comparative Preparation Examples 1 to 3, and are shown in [Table 8]. As a result, Comparative Production Examples 1 to 3 the catalyst specific surface area of each of the heat treatment before the catalyst showed a ^{79.36, 100.55, 97.83 m 2 /} g showed a heat treatment after ^{31.75, 39.33, 40.17 m 2 /} g considerably reduced specific surface area characteristics . On the other hand, in the case of Preparation Example 1, the catalyst showed a high specific surface area of the vanadium the primary heat-treated before the sintering catalyst and then carrying 168.36 m ² / g, was found to exhibit a high specific surface area of 81.14 m ² / g even after the heat treatment.

Through this, it was confirmed that a specific surface area reduction of the catalyst due to high temperature heat energy was suppressed in a carrier and a catalyst using a silica precursor as dimetho dimethylsilane (DMDMS, Dimethoxy dimethylsilane, C ₄ H ₁₂ O ₂ Si).

Specific Surface Science (m ² / g) Firing temperature carrier Only TiO ₂ Comparative Production Example 4 Preparation Example 2 Comparative Production Example 5 Comparative Production Example 6 200 270.67 307.44 335.64 317.07 327.07 300 177 239.04 251.08 244.18 241.77 400 112 140.26 233.07 184.98 154.72 500 74 108.27 199.059 127.38 107.84 600 46 48.136 159.62 96.02 93.5 700 27 29.2 97.951 65.623 59.227 800 8 11.2 55.476 44.393 36.51

Specific Surface Science (m ² / g) Firing temperature Catalysts Comparative Production Example 1 Preparation Example 1 Comparative Production Example 2 Comparative Production Example 3 Fresh 79.36 168.36 100.55 97.83 Aging 31.75 81.14 39.33 40.17

Example  3

When preparing a vanadium / silica / tungsten / titania catalyst, it was confirmed that the thermal durability of the carrier was enhanced through the combination of silica and titania before vanadium was supported. In order to confirm this more clearly, one of the physical properties of the catalyst before and after the heat treatment of the catalysts prepared in Example 1 and Comparative Preparation Examples 1 to 3 with catalysts supporting vanadium as an active metal for the carriers prepared according to the above-mentioned silica precursor type Pore distribution and pore size were compared through phosphorus BJH analysis and are shown in [FIG. 2] and [Table 9], respectively. As a result, each catalyst pore distribution before heat treatment of Comparative Preparation Examples 1 to 3 catalysts showed the highest distribution at about 10.0 dp / nm similarly, and small pores at 2.5 to 3.0 dp / nm in Preparation Example 1 catalyst. The distribution of in is shown. After the heat treatment, in Comparative Preparation Examples 1 to 3 catalysts, it was confirmed that the characteristics of the distribution peak which is about twice as large as about 20.0 dp / nm were developed. Was confirmed.

Next, as a result of comparing the pore sizes of the respective catalysts, all of the pore sizes before heat treatment of both the Preparation Example 1 catalyst and Comparative Preparation Examples 1 to 3 catalysts showed a result value of about 0.3 cm ³ / g or more, and the pore sizes were compared. Example 3> Preparation Example 1> Comparative Production Example 1> Comparative Production Example 2. However, after the heat treatment, Comparative Preparation Examples 1 to 3 catalysts showed a size of 0.2452, 0.2558, and 0.2933 cm ³ / g, respectively, but in the Preparation Example 1 catalyst, the pore size of 0.3265 cm ³ / g was maintained similar to the catalyst before the heat treatment. Was confirmed.

Through this, it was confirmed that the pore distribution and the pore size of the catalyst were suppressed by the high temperature heat energy in the carrier and the catalyst using the silica precursor as dimetho dimethylsilane (DMDMS, Dimethoxy dimethylsilane, C ₄ H ₁₂ O ₂ Si). .

