Organic matter decomposition catalyst, honeycomb structure, decomposition method for organic matter, and organic matter decomposition device
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- MURATA MFG CO LTD
- Filing Date
- 2025-12-24
- Publication Date
- 2026-07-30
Smart Images
Figure JP2025045319_30072026_PF_FP_ABST
Abstract
Description
Organic matter decomposition catalyst, honeycomb structure, method for decomposing organic matter, and organic matter decomposition apparatus
[0001] This disclosure relates to an organic matter decomposition catalyst, and further to an organic matter decomposition structure, a method for decomposing organic matter, and an organic matter decomposition apparatus.
[0002] The purification of exhaust gases, which consist of hydrocarbon-based organic substances, generally involves mixing the exhaust gas with an oxygen-containing gas such as air, heating it, and decomposing it into water and carbon dioxide through an oxidative combustion reaction. Using catalytic materials allows for exhaust gas purification at lower temperatures and higher speeds, thus saving energy and costs associated with exhaust gas treatment. Common catalyst materials include ceramics such as alumina on which active components such as platinum, palladium, manganese, and cobalt are supported. While precious metals like platinum and palladium allow for exhaust gas treatment at lower temperatures compared to manganese and cobalt-based catalysts, they are more expensive.
[0003] Patent Document 1 describes BaZr(Mn)O for the purpose of improving the heat resistance of perovskite-type composite oxide catalysts. ３ A catalyst (BZM-based catalyst) has been proposed. Non-patent documents 1 and 2 propose a Zr-Mn-based catalyst for the purpose of suppressing degradation in the decomposition of hydrocarbon gases containing Cl. Furthermore, patent document 2 proposes improving the properties of the Zr-Mn-based catalyst by performing hydrothermal treatment and high-temperature steam treatment during the manufacturing process.
[0004] Japanese Patent Publication No. 2015-229137, Chinese Patent No. 111790374 Specification
[0005] Jose I. Gutierrez-Ortiz, et al., "Structure of Mn-Zr mixed oxides catalyticists and their catalytic performance in the gas-phase oxidation of chloride carbons," Chemosphere, 2007, Vol. 68, pp. 1004-1012. Doebber, 3 others, "MnOx / ZrO2 catalysts for the total oxidation of methane and chloromethane", Applied Catalysis B: Environmental, 2004, Volume 52, Pages 135-143
[0006] As exhaust gas decomposition catalysts, catalysts are generally used in which platinum group elements such as platinum, rhodium, and palladium are supported on heat-resistant materials such as alumina. In catalysts where the active component is supported on a support such as alumina, the active component is often supported on the support in the form of fine particles in order to obtain high catalytic activity. As a result, there is a tendency for the catalyst's activity to deteriorate due to a decrease in the surface area of the material. In addition, catalysts used for exhaust gas decomposition treatment are often exposed to high-temperature environments due to the high temperature of the exhaust gas and the heat generated by the decomposition reaction. Furthermore, platinum, rhodium, and palladium are rare resources and therefore expensive, making it difficult to use them in large quantities in large-scale catalytic exhaust gas treatment systems due to cost constraints.
[0007] Furthermore, if the catalyst's heat resistance or poisoning resistance is insufficient, its performance deteriorates rapidly, making it difficult to utilize catalytic exhaust gas treatment and increasing energy costs for exhaust gas treatment. Therefore, there is a need for catalysts that can be used stably even at higher temperatures, and catalyst materials that are less susceptible to degradation by catalyst poison components such as sulfur (S), chlorine (Cl), and phosphorus (P).
[0008] Although the BZM catalyst disclosed in Patent Document 1 has improved heat resistance, its catalytic properties may deteriorate due to reactions with catalytic components when exposed to exhaust gas containing high concentrations of S and Cl.
[0009] Although the Zr-Mn catalysts disclosed in Non-Patent Document 1, Non-Patent Document 2, and Patent Document 2 are durable against chlorinated hydrocarbons, their heat resistance at higher temperatures is still insufficient. Therefore, when the exhaust gas treatment temperature reaches high temperatures, the catalyst particles may aggregate, reducing the contact area with the gas and potentially lowering the exhaust gas purification performance. Furthermore, the aggregation of catalyst particles causes the catalyst itself to deform, leading to cracking in pellet-shaped catalysts and peeling in honeycomb-shaped structures with a catalyst coating. This can generate dust, which may adversely affect exhaust gas treatment equipment and downstream processes.
[0010] Thus, the thermal durability of catalysts requires ample margin, taking into account not only the operating temperature of the exhaust gas treatment equipment but also the temperature rise due to the combustion of organic matter, and the possibility of raising the operating temperature to compensate for insufficient treatment capacity.
[0011] The purpose of this disclosure is to provide an organic matter decomposition catalyst that exhibits high catalytic activity in its initial stage, maintains high catalytic activity even after poisoning, and can be regenerated by heating even after poisoning, as well as a honeycomb structure using the same, a method for decomposing organic matter, and an organic matter decomposition apparatus.
[0012] The organic decomposition catalyst relating to this disclosure is an organic decomposition catalyst for oxidative decomposition of organic matter. The organic decomposition catalyst comprises a ternary complex oxide containing zirconium, manganese, and a rare earth element. The rare earth element includes at least one selected from the group consisting of lanthanum, praseodymium, samarium, and yttrium.
[0013] According to this disclosure, it is possible to provide an organic matter decomposition catalyst that exhibits high catalytic activity in its initial stage, maintains high catalytic activity even after poisoning, and can be regenerated by heating even after poisoning, a honeycomb structure using the same, a method for decomposing organic matter, and an organic matter decomposition apparatus.
