Catalyst composition and method for removing nitrogen oxides

Abstract

This invention provides a catalyst composition and a method for removing nitrogen oxides. The catalyst composition includes a carrier, a first active ingredient, and a second active ingredient. The first active ingredient is coated on the surface of the carrier, wherein the first active ingredient includes a first catalyst, which is manganese oxide. The second active ingredient includes a second catalyst and a third catalyst, and is coated on the surface of the first active ingredient and the surface of the carrier where the first active ingredient is not coated. The second catalyst contains platinum metal, palladium metal, or a combination thereof, and the third catalyst contains potassium oxide, sodium oxide, or a combination thereof. The molar ratio of the first catalyst to the second catalyst is from 1:0.001 to 1:0.2, and the molar ratio of the first catalyst to the third catalyst is from 1:0.1 to 1:10.

Description

Technical Field

[0001] This invention relates to a catalyst composition and a method for removing nitrogen oxides. Background Technology

[0002] Nitrogen in the air reacts with oxygen during high-temperature combustion (>800℃) to produce nitrogen oxides (NOx). X These pollutants contribute to problems such as acid rain, photochemical smog, ozone layer depletion, and eutrophication. Therefore, reducing NOx is crucial. X Emissions are crucial for environmental protection. Currently, NOx emissions are the most mature and mainstream emission standard globally. X The removal method is ammonia selective catalytic reduction (NH3-SCR).

[0003] However, NH3-SCR technology encounters problems such as heater fouling and catalyst deterioration during use. Therefore, there is an urgent need to develop other methods for removing NO. X The technology improves processing efficiency. Summary of the Invention

[0004] According to an embodiment of the present invention, a catalyst composition includes a carrier, a first active ingredient, and a second active ingredient. The first active ingredient is coated on the surface of the carrier, wherein the first active ingredient includes a first catalyst, which is manganese oxide. The second active ingredient includes a second catalyst and a third catalyst, and is coated on the surface of the first active ingredient and the surface of the carrier not coated with the first active ingredient. The second catalyst comprises platinum metal, palladium metal, or a combination thereof, and the third catalyst comprises potassium oxide, sodium oxide, or a combination thereof. The molar ratio of the first catalyst to the second catalyst is from 1:0.001 to 1:0.2, and the molar ratio of the first catalyst to the third catalyst is from 1:0.1 to 1:10.

[0005] According to another embodiment of the present invention, a method for removing nitrogen oxides includes performing a selective catalytic reduction (H2-SCR) reaction on nitrogen oxides using the above-described catalyst composition.

[0006] Based on the above, the catalyst composition of the present invention can be used as a high-efficiency H2-SCR catalyst, and this catalyst composition can be used to convert low concentrations of H2 into NO. X It is converted into N2 and H2O, thus achieving the goal of purifying harmful gases. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of a catalyst composition according to a first embodiment of the present invention;

[0008] Figure 2This is a schematic diagram of a catalyst composition according to a second embodiment of the present invention;

[0009] Figure 3 This is a schematic diagram of the equipment used to remove nitrogen oxides in the experimental example.

[0010] [Symbol Explanation]

[0011] 100, 200: Catalyst composition;

[0012] 102: Carrier;

[0013] 102s, 104s, 202s: surface;

[0014] 104, 202: First active ingredients;

[0015] 106: Second active ingredient;

[0016] C1: First catalyst;

[0017] C2: Second catalyst;

[0018] C3: Third catalyst;

[0019] C4: Fourth catalyst;

[0020] FTIR: Fourier Transform Infrared Spectrometer;

[0021] H2: Hydrogen gas;

[0022] H2O: water;

[0023] MFC: Mass Flow Controller;

[0024] N2: Nitrogen gas;

[0025] NOx: Nitrogen oxides. Detailed Implementation

[0026] The following description provides detailed examples and accompanying drawings, but these examples are not intended to limit the scope of the invention. Furthermore, the drawings are for illustrative purposes only and are not drawn to scale. For ease of understanding, the same components will be referred to by the same reference numerals in the following description.

