WO2024035057A1 - Emission treatment catalyst comprising zeolite and metal oxide - Google Patents

Abstract

The present invention relates to an emission treatment catalyst in which a first catalyst and a second catalyst are introduced on a support. The first catalyst is a zeolite catalyst, and the second catalyst is a catalyst in which nickel and magnesium are added to alumina. The first catalyst and the second catalyst may be mixed and introduced as one or more coating layers, or may also be introduced as separate respective coating layers. By comprising the first catalyst and the second catalyst, the emission treatment catalyst according to the present invention has a long lifespan due to excellent durability thereof even when used to treat emissions of various components, such as volatile organic compounds and odor-causing compounds, and has high selectivity for converting pollutants into a form that can be emitted, such as nitrogen, carbon dioxide, or the like, and thus is highly effectively used in related industries.

Description

Emission treatment catalyst comprising zeolites and metal oxides

The present invention relates to effluent treatment catalysts comprising zeolites and metal oxides. Specifically, the present invention relates to an exhaust treatment catalyst comprising a first catalyst and a second catalyst, wherein the first catalyst is a zeolite catalyst and the second catalyst is a catalyst obtained by adding nickel and magnesium to alumina.

This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0099316, dated August 9, 2022, and includes all contents disclosed in the document of the Korean Patent Application as part of this specification.

In certain industrial fields such as semiconductor and display processes, process emissions mainly include volatile organic compounds (VOC) and odor-causing compounds. Process emissions containing organic volatile substances and odor-causing substances are a cause of air pollution, and therefore treatment technologies for organic volatile substances and odor-causing substances are required.

According to conventional methods, organic volatile substances are treated by means such as regenerative thermal oxidation or regenerative catalytic oxidation. Low concentrations of organic volatile substances are concentrated and then treated using a concentrator (e.g., a rotating rotor containing an adsorbent) to increase treatment efficiency. When the flow rate of exhaust gas is large, the regenerative thermal oxidation method can be an economical method, but when the reaction temperature is too high to increase treatment efficiency, there is a problem in that NO _x is generated and secondary pollutants are emitted.

In addition, ammonia, among odor-causing substances, is easily soluble in water, so exhaust gas containing ammonia is treated by washing with water. Specifically, ammonia can be treated by dissolving it in water or an aqueous solution containing specific chemicals designed to increase the solubility of ammonia, but considering that regulations on total nitrogen content are becoming stricter in terms of water quality environment, inside the workplace Alternatively, secondary treatment is required externally, such as wet oxidation. When ammonia itself is oxidized, _nitrogen oxides ₍ for example, _NO A reducing agent such as urea solution must be additionally used. At this time, a separate de- _NO

Among organic volatile substances, substances soluble in water (e.g., alcohols, ketones, aldehydes, etc.) can be removed by washing with water and using a wet oxidation method. In the case of workplaces where water-soluble organic volatile substances and ammonia are discharged simultaneously, wet oxidation methods are used. It can be treated by dissolving it in water or an aqueous solution containing chemicals to increase the solubility of water-soluble organic volatile substances and ammonia, but secondary pollution sources may occur.

In particular, in recent years, due to the strengthening of environmental regulations, existing wet abatement methods (e.g., wet scrubbers) that require wastewater treatment (e.g., wet oxidation) have become difficult to use, and the occurrence of both the primary and secondary pollutants has increased. There is a need for replacement with minimized dry abatement methods.

Accordingly, the present inventor completed the present invention after continuous research on a catalyst that can effectively treat not only primary pollutants such as organic volatile substances and odor-causing substances but also secondary pollutants such as nitrogen oxides through oxidation or reduction reactions.

[Prior art literature]

[Patent Document]

(Patent Document 1) Republic of Korea Patent Publication No. 10-2020-0130845

(Patent Document 2) Republic of Korea Patent Publication No. 10-2022-0057376

The present invention provides an emission treatment catalyst that has high durability in treating emissions such as organic volatile substances and odor-causing substances and has high selectivity in converting pollutants into an emissible form such as nitrogen and carbon dioxide.

According to the first aspect of the present invention,

The present invention provides an exhaust treatment catalyst in which a first catalyst and a second catalyst are introduced on a support, wherein the first catalyst is a zeolite catalyst and the second catalyst is a catalyst obtained by adding nickel and magnesium to alumina. do.

In one embodiment of the present invention, the support is a honeycomb structure made of ceramic material, and the ceramic material includes at least one of cordierite, silica, and titania.

In one embodiment of the present invention, the zeolite catalyst is ZSM-5, ZSM-11, ZSM-12, ZSM-18, ZSM-23, MCM-zeolite, mordenite, posersite, ferrierite, zeolite beta, It is selected from the group consisting of chabazite and mixtures thereof.

In one embodiment of the present invention, the zeolite catalyst is a metal ion-exchanged zeolite catalyst, and the metal ion is Fe, Cu, or a combination thereof.

In one embodiment of the present invention, the total content of nickel and magnesium in the second catalyst is 20 to 40 parts by weight based on 100 parts by weight of alumina.

In one embodiment of the present invention, the weight ratio of nickel and magnesium in the second catalyst is 5:1 to 15:1.

In one embodiment of the present invention, the weight ratio of the first catalyst and the second catalyst in the exhaust treatment catalyst is 1:1 to 9:1.

In one embodiment of the present invention, the first catalyst and the second catalyst are mixed and introduced into one or more coating layers.

In one embodiment of the present invention, the first catalyst and the second catalyst are introduced separately as separate coating layers.

In one embodiment of the present invention, the exhaust treatment catalyst includes a structure in which a first coating layer including a first catalyst is coated on a support, and a second coating layer including a second catalyst is coated on the first coating layer. do.

In one embodiment of the present invention, the first catalyst is introduced in an amount of 50 g/L to 150 g/L based on the total exhaust treatment catalyst.

In one embodiment of the present invention, the second catalyst is introduced in an amount of 20 g/L to 80 g/L based on the total exhaust treatment catalyst.

