A light rare earth and potassium modified copper-based catalyst, its preparation method and application

Abstract

The present invention discloses a light rare earth and potassium modified copper-based catalyst, its preparation method and application, belonging to the field of catalyst preparation and N2O emission reduction. The light rare earth and potassium modified copper-based catalyst provided by the present invention is K z -Cu / Ce x La 1‑x O2 / Al2O3, which consists of a γ-Al2O3 support loaded with CeO2 and La2O3 and CuO and K loaded on its surface, wherein 0.01 ≤ z ≤ 0.10 and 0.1 ≤ x ≤ 0.9. The preparation method of the catalyst is to use γ-Al2O3 as the support, add CeO2, La2O3 and ammonia water, and prepare Ce x La 1‑x O2 / Al2O3 by solid-phase impregnation method; using copper source and potassium source as precursors, and preparing Ce x La 1‑x O2 / Al2O3 into K z -Cu / Ce x La 1‑x O2 / Al2O3 catalyst. The synthesis method of this catalyst is simple and has excellent performance. When used as an N2O decomposition catalyst, it achieves high decomposition efficiency at low temperature (300-400 °C), and this catalyst has good tolerance to impurity gases (including NO x , O2 and H2O) and thermal stability.

Description

Technical Field

[0001] The present invention belongs to the fields of catalyst preparation and N2O emission reduction, and particularly relates to a light rare earth and potassium modified copper-based catalyst, a preparation method thereof and an application thereof. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and it is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] In recent years, ammonia-hydrogen co-combustion based on on-vehicle hydrogen production for ammonia engines has been widely studied, effectively improving the carbon emission problem. However, due to the incomplete combustion of ammonia, some nitrogen oxides such as N2O (NO x , x = 1, 2) will be generated. Among them, N2O is considered to be one of the six major greenhouse gases, and its global warming potential is about 310 times that of CO2. The Greenhouse Gas Bulletin 2023 released by the World Meteorological Organization shows that the concentration of N2O in the atmosphere has soared from about 270 ppb in 1984 to 335.8 ppb in 2022. Therefore, reducing the emission of N2O is still a challenge. Selective absorption, thermal decomposition, direct catalytic decomposition and selective catalytic reduction technology with a reducing agent are the main methods for removing N2O at present. Among them, the direct catalytic decomposition technology of N2O has good application prospects because of its simple operation, high decomposition efficiency and prevention of secondary pollution.

[0004] The decomposition reaction of N2O has been widely studied. Besides noble metals, light rare-earth elements, due to their special intrinsic physical and chemical properties such as large ionic radii, adjustable 4f electrons, and low redox potentials, and being rich in defective structures, are usually used as carriers to prepare catalysts for the N2O decomposition reaction. In 1996, Tokyo Institute of Technology used Al2O3, Mn2O3, Fe2O3, Co3O4, SiO2, and CeO2 as carriers and loaded noble metals such as Ru, Pt, Pd, and Rh, and found that the Rh / CeO2 catalyst had the best catalytic decomposition performance for N2O. The National Chemical Research Institute of the United States studied the application of nano-CuO / CeO2 materials in the N2O decomposition reaction. By using various catalyst characterization techniques, the effect of terminating CeO2 crystal planes on the behavior of CuO dispersed on CeO2 nanocubes, nanorods, and polyhedral grains was studied in detail. The results showed that CeO2 nanorods loaded with 4 wt% Cu had the best N2O decomposition performance. Al2O3, a metal oxide, is usually studied as a carrier for supported catalysts. Jagiellonian University added glycerol to the solution during the catalyst preparation process and found that the Co3O4 / α-Al2O3 catalyst synthesized with glycerol assistance had excellent N2O decomposition activity compared with the Co3O4 / α-Al2O3 catalyst obtained by aqueous solution impregnation.

[0005] However, although the existing supported catalysts have good N2O decomposition activity, there are also some common bottlenecks, such as low decomposition efficiency in the low-temperature region (300 - 400 °C); many catalysts have poor tolerance to impurity gases. Therefore, it is urgently necessary to provide an N2O decomposition catalyst with good activity and tolerance to impurity gases (O2, NO x and water vapor). Summary of the Invention

[0006] To solve the deficiencies of the prior art, the purpose of the present invention is to provide a light rare-earth and potassium modified copper-based catalyst, its preparation method, and application. The synthesis method of the N2O decomposition catalyst provided by the present invention is simple and has excellent performance, achieving high decomposition efficiency at low temperatures (300 - 400 °C), and the catalyst has good tolerance to impurity gases (including NO x , O2, and H2O) and thermal stability.