BJH analysis Catalysts Pore size (V _p , cm ³ / g) Fresh Aging Comparative Production Example 1 0.3308 0.2452 Preparation Example 1 0.3561 0.3265 Comparative Production Example 2 0.3113 0.2558 Comparative Production Example 3 0.3661 0.2933

Example  4

The silica / tungsten / titania carrier according to the precursor type was subjected to FE-SEM / EDX analysis to confirm the ratio and amount of silica, which is a material that has thermal durability on the surface after firing, and the results are shown in [Table 10]. Shown. The analysis is shown in Preparation Example 2, Comparative Preparation Example 5, and Comparative Preparation Example 6 according to the precursor type as a silica / tungsten / titania carrier that does not contain vanadium, an active metal. As a result of confirming the ratio and amount of silica on the surface of the carrier after firing through EDX analysis, a ratio of 2.67 wt.% In Preparation Example 2 using the precursor as DMDMS was shown, and 2.88 wt. In Comparative Preparation Example 5 using the precursor as a colloid. %. However, it was confirmed that silica having a detectability error value of about 0.01 wt.% Of the diameter of Comparative Production Example 6 using the precursor as TEOS was detected. This is, even if the same silica is used in the preparation of the catalyst, the difference occurs depending on the characteristics of the precursor. When preparing an aqueous silica solution using distilled water in the impregnation method of the catalyst preparation method of the present invention, the preparation of Example 2 and Comparative Preparation Example 5 In the case of the TEOS precursor of Comparative Preparation Example 6, it is well-dissolved to form an aqueous solution, whereas it is considered that it is volatilized during the impregnation process as a polar molecular form that is not dissolved in distilled water, such as a molecular formula such as Si (OCH ₃ ) ₄ . Through this, even if the same silica is supported, a precursor soluble in distilled water, which is a solvent used in the manufacturing process of impregnation in the catalyst slurry in the manufacturing method, can be used.

FE-SEM / EDX result element carrier Preparation Example 2 Comparative Production Example 5 Comparative Production Example 6 Weight% Weight% Weight% C 2.74 1.81 1.52 O 41.76 35.52 47.22 Si 2.67 2.88 0.01 Ti 42.38 52.47 43.44 W 10.45 7.32 7.81 Sum 100.00 100.00 100.00

Example  5

Pre- and post-heat treatment Preparation Example 1, Comparative Production Example 2, Comparative Production Example 3 to confirm the bonding state and ratio of silica and titania of catalysts having thermal durability with or without thermal vanadium / silica / tungsten / titania catalyst precursors The catalysts are subjected to XPS analysis and are shown in [FIG. 3] and [Table 11].

In order to confirm the thermal durability of the catalyst prepared by adding different precursor silica, Si 2P was measured for the three catalysts to separate the SiO ₂ , Si-O-Ti, and Si-O-Si bonding structures, depending on the precursor type. Respectively. As a result, different Si 2P results were confirmed in the three catalysts.

Si 2P catalyst Preparation Example 1 Comparative Production Example 2 Comparative Production Example 3 Rescue Fresh Aging Fresh Aging Fresh Aging Si-O-Ti 84.34 53.02 0.2 0.0 - - Si-O-Si 14.84 18.3 - - - - SiO ₂ 0.8 28.68 99.8 100.0 - -

First, in the case of the catalyst of Preparation Example 1, in which the silica precursor was prepared by DMDMS, all three types of Si-O-Ti, Si-O-Si, and SiO ₂ were observed in the catalyst before heat treatment, and each ratio was 0.8%. At 14.84% and 84.34%, the Si-O-Ti bond ratio showed the largest proportion among the bonds formed by all silica. After the heat treatment, it was confirmed that the Si-O-Ti ratio was reduced and the SiO ₂ and Si-O-Si ratios were increased to 28.68%, 18.3%, and 53% of the previous binding species.

Next, in the case of Comparative Preparation Example 2 using a silica precursor as a colloid, SiO ₂ and Si-O-Si were observed in the catalyst before heat treatment, but most of them were SiO ₂ , and Si-O-Ti was very insignificantly confirmed. . However, it was confirmed that all of the silica forms of the catalyst were converted to SiO ₂ after heat treatment.