The emission treatment catalyst according to the present invention includes a zeolite catalyst as a first catalyst and a catalyst obtained by adding nickel and magnesium to alumina as a second catalyst, thereby treating emissions of various components such as organic volatile substances, odor-causing substances, etc. It has a long lifespan due to the excellent durability of the catalyst, and has high utility value in related industrial fields due to its high selectivity in converting pollutants into exudable forms such as nitrogen and carbon dioxide.

Figure 1a is a diagram schematically showing the structure of an emission treatment catalyst according to an embodiment of the present invention.

Figure 1b is a diagram schematically showing the structure of an emission treatment catalyst according to an embodiment of the present invention.

2 is a schematic diagram of an exemplary process in which an effluent treatment catalyst according to one embodiment of the present invention may be utilized.

Figure 3a is an overall SEM image of the catalyst of Example 1 according to Experimental Example 1, and Figure 3b is an SEM image of each component of a portion of Figure 3a.

Figure 4a is an overall SEM image of the catalyst of Example 2 according to Experimental Example 1, and Figure 4b is an SEM image of each component of a portion of Figure 4a.

Figure 5a is an overall SEM image of the catalyst of Example 3 according to Experimental Example 1, and Figure 5b is an SEM image of each component of a portion of Figure 5a.

Figure 6a is an overall SEM image of the catalyst of Example 4 according to Experimental Example 1, and Figure 6b is an SEM image of each component of a portion of Figure 6a.

Figure 7a is a graph showing the results of measuring the emissions (ppm) of isopropanol and CO for the catalyst of Comparative Example 2 according to Experimental Example 2.

Figure 7b is a graph showing the results of measuring the emissions (ppm) of isopropanol and CO for the catalyst of Comparative Example 3 according to Experimental Example 2.

Figure 8 is a graph showing the results of measuring catalyst durability (k/k ₀ value) for each of the catalyst of Comparative Example 1, the catalyst of Example 1, and the catalyst of Example 2 according to Experimental Example 3.

Figure 9a is a graph showing the concentration of each component by day in flow c of Experimental Example 5.

Figure 9b is a graph showing the concentration of each component by day in flow d of Experimental Example 5.

The present invention can be achieved by the following description with reference to the attached drawings. The following description should be understood as describing preferred embodiments of the present invention, but the present invention is not necessarily limited thereto.

The present invention provides an exhaust treatment catalyst incorporating a first catalyst and a second catalyst on a support. The catalyst is a catalyst that can be used in general oxidation or reduction reactions of organic or inorganic compounds. Specifically, it oxidizes or reduces process emissions of organic or inorganic compounds emitted from specific industrial fields such as semiconductor and display processes to water, nitrogen, etc. And it can be used in the process of processing it into an emissible form such as carbon dioxide. These emissions include primary pollutants such as organic volatile substances and odor-causing substances, and the catalyst can be suitably used to oxidize or reduce these primary pollutants. In addition, the catalyst can be suitably used to oxidize or reduce secondary pollutants that may be generated during the treatment of primary pollutants as well as the treatment of primary pollutants. The primary or secondary pollutants include, for example, ammonia (NH ₃ ), nitrogen oxides (for example, NO _x (NO, NO ₂ ) or N ₂ O, etc.), or organic volatiles such as isopropanol (IPA). It can be a substance. According to one embodiment of the present invention, the catalyst is used for a simultaneous oxidation reaction of ammonia and organic volatile substances, or a selective reduction reaction of nitrogen oxides, etc.

The emission treatment catalyst according to the present invention may be in the form of a first catalyst and a second catalyst introduced onto a support. The support has the function of supporting and fixing the first catalyst and the second catalyst, and is not particularly limited as long as it is a material commonly used in the relevant technical field. According to one embodiment of the present invention, the support may have a honeycomb structure and may be made of a ceramic material containing at least one of cordierite, silica, and titania. Specifically, the ceramic material may be cordierite.

The first catalyst introduced into the support is a substance that affects the reaction rate during the oxidation or reduction of primary pollutants included in the discharge or secondary pollutants that may be generated during the treatment of the primary pollutants. It helps secondary pollutants to ultimately be converted into non-emissionable non-pollutants such as water, nitrogen, and carbon dioxide. The first catalyst is not particularly limited as long as it is a material having the above-described functionality. According to one embodiment of the present invention, the first catalyst is a zeolite catalyst. Specifically, the zeolites include ZSM-5, ZSM-11, ZSM-12, ZSM-18, ZSM-23, MCM-zeolite, mordenite, faujasite, ferrierite, and beta. It may be selected from the group consisting of zeolite, chabazite, and mixtures thereof, and more specifically, the zeolite may be chabazite or beta zeolite. According to one embodiment of the present invention, the first catalyst has a ratio of 500 ㎡/g to 800 ㎡/g, specifically 525 ㎡/g to 750 ㎡/g, more specifically 550 ㎡/g to 700 ㎡/g. It has a surface area. The specific surface area is measured by the BET method.

According to one embodiment of the present invention, the zeolite catalyst is a metal ion-exchanged zeolite catalyst. The type of the metal ion is not particularly limited as long as it is a metal ion that can be generally introduced into zeolite catalysts in the relevant technical field. According to one embodiment of the present invention, the metal ion is Fe, Cu, or a combination thereof. According to one embodiment of the present invention, the metal ion is 0.1% by weight to 10% by weight, specifically 0.5% by weight to 7.5% by weight, more specifically 1% by weight to 5% by weight based on the total weight of the catalyst. is introduced in

The second catalyst introduced into the support, like the first catalyst, is a substance that affects the reaction rate when oxidizing or reducing primary pollutants included in the discharge or secondary pollutants that may be generated during the treatment of the primary pollutants. , helps primary or secondary pollutants to be finally converted into non-polluting sources that can be discharged, such as water, nitrogen, and carbon dioxide. The second catalyst is not particularly limited as long as it is a material having the above-mentioned functionality. According to one embodiment of the present invention, the second catalyst is a catalyst obtained by adding nickel (Ni) and magnesium (Mg) to alumina (Al ₂ O ₃ ). According to one embodiment of the present invention, the second catalyst has a ratio of 50 ㎡/g to 250 ㎡/g, specifically 75 ㎡/g to 200 ㎡/g, more specifically 100 ㎡/g to 150 ㎡/g. It has a surface area. The specific surface area is measured by the BET method.