[0027] Figure 1 This is a schematic diagram of a catalyst composition according to a first embodiment of the present invention.

[0028] Please refer to Figure 1The catalyst composition 100 of the first embodiment includes a carrier 102, a first active ingredient 104, and a second active ingredient 106. In some embodiments, the carrier 102 includes aluminum oxide, titanium oxide, zirconium oxide, cerium oxide, magnesium oxide, or a combination thereof. The first active ingredient 104 is coated on the surface 102s of the carrier 102, wherein the first active ingredient 104 includes a first catalyst C1, which is manganese oxide. The first active ingredient 104 may partially or completely coat the surface of the carrier 102. The second active ingredient 106 includes a second catalyst C2 and a third catalyst C3, and is coated on the surface 104s of the first active ingredient 104 and the surface 102s of the carrier 102 where the first active ingredient 104 is not coated. The second catalyst C2 includes platinum metal, palladium metal, or a combination thereof, and the third catalyst C3 includes potassium oxide, sodium oxide, or a combination thereof.

[0029] The molar ratio of the first catalyst C1 to the second catalyst C2 is 1:0.001 to 1:0.2, for example, 1:0.001 to 1:0.1 or 1:0.001 to 1:0.02. The molar ratio of the first catalyst C1 to the third catalyst C3 is 1:0.1 to 1:10, for example, 1:0.1 to 1:5 or 1:0.1 to 1:2. In some embodiments, the molar ratio of the first catalyst C1 to the carrier 102 is 1:3 to 1:20.

[0030] In some embodiments, the specific surface area (BET) of the catalyst composition 100 may be 140 m². 2 g -1 up to 500 m 2 g -1 For example, 160 m 2 g -1 Up to 400 m 2 g -1 or 170 m 2 g -1 Up to 300 m 2 g -1 In some embodiments, the particle size 100 of the catalyst composition may be from 100 µm to 10 mm, for example, from 500 µm to 10 mm or from 1 mm to 10 mm, but is not limited thereto.

[0031] exist Figure 1 In this process, the first catalyst C1 in the first active ingredient 104 is used to adsorb nitrogen oxides (NO). X The process involves using hydrogen (H2) as a reducing agent. The second catalyst C2 in the second active ingredient 106 adsorbs H2 and dissociates it into hydrogen free radicals (hydrogen atoms). These strongly reducing hydrogen free radicals then decompose the adsorbed nitrogen oxides (NOx) into hydrogen free radicals. XThe nitrogen-oxygen bonds in the catalyst 100 are broken, reacting to produce nitrogen gas (N2) and water (H2O). The third catalyst, C3, can adjust the activity, acidity, and alkalinity of the catalyst composition 100. Therefore, the catalyst composition 100 of this embodiment can not only reduce pollutant emissions but also promote the application of hydrogen energy in the energy structure, thus driving sustainable development.

[0032] Figure 2 This is a schematic diagram of a catalyst composition according to a second embodiment of the present invention, wherein the same element symbols as in the first embodiment are used to represent the same or similar parts, structures or size definitions, and the description of the same parts, structures or size definitions can be referred to the relevant description of the first embodiment, and will not be repeated here.

[0033] exist Figure 2 The difference between the second embodiment and the first embodiment is that the first active ingredient 202 in the catalyst composition 200 further includes a fourth catalyst C4, so the first active ingredient 202 includes both the first catalyst C1 and the fourth catalyst C4. The fourth catalyst C4 comprises copper oxide, nickel oxide, or a combination thereof, and is formed together with the first catalyst C1 on the surface 102s of the carrier 102. In other words, the first catalyst C1 and the fourth catalyst C4 are coated on the surface 102s of the carrier 102, while the second catalyst C2 and the third catalyst C3 in the second active ingredient 106 can be coated on the surface 202s of the first active ingredient 202 and on the surface 102s of the carrier 102 where the first active ingredient 202 is not coated. The fourth catalyst C4 has the effect of improving the dispersibility of the first active ingredient 202 and suppressing side reactions. In some embodiments, the molar ratio of the first catalyst C1 to the fourth catalyst C4 is 1:0.01 to 1:10, for example, 1:0.01 to 1:5 or 1:0.01 to 1:2.