[0007] To achieve the above purpose, the technical solution of the present invention is as follows:

[0008] On the one hand, the present invention provides a light rare-earth and potassium modified copper-based catalyst, and the light rare-earth and potassium modified copper-based catalyst is K z -Cu / Ce x La 1-xO2 / Al2O3, which consists of a γ-Al2O3 support loaded with CeO2 and La2O3 and CuO and K loaded on its surface, where 0.01 ≤ z ≤ 0.10 and 0.1 ≤ x ≤ 0.9.

[0009] Preferably, 0.05 ≤ z ≤ 0.10 and 0.3 ≤ x ≤ 0.6.

[0010] Preferably, the morphology of the light rare earth and potassium modified copper-based catalyst is micron granular, and the particle size is 40 - 60 mesh.

[0011] In a second aspect, the present invention provides a method for preparing the above-mentioned light rare earth and potassium modified copper-based catalyst, including the following steps:

[0012] (1) Using γ-Al2O3 as the support, adding CeO2, La2O3 and ammonia water, and preparing Ce x La 1-x O2 / Al2O3 by solid-phase impregnation method;

[0013] (2) Using a copper source and a potassium source as precursors, and preparing K x La 1-x O2 / Al2O3 into a K z -Cu / Ce x La 1-x O2 / Al2O3 catalyst.

[0014] In one or more embodiments, in step (1), the γ-Al2O3 is obtained by calcining Al2O3 in a mixed atmosphere.

[0015] Further, the mixed atmosphere is a H2 / Ar mixed gas, and hydrogen accounts for 5 - 20% of the mixed gas.

[0016] Further, the calcination temperature is 500 - 600 °C, the calcination time is 8 - 12 h, and the heating rate is 3 - 6 °C / min.

[0017] In one or more embodiments, in step (1), for the added CeO2 and La2O3, the Ce:La molar ratio is (0.1 - 0.9):(0.1 - 0.9), preferably (0.3 - 0.6):(0.4 - 0.7), and further preferably (0.4 - 0.5):(0.5 - 0.6).

[0018] In one or more embodiments, in step (1), using γ-Al2O3 as the support, the CeO2 loading is 10 - 30 wt.%, preferably 15 - 25 wt.%; the La2O3 loading is 10 - 30 wt.%, preferably 15 - 25 wt.%.

[0019] In one or more embodiments, in step (1), the concentration of the ammonia water is 25-28 wt.%. The dosage ratio of the ammonia water to γ-Al2O3 is (4-6 mL):(4-5 g).

[0020] In one or more embodiments, in step (1), the specific preparation method of the solid-phase impregnation method is: adding CeO2 and La2O3 into water and mixing, then successively adding γ-Al2O3 and ammonia water, removing moisture, drying and then calcining to obtain Ce x La 1- x O2 / Al2O3.

[0021] Further, using Al2O3 as the carrier, the loading amount of Ce x La 1-x O2 is 10-30 wt.%, preferably 15-25 wt.%.

[0022] Further, the removal of moisture is by water bath evaporation, and the evaporation temperature is 70-90 °C.

[0023] Further, the drying is by baking, the drying temperature is 90-110 °C, and the drying time is 10-14 h.

[0024] Further, the calcination is carried out at a calcination temperature of 350-550 °C, a calcination time of 4-8 h, and a heating rate of 1-4 °C / min.

[0025] In one or more embodiments, in step (2), the copper source is copper citrate and the potassium source is potassium carbonate.

[0026] In one or more embodiments, in step (2), for the K z -Cu / Ce x La 1-x O2 / Al2O3 catalyst, the loading amount of CuO is 10-30 wt.%, preferably 10-20 wt.%, the loading amount of K metal is 0.01-10 wt.%, preferably 0.01-0.10 wt.%, and further preferably 0.05-0.10 wt.%.