Next, in Comparative Preparation Example 3 catalyst using silica precursor as TEOS, XPS Si 2P peak before / after heat treatment was not observed. This cause was not detected in the XPS analysis because most of it was not volatilized and remained without silica remaining on the catalyst surface when it appeared in connection with the volatile problem arising from the method for preparing the impregnation method of the silica precursor mentioned in Example 4 above. I could confirm.

Accordingly, it was confirmed that the catalyst having a Ti-O-Si bonding type in combination with titania, which is a carrier, has thermal durability even when silica of different precursors is supported in the vanadium / silica / tungsten / titania catalyst.

In the silica / tungsten / titania carrier, in order to confirm the formation of Si-O-Ti bonds generated by heat treatment of silica according to the precursor type, Preparation Example 2, Comparative Production Example 4, Comparative Production Example 5, and Comparative Production Example 6 were fired. O ₂ -TPO analysis that measures and records the CO ₂ concentration generated by raising the temperature from 100 ℃ to 500 ℃, which is the firing condition by introducing oxygen and nitrogen to the drying bodies, not until the drying process It was carried out and is shown in [Figure 4].

The silica precursor used in Preparation Example 2, dimetho dimethylsilane (DMDMS, Dimethoxy dimethylsilane, C ₄ H ₁₂ O ₂ Si) is a molecular formula Si (OCH ₃ ) ₂ (CH ₃ ) ₂ This silica is a group 14 element on the periodic table, and like carbon, has four bonding legs. Through this, the -OCH ₃ group and -CH ₃ group combined with silica have a combustion formula that encounters oxygen to cause an oxidation reaction, and the formulas are shown in [Reaction Scheme 1] and [Reaction Scheme 2].

[Scheme 1]

_{4CH 3 O + 5O 2 → 4CO} 2 + 6H 2 O

[Scheme 2]

_{4CH 3 + 5O 2 → 4CO 2} + 6H 2 O

When the -OCH ₃ group and -CH ₃ group combined with silica were burned through the above reaction, free silica bound to titania was formed, and CO ₂ was measured to confirm this combustion reaction. As a specific result, in DMDMS, CO ₂ was formed by a combustion reaction from 300 ° C. and showed the highest concentration at 450 ° C., which was gradually reduced, and the combined -OCH ₃ groups and -CH ₃ groups in the carrier were all burned, resulting in a CO ₂ concentration. It was confirmed to decrease gradually.

On the other hand, in Comparative Preparation Example 4 in which the silica precursor was not supported and in Comparative Preparation Example 5 using colloid SiO ₂ as the silica precursor, CO ₂ was not observed even when the temperature was increased, which is the -OCH ₃ group that will be burned upon encountering oxygen,- No signal is observed because the CH ₃ group is not present. In addition, it was confirmed that the carrier of Comparative Preparation Example 6 using TEOS as a silica precursor was not volatilized in the manufacturing process, and thus, combustors were also volatilized and CO ₂ was not formed.

This allows it to be used for impregnation and burns during the firing process and combines with titania to show Si-O-Si and Si-O-Ti bonding structures. Dimesso dimethylsilane (DMDMS, Dimethoxy dimethylsilane, C ₄ H ₁₂ O ₂ Si) The precursor is a vanadium / silica / tungsten / titania catalyst with a high thermal energy, which decreases the specific surface area, which is an inactivation factor of the catalyst, converts it to the rutile phase on the titania anatase, and the active point of the catalyst surface upon formation of Ti-VO substituted species It was confirmed that it is possible to further improve the thermal durability by suppressing the loss to the interior of the.