The first catalyst and the second catalyst individually have excellent functionality in treating effluents, but when the types of pollutants vary, the functionality of the first catalyst or the second catalyst deteriorates, which reduces the functionality of the entire catalyst. may lead to degradation. In the present invention, the first catalyst and the second catalyst are selected as a combination that does not deteriorate the functionality of the overall catalyst even if there are various types of contaminants. The emission treatment catalyst according to the present invention can be preferably used for the simultaneous treatment of ammonia and organic volatile substances as well as the treatment of nitrogen oxides. According to one embodiment of the present invention, the first catalyst is 50 g/L to 150 g/L, specifically 65 g/L to 135 g/L, more specifically 80 g/L, based on the total effluent treatment catalyst. to 120 g/L is introduced. According to one embodiment of the present invention, the second catalyst is 20 g/L to 80 g/L, specifically 25 g/L to 75 g/L, more specifically 30 g/L, based on the total effluent treatment catalyst. to 70 g/L are introduced.

According to one embodiment of the present invention, the weight ratio of the first catalyst and the second catalyst in the exhaust treatment catalyst is 1:1 to 9:1, specifically 1:1 to 6:1, more specifically 1:1 to 4. :1. Within the above-mentioned range, the effect of using the first catalyst and the second catalyst in combination may be more highlighted.

For example, in simultaneously treating ammonia and organic volatile substances, the zeolite catalyst used as the first catalyst is selective for ammonia (SCO reaction) and partially oxidized nitrogen oxides (NO _x ) and ammonia. It may be suitable for catalytic reduction reaction (SCR reaction), and the catalyst with nickel and magnesium added to alumina used as a second catalyst is suitable for the production of nitrogen oxides by partial oxidation of ammonia and the oxidation reaction of organic volatile substances such as isopropanol. can do. In addition, the second catalyst has resistance to coke, so the performance of the catalyst can be maintained for a long time when treating organic volatile substances. On the other hand, when the first catalyst, the zeolite catalyst, is used alone, the oxidizing power of the catalyst may be insufficient. To compensate for this, the oxidizing power of the catalyst is increased by mixing noble metals such as palladium (Pd) and platinum (Pt). , a complete oxidation reaction may occur for organic volatile substances, but for ammonia, the selectivity (or conversion rate) to nitrogen may be significantly reduced, which may be undesirable. When the second catalyst, a catalyst in which nickel and magnesium are added to alumina, is used alone, it may be possible to use it alone, but it is preferable because the selectivity (or conversion rate) for ammonia to nitrogen is not high compared to the zeolite catalyst. You may not.

The second catalyst is basically an alumina-based catalyst and contains both nickel and magnesium as essential components. Through the addition of nickel and magnesium, not only the oxidizing power of the catalyst can be improved, but also resistance to by-products such as coke can be improved. Specifically, nickel may exhibit oxidizing properties, and magnesium may exhibit reducing properties. For example, nickel can be decomposed by oxidizing isopropanol adsorbed on the catalyst surface. In this case, the formation of coke on the catalyst surface due to incomplete oxidation can be prevented through the reducing properties of magnesium. In addition, NH ₃ can generate _some NO _x by NiMg-Al ₂ O ₃ , and at this time _{, the} generated _NO It can be converted to ₂ .

According to one embodiment of the present invention, the total content of nickel and magnesium in the second catalyst is 20 parts by weight to 40 parts by weight, specifically 23 parts by weight to 36 parts by weight, more specifically 26 parts by weight, based on 100 parts by weight of alumina. to 32 parts by weight. Within the above-mentioned range, the effects of adding nickel and magnesium may be more prominent.

Considering the functionality of the second catalyst described above, nickel can be added to alumina in a much larger amount than magnesium. According to one embodiment of the present invention, the weight ratio of nickel and magnesium in the second catalyst is 5:1 to 15:1, specifically 6.5:1 to 13.5:1, and more specifically 8:1 to 12:1. Within the above-mentioned range, the effects of adding nickel and magnesium may be more prominent.

1A and 1B show a schematic structure of an exhaust treatment catalyst according to one embodiment of the present invention. Figures 1a and 1b are intended to briefly explain the structure into which the first and second catalysts are introduced, focusing on the surface of the support, and the structures shown in Figures 1a and 1b do not represent the entire structure of the catalyst. .

According to one embodiment of the present invention, the first catalyst and the second catalyst are mixed and introduced into one or more coating layers, and the structure of the catalyst follows FIG. 1A. According to one embodiment of the present invention, the first catalyst and the second catalyst are introduced separately as separate coating layers, and the structure of these catalysts follows Figure 1b. The order of the coating layer containing the first catalyst and the coating layer containing the second catalyst is not particularly limited, but after coating the first coating layer containing the first catalyst on the support, the second coating layer containing the second catalyst is applied. When coated, the durability of the catalyst against coke generated when treating carbon-based compounds such as organic volatile substances increases, which may be advantageous for its lifespan.

Below, an exemplary process in which the above-described catalyst can be utilized will be described in detail.

The exemplary process is a simultaneous reduction of isopropanol and ammonia, the process comprising: (1) supplying industrial exhaust gas containing isopropanol and ammonia to a first reactor; (2) oxidizing isopropanol and ammonia in the first reactor; (3) supplying the discharge from the first reactor to a second reactor; (4) producing nitrogen, carbon dioxide, and water in the second reactor; and (5) discharging the effluent from the second reactor.