[0027] In one or more embodiments, in step (2), using the copper source and the potassium source as precursors, preparing Ce x La 1-x O2 / Al2O3 into a K z -Cu / Ce x La 1-x O2 / Al2O3 catalyst, the specific preparation method is: mixing the copper source, the potassium source and Ce x La 1-xMix with O2 / Al2O3 support, calcine after drying to obtain K z -Cu / Ce x La 1-x O2 / Al2O3 catalyst.

[0028] Furthermore, the mixing is grinding, and the grinding time is 1 - 3 h.

[0029] Furthermore, the drying is drying by baking, the drying temperature is 90 - 110 °C, and the drying time is 10 - 14 h.

[0030] Furthermore, the calcination is carried out at a calcination temperature of 550 - 650 °C, a calcination time of 4 - 8 h, and a heating rate of 1 - 4 °C / min.

[0031] In a third aspect, the present invention provides the application of the above-mentioned light rare earth and potassium modified copper-based catalyst in the decomposition of N2O.

[0032] In a fourth aspect, the present invention provides a method for low-temperature catalytic decomposition of N2O, which uses the above-mentioned light rare earth and potassium modified copper-based catalyst, and includes the following steps: carried out in a fixed-bed reactor, adding the above-mentioned K z -Cu / Ce x La 1-x O2 / Al2O3 catalyst into a quartz tube reactor, introducing N2O, and carrying out decomposition under the condition of 300 °C to 400 °C.

[0033] Preferably, the low temperature is 350 °C to 400 °C.

[0034] The principle of the present invention is as follows: The present invention provides a light rare earth and potassium modified copper-based catalyst for low-temperature catalytic decomposition of N2O. Under the promotion of ammonia water, rare earth oxides CeO2 and La2O3 are loaded on the γ-Al2O3 support. On the Ce x La 1-x O2 / Al2O3 support with different Ce / La molar ratios, CuO and metal K ions with different impregnation amounts are loaded by solid-phase impregnation method. Due to the characteristics of rare earth elements such as large ionic radius, adjustable 4f electrons, low redox potential and rich defect structure, and the unique chemisorption properties of transition metal-based oxides, that is, the existence of partially filled d shells of metal ions, there is a strong electronic interaction between the Ce x La 1- x O2 / Al2O3 support and CuO, thereby improving its N2O decomposition performance. The incorporation of alkali metal K improves the basicity of the catalyst, thereby further promoting the decomposition performance of the catalyst.

[0035] A specific implementation process of the present invention is as follows: First, put Al2O3 into a tubular furnace, introduce a 10% H2 / Ar mixed gas, and heat it to 550 °C at a heating rate of 5 °C / min for 10 h. Mark the treated Al2O3 support obtained as γ-Al2O3. Prepare the Ce x La 1-x O2 / Al2O3 support by the impregnation method, that is, dissolve a certain amount of cerium acetate and lanthanum acetate in deionized water, stir for 1 h, add γ-Al2O3, stir for 1 h, add 5 mL of concentrated ammonia water (25-28 wt.%), and continue to stir for 1 h. Then evaporate to dryness in a water bath at 80 °C. Dry in an oven at 90-110 °C for 12 h. Calcinate in a muffle furnace at 350-550 °C for 4-8 h, with a heating rate of 2 °C / min. Prepare the Cu / Ce x La 1-x O2 / Al2O3 catalyst by the solid-phase impregnation method, using copper citrate as the precursor and the CuO loading being 15 wt.%. Grind copper citrate and Ce x La 1-x O2 / Al2O3 support together for 2 h, then dry in an oven at 90-110 °C for 12 h. Calcinate in a muffle furnace at 550-650 °C for 4-8 h, with a heating rate of 2 °C / min. Prepare the K z -Cu / Ce x La 1-x O2 / Al2O3 catalyst by the solid-phase impregnation method, using potassium carbonate and copper citrate as the precursors, the CuO loading being 15 wt.%, and the masses of K metal being 0.01 wt.%, 0.03 wt.%, 0.05 wt.%, 0.08 wt.%, and 0.10 wt.% respectively. Grind copper citrate, potassium carbonate and Ce x La 1-x O2 / Al2O3 support together for 2 h, then dry in an oven at 90-110 °C for 12 h. Calcinate in a muffle furnace at 550-650 °C for 4-8 h, with a heating rate of 2 °C / min.