[0034] The catalyst composition of the present invention can be used to treat process gases or waste gases containing NOx, such as those from electronics factories, power plants, incinerators, glass factories, cement plants, and oil refineries. The catalyst composition can be used alone, for example, by filling a column with the catalyst composition and allowing the gas to be treated to flow through the column to achieve the treatment purpose; or, the catalyst composition can be combined with a carrier, for example, by placing the catalyst composition on the surface or in the structure of a carrier, placing it in a chamber or container, and allowing the gas to be treated to flow through the chamber or container to achieve the treatment purpose.

[0035] A third embodiment of the present invention provides a method for removing nitrogen oxides, comprising using the catalyst composition 100 or 200 in the above embodiments to perform hydrogen selective catalytic reduction (H2-SCR) on nitrogen oxides (NOx).

[0036] In the third embodiment, the removal rate of nitrogen oxides can reach more than 90%, for example more than 95% or more than 98%.

[0037] In the third embodiment, the above-described hydrogen selective catalytic reduction reaction can be carried out at a temperature of 100°C to 250°C, but is not limited thereto. In other embodiments, the above-described hydrogen selective catalytic reduction reaction can be carried out at a higher temperature, such as 250°C to 300°C.

[0038] The following experiments are listed to verify the implementation effect of the present invention, but the present invention is not limited to the following content.

[0039] The following preparation examples (including comparative preparation examples) mainly use a hot water granulation process to introduce the active ingredients into the carrier, followed by high-temperature calcination to form a catalyst composition. Compared with conventional catalyst powders that have not undergone a granulation process and are directly calcined at high temperatures after hydrothermal drying, the catalyst compositions prepared in the examples of this invention have more uniform particle sizes and can be made into specific sizes that facilitate stacking and industrial operation. They are also less likely to generate dust and are suitable for dust-free environments, such as semiconductor plants.

[0040] First, the alumina support used in the following preparation examples (including comparative preparation examples) is alumina. Essentially, the support must be able to bind with the metal ions to be introduced, and its specific surface area must be large enough. The alumina in the preparation examples has a specific surface area of ​​373 m². 2 g -1 .

[0041] <Preparation Example 1>

[0042] In Preparation Example 1, a colloidal solution was first prepared, in which the weight ratio of the carrier, sodium alginate powder, and water was 20:3:200. Then, the colloidal solution was added to a hot aqueous solution (approximately 40 to 90°C) containing divalent manganese ions to form particles containing the first active ingredient, wherein the concentration of divalent manganese ions was 30,000 ppm.

[0043] Then, a 0.4 M K2C2O4 reducing solution, a 0.02 M Pd(NO3)2 and particles containing the first active ingredient were mixed and stirred in a ratio of 8.5:85:18. After being dried and calcined at 500°C for 6 hours, the catalyst composition of Preparation Example 1 was obtained.

[0044] <Preparation Example 2>

[0045] The same method as in Preparation Example 1 was used, but the components added to the colloidal solution were changed to a hot aqueous solution containing 25,000 ppm manganese ions and 5,000 ppm nickel ions.

[0046] <Preparation Example 3>

[0047] The same method as in Preparation Example 1 was used, but the components added to the colloidal solution were changed to a hot aqueous solution containing 25,000 ppm manganese ions and 5,000 ppm copper ions.

[0048] <Preparation Example 4>

[0049] The same method as in Preparation Example 1 was used, but the components added to the colloidal solution were changed to a hot aqueous solution containing 25,000 ppm manganese ions and 5,000 ppm nickel ions, and the reducing solution was changed to Na3C6H5O7.

