A method for removing NO x Preparation method of multifunctional catalysts for CO and HC

Abstract

A method for removing NO x A method for preparing a multifunctional catalyst for CO and HC. The key feature is the preparation of FeCeO₂ via a hydrothermal method. x Micron-sized spherical particles were then coated with a layer of ZrWSnO on the catalyst surface using a microparticle enrichment method. x The outer shell is used to construct a core-shell structure with separate dual active sites, thereby achieving NO... x Simultaneous removal of CO and HC. The advantage of this invention lies in the ability to adjust the thickness of the zirconium-tungsten-tin composite oxide shell on the catalyst by adding a pH adjuster to regulate the pH value and reaction temperature, enabling the simultaneous removal of ZrWSnO from catalysts with particle sizes of 20–3000 nm. x The core-shell structure is encapsulated, and the shell thickness can be controlled from 0 to 300 nm. The preparation method of this invention is simple, requires no expensive equipment, and has low production costs. The resulting multifunctional catalyst with a core-shell structure exhibits superior catalytic performance and resistance to poisoning compared to traditional multifunctional catalysts.

Description

Technical Field

[0001] This invention provides a method for removing NO x The preparation method of multifunctional catalysts for CO and HC belongs to the field of environmental catalytic materials and air pollution control, and is particularly suitable for high-temperature synergistic catalysis of NO in gas exhaust gas. x CO and HC. Technical Background

[0002] Because fuel gases (such as natural gas and coal gas) have a higher calorific value than coal, and the exhaust gas purification space is limited, the exhaust gas temperature generated by their combustion is excessively high (450-650℃). Existing multifunctional catalysts suffer from drawbacks such as poor high-temperature activity and a narrow temperature window. Patent (CN108940299A) discloses a Ti-Si-O catalyst... x VWMO is supported by composite oxides. x While the catalyst prepared using this active component exhibits good thermal stability, its active temperature range is narrow, limited to 250-340℃. Patent (CN116786110A) developed a praseodymium manganese perovskite catalyst, which shows good removal efficiency for NO and HC at low temperatures but is unusable at high temperatures (450-650℃). The removal of NO under high-temperature (450-650℃) conditions... x There is limited research on the preparation methods of multifunctional catalysts for NO, CO, and HC. The preparation method of this invention is simple, requires no expensive equipment, and has low production costs. The resulting multifunctional catalyst with a core-shell structure exhibits superior catalytic activity and resistance to poisoning compared to traditional multifunctional catalysts. Based on these reasons, a method for removing NO is being researched and developed. x The preparation method of multifunctional catalysts for CO and HC has significant economic and application value. Summary of the Invention

[0003] The purpose of this invention is to develop a method for removing NO. x This paper proposes a method for preparing a multifunctional catalyst for NO, CO, and HC, aiming to address the problems of existing high-temperature denitrification catalysts, such as narrow activity temperature range, high cost, and poor stability against water and sulfur poisoning. x Preparation method of multifunctional catalysts for CO and HC.

[0004] The specific technical solution of this invention is: a method for removing NO x A method for preparing a multifunctional catalyst for CO and HC, characterized by preparing FeCeO by a hydrothermal method. x Micron-sized spherical particles were then coated with a layer of ZrWSnO on the catalyst surface using a microparticle enrichment method. x The outer shell is used to construct a core-shell structure with separate dual active sites, thereby achieving NO... x Simultaneous removal of CO and HC. The specific steps are as follows:

[0005] (1) Micron-sized spherical FeCeO x Preparation

[0006] According to a glycerol / isopropanol volume ratio of 1:(5-7), a certain amount of glycerol and isopropanol were weighed and placed in the same container and stirred evenly to obtain a transparent and homogeneous solution A. According to a Fe / Ce element molar ratio of 1:(2-8), a certain amount of iron salt and cerium salt were weighed. The weighed iron salt and cerium nitrate were added to solution A and stirred continuously for 1-2 hours to obtain a mixed solution B. Solution B was then transferred to a reaction vessel for hydrothermal reaction. The product after reaction was centrifuged, washed, dried, and calcined to obtain micron-sized spherical FeCeO₂. x Powder;

[0007] (2) Preparation of core-shell catalysts

[0008] FeCeO x The powder and surface modifier were dispersed in deionized water and ultrasonically treated to obtain solution C. Ammonium metatungstate, zirconium oxychloride, and tin tetrachloride were dissolved in solution C and ultrasonically treated to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred while adding a pH adjuster dropwise to make the solution weakly alkaline. After pH adjustment, the solution was magnetically stirred for 2–6 hours to obtain a flocculent product. The product was centrifuged, washed, dried, and calcined to obtain FeCeO₂. x @ZrWSnO x Multifunctional catalyst.