[0014] Figure 1 is a schematic diagram illustrating the organic matter decomposition apparatus of this disclosure. Figure 2 shows the XRD measurement results of the organic matter decomposition catalysts of Examples 3, 6, 10, 19 and Comparative Example 4. Figure 3 shows the TEM (transmission electron microscope) image and EDX (energy dispersive X-ray spectroscopy) elemental mapping image of the organic matter decomposition catalyst of Example 2. Figure 4 shows the TEM image and EDX elemental mapping image of the organic matter decomposition catalyst of Example 5. Figure 5 shows the TEM image and EDX elemental mapping image of the organic matter decomposition catalyst of Example 8. Figure 6 shows the TEM image and EDX elemental mapping image of the organic matter decomposition catalyst of Example 19. Figure 7 is a schematic diagram illustrating the organic matter decomposition apparatus used in the examples.
[0015] Hereinafter, the organic matter decomposition catalysts according to each embodiment of this disclosure will be described with reference to the figures. In the following descriptions of each embodiment, the same or corresponding parts in the figures will be denoted by the same reference numerals, and their descriptions will not be repeated.
[0016] <Organic Decomposition Catalyst> The organic decomposition catalyst of this disclosure is an organic decomposition catalyst for oxidative decomposition of organic matter, and comprises a ternary complex oxide (hereinafter also referred to as the first oxide) containing zirconium (Zr), manganese (Mn), and a rare earth element, wherein the rare earth element comprises at least one selected from the group consisting of lanthanum (La), praseodymium (Pr), samarium (Sm), and yttrium (Y) [hereinafter also referred to as the specific rare earth element (R)]. In this specification, the ternary complex oxide refers to an oxide containing three elements other than oxygen (Zr, Mn, and R in this disclosure) and having a stable crystalline structure. Note that the specific rare earth element (R) may contain multiple elements.
[0017] The organic matter decomposition catalyst may include, as the first oxide, at least one ternary composite oxide selected from the group consisting of a ternary composite oxide containing Zr, Mn, and La; a ternary composite oxide containing Zr, Mn, and Pr; a ternary composite oxide containing Zr, Mn, and Sm; and a ternary composite oxide containing Zr, Mn, and Y.
[0018] The first oxide comprises at least one rare earth element selected from the group consisting of La, Pr, Sm, and Y, and preferably comprises at least one selected from the group consisting of La, Pr, and Sm from the viewpoint of catalytic activity after poisoning and catalytic activity after regeneration.
[0019] The first oxide can be an oxide containing Zr, Mn, and R. The presence of the first oxide in the organic matter decomposition catalyst can be confirmed by X-ray diffraction (XRD) analysis or elemental mapping by TEM (transmission electron microscope) EDX (energy dispersive X-ray spectroscopy). By XRD analysis or TEM-EDX analysis, the crystal structure of the first oxide is zirconium oxide (ZrO ２ It is confirmed that the crystal structure is a solid solution in which Mn and R are dispersed and embedded in the crystal lattice of ). When R is at least one selected from the group consisting of La, Pr and Sm, the first oxide is ZrO ２ The first oxide can have a crystalline structure (first crystalline structure) in which Mn and R are solid-dissolved at a higher concentration near the surface layer, including the surface of the crystalline grains, compared to the interior of the crystalline grains. When R is Y, the first oxide can have a crystalline structure (second crystalline structure) in which a region exists where Y is concentrated and solid-dissolved inside the crystalline grains.
[0020] Examples of organic substances that can be oxidatively decomposed by an organic decomposition catalyst include hydrocarbon gases, sulfur compounds, and nitrogen compounds. The organic substances may also be volatile organic compounds (VOCs), for example. The organic decomposition catalyst of this disclosure is particularly suitable for the oxidative decomposition of hydrocarbon gases (e.g., aromatic hydrocarbons, alcohols, ketones, aldehydes, carboxylic acids). The organic decomposition catalyst can be used, for example, to purify harmful gases such as exhaust gas.
[0021] Regarding oxidative decomposition, see formula (1): C ７ H ８ +9O ２ → 4H ２ O+7CO ２Taking the toluene combustion reaction represented by (1) as an example, harmful toluene with discharge restrictions into the atmosphere is reacted with air (oxygen) to be converted into harmless water vapor and carbon dioxide. Since this reaction is an exothermic reaction, especially when treating high-concentration gases or large amounts of gases, the reaction field will be heated to a high temperature. Also, when the organic structure of hydrocarbons constituting hydrocarbon-based gases contains elements such as sulfur and chlorine, sulfur and chlorine are poisoned by reacting with catalyst components or strongly binding to adsorption points on the catalyst surface, resulting in a decrease in catalyst performance.
[0022] The organic matter decomposition catalyst tends to have improved heat resistance by containing the first oxide. This is because by adding both Mn and R to ZrO ２ the number of active sites increases, improving the decomposition performance of organic matter, and at the same time, the surface energy of ZrO ２ changes, inhibiting the growth of crystal grains, which is considered to be the reason for the improved heat resistance. As a result, the organic matter decomposition catalyst of the present disclosure tends to exhibit high catalytic activity in terms of initial activity when calcined at a high temperature (for example, 900 °C) in the manufacturing process and when the temperature at which the catalyst is used is high, and also tends to maintain high catalytic activity in terms of catalytic activity after poisoning, and even when poisoned, it tends to be easily regenerated by heating. When the first oxide has a first crystal structure, due to the surface dispersion effect of R, the number of active sites increases, improving the decomposition performance of organic matter, and at the same time, the surface energy of ZrO ２ changes, making it easier to inhibit the growth of crystal grains and easier to improve heat resistance. The initial activity, catalytic activity after poisoning, and catalytic activity after regeneration are evaluated according to the methods described in the examples section below.