Example  6

Vanadium structural species of Preparation Example 1, Comparative Production Examples 1 to 3 catalysts identified before and after heat treatment of the precursors that formed the thermal durability enhancing structural species and the catalysts that did not form the vanadium / silica / tungsten / titania catalyst according to the precursor type XRD analysis was performed to observe the change in [Fig. 5]. As a result, XRD analysis of the three silica precursor catalysts confirmed that the main peak of the titania anatase (101) plane diffraction peak was observed at 2 Theta = 25.28 ° to have the crystal structure of the carrier anatase titania. In addition, the anatase titania peaks showed peak crystal structures of Theta = 37.34, 38.05, 38.75, 48.21, 54.00, 55.22, 62.74, 69.00, 70.4, and 75.9 °. In the crystal structure of titania, amorphous titanic acid is crystallized according to heat treatment conditions to increase the crystallinity of anatase titania. In addition, anatase exhibiting metastability is known to be converted to rutile by high temperature heat.

First, Comparative Preparation Example 1, in which catalyst was prepared by supporting only tungsten on which silica was not supported, and Colloid and TEOS precursors were supported by tungsten, followed by calcination, followed by calcination and vanadium loading. When compared, the catalyst surface showed significantly different vanadium structural species. As observed vanadium species peaks, VO ₂ , V ₂ O ₅ , and TiVO ₄ species were observed, and the VO ₂ = 33.3 °, V ₂ O ₅ = 23.5 °, 34 °, and TiVO ₄ = 41.8 ° peak crystal structures were observed. . In particular, V ₂ O ₅ is a structural species well known as a crystalline VOx species with increased crystallinity, which causes a reduction in overall catalytic efficiency by oxidation of ammonia, a reducing agent, at high temperature denitrification. In addition, in the case of the TiVO4 structural species, vanadium is a structural species that is lost inside the titania in the substitution reaction, which is a factor that decreases the denitrification activity point of the catalyst and causes denitrification efficiency at low temperatures.

On the other hand, in the case of the catalyst using the silica precursor as a DMDMS, there was no change in the catalyst crystal phase peak before / after heat treatment, and thus the vanadium structural species formed was not observed, and only the titania anatase structure was observed, thereby improving thermal durability. Can be confirmed.

Example  7

H ₂ -TPR (H ₂ Temperature Programmed Reduction) analysis was carried out to confirm the effect of vanadium, which is an active metal, before and after heat treatment on the structural species of the vanadium / silica / tungsten / titania catalyst. The position of the maximum reduction temperature (Tmax) in H ₂ -TPR is generally known to be shifted by the amount of carrier and active metal supported. Therefore, by observing the hydrogen consumption characteristics through H ₂ -TPR analysis for the before and after heat treatment of the three Preparation Examples 1, Comparative Preparation Examples 2 and Comparative Preparation Example 3 catalysts, the change in the vanadium structural species on the catalyst surface was observed. Specifically, 2920 Autochem (Micromeritics) was used, and a detector for concentration measurement was performed by H ₂ -TPR analysis using a Thermal Conductivity Detector (TCD). The order of analysis is after filling 0.3 g of a catalyst crushed to 100 um or less, and first, 5 vol.% O ₂ / He of 50 cc / min is heated to 10 ° C./min while flowing at 400 ° C. for 30 minutes to remove impurities on the surface. Removed. Subsequently, the temperature was lowered to room temperature, and 5 vol.% H ₂ / Ar was injected for 1 hour to make the catalyst in a reducing atmosphere. Thereafter, while increasing the temperature to 10 ° C / min, hydrogen consumption was measured up to 800 ^° C and shown in [Fig. 6].

As a result, the Tmax peak observed before the heat treatment of the catalyst using Colloid and TEOS as precursors was confirmed that in the case of Colloid, surface monomeric V observed at 426 ° C and some polymeric V species observed at 557 ° C were observed, and the monomeric species at low temperatures. It can be seen from the results that oxygen species that are desorbed by reacting with hydrogen are high in reaction activity before heat treatment at low temperature. In addition, in the case of a catalyst using TEOS as a precursor, it was confirmed that surface monomeric V observed at 436 ° C and some polymeric V species observed at 561 ° C were observed. It can be seen that the reaction activity before heat treatment at low temperature is high. On the other hand, in the case of Colloid and TEOS catalysts after heat treatment, the first oxygen consumption peak shifts to 460 ℃ and 473 ℃, respectively, and the peak known as oxygen consumed in the surface crystalline VOx species near 648 ℃ can be confirmed.