In step (1), industrial exhaust gas containing isopropanol and ammonia is first supplied to the first reactor. In order to increase the efficiency of the process, it is desirable for the concentration of isopropanol and ammonia in industrial exhaust gas to be above a certain level. As an embodiment, the sum of the concentrations of isopropanol and ammonia in industrial exhaust gas is 100 ppm to 10,000 ppm, specifically 2,000 ppm to 9,000 ppm, more specifically 4,000 ppm to 8,000 ppm, and the concentration of isopropanol is 10% based on the concentration of ammonia. % to 5,000%, specifically 30 to 3,000%, more specifically 50 to 1,000%, and the concentrations of isopropanol and ammonia may each be 100 ppm or more, specifically 1,000 ppm or more, and more specifically 2,000 ppm or more. If the concentration of either isopropanol or ammonia is too low, the interference between the two components is minimal, and a similar effect can be achieved through an invention designed to remove either component, which may reduce the effectiveness of the process alone. there is. On the contrary, if the concentration of either isopropanol or ammonia is too high, excellent effects cannot be achieved through the process, and the effectiveness of the process may be reduced. As an example, the process includes a selective oxidation reaction of ammonia (i.e., a reaction in which ammonia is selectively oxidized to nitrogen (N ₂ ) and water (H ₂ O) under specific conditions or on a catalyst), where the concentration of isopropanol is excessive. In low cases, the purpose of treating isopropanol and ammonia can be achieved by combining the selective oxidation reaction of ammonia with the prior art. Conversely, if the concentration of isopropanol is too high, the reaction heat generated during the oxidation treatment of isopropanol can cause ammonia to be removed. As the oxidation reaction is also activated and a large amount of NO _x (i.e. NO or NO ₂ ) is generated, the purpose of the process cannot be achieved without a separate reducing agent supply step.

The sum of the concentrations of isopropanol and ammonia described above is at a level that can increase treatment efficiency when applied to actual industrial fields. If the concentration of isopropanol and ammonia in the supplied industrial exhaust gas is low, a concentrator capable of adsorbing isopropanol and ammonia can be used to control the concentration of isopropanol and ammonia before feeding it to the first reactor.

Before supplying the industrial exhaust gas satisfying the above-described concentrations of isopropanol and ammonia to the first reactor, the supply flow rate is separated into a first flow rate and a second flow rate, and the first flow rate is supplied to the first reactor, and the second flow rate is supplied to the first reactor. The flow rate may be mixed with the effluent from the first reactor. After separating the supply flow rate into a first flow rate and a second flow rate, when the second flow rate is mixed with the discharge from the first reactor, the ammonia contained in the second flow rate in the second reactor decomposes NO _x or N ₂ O. It can be used as a reducing agent to increase reaction efficiency. The distribution of the first flow rate and the second flow rate can be determined by the following calculation equation 1.

[Calculation Formula 1]

Here, Q _a means the supply flow rate before distribution, Q _a2 means the second flow rate, and the corresponding symbols refer to FIG. 2. _f is related to the amount of NO _x discharged from the first reactor (c ₎ , the amount of ammonia required to completely remove the equivalent amount of NO It can be defined as the amount (a) of ammonia that must be introduced into the second reactor to remove _NO there is. This is summarized in the following calculation formula 2.

[Calculation Formula 2]

Here, a is calculated by c×d×x. c refers to the amount of NO _x discharged from the first reactor, and is determined by adding the amount of NO (c ₁ ) and the amount of NO ₂ (c ₂ ). d means the equivalent amount of ammonia required to completely remove 1 equivalent amount _{of NO} x refers to the desired removal efficiency of NO _x , and is determined in advance taking into account the concentrations of isopropanol, ammonia, and _NO x can be set to 0.5 to 1.5, specifically 0.6 to 1.4, and more specifically 0.7 to 1.3. If the x value is smaller than the above range, the reduction efficiency of _NO This may deteriorate.

[Calculation Formula 3]

According to one embodiment, the second flow rate is more than 1% (f=0.01), more than 5% (f=0.05), and more than 10% (f=0.1) based on the supply flow rate of the first flow rate and the second flow rate combined. and may be less than 40% (f=0.4), less than 30% (f=0.3), less than 20% (f=0.2), less than 15% (f=0.15), and for example, may be 5% to 30%. . When the second flow rate satisfies the above range, emissions of secondary pollutants such as NO _x and N ₂ O can be minimized.

The feed flow of industrial exhaust gases (if separated, the first flow) is fed to a first reactor, in which isopropanol and ammonia are oxidized. Oxidation of isopropanol and ammonia is the reaction of isopropanol and ammonia with oxygen, respectively, whereby the following reactions can be performed.

[Scheme 1]

C ₃ H ₈ O + 4.5O ₂ → 3CO ₂ + 4H ₂ O

[Scheme 2]

2NH ₃ + 1.5O ₂ → N ₂ + 3H ₂ O

[Scheme 3]

C ₃ H ₈ O + 2O ₂ → 2C + CO + 4H ₂ O

[Scheme 4]

C ₃ H ₈ O + 3O ₂ → 3CO + 4H ₂ O

[Scheme 5]

2NH ₃ + 2.5O ₂ → 2NO + 3H ₂ O

[Scheme 6]

2NH ₃ + 3.5O ₂ → 2NO ₂ + 3H ₂ O

[Scheme 7]

4NH ₃ + 4NO + O ₂ → 4N ₂ + 6H ₂ O

[Scheme 8]

8NH ₃ + 6NO ₂ → 7N ₂ + 12H ₂ O

Schemes 1 and 2 are the main reactions targeted in the first reactor, and Schemes 3 to 8 are side reactions that may occur during the actual reaction. When isopropanol and ammonia are oxidized at the same time, since the reaction cannot be performed under optimal conditions for each reactant, a certain level of side reactions are inevitably accompanied. To remove secondary contaminants caused by these side reactions, additional reactions are required. Oxygen, which is a reactant other than isopropanol and ammonia, is generally contained in a sufficient amount in the exhaust gas, but additional air can be supplied to the reactor as needed.

In the first reactor, isopropanol and ammonia may be oxidized by a catalyst. Figure 2 shows an exemplary process diagram when the first reactor is a catalytic oxidation reactor. The first reactor is equipped with a catalyst in the form of a fixed bed catalytic reactor. At this time, it may be desirable to select a catalyst that has oxidation reaction performance and is effective in the selective oxidation reaction of NH ₃ and NH ₃ -deNO _x reaction, and is not particularly limited as long as the catalyst has such functionality. The effluent treatment catalyst according to the present invention can be preferably applied to the first reactor.