[0023] Organic decomposition catalysts containing the first oxide exhibit higher catalytic activity in their initial stages compared to organic decomposition catalysts containing a binary complex oxide but without the first oxide, and can maintain high catalytic activity even after poisoning. For example, organic decomposition catalysts containing the first oxide exhibit higher catalytic activity in their initial stages and can maintain high catalytic activity even after poisoning compared to organic decomposition catalysts containing a binary complex oxide containing Zr and Mn but without the first oxide, organic decomposition catalysts containing a binary complex oxide containing Zr and La but without the first oxide, organic decomposition catalysts containing a binary complex oxide containing Zr and Pr but without the first oxide, organic decomposition catalysts containing a binary complex oxide containing Zr and Sm but without the first oxide, and organic decomposition catalysts containing a binary complex oxide containing Zr and Y but without the first oxide. This is because ZrO ２ By adding both Mn and R to the mixture, compared to a binary composite oxide with only one of Mn or R added, the mixture containing Mn and R is superior to a ZrO2-based composite oxide. ２ It becomes easier to disperse inside, and as a result the number of active sites increases, improving the decomposition performance of organic matter, and ZrO ２ This is thought to be because the surface energy changes, inhibiting grain growth and improving heat resistance.
[0024] The organic decomposition catalyst of this disclosure does not contain a primary oxide and can exhibit high catalytic activity in its initial stage compared to organic decomposition catalysts containing a binary complex oxide containing Zr and Mn, or a mixture of a binary complex oxide containing Zr and R, and can maintain high catalytic activity even after poisoning.
[0025] The organic matter decomposition catalyst may further contain an oxide that exhibits catalytic activity in addition to the primary oxide (hereinafter also referred to as the secondary oxide). The secondary oxide may contain, for example, one or more oxides containing Mn and / or R. The secondary oxide may be, for example, a monocrystalline oxide and a binary complex oxide, and a specific example thereof is Mn ３ O ４ Mn ２ O ３ La２ O ３ , Pr ２ O ３ Sm ２ O ３ , Y ２ O ３ LaMnO ３ ,PrMnO ３ SmMnO ３ Examples include the above. The organic matter decomposition catalyst may contain only the first oxide as the oxide that exhibits catalytic activity, or it may contain only the first oxide and the second oxide.
[0026] The organic matter decomposition catalyst may consist only of the first oxide, or only of the first and second oxides. Furthermore, the organic matter decomposition catalyst may contain a binder or organic solvent to facilitate its formation into particulate or honeycomb shapes, or its coating onto structures, as described later. The content of the first oxide in the organic matter decomposition catalyst may be, for example, 100% by mass or less, 95% by mass or less, or 90% by mass or less, or 50% by mass or more, based on the mass of the organic matter decomposition catalyst. In the case of structures coated with an organic matter decomposition catalyst, such as the honeycomb structure coated with the organic matter decomposition catalyst described later, the mass of the organic matter decomposition catalyst refers to the mass of the organic matter decomposition catalyst coated onto the structure, and does not include the mass of the structure (e.g., honeycomb ceramics).
[0027] When the organic matter decomposition catalyst contains a second oxide, the content of the second oxide may be, for example, 40 parts by mass or less, preferably 30 parts by mass or less, and may be, for example, more than 0 parts by mass, per 100 parts by mass of the first oxide.
[0028] The molar ratio of Mn to Zr in the organic matter decomposition catalyst may be in the range of 0.02 to 0.40, and preferably in the range of 0.05 to 0.40. By having the molar ratio of Mn to Zr in the organic matter decomposition catalyst within the above range, the heat resistance of the organic matter decomposition catalyst is improved, as a result it is easier to exhibit high catalytic activity in the initial activity stage, easier to maintain high catalytic activity even after poisoning, and tends to regenerate easily by heating even after poisoning.
[0029] The molar ratio of R to Zr in the organic matter decomposition catalyst may be in the range of 0.01 to 0.10, and preferably in the range of 0.02 to 0.10. Having the molar ratio of R to Zr in the organic matter decomposition catalyst within this range improves heat resistance, resulting in easier high catalytic activity in the initial stage, easier maintenance of high catalytic activity even after poisoning, and a tendency for easier regeneration by heating even after poisoning.
[0030] The organic matter decomposition catalyst is a monoclinic ZrO ２ The catalyst may include a crystalline phase (first crystalline phase). The first crystalline phase may be a solid solution crystalline phase in which Mn and R are dispersed. The organic matter decomposition catalyst may include one or more crystalline phases other than the first crystalline phase (second crystalline phase). The second crystalline phase may be, for example, Mn ３ O ４ Crystal phase, Mn ２ O ３ Crystal phase, La ２ O ３ Crystal phase, Pr ２ O ３ Crystal phase, Sm ２ O ３ Crystal phase, Y ２ O ３ Crystal phase, LaMnO ３ Crystalline phase, PrMnO ３ Crystal phase, SmMnO ３ Crystalline phase, cubic ZrO ２ ZrO in crystalline and tetragonal phases ２ It may contain crystalline phases, etc. The crystalline phase of the organic matter decomposition catalyst can be confirmed by XRD analysis.