Next, in the case of the DMDMS catalyst, only the monomeric V species observed at 448 ° C before heat treatment were observed, but after heat treatment, the temperature shift of the three catalysts was the lowest among 4 catalysts and the formation of some polymeric V species near 545 ° C was observed. I could confirm.

Based on the properties of each of these catalysts, it can be confirmed that the formation of the crystalline V species is more predominant than the formation of the polymeric V as it is shifted to higher temperatures. It can be seen that the structural change due to the thermal energy of the metal vanadium is large. However, in the case of the DMDMS catalyst having the thermal durability-enhancing structural species Ti-O-Si, it was confirmed that the hydrogen consumption peak of H ₂ -TPR is almost maintained even after heat treatment.

Example  8

In the preparation of a vanadium / silica / tungsten / titania-based catalyst for removing gaseous nitrogen oxides according to the present invention, a silica precursor is selected as 'dimesso dimethylsilane' as in Preparation Example 1, and the silica / tungsten / titania carrier is supported before loading vanadium. In order to control the specific surface area, the specific surface area is controlled by setting the firing temperature from 600 ° C to 700 ° C in 50 ° C intervals. Thereafter, vanadium having the same loading amount was supported to prepare catalysts in Preparation Examples 3-1 to 3-3. In addition, in order to evaluate the denitrification efficiency of the catalyst prepared in Comparative Catalyst 7 prepared by using 'DT58' having a silica / tungsten / titania composition as a carrier among commercial catalysts, nitrogen oxide removal rates of fresh catalyst and aging catalyst were measured at 200 ~ 500 ^o C. It was measured. In the case of the experimental conditions, it was performed under the same conditions as in Example 1, and the results are shown in [Fig. 7-a], [Fig. 7-b], and [Fig. 7-c].

As a result, in [Fig. 7-a], which shows the denitrification efficiency of the entire temperature range of the catalysts, in the case of the catalyst prepared in Example 3-1 in which the silica / tungsten / titania carrier was fired at 600 ° C, before / after heat treatment at a temperature of 450 ° C or higher In comparison, the reaction activity was lowered, and in the case of a temperature of 300 ° C. or lower, the reaction activity was improved after heat treatment. On the other hand, in the case of Comparative Preparation Example 7 catalyst, which was conducted under the same conditions to compare the catalysts of Preparation Examples 3-2 and 3-3, which further increased the firing temperature of the silica / tungsten / titania carrier, the temperature range of 500 ° C before heat treatment The conversion rate was about 80%, and some efficiencies were reduced after heat treatment, but the reduction was different depending on the catalyst. In addition, at a temperature of 300 ° C. or lower, a conversion rate of about 80% or higher was high, and a change value of denitrification efficiency after heat treatment was different depending on the catalyst.

In order to compare this more clearly, the reaction activities before and after heat treatment in the high temperature region (500 ° C) and the low temperature region (250 ° C) showing the largest reaction activity are shown in [Fig. 7-b] and [Fig. 7-c]. Did. In the case of a high temperature reaction temperature of 500 ° C, the reaction activity was reduced in all catalysts, but the reduction width of all four catalysts was different. First, in Comparative Production Example 7, the reduction rate of -12.625%, Production Example 3-1 was -8.75%, Production Example 3-2 was -3.365%, and Production Example 3-3 was -4.0%, with a reduction rate of 10% or more. In the case of the catalyst shown, Comparative Production Example 7 showed the largest rate of change at a high temperature reaction temperature. Next, the reaction activity change rate was shown in the order of Preparation Example 3-1> Preparation Example 3-3> Preparation Example 3-2. Next, at a low-temperature reaction temperature of 250 ° C, -11.625% for Comparative Production Example 7, + 18.875% for Production Example 3-1, -4.75% for Production Example 3-2, and -12.75% for Production Example 3-3. The catalysts that showed a reduction rate of 10% or more at a reduction rate were the catalysts of Comparative Production Example 7 and Production Example 3-3, and in the case of the Production Example 3-1 catalyst, the reaction activity was improved, but after the improvement, the activity was 71.375%, whereas Production Example 3 In the case of the -2 catalyst, the reduction rate was 4.75%, which was 5% or less, and even after the reduction, the denitrification efficiency of 77% was maintained.