[0036] One or some of the above technical solutions have the following advantages or beneficial effects:

[0037] (1) The K z -Cu / Ce x La 1-x O2 / Al2O3 catalyst provided by the present invention, due to the strong electronic interaction between the Ce x La 1-x O2 / Al2O3 support and CuO, and the incorporation of the alkali metal K improving the basicity of the catalyst, thus promoting the decomposition performance of the catalyst and achieving excellent catalytic N2O decomposition performance at low temperatures (300-400 °C).

[0038] (2) The K z -Cu / Ce x La 1-x O2 / Al2O3 catalyst provided by the present invention has excellent N2O decomposition performance at low temperature (300 - 400 °C) when used as an N2O decomposition catalyst, strong tolerance to impurity gases (including NO x , O2 and H2O), and good thermal stability. When O2, NO x and H2O are introduced at 450 °C, its N2O decomposition efficiency only drops from 100% to 98%; especially at 375 °C, when the three impurity gases coexist, the N2O decomposition efficiency of the catalyst can still reach more than 75%.

[0039] (3) The K z -Cu / Ce x La 1-x O2 / Al2O3 catalyst provided by the present invention has a simple synthesis method, a short cycle, and the required raw materials are simple, easy to obtain, and inexpensive. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0041] Figure 1 It shows the N2O decomposition reaction activity varying with temperature of the Cu / Al2O3, Cu / Ce / Al2O3, Cu / La / Al2O3 catalysts prepared in the examples of the present invention and the Cu / Ce x La 1-x / Al2O3 catalysts with different Ce / La molar ratios;

[0042] Figure 2 It shows the N2O decomposition reaction activity varying with temperature of the Cu / CeLa / Al2O3 catalysts with different K ion impregnation amounts in the examples of the present invention;

[0043] Figure 3 It shows the O2 + NO 0.05 -Cu / Ce 0.5 La 0.5 / Al2O3 catalyst at 375 °C, 400 °C, 425 °C and 450 °C in the O2 + NO x +H2O tolerance test results;

[0044] Figure 4 It shows the N2O reaction activity diagram varying with temperature of the K z / Ce x La 1-x O2 / Al2O3 catalyst in Comparative Example 1 of the present invention;

[0045] Figure 5 It is the N2O reaction activity diagram of the traditional Fe-ZSM-5 catalyst with temperature change in Comparative Example 2 of the present invention;

[0046] Figure 6 It is Cu / Al2O3, K prepared in the examples of the present invention z -Cu / Al2O3 and K with different Ce / La molar ratios z -Cu / Ce x La 1-x XRD spectra of O2 / Al2O3 catalysts;

[0047] Figure 7 It is K prepared in the examples of the present invention 0.08 -Cu / CeO2 / Al2O3, K 0.08 -Cu / La2O3 / Al2O3, K 0.08 -Cu / Ce 0.7 La 0.3 O2 / Al2O3, K 0.08 -Cu / Ce 0.5 La 0.5 SEM images of O2 / Al2O3 catalysts at different magnifications; among them, (A)-(D) are K 0.08 -Cu / CeO2 / Al2O3, K 0.08 -Cu / La2O3 / Al2O3, K 0.08 -Cu / Ce 0.7 La 0.3 O2 / Al2O3, K 0.08 -Cu / Ce 0.5 La 0.5 O2 / Al2O3, (A1) is the detailed enlarged view of (A), (B1) is the detailed enlarged view of (B), (C1) is the detailed enlarged view of (C), and (D1) is the detailed enlarged view of (D);

[0048] Figure 8 It is K prepared in the examples of the present invention 0.08 -Cu / Ce 0.3 La 0.7 O2 / Al2O3, K 0.08 SEM images of O2 / Al2O3, K 0.08 -Cu / Ce 0.3 La 0.7 O2 / Al2O3, K 0.08-Cu / Al2O3, Cu / Al2O3, (E1) is the detailed enlarged view of (E), (F1) is the detailed enlarged view of (F), and (G1) is the detailed enlarged view of (G);

[0049] Figure 9 K prepared in the embodiment of the present invention 0.08 -Cu / CeO2 / Al2O3, K 0.08 -Cu / La2O3 / Al2O3, K 0.08 -Cu / Ce 0.7 La 0.3 EDX-Mapping images of the O2 / Al2O3 catalyst; among them, (A)-(C) are K in sequence 0.08 -Cu / CeO2 / Al2O3, K 0.08 -Cu / La2O3 / Al2O3, K 0.08 -Cu / Ce 0.7 La 0.3 O2 / Al2O3;