[0009] The preferred hydrothermal reaction temperature in step (1) is 140–180°C, the reaction time is 8–12 h; the drying temperature is 60–80°C, the drying time is 6–12 h; the calcination temperature is 600–700°C, and the holding time is 2–4 h.

[0010] The preferred cerium salt in step (1) is cerium nitrate, cerium carbonate, or cerium sulfate; the iron salt is ferric nitrate.

[0011] The preferred pH adjuster in step (2) is an aqueous solution of ammonium carbonate, ammonia, or sodium hydroxide; the pH of the solution is adjusted to 7.8–8.4; and the surface modifier is cetyltrimethylammonium bromide (CTAB).

[0012] In preferred step (2), the temperature of the temperature-controlled stirrer is 60-90℃; the drying temperature is 60-80℃, the drying time is 6-12h; the calcination temperature is 600-700℃, and the holding time is 2-4h.

[0013] In preferred step (2), FeCeO xThe mass ratio of ammonium metatungstate to surface modifier is 1:(0.1-1); the molar ratio of Zr, W, and Sn in ammonium metatungstate, zirconium oxychloride, and tin tetrachloride is 1:(0.5-3):(0.1-1); ammonium metatungstate, zirconium oxychloride, and tin tetrachloride are dissolved in solution C to control FeCeO x The powder and ammonium metatungstate are added at a mass ratio of 1:(0.1-1).

[0014] The present invention is characterized by preparing FeCeO by a hydrothermal method. x Spherical particles were then coated with a layer of ZrWSnO on the catalyst surface using a microparticle enrichment method. x The outer shell is used to construct a core-shell structure with separate dual active sites, thereby achieving NO... x Simultaneous removal of CO and HC. The molar ratio of Zr, W, and Sn is 1:(0.5–3):(0.1–1). The thickness of the catalyst-coated zirconium-tungsten-tin composite oxide shell is controllable by adjusting the pH value and reaction temperature through the addition of a pH adjuster.

[0015] Beneficial effects:

[0016] Especially suitable for high-temperature co-catalytic NO reduction in gas exhaust. x The catalyst removes NO, CO, and HC with a denitrification efficiency >90% and reaching up to 100% within the temperature range of 400-625℃; N2 selectivity >95%; CO removal efficiency >90% within the temperature range of 450-500℃; CH4 removal efficiency >90% within the temperature range of 400-475℃; and exhibits strong resistance to water and sulfur poisoning. This preparation method achieves controllable thickness of the zirconium-tungsten-tin composite oxide shell by adjusting the pH value and reaction temperature through the addition of a pH adjuster. The core-shell structure enables the separation of active sites on the catalyst surface, achieving simultaneous removal of NO. x The purpose is to obtain CO and HC. Compared with existing multifunctional catalysts, the preparation method of this invention is simple, requires no expensive equipment, and has low production cost; the multifunctional catalyst with a core-shell structure prepared has superior catalytic properties and anti-poisoning ability compared with traditional multifunctional catalysts. Attached Figure Description

[0017] Figure 1 Example 1: FeCeO x @ZrWSnO x TEM image of a multifunctional core-shell catalyst. Detailed Implementation

[0018] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto.

[0019] The denitrification performance evaluation method of the catalyst of this invention is as follows: Simulating the composition of exhaust gas, the inlet concentrations are: NO 1000 ppm, NH3 1000 ppm, CO 1000 ppm, CH4 1000 ppm, O2 content 10%, SO2 200 ppm (added during use), and H2O 5 vol.% (added during use), with N2 as the carrier gas. NO removal is carried out in a fixed-bed reaction system. x The synergistic catalytic reaction of CO and CH4, with a catalyst particle size of 20-40 mesh, and a set reaction space velocity (GHSV) of 30,000 h⁻¹. -1 The reaction temperature range was set at 350–650℃, and NO was monitored online before and after the reaction using a flue gas analyzer. x Changes in the concentrations of CO and CH4.