As a result, in the case of a catalyst prepared through a silica / tungsten-titania carrier using DMDMS, the calcination temperature is set to 650 ° C to improve thermal durability from the best structural stability in the catalyst having a specific surface area control and to improve SCR denitrification efficiency. I could confirm.

Example  9

Next, the specific surface areas before and after the heat treatment of the catalysts prepared in Comparative Example 7 and Preparation Examples 3-1 to 3-3, which are catalysts prepared by supporting vanadium as an active metal through the above carriers, are compared and are shown in [Table 12]. . As a result, in Comparative Production Example 7 and Production Example 3-3, the specific surface area of each catalyst was 89.94, 77.56 m ² / g before the heat treatment of the catalyst, and the specific surface area was about 70.0 m ² / 54.29, 56.86 m ² / g after the heat treatment. It showed a significantly reduced characteristic below g. On the other hand, in the case of the catalysts of Preparation Examples 3-2 and 3-3, after the vanadium loading, the catalysts showed a high specific surface area of 114.63, 105.56 m ² / g, and a high specific surface area of 76.58, 70.94 m ² / g even after the heat treatment. It confirmed that it showed.

Through this, it was confirmed that the silica / tungsten-titania carrier using DMDMS had a firing temperature of 600 and 650 ° C., and that the specific surface area was maintained high before and after heat treatment when vanadium was supported, and denitrification efficiency in Example 8 above. Considering the change in, it is determined that it is desirable to maintain a specific surface area of about 100.0 m ² / g or more after vanadium loading, and about 70.0 m ² / g or more after heat treatment.

Specific Surface Science (m ² / g) catalyst Heat treatment step Fresh Aging Comparative Production Example 7 89.94 54.29 Preparation Example 3-1 114.63 76.58 Preparation Example 3-2 105.56 70.94 Preparation Example 3-3 77.56 53.86

Example  10

Next, before the heat treatment to confirm the structural species and the ratio of the thermal durability of the catalyst prepared in Comparative Preparation Example 7 and Preparation Examples 3-1 to 3-3, which are catalysts prepared by supporting vanadium as an active metal on the carriers / After performing XPS analysis, it is shown in [FIG. 8] and [Table 13].

Catalysts prepared with silica / tungsten / titania carriers with specific surface area control at different firing temperatures showed different denitrification efficiency differently. Through this, the ratio of Ti-O-Si species, which are silica structural species that improved thermal durability, was measured by measuring Si 2P for the three catalysts, separating the Si-O-Ti, Si-O-Si, and SiO ₂ bonding structures to separate catalysts. It is shown according to the results of each. As a result, it was confirmed that the three catalysts controlling the specific surface area showed different Si 2P formation ratios, and that the catalysts using DT58 were formed of only two structural species: Si-O-Si and SiO ₂ .

Si 2P catalyst Preparation Example 3-1 Preparation Example 3-2 Preparation Example 3-3 Comparative Production Example 7 Rescue Fresh Aging Fresh Aging Fresh Aging Fresh Aging Si-O-Ti 88.22 51.84 71.26 52.22 66.45 39.36 - - Si-O-Si 10.478 18.95 8.35 12.31 5.94 14.57 49.38 13.95 SiO ₂ 1.3 29.2 20.38 35.46 27.6 46.06 50.54 86.04

First, in the case of the catalysts of Preparation Examples 3-1 to 3-3, three types of Si-O-Ti, Si-O-Si, and SiO ₂ were observed in the catalyst before heat treatment, and Si, which promoted thermal durability, was observed. The proportion of -O-Ti structural species was 88.22%, 71.26%, and 66.45%, respectively. In addition, in the case of the comparative production example 7 catalyst made of commercially available titania 'DT58', the Si-O-Ti structural species were not observed, and the ratio of Si-O-Si and SiO ₂ was 49.38% and 50.54% before heat treatment. After the heat treatment, it was confirmed that the conversion rate to SiO ₂ increased to 13.95% and 86.04%, respectively.