[0031] Organic matter decomposition catalysts can be prepared, for example, as follows: First, ZrO ２ Mn ３ O ４A mixture is obtained by adding cobblestones, water, and an organic binder to an oxide or hydroxide of a specific rare earth element. A ball mill or similar device can be used for mixing. Next, the mixture is dried in an oven at 120°C, then crushed and classified to obtain particles with a particle size of several hundred micrometers to several millimeters. After that, the obtained particulate sample is calcined in air at 900°C for 2 hours. In this way, an organic matter decomposition catalyst can be obtained.
[0032] The organic matter decomposition catalyst may exhibit catalytic activity at an initial temperature of, for example, 300°C to 450°C, preferably 310°C to 390°C, and more preferably 310°C to 360°C.
[0033] The organic matter decomposition catalyst may exhibit catalytic activity at a temperature of, for example, 400°C to 550°C after poisoning, preferably 420°C to 490°C, and more preferably 420°C to 480°C.
[0034] The organic matter decomposition catalyst may exhibit catalytic activity at a temperature of, for example, 300°C to 450°C after regeneration by heating, preferably 320°C to 410°C, and more preferably 340°C to 390°C.
[0035] The organic matter decomposition catalyst has improved heat resistance, exhibits high catalytic activity in its initial stage, maintains high catalytic activity even after poisoning, and can be regenerated by heating even after poisoning. Therefore, it is suitable for decomposing volatile organic compounds (VOCs) that are generated in processes such as painting, molding, combustion, and waste treatment in living environments and industrial fields, and which cause environmental pollution. Furthermore, the organic matter decomposition catalyst can also be used in applications such as purifying automobile exhaust gases.
[0036] <Forms of Organic Matter Decomposition Catalysts> Organic matter decomposition catalysts can be used in the form of pellet catalysts processed into granular shapes of several mm to several cm in size, and honeycomb catalysts processed into a honeycomb shape. Furthermore, by coating the surface of a honeycomb-shaped ceramic with the organic matter decomposition catalyst, it can be used as a honeycomb structure coated with the catalyst. The honeycomb structure reduces pressure loss when gas is passed through it. Increasing the cell density of the honeycomb increases the effective surface area, making it easier to increase the organic matter decomposition rate.
[0037] <Method for Decomposing Organic Matter> Another embodiment of the present disclosure is a method for decomposing organic matter, comprising a decomposition step of oxidatively decomposing organic matter by heating using the above-described organic matter decomposition catalyst. In the decomposition step, organic matter can be decomposed by heating while in contact with the organic matter decomposition catalyst. The above-described description of organic matter applies to organic matter. The method for decomposing organic matter can be carried out using the organic matter decomposition apparatus described later.
[0038] The heating temperature in the decomposition process may be, for example, 300°C to 900°C. If the heating temperature in the decomposition process is within the above range, it becomes possible to exert the catalytic activity of the organic matter decomposition catalyst, and it becomes possible to exert catalytic activity even after poisoning. From the viewpoint of suppressing the deterioration of catalyst performance and energy costs, the heating temperature in the decomposition process is preferably 300°C to 700°C, more preferably 300°C to 600°C, and even more preferably 300°C to 500°C.
[0039] One method for heating organic matter while bringing it into contact with an organic matter decomposition catalyst is to fill a tube with the organic matter decomposition catalyst, introduce organic matter into the tube, and then heat the area where the organic matter decomposition catalyst and the organic matter are in contact from the outside of the tube. The organic matter decomposition catalyst filled into the tube can be the aforementioned pellet-shaped catalyst, honeycomb catalyst, or honeycomb structure coated with the organic matter decomposition catalyst. It may also be an aggregate of the organic matter decomposition catalyst.
[0040] The method for decomposing organic matter may further include a regeneration step in which the catalytic activity of the organic matter decomposition catalyst used in the decomposition step is restored by heating it to a temperature higher than the heating temperature in the decomposition step. The regeneration step can be carried out by heating the organic matter decomposition catalyst used in the decomposition step to a temperature higher than the heating temperature in the decomposition step while in contact with air. The organic matter decomposition catalyst used in the decomposition step may be poisoned with S, Cl, P, etc.
[0041] The temperature above the heating temperature in the above decomposition step may be, for example, 300°C to 900°C, and is preferably 400°C to 800°C, and more preferably 600°C to 800°C, from the viewpoint of catalytic activity of the regenerated catalyst and energy cost.
[0042] A method of heating the organic matter decomposition catalyst used in the decomposition process while bringing it into contact with air can be carried out, for example, by introducing air into a tube filled with the organic matter decomposition catalyst used in the decomposition process and heating it from the outside of the tube.
[0043] <Organic Matter Decomposition Apparatus> An organic matter decomposition apparatus according to another embodiment of the present disclosure comprises a pipe through which organic matter flows and a heating unit for heating the organic matter flowing through the pipe. The above-mentioned organic matter decomposition catalyst is placed in a region heated by the heating unit inside the pipe.
[0044] The organic matter decomposition apparatus will be described with reference to Figure 1. The organic matter decomposition apparatus 10 shown in Figure 1 comprises a pipe 1 through which organic matter flows, a heating unit 2 for heating the organic matter flowing through pipe 1, and a control unit 3 for controlling the heating unit 2.
[0045] An organic matter decomposition catalyst 6 is placed in the region heated by the heating section 2 inside the tube 1. The organic matter decomposition catalyst 6 may be the organic matter decomposition catalyst described above, and its form may be an aggregate, the pellet-shaped catalyst described above, a honeycomb catalyst, or a honeycomb-shaped structure coated with the organic matter decomposition catalyst.