[0050] Figure 10 K prepared in the embodiment of the present invention 0.08 -Cu / Ce 0.5 La 0.5 O2 / Al2O3, K 0.08 -Cu / Ce 0.3 La 0.7 O2 / Al2O3, K 0.08 EDX-Mapping images of the -Cu / Al2O3 catalyst; among them, (D)-(F) are K in sequence 0.08 -Cu / Ce 0.5 La 0.5 O2 / Al2O3, K 0.08 -Cu / Ce 0.3 La 0.7 O2 / Al2O3, K 0.08 -Cu / Al2O3;

[0051] Figure 11 EDX-Mapping images of the Cu / Al2O3 catalyst prepared in the embodiment of the present invention. Detailed implementation mode

[0052] Cu / Ce 0.5 La 0.5 / Al2O3 catalyst can be abbreviated as Cu / CeLa / Al2O3.

[0053] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific embodiments.

[0054] Example 1 Pretreatment of the carrier Al2O3

[0055] Put 50 g of Al2O3 into a tubular furnace, introduce a 10% H2 / Ar mixed gas, and heat it to 550 °C at a heating rate of 5 °C / min for 10 h. Mark the treated Al2O3 carrier obtained as γ-Al2O3.

[0056] Example 2 Preparation of CeO2 / Al2O3 carrier

[0057] Dissolve 3.02 g of cerium acetate in 6 ml of deionized water. After stirring for 1 h, add 4.8 g of γ-Al2O3 obtained from the treatment in Example 1. After stirring for 1 h, add 5 mL of concentrated ammonia water (26 wt.%). Continue stirring for 1 h. Then evaporate to dryness in a water bath at 80 °C and dry in an oven at 110 °C for 12 h. Calcinate the obtained sample in a muffle furnace at a heating rate of 2 °C / min to 550 °C for 4 h. Mark the obtained carrier as CeO2 / Al2O3. The CeO2 loading is 20 wt.%.

[0058] Example 3 Preparation of La2O3 / Al2O3 carrier

[0059] Dissolve 1.59 g of lanthanum acetate in 6 ml of deionized water. After stirring for 1 h, add 4.8 g of γ-Al2O3 obtained from the treatment in Example 1. After stirring for 1 h, add 5 mL of concentrated ammonia water (26 wt.%). Continue stirring for 1 h. Then evaporate to dryness in a water bath at 80 °C and dry in an oven at 110 °C for 12 h. Calcinate the obtained sample in a muffle furnace at a heating rate of 2 °C / min to 550 °C for 4 h. Mark the obtained carrier as La2O3 / Al2O3. The La2O3 loading is 20 wt.%.

[0060] Example 4 Preparation of Ce x La 1-x O2 / Al2O3 carriers with different Ce / La molar ratios

[0061] Dissolve lanthanum acetate and cerium acetate in 6 ml of deionized water. After stirring for 1 h, add γ-Al2O3 obtained from the treatment in Example 1. After stirring for 1 h, add 5 mL of concentrated ammonia water (25 - 28 wt.%). Continue stirring for 1 h. Then evaporate to dryness in a water bath at 80 °C and dry in an oven at 110 °C for 12 h. Calcinate the obtained sample in a muffle furnace at a heating rate of 2 °C / min to 550 °C for 4 h. Mark the obtained carrier as Ce x La 1-x O2 / Al2O3 (0 ≤ x ≤ 1). The Ce x La 1-x O2 loading is 20 wt.%.

[0062] Example 5 Preparation of copper oxide-containing catalyst

[0063] Prepare Cu / Ce by solid-phase impregnation method x La 1-x O2 / Al2O3 catalyst, using copper citrate as the precursor and the CuO loading is 15 wt.%. Specifically, grind copper citrate with γ-Al2O3 in Example 1, CeO2 / Al2O3 in Example 2, La2O3 / Al2O3 in Example 3, and Ce x La 1-x O2 / Al2O3 support together for 2 h, and dry in an oven at 110 °C for 12 h. Heat the obtained sample in a muffle furnace to 650 °C at a heating rate of 2 °C / min and calcine for 4 h.