[0020] Example 1:

[0021] (1) Micron-sized spherical FeCeO x Preparation

[0022] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 2.605 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 10 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 600 °C for 2 h to obtain micron-sized spherical FeCeO. x Powder.

[0023] (2) Preparation of core-shell catalysts

[0024] 0.6g FeCeO x The powder and 0.06 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.322 g of zirconium oxychloride, and 0.175 g of tin tetrachloride pentahydrate (molar ratio of Zr, W, and Sn: 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. Ammonium carbonate aqueous solution was added dropwise while stirring to adjust the pH to 8.0. After pH adjustment, the solution was magnetically stirred for 2 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 650 °C for 2 h to obtain a multifunctional core-shell catalyst. TEM images of the prepared FeCeOx@ZrWSnOx multifunctional core-shell catalyst are shown below. Figure 1 As shown.

[0025] (3) Catalyst performance evaluation

[0026] The catalyst of this invention exhibits NO removal efficiency >90% and N2 selectivity >90% with NH3-SCR at 400-600℃, and 100% denitrification efficiency at 500-550℃; CO removal efficiency >90% at 450-500℃; and CH4 removal efficiency >90% at 400-475℃.

[0027] Example 2:

[0028] (1) Micron-sized spherical FeCeO x Preparation

[0029] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 2.605 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 10 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 600 °C for 2 h to obtain micron-sized spherical FeCeO. x Powder.

[0030] (2) Preparation of core-shell catalysts

[0031] 0.6g FeCeO x The powder and 0.3 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.322 g of zirconium oxychloride, and 0.175 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. While stirring, a saturated aqueous solution of ammonium carbonate was added dropwise to adjust the pH to 8.0. After adjusting the pH, the solution was stirred vigorously for 3 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 650 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0032] (3) Catalyst performance evaluation

[0033] The catalyst of this invention exhibits NO removal efficiency >90% and N2 selectivity >90% with NH3-SCR at 400-600℃, and 100% denitrification efficiency at 500-550℃; CO removal efficiency >90% at 450-500℃; and CH4 removal efficiency >90% at 400-475℃.

[0034] Example 3:

[0035] (1) Micron-sized spherical FeCeO x Preparation

[0036] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 2.605 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 10 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 650 °C for 2 h to obtain porous spherical FeCeO. x Powder.

[0037] (2) Preparation of core-shell catalysts

[0038] 0.6g FeCeO x The powder and 0.6 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.322 g of zirconium oxychloride, and 0.175 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. While stirring, an aqueous solution of ammonium carbonate was added dropwise to adjust the pH to 8.0. After adjusting the pH, the solution was magnetically stirred for 4 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 600 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0039] (3) Catalyst performance evaluation

[0040] The catalyst of this invention exhibits NO removal efficiency >90% and N2 selectivity >90% with NH3-SCR at 400-600℃, and 100% denitrification efficiency at 500-550℃; CO removal efficiency >90% at 450-500℃; and CH4 removal efficiency >90% at 400-500℃.

[0041] Example 4:

[0042] (1) Micron-sized spherical FeCeO x Preparation

[0043] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir well to obtain a transparent and homogeneous solution A; according to a Fe / Ce element molar ratio of 1:2, weigh out 0.606 g of ferric nitrate (nonahydrate) and 1.303 g of cerium nitrate; add the weighed ferric nitrate and cerium nitrate to solution A, and stir continuously for 1 h to obtain a mixed solution B; then transfer solution B to a reaction vessel and hydrothermally react at 140 °C for 10 h, centrifuge and wash the product after reaction, dry at 80 °C for 6 h, and calcine at 600 °C for 2 h to obtain porous spherical FeCeO x Powder.

[0044] (2) Preparation of core-shell catalysts

[0045] 0.6g FeCeO x The powder and 0.3 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.322 g of zirconium oxychloride, and 0.175 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. While stirring, an aqueous solution of ammonium carbonate was added dropwise to adjust the pH to 8.0. After adjusting the pH, the solution was magnetically stirred for 5 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 650 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0046] (3) Catalyst performance evaluation

[0047] The catalyst of this invention exhibits NO removal efficiency >90% and N2 selectivity >90% with NH3-SCR at 400-600℃, and 100% denitrification efficiency at 500-550℃; CO removal efficiency >90% at 450-525℃; and CH4 removal efficiency >90% at 400-500℃.

[0048] Example 5:

[0049] (1) Micron-sized spherical FeCeO x Preparation

[0050] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 2.605 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 180 °C for 10 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 600 °C for 2 h to obtain micron-sized spherical FeCeO. x Powder.