[0050] <Preparation Example 5>

[0051] The same method as in Preparation Example 4 was used, but the components added to the colloidal solution were changed to a hot aqueous solution containing 25,000 ppm manganese ions and 5,000 ppm copper ions.

[0052] <Preparation Example 6>

[0053] The same method as in Preparation Example 1 was used, but Pd(NO3)2 was replaced with Pt(NO3)2.

[0054] <Comparative Preparation Example 1>

[0055] After obtaining particles containing the first active ingredient using the same method as in Preparation Example 1, the particles were directly calcined to obtain a catalyst composition containing only manganese oxide.

[0056] <Comparative Preparation Example 2>

[0057] The same method as in Preparation Example 1 was used, but without the addition of K2C2O4 reducing solution.

[0058] <Comparative Preparation Example 3>

[0059] The same method as in Preparation Example 6 was used, but without the addition of K2C2O4 reducing solution.

[0060] <Comparative Preparation Example 4>

[0061] The same method as in Preparation Example 2 was used, but the components added to the colloidal solution were changed to a hot aqueous solution containing 25,000 ppm manganese ions and 5,000 ppm iron ions, and the K2C2O4 reduction solution was replaced with Ca3(C6H5O7)2.

[0062] <Comparative Preparation Example 5>

[0063] The same method as in Preparation Example 5 was used, but the manganese ions added to the colloidal solution were replaced with 25,000 ppm of molybdenum ions.

[0064] <Component Analysis>

[0065] 1. The component ratios of the catalyst compositions of Preparation Examples 1-6 and Comparative Preparation Examples 1-5 were determined by energy-scattered X-ray spectroscopy (EDS) and are recorded in Table 1 below.

[0066] 2. The specific surface areas of the catalyst compositions of Preparation Examples 1-6 and Comparative Preparation Examples 1-5 were obtained by nitrogen adsorption-desorption (BET method) and are also recorded in Table 1 below.

[0067] Table 1

[0068]

[0069] The component values ​​in Table 1 are all in atomic percentage (at%), and the oxides in parentheses represent other catalyst components used in the comparative preparation examples.

[0070] Table 2 below shows the calculated molar ratios of each catalyst in the catalyst compositions of Preparation Examples 1-6 and Comparative Preparation Examples 2-5.

[0071] Table 2

[0072]

[0073] To verify the treatment efficiency of the above catalyst composition, a device for removing nitrogen oxides was constructed, the framework diagram of which is shown below. Figure 3 As shown. In Figure 3 In the reactor (i.e., heating furnace), a catalyst composition is contained, and the gas to be tested is introduced into the heating furnace via path 2 through a three-way valve. Fourier transform infrared spectroscopy (FTIR) can be used to determine NO. X concentration.

[0074] <Experimental Example 1>

[0075] Take 20 ml of the catalyst composition from Preparation Example 1 and place it in Figure 3 In the heating furnace, the temperature is controlled between 100℃ and 350℃, and 1% NO is... X 3% H2 (reducing agent) and compressed dry air (CDA) are delivered to a three-way valve via a mass flow controller (MFC) and mixed to form a test gas with a total flow rate of 600 sccm, wherein the gas hourly space velocity (GHSV) is approximately 1800 h⁻¹. -1 The flow rate of NO gas is approximately 360 ppm, and the flow rate of NO2 gas is approximately 240 ppm.

[0076] The NO of the above-mentioned test gas entering the FTIR via path 1 was tested respectively. X The concentration and the gas to be measured enter the FTIR NO via path 2. XConcentration, based on NO levels measured before and after treatment. X The concentration was used to calculate the treatment efficiency and selectivity, which are recorded in Table 3 below.

[0077] Table 3

[0078]

[0079] The table shows the Destruction and Removal Efficiencies (DRE) = [1 - (NO from path 2 into FTIR)]. X Concentration ÷ NO entering FTIR via path 1 X [Concentration] × 100%.