[0046] Pipe 1 is equipped with a gas inlet 4 on its upstream side. A gas supply pipe 7 is connected to the gas inlet 4. The gas supply pipe 7 has an organic matter supply line 41 for supplying organic matter (e.g., toluene) and nitrogen (N ２A nitrogen supply line 42 for supplying oxygen (O ２ A gas supply line 43 for supplying oxygen is connected to the pipe 1. In other words, the gas to be treated, which contains organic matter, nitrogen, and oxygen, is supplied to the pipe 1 via the gas supply pipe 7.
[0047] Pipe 1 is equipped with a reaction gas outlet 5 on its downstream side. A gas discharge pipe 8 is connected to the reaction gas outlet 5 for discharging the treated gas, which is the result of organic matter decomposition in pipe 1, out of the system. A sampling line 51 is connected to the gas discharge pipe 8 for sampling the treated gas, and the system is configured to allow analysis of the concentration of organic matter in the treated gas using a gas chromatograph.
[0048] The control unit 3 is configured to control the temperature of the area heated by the heating unit 2 so that it is, for example, between 300°C and 900°C.
[0049] Furthermore, the control unit 3 is configured to control the heating unit 2 so that the temperature of the organic matter decomposition catalyst 6 is between 300°C and 900°C. By controlling the temperature of the organic matter decomposition catalyst 6 to be between 300°C and 900°C, the catalytic activity of the organic matter decomposition catalyst 6 can be further enhanced. Also, by controlling the temperature of the organic matter decomposition catalyst 6 to be below 900°C, the deterioration of the organic matter decomposition catalyst 6 can be suppressed.
[0050] Furthermore, after the decomposition of organic matter, the organic matter decomposition catalyst 6 can be regenerated to restore its catalytic activity by supplying oxygen and nitrogen to the tube 1 while heating it with the heating unit 2, controlling the temperature of the organic matter decomposition catalyst 6 to a temperature higher than the heating temperature in the decomposition process, while the control unit 3 controls the heating. The purpose of the regeneration process is to remove catalyst toxin components by heating, so it is necessary to heat it to a temperature higher than the heating temperature in the decomposition process, but it is also possible to carry out the process while supplying organic matter.
[0051] The present disclosure will be further described below with reference to examples. Unless otherwise specified, "%" and "parts" in the examples refer to mass percent and parts by mass. The organic decomposition catalysts of each of the following examples and comparative examples were analyzed using an X-ray fluorescence analyzer to confirm that they had the compositions of the organic decomposition catalysts described in Tables 1 and 2.
[0052] <Example 1> ZrO as a raw material for an organic matter decomposition catalyst ２ and Mn ３ O ４ and La(OH) ３ Using the above, the materials were weighed so that the molar ratio of Zr:Mn:La was 1.00:0.1:0.01, and the pebbles, water, and organic binder were added and mixed. The resulting mixture was dried in an oven at 120°C, and then crushed and classified to obtain granules of 0.5 to 0.7 mm. The obtained granular sample was calcined in air at 900°C / 2h to obtain the organic matter decomposition catalyst of Example 1.
[0053] <Example 2> ZrO as a raw material for an organic matter decomposition catalyst ２ and Mn ３ O ４ and La(OH) ３ The organic matter decomposition catalyst of Example 2 was obtained in the same manner as in Example 1, except that the materials used were weighed so that the molar ratio of Zr:Mn:La was 1.00:0.1:0.02.
[0054] <Example 3> ZrO as a raw material for an organic matter decomposition catalyst ２ and Mn ３ O ４ and La(OH) ３ The organic matter decomposition catalyst of Example 3 was obtained in the same manner as in Example 1, except that the materials used were weighed so that the molar ratio of Zr:Mn:La was 1.00:0.1:0.1.
[0055] <Example 4> ZrO as a raw material for an organic matter decomposition catalyst ２ and Mn ３ O ４ and Sm ２ O ３ The organic matter decomposition catalyst of Example 4 was obtained in the same manner as in Example 1, except that the materials used were weighed so that the molar ratio of Zr:Mn:Sm was 1.00:0.1:0.01.
[0056] <Example 5> Using ZrO ２ and Mn ３ O ４ and Sm ２ O ３ As raw materials for the organic matter decomposition catalyst, an organic matter decomposition catalyst of Example 5 was obtained in the same manner as in Example 1, except that they were weighed so that the molar ratio of Zr:Mn:Sm was 1.00:0.1:0.02.
[0057] <Example 6> Using ZrO ２ and Mn ３ O ４ and Sm ２ O ３ As raw materials for the organic matter decomposition catalyst, an organic matter decomposition catalyst of Example 6 was obtained in the same manner as in Example 1, except that they were weighed so that the molar ratio of Zr:Mn:Sm was 1.00:0.1:0.1.
[0058] <Example 7> Using ZrO ２ and Mn ３ O ４ and Pr ２ O ３ As raw materials for the organic matter decomposition catalyst, an organic matter decomposition catalyst of Example 7 was obtained in the same manner as in Example 1, except that they were weighed so that the molar ratio of Zr:Mn:Pr was 1.00:0.1:0.01.
[0059] <Example 8> Using ZrO ２ and Mn ３ O ４ and Pr ２ O ３ As raw materials for the organic matter decomposition catalyst, an organic matter decomposition catalyst of Example 8 was obtained in the same manner as in Example 1, except that they were weighed so that the molar ratio of Zr:Mn:Pr was 1.00:0.1:0.02.
[0060] <Example 9> Using ZrO ２ and Mn ３ O ４ and Pr ２ O ３ As raw materials for the organic matter decomposition catalyst, an organic matter decomposition catalyst of Example 9 was obtained in the same manner as in Example 1, except that they were weighed so that the molar ratio of Zr:Mn:Pr was 1.00:0.1:0.05.