The first reactor, which is a catalytic oxidation reactor, may be operated under temperature conditions of 100°C to 650°C, specifically 200°C to 600°C, and more specifically 300°C to 550°C. If the temperature is lower than the corresponding range, the overall oxidation reaction does not proceed actively, which is undesirable, and if the temperature is higher than the corresponding range, excessive NO _x is generated, which is undesirable. The first reactor may be operated under pressure conditions of atmospheric pressure to 10 atmospheres, specifically atmospheric pressure to 7 atmospheres, and more specifically atmospheric pressure to 5 atmospheres. At high pressures, device costs may increase because pressure-resistant vessels must be adopted. The first reactor may be operated under gas space velocity (GHSV) conditions of 200hr ^-1 to 20,000hr ^-1 , specifically, 500hr ^-1 to 10,000hr ^-1 , and more specifically 1,000hr ^-1 to 5,000hr ^-1 there is. If the gas space velocity is lower than the corresponding range, it is undesirable because the device must be enlarged, and if the gas space velocity is higher than the corresponding range, it is undesirable because the efficiency and selectivity of the reaction decreases.

In order to achieve the purpose _, the catalytic oxidation reactor may be designed so that the ratio of ammonia in _the reactant converted to nitrogen oxides ( _NO there is.

The discharge from the first reactor is fed to the second reactor. When the supply flow rate is separated into a first flow rate and a second flow rate before being supplied to the first reactor, the second flow rate is mixed with the discharge from the first reactor and supplied to the second reactor. Nitrogen, carbon dioxide and water are mainly produced in the second reactor. The following reactions can mainly be performed in the second reactor.

[Scheme 9]

C ₃ H ₈ O + 4.5O ₂ → 3CO ₂ + 4H ₂ O

[Scheme 10]

4NH ₃ + 4NO + O ₂ → 4N ₂ + 6H ₂ O

[Scheme 11]

8NH ₃ + 6NO ₂ → 7N ₂ + 12H ₂ O

[Scheme 12]

C ₃ H ₈ O + 2.5O ₂ → 2C + CO ₂ + 4H ₂ O

[Scheme 13]

C ₃ H ₈ O + 3O ₂ → 3CO + 4H ₂ O

[Scheme 14]

2NH ₃ + 1.5O ₂ → N ₂ + 3H ₂ O

Schemes 9 to 11 are the main reactions targeted in the second reactor, and Schemes 12 to 14 are side reactions that may occur during the actual reaction. Compared to the first reactor, there is no significant difference in the oxidation of isopropanol as the main reaction, but in the case of ammonia, the NO _x component generated in the first reaction reacts with ammonia and is decomposed into nitrogen and water.

In the second reactor, the _NO At this time, it may be desirable to select a catalyst that has oxidation reaction performance and is effective in NH ₃ -deN ₂ O and NH ₃ -deNO _x reactions, and is not particularly limited as long as the catalyst has such functionality. The effluent treatment catalyst according to the present invention can be preferably applied to the second reactor.

The second reactor may be operated under temperature conditions of 100°C to 650°C, specifically 150°C to 600°C, and more specifically 200°C to 550°C. If the temperature is lower than that range, it is not desirable because the overall oxidation reaction does not proceed actively, and if the temperature is higher than that range, the oxidation reaction of ammonia proceeds competitively with the de-NO _x reaction, resulting in excessive NO _x generation. Therefore, it is not desirable. The first reactor may be operated under pressure conditions of atmospheric pressure to 10 atmospheres, specifically atmospheric pressure to 7 atmospheres, and more specifically atmospheric pressure to 5 atmospheres. At high pressures, device costs may increase because pressure-resistant vessels must be adopted. The second reactor may be operated under gas space velocity (GHSV) conditions of 200hr ^-1 to 20,000hr ^-1 , specifically 500hr ^-1 to 15,000hr ^-1 , and more specifically 1,000hr ^-1 to 10,000hr ^-1 . If the gas space velocity is lower than the corresponding range, it is undesirable because the device must be enlarged, and if the gas space velocity is higher than the corresponding range, it is undesirable because the efficiency and selectivity of the reaction decreases.

Hereinafter, preferred examples are presented to aid understanding of the present invention, but the following examples are provided to facilitate understanding of the present invention and do not limit the present invention thereto.

Example

Preparation of catalyst

Cu_chabazite (hereinafter referred to as 'catalyst 1'), Fe_beta zeolite (hereinafter referred to as 'catalyst 2'), and NiMg-Al ₂ O ₃ (hereinafter referred to as 'catalyst 3') (name) was prepared. The specific components of the catalyst are shown in Table 1 below. For reference, NiMg-Al ₂ O ₃ is a catalyst in which nickel and magnesium are added to alumina, and the contents of the added nickel and magnesium are according to Table 1 below.

	catalyst 1	catalyst 2	catalyst 3
Cu content (wt%)	3~4	-	-
Fe content (wt%)	-	1~2	-
Ni content (wt%)	-	-	20
Mg content (wt%)	-	-	2
SiO 2 content (wt%)	86.4	92.8	-
Al 2 O 3 content (wt %)	9.9	5.1	78
SiO 2 /Al 2 O 3	15~18	30~40	-
Specific surface area (㎡/g)	500~650	550~700	100~150

In addition, Pt-Al ₂ O ₃ (hereinafter referred to as 'Catalyst 4'), Pd-Al ₂ O ₃ (hereinafter referred to as 'Catalyst 5'), and Pt/Fe_beta zeolite (hereinafter referred to as 'Catalyst 5') (referred to as 'Catalyst 6') was prepared. The specific components of the catalyst are shown in Table 1 below. For reference, Pt-Al ₂ O ₃ is a catalyst in which platinum is added to alumina, Pd-Al ₂ O ₃ is a catalyst in which palladium is added to alumina, and Pt/Fe_beta zeolite is a catalyst in which platinum is added to Fe_beta zeolite. It is an added catalyst. The content of added platinum or palladium follows Table 2 below.