[0051] (2) Preparation of core-shell catalysts

[0052] 0.6g FeCeO x The powder and 0.3 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.322 g of zirconium oxychloride, and 0.175 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. While stirring, an aqueous solution of ammonium carbonate was added dropwise to adjust the pH of the solution to 7.8. After adjusting the pH, the solution was magnetically stirred for 3 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 650 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0053] (3) Catalyst performance evaluation

[0054] The catalyst of this invention exhibits a NO removal efficiency >90% and an N2 selectivity >90% in NH3-SCR at 375-600℃, and a denitrification efficiency of 100% at 500-550℃; a CO removal efficiency >90% at 450-525℃; and a CH4 removal efficiency >90% at 400-475℃.

[0055] Example 6:

[0056] (1) Micron-sized spherical FeCeO x Preparation

[0057] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:8, weigh out 0.606 g of ferric nitrate (nonahydrate) and 5.210 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 180 °C for 12 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 600 °C for 2 h to obtain micron-sized spherical FeCeO. x Powder.

[0058] (2) Preparation of core-shell catalysts

[0059] 0.6g FeCeO x The powder and 0.3 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.322 g of zirconium oxychloride, and 0.175 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. While stirring, an aqueous solution of ammonium carbonate was added dropwise to adjust the pH of the solution to 8.2. After adjusting the pH, the solution was magnetically stirred for 3 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 650 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0060] (3) Catalyst performance evaluation

[0061] The catalyst of this invention exhibits NO removal efficiency >90% and N2 selectivity >90% with NH3-SCR at 400-600℃, and 100% denitrification efficiency at 500-550℃; CO removal efficiency >90% at 450-520℃; and CH4 removal efficiency >90% at 400-500℃.

[0062] Example 7:

[0063] (1) Micron-sized spherical FeCeO x Preparation

[0064] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 2.605 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 10 h. After the reaction, centrifuge and wash the product, dry it at 60 °C for 12 h, and calcine it at 600 °C for 4 h to obtain micron-sized spherical FeCeO. x Powder.

[0065] (2) Preparation of core-shell catalysts

[0066] 0.6g FeCeO x The powder and 0.3 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.322 g of zirconium oxychloride, and 0.175 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. While stirring, an aqueous solution of ammonium carbonate was added dropwise to adjust the pH of the solution to 8.4. After adjusting the pH, the solution was magnetically stirred for 3 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 650 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0067] (3) Catalyst performance evaluation

[0068] The catalyst of this invention exhibits NO removal efficiency >90% and N2 selectivity >90% in NH3-SCR at 475-625℃, and 100% denitrification efficiency at 500-600℃; CO removal efficiency >90% at 450-500℃; and CH4 removal efficiency >90% at 400-475℃.

[0069] Example 8:

[0070] (1) Micron-sized spherical FeCeO x Preparation

[0071] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 2.605 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 10 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 700 °C for 2 h to obtain micron-sized spherical FeCeO. x Powder.

[0072] (2) Preparation of core-shell catalysts

[0073] 0.6g FeCeO x The powder and 0.4 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.322 g of zirconium oxychloride, and 0.175 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. While stirring, an aqueous solution of ammonium carbonate was added dropwise to adjust the pH to 8.0. After adjusting the pH, the solution was magnetically stirred for 3 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 650 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0074] (3) Catalyst performance evaluation

[0075] The catalyst of this invention exhibits NO removal efficiency >90% and N2 selectivity >90% in NH3-SCR at 425-600℃, and 100% denitrification efficiency at 500-575℃; CO removal efficiency >90% at 450-500℃; and CH4 removal efficiency >90% at 400-500℃.

[0076] Example 9:

[0077] (1) Micron-sized spherical FeCeO x Preparation

[0078] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 2.605 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 10 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 600 °C for 2 h to obtain micron-sized spherical FeCeO. x Powder.

[0079] (2) Preparation of core-shell catalysts

[0080] 0.6g FeCeO x The powder and 0.5 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.322 g of zirconium oxychloride, and 0.175 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. While stirring, an aqueous solution of ammonium carbonate was added dropwise to adjust the pH to 8.0. After adjusting the pH, the solution was magnetically stirred for 3 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 650 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0081] (3) Catalyst performance evaluation

[0082] The catalyst of this invention exhibits NO removal efficiency >90% and N2 selectivity >90% with NH3-SCR at 400-600℃, and 100% denitrification efficiency at 500-550℃; CO removal efficiency >90% at 450-500℃; and CH4 removal efficiency >90% at 400-450℃.