[0061] <Example 10> Using ZrO as a raw material for the organic matter decomposition catalyst ２ and Mn ３ O ４ and Pr ２ O ３ A catalyst for decomposing organic substances of Example 10 was obtained in the same manner as in Example 1, except that they were weighed so that the molar ratio of Zr:Mn:Pr was 1.00:0.1:0.1.
[0062] <Example 11> Using ZrO as a raw material for the organic matter decomposition catalyst ２ and Mn ３ O ４ and Pr ２ O ３ A catalyst for decomposing organic substances of Example 11 was obtained in the same manner as in Example 1, except that they were weighed so that the molar ratio of Zr:Mn:Pr was 1.00:0.02:0.05.
[0063] <Example 12> Using ZrO as a raw material for the organic matter decomposition catalyst ２ and Mn ３ O ４ and Pr ２ O ３ A catalyst for decomposing organic substances of Example 12 was obtained in the same manner as in Example 1, except that they were weighed so that the molar ratio of Zr:Mn:Pr was 1.00:0.05:0.05.
[0064] <Example 13> Using ZrO as a raw material for the organic matter decomposition catalyst ２ and Mn ３ O ４ and Pr ２ O ３ A catalyst for decomposing organic substances of Example 13 was obtained in the same manner as in Example 1, except that they were weighed so that the molar ratio of Zr:Mn:Pr was 1.00:0.2:0.05.
[0065] <Example 14> Using ZrO as a raw material for the organic matter decomposition catalyst ２ and Mn ３ O ４ and Pr ２ O ３ A catalyst for decomposing organic substances of Example 14 was obtained in the same manner as in Example 1, except that they were weighed so that the molar ratio of Zr:Mn:Pr was 1.00:0.4:0.05.
[0066] <Example 15> ZrO as a raw material for an organic matter decomposition catalyst ２ and Mn ３ O ４ and Pr ２ O ３ The organic matter decomposition catalyst of Example 15 was obtained in the same manner as in Example 1, except that the materials were weighed so that the molar ratio of Zr:Mn:Pr was 1.00:0.02:0.01.
[0067] <Example 16> ZrO as a raw material for an organic matter decomposition catalyst ２ and Mn ３ O ４ and Pr ２ O ３ The organic matter decomposition catalyst of Example 16 was obtained in the same manner as in Example 1, except that the materials were weighed so that the molar ratio of Zr:Mn:Pr was 1.00:0.02:0.1.
[0068] <Example 17> ZrO as a raw material for an organic matter decomposition catalyst ２ and Mn ３ O ４ and Pr ２ O ３ The organic matter decomposition catalyst of Example 17 was obtained in the same manner as in Example 1, except that the materials were weighed so that the molar ratio of Zr:Mn:Pr was 1.00:0.4:0.01.
[0069] <Example 18> ZrO as a raw material for an organic matter decomposition catalyst ２ and Mn ３ O ４ and Pr ２ O ３ The organic matter decomposition catalyst of Example 18 was obtained in the same manner as in Example 1, except that the materials were weighed so that the molar ratio of Zr:Mn:Pr was 1.00:0.4:0.1.
[0070] <Example 19> ZrO as a raw material for an organic matter decomposition catalyst ２ and Mn ３ O ４ and Y ２ O ３ The organic matter decomposition catalyst of Example 19 was obtained in the same manner as in Example 1, except that the materials were weighed so that the molar ratio of Zr:Mn:Y was 1.00:0.1:0.1.
[0071] <Comparative Example 1> BaCO3 as a raw material for an organic matter decomposition catalyst ３ and ZrO ２ and Mn ３ O ４ Using the above, the materials were weighed so that the molar ratio of Ba:Zr:Mn was 1.00:0.90:0.10, and the pebbles, water, and organic binder were added and mixed. The resulting mixture was dried in an oven at 120°C, and then crushed and classified to obtain granules of 0.5 to 0.7 mm. The obtained granular sample was calcined in air at 1000°C / 2h to obtain the organic matter decomposition catalyst of Comparative Example 1.
[0072] <Comparative Example 2> ZrO as a raw material for an organic matter decomposition catalyst ２ and Mn ３ O ４ The organic matter decomposition catalyst for Comparative Example 2 was obtained in the same manner as in Example 1, except that the materials used were weighed so that the molar ratio of Zr:Mn was 1.00:0.1.
[0073] <Comparative Example 3> ZrO as a raw material for an organic matter decomposition catalyst ２ and Pr ２ O ３ The organic matter decomposition catalyst for Comparative Example 3 was obtained in the same manner as in Example 1, except that the materials used were weighed so that the molar ratio of Zr:Pr was 1.00:0.1.
[0074] <Comparative Example 4> ZrO as a raw material for an organic matter decomposition catalyst ２ and Mn ３ O ４ and CEO ２ The organic matter decomposition catalyst for Comparative Example 4 was obtained in the same manner as in Example 1, except that the materials used were weighed so that the molar ratio of Zr:Mn:Ce was 1.00:0.1:0.1.
[0075] [Confirmation of Crystalline Phase] The organic decomposition catalysts of the examples and comparative examples were pulverized in a mortar and pestle, and the crystalline phase was confirmed by powder XRD measurement (X-ray light source: Cu-Kα1). Table 1 shows the types of crystalline phases detected from the organic decomposition catalysts of the examples and comparative examples. In Table 1, "Composition of Organic Decomposition Catalyst" represents the molar ratio of each element to Zr in the organic decomposition catalyst.