	catalyst 4	catalyst 5	catalyst 6
Pt content (wt%)	0.3	-	0.3
Pd content (wt%)	-	0.3	-
Fe content (wt%)	-	-	1~2
SiO 2 content (wt%)	-	-	92.6
Al 2 O 3 content (wt %)	99.7	99.7	5.1
SiO 2 /Al 2 O 3	-	-	30~40
Specific surface area (㎡/g)	100~150	100~150	550~700

Example 1

About 120 g/L per volume of cordierite was first coated with Catalyst 1 (Cu_chabazite), the first catalyst, on the honeycomb-structured cordierite support, and then secondarily coated with Catalyst 3 (NiMg-), the second catalyst. Al ₂ O ₃ ) was coated at about 30 g/L per volume of cordierite. Afterwards, the catalyst was finally prepared by calcining at 550°C for 4 hours.

Example 2

A mixture was prepared by mixing the first catalyst, Catalyst 1 (Cu_chabazite), and the second catalyst, Catalyst 3 (NiMg-Al ₂ O ₃ ) in a 1:1 weight ratio, and then placed on a honeycomb-structured cordierite support. The mixture was coated at approximately 150 g/L per volume of cordierite. Afterwards, the catalyst was finally prepared by calcining at 550°C for 4 hours.

Example 3

About 120 g/L per volume of cordierite was first coated with Catalyst 2 (Fe_beta zeolite), the first catalyst, on the honeycomb-structured cordierite support, and then secondarily coated with Catalyst 3 (NiMg-Al), the second catalyst. ₂ O ₃ ) was coated at about 30 g/L per volume of cordierite. Afterwards, the catalyst was finally prepared by calcining at 550°C for 4 hours.

Example 4

After preparing a mixture by mixing the first catalyst, Catalyst 2 (Fe_beta zeolite), and the second catalyst, Catalyst 3 (NiMg-Al ₂ O ₃ ) in a 1:1 weight ratio, the above catalyst was placed on a honeycomb-structured cordierite support. The mixture was coated at approximately 150 g/L per volume of cordierite. Afterwards, the catalyst was finally prepared by calcining at 550°C for 4 hours.

Comparative Example 1

Catalyst 1 (Cu_chabazite) was used as is.

Comparative Example 2

Catalyst 2 (Fe_beta zeolite) was used as is.

Comparative Example 3

Catalyst 3 (NiMg-Al ₂ O ₃ ) was used as is.

Comparative Example 4

Catalyst 4 (Pt-Al ₂ O ₃ ) was used as is.

Comparative Example 5

Catalyst 5 (Pd-Al ₂ O ₃ ) was used as is.

Comparative Example 6

Catalyst 6 (Pt/Fe_beta zeolite) was used as is.

Experiment example

Experimental Example 1

Scanning Electron Microscope (SEM) images for the catalyst of Example 1, the catalyst of Example 2, the catalyst of Example 3, and the catalyst of Example 4 are shown in Figures 3 to 6. In Figures 3 to 6, part a is for the entire SEM image, and part b is for the SEM image for each specific component.

Figures 3a and 3b are SEM images of the catalyst of Example 1. According to Figures 3a and 3b, it can be seen that Cu and Si are coated on the inside, and Ni, Mg, and Al are coated on the outside.

Figures 4a and 4b are SEM images of the catalyst of Example 2. According to Figures 4a and 4b, it can be seen that Ni, Cu, etc. are mixed and coated.

Figures 5a and 5b are SEM images of the catalyst of Example 3. According to Figures 5a and 5b, it can be seen that Fe and Si are coated on the inside, and Ni, Mg, and Al are coated on the outside.

Figures 6a and 6b are SEM images of the catalyst of Example 4. According to Figures 6a and 6b, it can be seen that Ni, Fe, etc. are mixed and coated.

Experimental Example 2

Stream a passing through the concentrator 20 had a total flow rate of 1 L/min, where isopropanol and ammonia each had a concentration of 3,000 ppm. The stream a was supplied to the first reactor without a separate bypass stream (a2). The first reactor was a fixed bed catalyst reactor, and the temperature was changed while the pressure of 1.5 atm and gas space velocity (GHSV) of 15,000 hr ^-1 were fixed, and the degree of oxidation of isopropanol was evaluated.

In Experimental Example 2, the first reactor was charged with the catalyst of Comparative Example 2 and the catalyst of Comparative Example 3, respectively, and the emissions (ppm) of isopropanol and CO according to temperature were measured and shown in FIGS. 7A and 7B. Here, Figure 7a shows the results of evaluating the catalyst of Comparative Example 2 within the range of 500°C to 700°C, and Figure 7b shows the results of evaluating the catalyst of Comparative Example 3 within the range of 360°C to 560°C.

According to Figure 7a, it can be seen that in the case of Catalyst 2 (Fe_beta zeolite) of Comparative Example 2, isopropanol is not completely oxidized even at a high temperature of 700°C or higher. Additionally, according to Figure 7b, it can be seen that in the case of Catalyst 3 (NiMg-Al ₂ O ₃ ) of Comparative Example 3, isopropanol is almost completely oxidized at around 400°C, unlike Catalyst 2 (Fe_beta zeolite) of Comparative Example 2. You can. Therefore, when treating ammonia and isopropanol simultaneously, an appropriate combination of catalyst 2 (Fe_beta zeolite) and catalyst 3 (NiMg-Al ₂ O ₃ ) is required.

Experimental Example 3

Stream a passing through the concentrator 20 had a total flow rate of 1 L/min, where isopropanol and ammonia each had a concentration of 3,000 ppm. The stream a was supplied to the first reactor without a separate bypass stream (a2). The first reactor was a fixed bed catalytic reactor operated at a pressure of 1.5 atm, a gas space velocity (GHSV) of 15,000 hr ^-1 , and a reaction temperature of 530°C.