Accordingly, when the ratio of the Ti-O-Si bond type is compared with the denitrification efficiency for the production examples 3-1 to 3-3, which are carriers having a controlled specific surface area in the vanadium / silica / tungsten / titania catalyst, the Si-O-Ti structure It is judged to exhibit thermal durability characteristics at about 70.0% or more, and if it is less than that, denitrification efficiency after heat treatment is judged to occur at 10% or more in the high and low temperature regions.

Example  11

Next, catalysts prepared by supporting vanadium as an active metal on carriers made of DMDMS silica precursors formed with TI-O-Si structural species having improved thermal durability, are prepared in Preparation Example 1 and Preparation Examples 3-1 to 3- 3 Raman analysis was performed to confirm the activity enhancer in the low temperature region (below 300 ° C) for denitrification efficiency that appeared before / after the heat treatment of the catalyst, and the results of vanadium structural species were observed and the results are shown in [Fig. 9].

Catalysts prepared with silica / tungsten / titania carriers with specific surface area control at different firing temperatures showed different denitrification efficiency increase / decrease in the low temperature region. In the case of the catalysts of Preparation Example 1 and Preparation Example 3-1, the initial activity showed a low conversion rate of less than 60%, but after the heat treatment, the reaction activity was enhanced to 70% or more, and Preparation Examples 3-2, 3- In the case of the 3 catalyst, the initial reaction activity showed a high denitration efficiency of 80%. In order to confirm the correlation with the vanadium structural species, Raman analysis confirmed that a polymeric V species, a vanadium structural species that promotes low-temperature reaction activity, was observed in the catalyst with improved reaction activity after heat treatment, and the catalyst exhibited excellent denitrification efficiency in the catalyst before heat treatment. They also confirmed that polymeric V species were observed.

Through this, it was confirmed that the specific surface area of the catalyst supporting vanadium was formed between 110 and 70 m ² / g, and the polymeric V species was formed when it decreased below 70 m ² / g. It was confirmed.

Example  12

In preparing the vanadium / silica / tungsten / titania-based catalyst for removing gaseous nitrogen oxides according to the present invention, it was confirmed that the catalyst prepared by selecting the silica precursor as 'dimetho dimethylsilane' as in Preparation Example 1 has improved thermal durability. On the other hand, in order to improve the reaction activity at a reaction temperature of 300 ° C or less, a study was conducted to derive the optimum amount of vanadium loading. In the case of the catalyst used to derive the optimum vanadium loading, the firing temperatures of the silica / tungsten / titania carriers used in Production Example 1 and Production Examples 3-1 to 3-3 were calcined to 500 to 700 ° C, respectively, and then the specific surface area was controlled. The amount of vanadium supported was varied and supported. The catalyst was prepared by supporting the vanadium loading amount to 2.0 to 6.0 parts by weight on a 500 ° C calcined carrier corresponding to Preparation Example 4-1, and in the case of a carrier calcined at 600, 650, 700 ° C, the vanadium loading amount was 2.0 to 4.0 parts by weight. The denitrification efficiency was compared with each other by preparing them as Preparation Examples 4-2, 4-3, and 4-4. In the case of experimental conditions, it was performed under the same conditions as in Example 1, and the results are shown in [Table 14] and [Table 15].