[0083] Example 10:

[0084] (1) Micron-sized spherical FeCeO x Preparation

[0085] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 2.605 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 10 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 600 °C for 2 h to obtain micron-sized spherical FeCeO. x Powder.

[0086] (2) Preparation of core-shell catalysts

[0087] 0.6g FeCeO x The powder and 0.6 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.322 g of zirconium oxychloride, and 0.175 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 80 °C. While stirring, an aqueous solution of ammonium carbonate was added dropwise to adjust the pH to 8.0. After adjusting the pH, the solution was magnetically stirred for 3 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 650 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0088] (3) Catalyst performance evaluation

[0089] The catalyst of this invention exhibits a NO removal efficiency >90% and an N2 selectivity >90% in NH3-SCR at 450-625℃, and a denitrification efficiency of 100% at 500-575℃; a CO removal efficiency >90% at 450-500℃; and a CH4 removal efficiency >90% at 400-475℃.

[0090] Example 11:

[0091] (1) Micron-sized spherical FeCeO x Preparation

[0092] According to a glycerol / isopropanol volume ratio of 1:5, weigh out 10 ml of glycerol and 50 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 2.605 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 10 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 600 °C for 2 h to obtain micron-sized spherical FeCeO. x Powder.

[0093] (2) Preparation of core-shell catalysts

[0094] 0.6g FeCeO x The powder and 0.6 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.322 g of zirconium oxychloride, and 0.175 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. While stirring, an aqueous solution of ammonium carbonate was added dropwise to adjust the pH to 8.0. After adjusting the pH, the solution was magnetically stirred for 3 h. The product was centrifuged, washed, dried at 90 °C for 6 h, and calcined at 700 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0095] (3) Catalyst performance evaluation

[0096] The catalyst of this invention exhibits a NO removal efficiency >90% and N2 selectivity >90% with NH3-SCR at 400-575℃, a denitrification efficiency of 100% at 475-525℃, a CO removal efficiency >90% at 475-525℃, and a CH4 removal efficiency >90% at 425-450℃.

[0097] Example 12:

[0098] (1) Micron-sized spherical FeCeO x Preparation

[0099] According to a glycerol / isopropanol volume ratio of 1:6, weigh out 10 ml of glycerol and 60 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 2.605 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 10 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 600 °C for 2 h to obtain micron-sized spherical FeCeO. x Powder.

[0100] (2) Preparation of core-shell catalysts

[0101] 0.6g FeCeO x The powder and 0.6 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.6 g of ammonium metatungstate, 0.390 g of zirconium oxychloride, and 0.212 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. While stirring, an aqueous solution of ammonium carbonate was added dropwise to adjust the pH to 8.0. After adjusting the pH, the solution was magnetically stirred for 3 h. The product was centrifuged, washed, dried at 60 °C for 12 h, and calcined at 650 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0102] (3) Catalyst performance evaluation

[0103] The catalyst of this invention exhibits NO removal efficiency >90% and N2 selectivity >90% in NH3-SCR at 375-575℃, and 100% denitrification efficiency at 400-525℃; CO removal efficiency >90% at 450-475℃; and CH4 removal efficiency >90% at 400-475℃.

[0104] Example 13:

[0105] (1) Micron-sized spherical FeCeO x Preparation

[0106] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:6, weigh out 0.606 g of ferric nitrate (nonahydrate) and 3.908 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 10 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 600 °C for 2 h to obtain micron-sized spherical FeCeO. x Powder.

[0107] (2) Preparation of core-shell catalysts

[0108] 1.0g FeCeO x The powder and 0.6 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.4 g of ammonium metatungstate, 0.260 g of zirconium oxychloride, and 0.141 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. Carbonic acid aqueous solution was added dropwise while stirring to adjust the pH of the solution to 8.0. After adjusting the pH, the solution was magnetically stirred for 3 h. The product was centrifuged and washed, dried at 80 °C for 6 h, and calcined at 650 °C for 4 h to obtain a multifunctional core-shell catalyst.