In Experimental Example 2, the first reactor was charged with the catalyst of Comparative Example 1, the catalyst of Example 1, and the catalyst of Example 2, respectively, and the durability of the catalyst over time was evaluated. The durability of the catalyst was evaluated using the k/k ₀ (current efficiency/initial efficiency) value when the initial reaction rate was expressed as k ₀ and the reaction rate on the relevant day was expressed as k, and the values are shown in Figure 8 shown in

According to Figure 8, in the case of the catalyst of Comparative Example 1, compared to the catalysts of Examples 1 and 2, the reaction rate gradually decreased from the beginning, and it can be seen that the reaction rate decreased significantly after 5 days. This is expected to be because in the case of Catalyst 1 (Cu_chabazite only) of Comparative Example 1, IPA was not completely oxidized, and the coke produced decreased the durability of the catalyst.

Experimental Example 4

Stream a passing through concentrator 20 had a total flow rate of 5 L/min, where isopropanol and ammonia each had a concentration of 3,000 ppm. The flow a was divided into flow a ₁ with a flow rate of 0.85 L/min and flow a ₂ with a flow rate of 0.15 L/min, and flow a ₁ was supplied to the first reactor.

The first reactor was a fixed bed catalytic reactor and was operated while changing the temperature while maintaining a fixed pressure of 1.5 atm and a gas space velocity (GHSV) of 3,000 hr ^-1 . The catalysts used were the catalyst of Example 1, the catalyst of Example 2, the catalyst of Example 3, the catalyst of Example 4, the catalyst of Comparative Example 3, the catalyst of Comparative Example 4, the catalyst of Comparative Example 5, and the catalyst of Comparative Example 6. Each was charged.

The stream b joined the distributed stream a2 before being fed to the first reactor and stream c was fed to the second reactor.

The second reactor was a fixed bed catalytic reactor operated at a pressure of 1.5 atm, a gas space velocity (GHSV) of 6,000 hr ^-1 and a reaction temperature of 450°C. The catalyst was first coated with Fe-BEA catalyst powder, in which 2% Fe was ion-exchanged to BEA (β-zeolite), on a 100cpsi (cells per square inch) honeycomb support made of cordierite, and 1.5% by weight of Cobalt-magnesium-alumina catalyst powder containing cobalt and 2% by weight of magnesium was secondarily coated. At this time, the weight ratio of the Fe-BEA catalyst and the cobalt-magnesium-alumina catalyst was adjusted to be 9:1, and the sum of the coating amounts of each catalyst was adjusted to be 150 g/L.

The conversion rate of NH ₃ (%), conversion rate from NH ₃ to N ₂ (%), conversion rate of IPA (%), and CO concentration (ppm) in the final product that passed through the second reactor were confirmed, and are shown in Tables 3 to 10. indicated.

Catalyst of Example 1
Temperature (℃)	Conversion rate of NH 3 (%)	Conversion rate of NH 3 to N 2 (%)	IPA conversion rate (%)	CO concentration (ppm)
400	100.0	94.8	99.90	141
430	100.0	91.5	99.97	74
450	100.0	90.3	99.97	51
500	100.0	81.8	99.98	38

Catalyst of Example 2
Temperature (℃)	Conversion rate of NH 3 (%)	Conversion rate of NH 3 to N 2 (%)	IPA conversion rate (%)	CO concentration (ppm)
400	100.0	89.7	99.97	292
430	100.0	87.9	99.97	95
450	100.0	85.4	99.97	37
500	100.0	81.3	99.97	29

Catalyst of Example 3
Temperature (℃)	Conversion rate of NH 3 (%)	Conversion rate of NH 3 to N 2 (%)	IPA conversion rate (%)	CO concentration (ppm)
450	99.8	91.7	99.33	3,000
480	99.9	85.5	99.78	1,000
500	99.9	82.4	99.84	546
530	100.0	78	99.9	101
550	100.0	77.9	99.9	31
580	100.0	77.6	99.9	11

Catalyst of Example 4
Temperature (℃)	Conversion rate of NH 3 (%)	Conversion rate of NH 3 to N 2 (%)	IPA conversion rate (%)	CO concentration (ppm)
400	100.0	82.6	99.87	4,068
430	100.0	88.7	99.98	968
450	100.0	94.8	99.98	206
500	100.0	88.8	99.98	23
530	100.0	83.6	99.98	22

Catalyst of Comparative Example 3
Temperature (℃)	Conversion rate of NH 3 (%)	Conversion rate of NH 3 to N 2 (%)	IPA conversion rate (%)	CO concentration (ppm)
350	66.7	54.0	57.90	2,357
380	90.0	74.5	90.60	7,800
400	99.7	78.3	98.03	169
500	100.0	68.7	98.93	52
560	100.0	62.4	99.26	8

Catalyst of Comparative Example 4
Temperature (℃)	Conversion rate of NH 3 (%)	Conversion rate of NH 3 to N 2 (%)	IPA conversion rate (%)	CO concentration (ppm)
200	13.3	13.3	0.49	9
230	34.3	34.3	1.14	14
250	39.3	39.3	6.89	68
280	55.8	54.9	39.84	638
300	64.0	25.2	47.34	850
330	99.8	29.2	100.00	0

Catalyst of Comparative Example 5
Temperature (℃)	Conversion rate of NH 3 (%)	Conversion rate of NH 3 to N 2 (%)	IPA conversion rate (%)	CO concentration (ppm)
200	6.7	6.6	1.80	18
230	38.6	38.5	2.49	24
250	100.0	54.4	100.00	0

Catalyst of Comparative Example 6
Temperature (℃)	Conversion rate of NH 3 (%)	Conversion rate of NH 3 to N 2 (%)	IPA conversion rate (%)	CO concentration (ppm)
150	4.1	4.1	0.08	7
180	8.7	8.7	0.09	8
200	12.2	12.2	1.43	12
230	13.9	13.9	2.80	26
250	22.3	22.3	3.83	36
300	42.3	38.1	7.99	129
330	59.8	49.2	53.16	178
350	61.3	50.0	75.99	209
380	99.9	57.0	100.00	0
400	100.0	54.4	100.00	0

According to Tables 3 and 4, the catalyst of Example 1 or the catalyst of Example 2, which introduced Catalyst 1 (Cu_chabazite) and Catalyst 3 (NiMg-Al ₂ O ₃ ) on cortierite, was used. In this case, it can be seen that not only the conversion rate of NH ₃ and IPA but also the conversion rate from NH ₃ to N ₂ is significantly high around 400°C to 500°C. Additionally, with regard to CO concentration, it can be seen that both catalysts of Examples 1 and 2 begin to drop below 100 ppm around 430°C.