[0080] N2 selectivity in the table = [NO reacted] X [-(byproducts generated × byproduct N equivalents)] ÷ NO reacted X .

[0081] As shown in Table 3, the catalyst composition of Preparation Example 1 achieves a NO2 removal rate of over 98.1% at temperatures ranging from 100°C to 250°C, and a NO removal rate of over 87.5% at the same temperature range. The N2 selectivity is greater than 80% in both cases.

[0082] <Experimental Example 2>

[0083] The same equipment and parameters as in Experimental Example 1 were used, but the catalyst composition of Preparation Example 1 was replaced with the catalyst composition of Preparation Example 2 for testing. The results are shown in Table 4 below.

[0084] Table 4

[0085]

[0086] As shown in Table 4, the catalyst composition of Preparation Example 2 achieves a NO2 removal rate of over 97.7% at temperatures ranging from 100°C to 250°C, and a NO removal rate of over 80% at the same temperature range. The N2 selectivity is greater than 80% in both cases.

[0087] <Experimental Example 3>

[0088] The same equipment and parameters as in Experimental Example 1 were used, but the catalyst composition of Preparation Example 1 was replaced with the catalyst composition of Preparation Example 3 for testing. The results are shown in Table 5 below.

[0089] Table 5

[0090]

[0091] As shown in Table 5, the catalyst composition of Preparation Example 3 achieved a NO2 removal rate of over 98.7% and a NO removal rate of over 80% at temperatures ranging from 100°C to 200°C. The N2 selectivity was greater than 90% in both cases.

[0092] <Experimental Example 4>

[0093] The same equipment and parameters as in Experimental Example 1 were used, but the catalyst composition of Preparation Example 1 was replaced with the catalyst composition of Preparation Example 4 for testing. The results are shown in Table 6 below.

[0094] Table 6

[0095]

[0096] As shown in Table 6, the catalyst composition of Preparation Example 4 achieves a NO2 removal rate of over 98.2% at temperatures ranging from 100°C to 300°C, and a NO removal rate of over 88.2% at the same temperatures. The N2 selectivity is greater than 80% in both cases.

[0097] <Experimental Example 5>

[0098] The same equipment and parameters as in Experimental Example 1 were used, but the catalyst composition of Preparation Example 1 was replaced with the catalyst composition of Preparation Example 5 for testing. The results are shown in Table 7 below.

[0099] Table 7

[0100]

[0101] As shown in Table 7, the catalyst composition of Preparation Example 5 achieved a NO2 removal rate and a NO removal rate of over 98.3% at temperatures ranging from 100°C to 200°C. The N2 selectivity was also greater than 90%.

[0102] <Experimental Example 6>

[0103] The same equipment and parameters as in Experimental Example 1 were used, but the catalyst composition of Preparation Example 1 was replaced with the catalyst composition of Preparation Example 6 for testing. The results are shown in Table 8 below.

[0104] Table 8

[0105]

[0106] As shown in Table 8, the catalyst composition of Preparation Example 6 achieved NO2 removal rates and NO removal rates of over 95% at temperatures ranging from 100°C to 350°C. The N2 selectivity was greater than 90% at temperatures ranging from 150°C to 350°C.

[0107] <Comparative Example 1>

[0108] The same equipment and parameters as in Experimental Example 1 were used, but the catalyst composition of Preparation Example 1 was replaced with the catalyst composition of Comparative Preparation Example 2 for testing. The results are shown in Table 9 below.

[0109] Table 9

[0110]

[0111] As shown in Table 9, the catalyst composition of Comparative Preparation Example 2 exhibits poor nitrogen oxide treatment efficiency and unsatisfactory N2 selectivity. Therefore, the lack of a third catalyst with a second active ingredient in the catalyst composition will be detrimental to nitrogen oxide treatment.