[0076]
[0077] The main phase of the catalysts in Examples 1-19 and Comparative Examples 2-4 is a monoclinic ZrO ２ Crystal phase (in Table 1, m-ZrO ２ It was confirmed that the catalyst of Example 19 to which Y was added contained cubic or tetragonal ZrO ２ Crystal phase (in Table 1, c-ZrO ２ (as indicated) was also confirmed. In addition, a perovskite crystalline phase was confirmed in the catalyst of Comparative Example 1.
[0078] Figure 2 shows the XRD measurement results for Examples 3, 6, 10, 19 and Comparative Example 4. When La, Sm, or Pr was added, no crystal structure derived from rare earth elements was observed at addition amounts with an R / Zr ratio of 0.02 or less, but at 0.05 or more, a composite oxide (LaMnO) of La, Sm, or Pr and Mn was observed. ３ SmMnO ３ ,PrMnO ３ ) diffraction lines were observed. In addition, m-ZrO was observed from the catalyst of Example 19 in which Y was added. ２ and c-ZrO ２ Both crystalline phases have been confirmed, and Y is ZrO ２ It dissolves in the high-temperature phase c-ZrO ２ It is thought that this is generating CeO. On the other hand, the catalyst of Comparative Example 4, to which cerium (Ce) was added, was found to be produced from CeO. ２ A phase has been identified, and it is presumed that Ce exists without forming a composite oxide with Zr or Mn.
[0079] Figure 3 shows TEM (transmission electron microscope) images of the catalysts from Example 2, Figure 4 shows TEM images from Example 5, Figure 5 shows TEM images from Example 8, and Figure 6 shows TEM images of the catalysts from Example 19, along with elemental mapping images of Zr, Mn, and R (La, Sm, Pr, or Y) obtained by EDX (energy-dispersive X-ray spectroscopy) of the same field of view. The distribution of Zr, Mn, and R present in the catalyst particles of the examples is consistent, and ZrO ２ It is thought to be a solid solution crystal structure in which Mn and R are incorporated into the crystal grains. Furthermore, when La, Sm, or Pr is added, ZrO ２While La, Sm, or Pr tend to be dissolved at higher concentrations near the surface of the crystal grains compared to the interior of the crystal grains, it was confirmed that when Y is added, there are also regions where solid solution is concentrated inside the crystal grains.
[0080] [Initial Activity Evaluation of Catalysts] The combustion reaction of toluene was carried out using the catalysts of the examples and comparative examples. 0.1 cc of organic matter decomposition catalyst 103 was packed into the reaction tube 101 of the organic matter decomposition apparatus 100 shown in Figure 7, heated to a predetermined temperature by heater 102, and air containing 1000 ppm of toluene was introduced from the gas inlet 104 at a flow rate of 580 cc / min. During the test, the gas after the reaction was collected from the reaction gas outlet 105, and the outlet toluene concentration [ppm] was measured by gas chromatography to confirm the toluene decomposition rate according to the following formula: Toluene decomposition rate [%] = (1000 - outlet toluene concentration) / 1000 The test temperature was increased in 10°C increments starting from 200°C, and the temperature at which the toluene decomposition rate reached 90% was defined as the "toluene 90% decomposition temperature". The results are shown in Table 2.
[0081] [SO ２ [Evaluation of catalytic activity after poisoning] SO2 for each catalyst of the examples and comparative examples. ２ Poisoning treatment was carried out using the following method. 0.1 cc of organic decomposition catalyst 103 was packed into the reaction tube 101 of the organic decomposition apparatus 100 shown in Figure 7, heated to a temperature of 600°C by heater 102, and 50 ppm SO4 was introduced from the gas inlet 104. ２ Air containing SO4 was introduced at a flow rate of 580 cc / min and maintained for 2 hours, after which it was cooled. Subsequently, the same method as in "Initial Catalyst Activity Evaluation" was used to evaluate SO4. ２ The "90% toluene decomposition temperature" of the catalyst after poisoning was measured. The results are shown in Table 2.
[0082] [Evaluation of catalyst activity after heating and regeneration] For each catalyst of the examples and comparative examples, "SO ２After poisoning using the same method as in "Evaluation of catalyst activity after poisoning," 0.1 cc of organic matter decomposition catalyst 103 was packed into the reaction tube 101 of the organic matter decomposition apparatus 100 shown in Figure 7. The catalyst was heated to 800°C using a heater 102, and air was introduced from the gas inlet 104 at a flow rate of 580 cc / min. This was maintained for 0.5 hours, after which the temperature was lowered. Subsequently, the "toluene 90% decomposition temperature" of the catalyst after heating and regeneration was measured using the same method as in "Evaluation of initial catalyst activity." The results are shown in Table 2.
[0083] <Example 20> The catalyst from Example 9 was mixed with pebbles, water, and an organic binder, and then crushed to form a catalyst slurry. A cordierite honeycomb (200 cpsi) was immersed in the resulting catalyst slurry for one minute, and then coated with catalyst by blowing air over it. After drying in an oven at 120°C, the honeycomb-coated catalyst of Example 20 was obtained by firing at 800°C for 2 hours. The catalyst coating weight per honeycomb volume was 100 g / L.
[0084] [Characterization of Honeycomb-Coated Catalysts] A 14-cell x 50 mm long honeycomb catalyst for activity evaluation was cut from the honeycomb-coated catalyst of Example 20. Using the same conditions as in Example 9, except that the honeycomb-coated catalyst of Example 20 was used as the organic matter decomposition catalyst 103, the following were performed: [Initial catalyst activity evaluation], [Catalyst activity evaluation after SO2 poisoning], and [Catalyst activity evaluation after heating regeneration]. The results are shown in Table 2.