catalyst Reaction temperature Vanadium loading 2 2.25 2.5 2.75 3.0 3.25 3.5 4.0 4.5 5 5.5 6.0 Production Example 4-1 group 300 79.27 90 91.25 92.5 94.75 95.5 95.6 95.25 96.25 97.87 92.75 96.5 270 61.72 75.06 77.78 79.33 82.43 84.76 85.9 87.1 89.03 92.13 86.5 84.76 250 44.05 60.625 64.5 66.87 70.5 73.75 75.6 78 81.87 86.62 79.62 76.12 220 32.37 38.625 40.62 43 46.25 49.5 51.6 56 62 67.12 57.75 56.75 200 27.62 29.75 32.5 35 36.25 37.875 40.8 42.62 48.75 50.25 46.25 43.5

catalyst Reaction temperature Vanadium loading 2.0 2.5 3.0 3.5 4.0 Manufacturing example
4-2
group 300 92.25 95.12 94 96 95 270 68.59 91.25 90.12 91.37 90.12 250 52.5 79.5 81.62 83.25 80.25 220 36 54.25 60.25 62.87 56.87 200 29.87 41.87 46.25 47.87 40 Manufacturing example
4-3
group 300 95.75 97.12 97.5 95.5 94.25 270 88.2 92.25 93.5 92.375 88 250 81.75 82.37 85.25 84 78.75 220 59.87 58.12 60.875 60.25 58.75 200 42.75 43.37 45.37 45 43.12 Manufacturing example
4-4
group 300 98 99.37 99.25 96.75 92.87 270 87.9 96 94.62 89.5 85.62 250 81.25 88.12 85.75 79.25 75.37 220 55 63.5 61.25 57.87 55 200 41.5 48.12 45.5 43.25 42.12

The denitrification efficiency within the reaction temperature of the catalysts differed depending on the specific surface area of the silica / tungsten / titania carrier and the amount of vanadium loading showing optimum denitrification efficiency was different. The amount of vanadium supported by each catalyst is 5.0, 3.5, 3.0, 2.5 parts by weight in the order of Preparation Examples 4-1 to 4-4, and the denitrification efficiency of each is 86.62%, 83.25%, 85.25%, 88.12 at 250 ° C. %, And it was confirmed that the denitrification efficiency decreases when the vanadium loading is increased.

Through this, the amount of vanadium supported on the silica / tungsten-titania carrier using DMDMS can be supported up to 5.0 parts by weight, but when denitrification efficiency and specific surface area are taken into consideration, conditions of preparing at about 170-100.0 m ² / g after vanadium loading Under the weight portion of 2.0 to 5.0, it was confirmed that the thermal durability was improved from the excellent structural stability, and excellent low-temperature SCR denitrification efficiency was obtained.

Claims (11)

A composite oxide carrier comprising 5 to 8 parts by weight of tungsten and 1 to 5 parts by weight of silica with respect to 100 parts by weight of titania, and 70% or more of the total silica structure of Si-O-Ti bonding structure paper. Method for producing a composite oxide carrier characterized in that it is prepared by carrying out a tungsten precursor and a silica precursor so as to contain 5 to 8 parts by weight of tungsten and 1 to 5 parts by weight of silica relative to 100 parts by weight of titania, and then firing at 500 to 650 ° C. The method of claim 2, wherein the silica precursor is dimetho dimethylsilane (DMDMS, Dimethoxy dimethylsilane, C ₄ H ₁₂ O ₂ Si). The method of claim 2, wherein the tungsten precursor is ammonium metatungstate ((NH ₄ ) 10H ₂ (W ₂ O ₇ ) ₆ ). The method of claim 2, wherein the tungsten precursor or silica precursor is a soluble compound. Denitration catalyst comprising 2 to 5 parts by weight of vanadium with respect to 100 parts by weight of the composite oxide carrier according to claim 1. The denitration catalyst according to claim 6, wherein the vanadium structural species has a polymeric V structure. 7. The denitration catalyst according to claim 6, wherein the denitration catalyst has a specific surface area of 70.0 m ² / g or more. Method for producing a denitration catalyst characterized by being prepared by carrying a vanadium precursor so that 2 to 5 parts by weight of vanadium with respect to 100 parts by weight of the composite oxide carrier according to claim 1 and then calcining at 500 to 600 ° C. The method for preparing a denitration catalyst according to claim 9, wherein the vanadium precursor is ammonium metavanadate (NH ₄ VO ₃ ). The method for preparing a denitration catalyst according to claim 9, wherein the vanadium precursor is a soluble compound.

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