[0112] <Comparative Example 2>

[0113] The same equipment and parameters as in Experimental Example 1 were used, but the catalyst composition of Preparation Example 1 was replaced with the catalyst composition of Comparative Preparation Example 3 for testing. The results are shown in Table 10 below.

[0114] Table 10

[0115]

[0116] As shown in Table 10, the catalyst composition of Comparative Preparation Example 3 exhibits poor nitrogen oxide treatment efficiency, and shows no N2 selectivity above 200°C. Therefore, the lack of a third catalyst with a second active ingredient in the catalyst composition will be detrimental to nitrogen oxide treatment.

[0117] <Comparative Example 3>

[0118] The same equipment and parameters as in Experimental Example 1 were used, but the catalyst composition of Preparation Example 1 was replaced with the catalyst composition of Comparative Preparation Example 4 for testing. The results are shown in Table 11 below.

[0119] Table 11

[0120]

[0121] As shown in Table 11, the catalyst composition of Comparative Preparation Example 4 exhibits poor nitrogen oxide treatment efficiency and very poor N2 selectivity. Therefore, if the third catalyst of the second active component in the catalyst composition is replaced with another metal oxide, it will also be detrimental to nitrogen oxide treatment.

[0122] <Comparative Example 4>

[0123] The same equipment and parameters as in Experimental Example 1 were used, but the catalyst composition of Preparation Example 1 was replaced with the catalyst composition of Comparative Preparation Example 5 for testing. The results are shown in Table 12 below.

[0124] Table 12

[0125]

[0126] Table 12 shows that the catalytic composition of Preparation Example 5 exhibits poor nitrogen oxide treatment efficiency, especially at low reaction temperatures. N2 selectivity is also poor. Therefore, the absence of manganese oxide as the primary active ingredient in the catalytic composition is detrimental to nitrogen oxide treatment.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A catalyst composition, characterized in that, include: carrier; A first active ingredient is coated on the surface of the carrier, wherein the first active ingredient includes a first catalyst, and the first catalyst is manganese oxide; as well as The second active ingredient, comprising a second catalyst and a third catalyst, is coated on the surface of the first active ingredient and on the surface of the carrier not coated with the first active ingredient. The second catalyst comprises platinum metal, palladium metal, or a combination thereof, and the third catalyst comprises potassium oxide, sodium oxide, or a combination thereof. The molar ratio of the first catalyst to the second catalyst is 1:0.001 to 1:0.2, and the molar ratio of the first catalyst to the third catalyst is 1:0.1 to 1:

10.

2. The catalyst composition according to claim 1, characterized in that, The first active ingredient also includes a fourth catalyst, which comprises copper oxide, nickel oxide, or a combination thereof.

3. The catalyst composition according to claim 2, characterized in that, The molar ratio of the first catalyst to the fourth catalyst is 1:0.1 to 1:

10.

4. The catalyst composition according to claim 1, characterized in that, The molar ratio of the first catalyst to the carrier is 1:3 to 1:

20.

5. The catalyst composition according to claim 1, characterized in that, The carrier includes aluminum oxide, titanium oxide, zirconium oxide, cerium oxide, magnesium oxide, or a combination thereof.

6. The catalyst composition according to claim 1, characterized in that, The specific surface area of ​​the catalyst composition is 140 m². 2 g -1 up to 500 m 2 g -1 .

7. The catalyst composition according to claim 1, characterized in that, The particle size of the catalyst composition is from 100 µm to 10 mm.

8. A method for removing nitrogen oxides, characterized in that, The method includes performing a hydrogen-selective catalytic reduction reaction of nitrogen oxides using a catalytic composition according to any one of claims 1 to 7.

9. The method for removing nitrogen oxides according to claim 8, characterized in that, The removal rate of nitrogen oxides is over 90%.

10. The method for removing nitrogen oxides according to claim 8, characterized in that, The hydrogen selective catalytic reduction reaction is carried out at a temperature of 100°C to 250°C.

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