[0109] (3) Catalyst performance evaluation

[0110] The catalyst of this invention exhibits NO removal efficiency >90% and N2 selectivity >90% in NH3-SCR at 375-600℃, and 100% denitrification efficiency at 425-550℃; CO removal efficiency >90% at 450-475℃; and CH4 removal efficiency >90% at 400-450℃.

[0111] Example 14:

[0112] (1) Micron-sized spherical FeCeO x Preparation

[0113] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 2.762 g of cerium carbonate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 10 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 600 °C for 2 h to obtain micron-sized spherical FeCeO. x Powder.

[0114] (2) Preparation of core-shell catalysts

[0115] 2.0g FeCeO x The powder and 0.6 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.2 g of ammonium metatungstate, 0.13 g of zirconium oxychloride, and 0.076 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. While stirring, an aqueous solution of ammonium carbonate was added dropwise to adjust the pH to 8.0. After adjusting the pH, the solution was magnetically stirred for 3 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 650 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0116] (3) Catalyst performance evaluation

[0117] The catalyst of this invention exhibits a NO removal efficiency >90% and an N2 selectivity >90% with NH3-SCR at 400-550℃, and a denitrification efficiency of 100% at 450-550℃; a CO removal efficiency >90% at 475-500℃; and a CH4 removal efficiency >90% at 450-475℃.

[0118] Example 15:

[0119] (1) Micron-sized spherical FeCeO x Preparation

[0120] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir well to obtain a transparent and homogeneous solution A; according to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 3.411 g of cerium sulfate; add the weighed ferric nitrate and cerium sulfate to solution A, and stir continuously for 1 h to obtain a mixed solution B; then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 10 h, centrifuge and wash the product after reaction, dry at 80 °C for 6 h, and calcine at 600 °C for 4 h to obtain micron-sized spherical FeCeO. x Powder.

[0121] (2) Preparation of core-shell catalysts

[0122] 0.6g FeCeO x The powder and 0.6 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.483 g of zirconium oxychloride, and 0.035 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:3:0.1) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. While stirring, an aqueous solution of ammonium carbonate was added dropwise to adjust the pH to 8.0. After adjusting the pH, the solution was magnetically stirred for 3 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 650 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0123] (3) Catalyst performance evaluation

[0124] The catalyst of this invention exhibits a NO removal efficiency >90% and an N2 selectivity >90% with NH3-SCR at 425-575℃, and a denitrification efficiency of 100% at 450-550℃; a CO removal efficiency >90% at 500-525℃; and a CH4 removal efficiency >90% at 450-500℃.

[0125] Example 16:

[0126] (1) Micron-sized spherical FeCeO x Preparation

[0127] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 2.605 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 12 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 600 °C for 2 h to obtain micron-sized spherical FeCeO. x Powder.

[0128] (2) Preparation of core-shell catalysts

[0129] 0.6g FeCeO x The powder and 0.3 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.0805 g of zirconium oxychloride, and 0.350 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:0.5:1) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. Ammonia solution was added dropwise while stirring to adjust the pH to 8.0. After adjusting the pH, the solution was magnetically stirred for 2 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 650 °C for 4 h to obtain a multifunctional core-shell catalyst.

[0130] (3) Catalyst performance evaluation

[0131] The catalyst of this invention exhibits NO removal efficiency >90% and N2 selectivity >90% in NH3-SCR at 425-625℃, and 100% denitrification efficiency at 450-600℃; CO removal efficiency >90% at 475-500℃; and CH4 removal efficiency >90% at 450-475℃.

[0132] Example 17:

[0133] (1) Micron-sized spherical FeCeO x Preparation

[0134] According to a glycerol / isopropanol volume ratio of 1:7, weigh out 10 ml of glycerol and 70 ml of isopropanol, place them in the same container and stir until homogeneous to obtain a transparent and uniform solution A. According to a Fe / Ce element molar ratio of 1:4, weigh out 0.606 g of ferric nitrate (nonahydrate) and 2.605 g of cerium nitrate. Add the weighed ferric nitrate and cerium nitrate to solution A and stir continuously for 1 h to obtain a mixed solution B. Then transfer solution B to a reaction vessel and hydrothermally react at 160 °C for 10 h. After the reaction, centrifuge and wash the product, dry it at 80 °C for 6 h, and calcine it at 600 °C for 2 h to obtain micron-sized spherical FeCeO. x Powder.