[0064] Preparation of potassium-doped copper oxide catalyst in Example 6

[0065] Prepare K z -Cu / Ce x La 1-x O2 / Al2O3 catalyst, using potassium carbonate and copper citrate as the precursors, the CuO loading is 15 wt.%, and the masses of K metal (0 ≤ z ≤ 0.1) are 0 wt.%, 0.01 wt.%, 0.03 wt.%, 0.05 wt.%, 0.08 wt.%, and 0.10 wt.% respectively. Grind copper citrate, potassium carbonate and Ce x La 1-x O2 / Al2O3 support together for 2 h, and dry in an oven at 110 °C for 12 h. Heat the obtained sample in a muffle furnace to 650 °C at a heating rate of 2 °C / min and calcine for 4 h to obtain K z -Cu / Ce x La 1-x O2 / Al2O3 catalyst.

[0066] Comparative Example 1

[0067] Different from Example 6, prepare a catalyst without copper element, that is, K z / Ce x La 1-x O2 / Al2O3 catalyst.

[0068] (1) Using γ-Al2O3 as the support, adding CeO2, La2O3 and ammonia water, prepare Ce x La 1-x O2 / Al2O3 support;

[0069] (2) Using the potassium source as the precursor, prepare Ce x La 1-x O2 / Al2O3 into K z / Ce x La 1-x K-O2 / Al2O3 catalyst.

[0070] Figure 4 is K z / Ce x La 1-x N2O reaction activity diagram of K-O2 / Al2O3 catalyst varying with temperature, K z / Ce x La 1-x K-O2 / Al2O3 includes K 0.08 / Ce 0.7 La 0.3 K-O2 / Al2O3, K 0.08 / Ce 0.3 La 0.7 K-O2 / Al2O3 and K 0.08 / Ce 0.5 La 0.5 K-O2 / Al2O3.

[0071] Comparative Example 2

[0072] Using the room temperature ion exchange method, H-ZSM-5 (Si:Al = 300) was added to 10 mL of 0.012 g / mL Fe(NO3)3 solution, stirred at room temperature for 12 h, washed, centrifuged, dried at 110 °C for 12 h, and the precursor material was calcined in air at 550 °C for 4 h to prepare the Fe-ZSM-5 catalyst.

[0073] Figure 5 is the N2O reaction activity diagram of the traditional Fe-ZSM-5 catalyst varying with temperature.

[0074] Figure 6 is the XRD pattern of the potassium-doped copper oxide catalyst prepared in Example 6, all showing the corresponding diffraction peaks of CuO, and no diffraction peaks caused by species such as cerium oxide and lanthanum oxide were detected, which may be due to the low doping amount of Ce or La or their uniform dispersion.

[0075] Figures 7 - 8 are SEM images of Cu / Al2O3, K z -Cu / Al2O3 and K with different Ce / La molar ratios z -Cu / Ce x La 1-x O2 / Al2O3 catalysts at different magnifications; among them, (A)-(G) are K 0.08 -Cu / CeO2 / Al2O3, K 0.08 -Cu / La2O3 / Al2O3, K 0.08 -Cu / Ce 0.7 La0.3 O2 / Al2O3, K 0.08 -Cu / Ce 0.5 La 0.5 O2 / Al2O3, K 0.08 -Cu / Ce 0.3 La 0.7 O2 / Al2O3, K 0.08 -Cu / Al2O3, Cu / Al2O3. (A1) is the detailed enlarged view of (A), (B1) is the detailed enlarged view of (B), (C1) is the detailed enlarged view of (C), (D1) is the detailed enlarged view of (D), (E1) is the detailed enlarged view of (E), (F1) is the detailed enlarged view of (F), (G1) is the detailed enlarged view of (G).

[0076] Figures 9 - 11 is Cu / Al2O3, K z -Cu / Al2O3 and K with different Ce / La molar ratios z -Cu / Ce x La 1-x EDX-Mapping images of O2 / Al2O3 catalyst; among them, (A)-(G) are K in turn 0.08 -Cu / CeO2 / Al2O3, K 0.08 -Cu / La2O3 / Al2O3, K 0.08 -Cu / Ce 0.7 La 0.3 O2 / Al2O3, K 0.08 -Cu / Ce 0.5 La 0.5 O2 / Al2O3, K 0.08 -Cu / Ce 0.3 La 0.7 O2 / Al2O3, K 0.08 -Cu / Al2O3, Cu / Al2O3.