[0085]
[0086] The organic matter decomposition catalysts of Examples 1 to 19 exhibited higher catalytic activity in their initial stage compared to the organic matter decomposition catalysts of Comparative Examples 1 to 4. Furthermore, they maintained high catalytic activity even after poisoning, and could be regenerated by heating even after poisoning. The organic matter decomposition catalysts of Examples 1 to 19 were composed of zirconium oxide (ZrO2). ２ The crystal structure of the solid solution, in which Mn and R are dispersed within the crystal lattice of ), increases the number of active sites and improves the decomposition performance of organic matter, and also ZrO ２It is presumed that the surface energy of the material changed, inhibiting the growth of crystal grains and improving heat resistance. In particular, the organic matter decomposition catalysts of Examples 1 to 18 showed improved organic matter decomposition performance due to the increased number of active sites caused by the surface dispersion effect of R, as well as ZrO ２ It is presumed that the surface energy changed, inhibiting grain growth and improving heat resistance. When Y was added (Example 19), Y was ZrO ２ By solid dissolution, a cubic or tetragonal crystalline phase, which is a high-temperature phase, is formed, and it is presumed that the surface dispersion effect of R was not sufficiently obtained compared to Examples 1 to 18, resulting in slightly lower catalytic activity. On the other hand, the organic decomposition catalyst of Comparative Example 1 has relatively high initial activity even after heat treatment at 1000°C, but SO ２ Poisoning significantly reduced the decomposition performance, and even at a temperature of 700°C, the toluene decomposition rate did not reach 90%. Furthermore, the catalytic activity of the organic matter decomposition catalyst in Comparative Example 1 did not recover even after heat regeneration treatment at a temperature of 800°C. In the organic matter decomposition catalysts of Comparative Examples 2 and 3, since Mn and Pr are present separately, unlike in Examples 1 to 19, ZrO ２ It does not contain dispersed Mn or R, has few active sites, and also ZrO ２ The growth of the crystal grains was also less suppressed, and as a result, improvements in catalytic activity and heat resistance could not be obtained. Furthermore, even though it was a rare earth element, the organic decomposition catalyst of Comparative Example 4, to which Ce was added, had the same catalytic activity as the organic decomposition catalyst of Comparative Example 2, to which no rare earth elements were added. As mentioned above, the added Ce did not form a complex oxide with Zr or Mn, and CeO ２ It exists in this form, and since the surface dispersion effect as in the examples cannot be obtained, it is presumed that the performance improvement effect was not achieved.
[0087] The initial activity, activity after poisoning, and activity after regeneration of the honeycomb-coated catalyst in Example 20 exhibited similar characteristics to the granular catalyst in Example 9. Furthermore, the honeycomb catalyst made it possible to reduce the pressure loss during the gas flow reaction. While the pressure loss during catalytic activity evaluation of the granular catalyst (Example 9) rose to 6 kPa, the honeycomb-coated catalyst (Example 20) was able to maintain a pressure loss of 1 kPa or less.
[0088] In the description of the embodiments described above, the combinable configurations may be combined with each other.
[0089] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended.
[0090] 1. Tube, 2. Heating section, 3. Control section, 4. 104. Gas inlet, 5. 105. Reaction gas outlet, 6. 103. Organic matter decomposition catalyst, 7. Gas supply pipe, 8. Gas discharge pipe, 10. 100. Organic matter decomposition apparatus, 41. Organic matter supply line, 42. Nitrogen supply line, 43. Oxygen supply line, 51. Sampling line, 101. Reaction tube, 102. Heater.
Claims
1. An organic matter decomposition catalyst for oxidative decomposition of organic matter, comprising a ternary complex oxide containing zirconium, manganese, and a rare earth element, wherein the rare earth element comprises at least one selected from the group consisting of lanthanum, praseodymium, samarium, and yttrium.
2. The organic matter decomposition catalyst according to claim 1, wherein the molar ratio of manganese to zirconium in the organic matter decomposition catalyst is in the range of 0.02 to 0.
40.
3. The organic matter decomposition catalyst according to claim 1, wherein the molar ratio of manganese to zirconium in the organic matter decomposition catalyst is in the range of 0.05 to 0.
40.
4. The organic matter decomposition catalyst according to any one of claims 1 to 3, wherein the molar ratio of rare earth elements to zirconium in the organic matter decomposition catalyst is in the range of 0.01 to 0.
10.
5. The organic matter decomposition catalyst according to any one of claims 1 to 3, wherein the molar ratio of rare earth elements to zirconium in the organic matter decomposition catalyst is in the range of 0.02 to 0.
10.
6. An organic matter decomposition catalyst according to any one of claims 1 to 5, comprising a monoclinic zirconium oxide crystalline phase.
7. A honeycomb structure coated with an organic matter decomposition catalyst according to any one of claims 1 to 6.
8. A method for decomposing organic matter, comprising a decomposition step of oxidatively decomposing the organic matter by heating it using an organic matter decomposition catalyst described in any one of claims 1 to 6.
9. The method for decomposing organic matter according to claim 8, further comprising a regeneration step of restoring catalytic activity of the organic matter decomposition catalyst used in the decomposition step by heating it to a temperature higher than the heating temperature in the decomposition step.
10. An organic matter decomposition apparatus comprising a pipe through which organic matter flows and a heating unit for heating the organic matter flowing through the pipe, wherein the organic matter decomposition catalyst described in any one of claims 1 to 6 is arranged in a region inside the pipe that is heated by the heating unit.