[0135] (2) Preparation of core-shell catalysts

[0136] 0.6g FeCeO x The powder and 0.3 g of hexadecyltrimethylammonium bromide (CTAB) were dispersed in 120 ml of deionized water and sonicated for 30 min to obtain solution C. 0.496 g of ammonium metatungstate, 0.322 g of zirconium oxychloride, and 0.175 g of tin tetrachloride pentahydrate (the molar ratio of Zr, W, and Sn was 1:2:0.5) were dissolved in solution C and sonicated for 30 min to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred at 60 °C. Sodium hydroxide aqueous solution was added dropwise while stirring to adjust the pH to 8.0. After adjusting the pH, the solution was stirred for 2 h. The product was centrifuged, washed, dried at 80 °C for 6 h, and calcined at 650 °C for 2 h to obtain a multifunctional core-shell catalyst.

[0137] (3) Catalyst performance evaluation

[0138] The catalyst of this invention exhibits NO removal efficiency >90% and N2 selectivity >90% in NH3-SCR at 450-600℃, and 100% denitrification efficiency at 450-550℃; CO removal efficiency >90% at 475-500℃; and CH4 removal efficiency >90% at 400-450℃.

[0139]

Claims

1. A method for removing NO x The method for preparing a multifunctional catalyst for CO and HC, characterized in that... FeCeO prepared by hydrothermal method x Micron-sized spherical particles were then coated with a layer of ZrWSnO on the catalyst surface using a microparticle enrichment method. x The outer shell is used to construct a core-shell structure with separate dual active sites, thereby achieving NO... x Simultaneous removal of CO and HC; the specific steps are as follows: (1) Micron-sized spherical FeCeO x Preparation According to a glycerol / isopropanol volume ratio of 1:(5-7), a certain amount of glycerol and isopropanol were weighed and placed in the same container and stirred evenly to obtain a transparent and homogeneous solution A. According to a Fe / Ce element molar ratio of 1:(2-8), a certain amount of iron salt and cerium salt were weighed. The weighed iron salt and cerium nitrate were added to solution A and stirred continuously for 1-2 hours to obtain a mixed solution B. Solution B was then transferred to a reaction vessel for hydrothermal reaction. The product after reaction was centrifuged, washed, dried, and calcined to obtain micron-sized spherical FeCeO₂. x Powder; (2) Preparation of core-shell catalysts FeCeO x The powder and surface modifier were dispersed in deionized water and ultrasonically treated to obtain solution C. Ammonium metatungstate, zirconium oxychloride, and tin tetrachloride were dissolved in solution C and ultrasonically treated to obtain solution D. Solution D was placed in a temperature-controlled stirrer and magnetically stirred while adding a pH adjuster dropwise to make the solution weakly alkaline. After pH adjustment, the solution was magnetically stirred for 2–6 hours to obtain a flocculent product. The product was centrifuged, washed, dried, and calcined to obtain FeCeO₂. x @ZrWSnO x Multifunctional catalyst.

2. A preparation method as described in claim 1, characterized in that... The hydrothermal reaction temperature in step (1) is 140-180℃, the reaction time is 8-12h; the drying temperature is 60-80℃, the drying time is 6-12h; the calcination temperature is 600-700℃, and the holding time is 2-4h.

3. A preparation method as described in claim 1, characterized in that... The cerium salt mentioned in step (1) is cerium nitrate, cerium carbonate, or cerium sulfate; the iron salt is ferric nitrate.

4. A preparation method as described in claim 1, characterized in that... The pH adjuster mentioned in step (2) is an aqueous solution of ammonium carbonate, ammonia, or sodium hydroxide; the pH value of the solution is adjusted to 7.8 to 8.4; the surface modifier is cetyltrimethylammonium bromide (CTAB).

5. A preparation method as described in claim 1, characterized in that... In step (2), the temperature of the temperature-controlled stirrer is 60-90℃; the drying temperature is 60-80℃ and the drying time is 6-12h; the calcination temperature is 600-700℃ and the holding time is 2-4h.

6. A preparation method as described in claim 1, characterized in that... In step (2) FeCeO x The mass ratio of ammonium metatungstate to surface modifier is 1:(0.1-1); the molar ratio of Zr, W, and Sn in ammonium metatungstate, zirconium oxychloride, and tin tetrachloride is 1:(0.5-3):(0.1-1); ammonium metatungstate, zirconium oxychloride, and tin tetrachloride are dissolved in solution C to control FeCeO x The powder and ammonium metatungstate are added at a mass ratio of 1:(0.1-1).

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