[0077] The results show that the obtained K z -Cu / Ce x La 1-x The O2 / Al2O3 catalyst is in the form of micron-sized particles, and elements such as Ce, La, Al, O, Cu, and K are evenly dispersed.

[0078] Test on the N2O decomposition reaction activity of the catalyst in Application Example 1

[0079] Press 200 mg of the required catalyst into tablets and make fine particles (sized 40 - 60 mesh). Subsequently, add a small amount of quartz wool into the fixed-bed reactor, place the catalyst above the quartz wool, and then fill a small amount of quartz wool above the catalyst particles. Adjust the concentration of the reaction gas component N2O to 5000 ppm, and keep the total gas flow rate at 100 mL·min -1 , with a gas hourly space velocity of 30000 mL·g -1 ·h -1 . Conduct tests through Gasmate. Before the test, switch the reaction gas to directly enter the detection system without passing through the sample tube to ensure whether the configured gas concentration reaches the set value. Subsequently, switch the reaction gas back to make it pass through the fixed-bed reactor and through the catalyst to be tested. Finally, set the heating control program with a heating rate of 5℃·min -1 , keep the temperature constant for 0.5 h at each temperature point, and use infrared to detect the components of the outlet tail gas in real time.

[0080] Application Example 2 Test on the tolerance of the catalyst to O2 + NO x +H2O during the N2O decomposition reaction

[0081] Press 200 mg of the required catalyst into tablets and make fine particles (sized 40 - 60 mesh). Subsequently, add a small amount of quartz wool into the fixed-bed reactor, place the catalyst above the quartz wool, and then fill a small amount of quartz wool above the catalyst particles. Adjust the concentrations of the reaction gas components N2O, NO x , O2, and H2O to 5000 ppm, 1000 ppm, 5 vol%, and 10 vol% respectively, and keep the total gas flow rate at 100 mL·min -1 , with a gas hourly space velocity of 30000 mL·g -1 ·h -1 . Introduce NO x , O2, and H2O at the 5th hour of the reaction. Before the test, switch the reaction gas to directly enter the detection system without passing through the sample tube to ensure whether the configured gas concentration reaches the set value. Subsequently, switch the reaction gas back to make it pass through the fixed-bed reactor and through the catalyst to be tested. Finally, set the reaction temperatures to 375℃, 400℃, 425℃, and 450℃ respectively, and the test duration is 45 h.

[0082] Figure 1 For Cu / Al2O3, Cu / Ce / Al2O3, Cu / La / Al2O3 catalysts and Cu / Ce with different Ce / La molar ratios x La 1-xN2O decomposition reaction activity of Cu / Al2O3 catalysts varying with temperature. Cu / Al2O3 has almost no decomposition activity below 500 °C, Cu / Ce / Al2O3 starts to have decomposition activity at 425 °C, and Cu / La / Al2O3 starts to have decomposition activity at 400 °C. Cu / Ce x La 1-x / Al2O3 catalysts have good decomposition activity, especially Cu / Ce 0.5 La 0.5 O2 / Al2O3 catalysts, where its T 10 (temperature when the N2O decomposition efficiency reaches 10%), T 50 (temperature when the N2O decomposition efficiency reaches 50%), and T 90 (temperature when the N2O decomposition efficiency reaches 90%) are 325 °C, 375 °C, and 425 °C respectively.

[0083] Figure 2 For Cu / Ce 0.5 La 0.5 / Al2O3 catalysts (abbreviated as K-Cu / CeLa / Al2O3) with varying N2O decomposition reaction activity with temperature. The catalytic activity of Cu / Ce 0.5 La 0.5 / Al2O3 catalysts doped with K is significantly improved. With the increase in K doping amount, the N2O decomposition activity of the catalyst shows a volcano-shaped trend, and the best activity is shown by K 0.05 -Cu / Ce 0.5 La 0.5 O 2 / Al2O3 catalysts, where its T 10 、T 50 and T 90 are 250 °C, 300 °C, and 350 °C respectively.