According to Table 5 and Table 6, using the catalyst of Example 3 or the catalyst of Example 4 in which catalyst 2 (Fe_beta zeolite) and catalyst 3 (NiMg-Al ₂ O ₃ ) were introduced onto cortierite. In this case, as in the case of using the catalyst of Example 1 or Example 2, it can be seen that not only the conversion rate of NH ₃ and IPA but also the conversion rate of NH ₃ to N ₂ is significantly high around 400°C to 500°C. You can. Additionally, with regard to CO concentration, it was confirmed that the catalyst of Example 3 began to drop below 100 ppm around about 530°C, and the catalyst of Example 4 began to fall below around about 500°C.

According to Table 7, when using the catalyst of Comparative Example 3 (NiMg-Al ₂ O ₃ ), the conversion rate of NH ₃ and IPA was high at around 400°C to 560°C, but above 500°C. It can be seen that the conversion rate from NH ₃ to N ₂ begins to fall below 80%.

According to Tables 8 and 9, when using the catalyst of Comparative Example 4, which is Catalyst 4 (Pt-Al ₂ O ₃ ), and the catalyst of Comparative Example 5, which is Catalyst 5 (Pd-Al ₂ O ₃ ), the catalyst is about 330, respectively. It can be seen that the conversion rate of NH ₃ and IPA was high at around ℃ and around 250 ℃, but the conversion rate from NH ₃ to N ₂ was less than 60%.

According to Table 10, when using the catalyst of Comparative Example 6, which is Catalyst 6 (Pt/Fe_beta zeolite), the conversion rate of NH ₃ and IPA was high at around 380°C to 400°C, but the conversion rate of Comparative Example 4 was high. As with the catalyst and the catalyst of Comparative Example 5, it can be seen that the conversion rate from NH ₃ to N ₂ is less than 60%.

Experimental Example 5

In the process shown in Figure 2, flow c supplied to the second reactor had a total flow rate of 1 L/min, and each component had the same concentration as shown in Figure 9a for each day.

The second reactor was a fixed bed catalytic reactor operated at a pressure of 1.5 atm, a gas space velocity (GHSV) of 6,000 hr ^-1 and a reaction temperature of 450°C. The catalyst of Example 1 was charged as a catalyst. The concentration of each component of the stream d discharged from the second reactor is shown in Figure 9b.

According to FIGS. 9A and 9B, when supplied to the second reactor, a large amount of NO _x component of NO or NO ₂ was contained, but when discharged from the second reactor, the NO _x component of NO or NO ₂ was significantly reduced. You can check it. This is a selective catalytic reduction in which the catalyst of Example 1 (Cu_chabazite) and Catalyst 3 (NiMg-Al ₂ O ₃ ) were introduced onto cortierite or the catalyst of Example 2 treats NO _x component ( This means that it can also be used appropriately for SCR) reactions.

All simple modifications or changes of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be made clear by the appended claims.

[Explanation of symbols]

1: Mixed coating layer of first catalyst and second catalyst

1A: Single coating layer of first or second catalyst (including a different catalyst than 1B)

1B: Single coating layer of first or second catalyst (including a different catalyst than 1A)

2: Support

10: feeder

20: Concentrator

30: flow distribution valve

40: heat exchanger

50: first reactor

60: Confluence point of flow a ₂ and flow b

70: second reactor

Claims (12)

1. An emission treatment catalyst comprising a first catalyst and a second catalyst introduced on a support,

   The first catalyst is a zeolite catalyst,

   The second catalyst is an emission treatment catalyst that is a catalyst obtained by adding nickel and magnesium to alumina.
2. In claim 1,

   The support is a honeycomb structure made of ceramic material,

   An emission treatment catalyst, wherein the ceramic material includes at least one of cordierite, silica, and titania.
3. In claim 1,

   The zeolite catalyst consists of ZSM-5, ZSM-11, ZSM-12, ZSM-18, ZSM-23, MCM-zeolite, mordenite, posersite, ferrierite, beta zeolite, chabazite, and mixtures thereof. An emission treatment catalyst selected from the group.
4. In claim 3,

   The zeolite catalyst is a metal ion-exchanged zeolite catalyst, and the metal ion is Fe, Cu, or a combination thereof.
5. In claim 1,

   An emission treatment catalyst, characterized in that the total content of nickel and magnesium in the second catalyst is 20 to 40 parts by weight based on 100 parts by weight of alumina.
6. In claim 5,

   An emission treatment catalyst, characterized in that the weight ratio of nickel and magnesium in the second catalyst is 5:1 to 15:1.
7. In claim 1,

   An emission treatment catalyst, characterized in that the weight ratio of the first catalyst and the second catalyst in the emission treatment catalyst is 1:1 to 9:1.
8. In claim 1,

   An emission treatment catalyst, characterized in that the first catalyst and the second catalyst are mixed and introduced into one or more coating layers.
9. In claim 1,

   An emission treatment catalyst, characterized in that the first catalyst and the second catalyst are introduced separately as separate coating layers.
10. In claim 9,

    The emission treatment catalyst is characterized in that it comprises a structure in which a first coating layer containing a first catalyst is coated on a support, and a second coating layer containing a second catalyst is coated on the first coating layer.
11. In claim 1,

    The first catalyst is an emission treatment catalyst, characterized in that 50 g/L to 150 g/L is introduced based on the total emission treatment catalyst.
12. In claim 1,

    The second catalyst is an emission treatment catalyst, characterized in that 20 g/L to 80 g/L is introduced based on the total emission treatment catalyst.

Images