[0084] Figure 3 For K 0.05 -Cu / Ce 0.5 La 0.5 / Al2O3 catalysts for O2+NO x +H2O tolerance test results at 375 °C, 400 °C, 425 °C, and 450 °C. K 0.05 -Cu / Ce 0.5 La 0.5 / Al2O3 catalysts have good tolerance to impurity gases at several temperature points. At 375 °C, after introducing O2, NO x and H2O, its N2O decomposition activity drops to about 77%. With the increase in temperature, the tolerance of the catalyst to impurity gases improves. At 450 °C, after introducing O2, NO xAfter [substance] and H2O, the N2O decomposition efficiency only drops from 100% to 98%. This indicates that this K 0.05 -Cu / Ce 0.5 La 0.5 / Al2O3 catalyst has very excellent impurity gas tolerance.

[0085] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Application of a light rare earth and potassium modified copper-based catalyst in catalytic decomposition of N2O, characterized in that, The light rare earth and potassium modified copper-based catalyst is K z -Cu / Ce x La 1-x O2 / Al2O3, which consists of a γ-Al2O3 support loaded with CeO2 and La2O3 and CuO and K loaded on its surface, where 0.01 ≤ z ≤ 0.10 and 0.3 ≤ x ≤ 0.6; decomposition is carried out under the condition of 300 °C to 400 °C; The preparation method of the catalyst comprises the following steps: Preparation of Ce by impregnation method x La 1-x O2 / Al2O3 carrier, that is, a certain amount of cerium acetate and lanthanum acetate are dissolved in deionized water, stirred for 1 hour, and then γ-Al2O3 is added. After stirring for 1 hour, 5 mL of 25-28 wt.% concentrated ammonia water is added, and stirring is continued for 1 hour, and then evaporated to dryness in a water bath at 80°C, dried in an oven at 90-110°C for 12 hours, and calcined in a muffle furnace at 350-550°C for 4-8 hours, with a heating rate of 2°C / min; K is prepared by solid phase impregnation method z -Cu / Ce x La 1-x O2 / Al2O3 catalyst, with potassium carbonate and copper citrate as precursors, CuO loading is 10~30wt.%, copper citrate, potassium carbonate and Ce x La 1-x The O2 / Al2O3 carriers were ground together for 1~3 h, then dried in an oven at 90~110°C for 10~14 h, and calcined in a muffle furnace at 550~650°C for 4~8 h, with a heating rate of 1~4°C / min.

2. The application according to claim 1, wherein 0.05 ≤ z ≤ 0.10, and the particle size of the light rare earth and potassium modified copper-based catalyst is 40 to 60 mesh.

3. A method for low-temperature catalytic decomposition of N2O by a light rare earth and potassium modified copper-based catalyst, characterized in that, The light rare earth- and potassium-modified copper-based catalyst is K z -Cu / Ce x La 1-x O2 / Al2O3, which consists of a γ-Al2O3 support loaded with CeO2 and La2O3 and CuO and K loaded on its surface, where 0.01 ≤ z ≤ 0.10 and 0.3 ≤ x ≤ 0.6; The preparation method of the catalyst comprises the following steps: Ce was prepared by the impregnation method x La 1-x O2 / Al2O3 support, that is, a certain amount of cerium acetate and lanthanum acetate were dissolved in deionized water. After stirring for 1 h, γ-Al2O3 was added. After stirring for 1 h, 5 mL of 25-28 wt.% concentrated ammonia water was added, and stirring was continued for 1 h. Then it was evaporated to dryness in a water bath at 80 °C and dried in an oven at 90-110 °C for 12 h, and calcined in a muffle furnace at 350-550 °C for 4-8 h with a heating rate of 2 °C / min; K was prepared by the solid-phase impregnation method z -Cu / Ce x La 1-x O2 / Al2O3 catalyst, using potassium carbonate and copper citrate as precursors, the loading amount of CuO was 10-30 wt.%. Copper citrate, potassium carbonate and Ce x La 1-x O2 / Al2O3 support were ground together for 1-3 h, then dried in an oven at 90-110 °C for 10-14 h, and calcined in a muffle furnace at 550-650 °C for 4-8 h with a heating rate of 1-4 °C / min; The method for decomposing N2O comprises the following steps: It is carried out in a fixed-bed reactor. K is added to a quartz tube reactor. z -Cu / Ce x La 1-x O2 / Al2O3 catalyst, N2O is introduced, and the decomposition is carried out at 300 °C to 400 °C.

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