Preparation method and application of NbmCe3-mOx composite metal oxide catalyst

Abstract

The invention discloses a preparation method and application of a NbmCe3-mOx composite metal oxide type catalyst, and relates to a preparation method of a catalyst. The invention aims to solve the problems that the existing catalyst is high in multi-pollutant elimination temperature and mismatched in active temperature window. The method comprises the following steps: preparing a cerous nitrate-ethanol solution, a niobium pentachloride-ethanol solution, a mixed salt-ethanol solution and a hexamethylenetetramine-water solution; and heating and stirring the mixed salt-ethanol solution, dropwise adding the hexamethylenetetramine-aqueous solution, stirring, filtering the solid precipitate, washing with distilled water and absolute ethyl alcohol, drying, grinding into powder, putting into a muffle furnace, carrying out high-temperature treatment for 5 hours, cooling to room temperature, grinding, tabletting and granulating to obtain the composite metal oxide type catalyst. The prepared catalyst can be used for removing NO through ammonia selective catalytic reduction, can also be used for catalytically oxidizing methylbenzene, and can also be used for removing NO and catalytically oxidizing methylbenzene through ammonia selective catalytic reduction at the same time. The invention belongs to the field of catalyst preparation.

Description

Technical Field

[0001] The invention relates to a preparation method and application of a catalyst for co-eliminating NO and toluene. Background Art

[0002] Nitrogen oxides (NO x ) and volatile organic compounds (VOCs) are the main pollutants in the current atmosphere. x When exposed to sunlight, VOCs and ozone will undergo photochemical reactions to form ozone (O3) and secondary aerosols; secondary aerosols and sulfates, nitrates, ammonium salts, organic compounds, etc. together form fine particulate matter (PM 2.5 Therefore, nitrogen oxides and volatile organic compounds (VOCs) are PM 2.5 and an important precursor of O3. x If VOCs are not controlled, photochemical pollution will be aggravated. x and VOCs are the solution to current PM 2.5 and O3 pollution. Strengthen the coordinated control of multiple pollutants and promote PM 2.5 The plan also includes coordinated control of nitrogen oxides and volatile organic compounds (VOCs) by more than 10%. In order to actively respond to the challenges of ecological environment governance in my country, we will explore the realization of multiple pollutants (NO x The synergistic catalytic elimination of multiple pollutants (VOCs and CO2) has important practical significance. The synergistic catalytic elimination of multiple pollutants on the same catalyst can also reduce facility space and capital investment, and therefore has significant economic benefits. For catalysts for the simultaneous elimination of multiple pollutants, there are reports of attempts to use precious metal catalysts, vanadium-containing catalysts, and other metal oxide-type catalysts, which face the problems of high prices, biological toxicity, high multi-pollutant elimination temperatures, and mismatched active temperature windows, which also limit the application of these catalysts in the synergistic elimination of multiple pollutants. Summary of the invention

[0003] The purpose of the present invention is to solve the technical problem that the existing catalyst has high multi-pollutant elimination temperature and mismatched active temperature window, and provides a Nb m Ce 3-m O x The invention relates to a preparation method and application of a composite metal oxide catalyst.

[0004] Nb m Ce 3-m O x The preparation method of the composite metal oxide catalyst is carried out according to the following steps:

[0005] 1. dissolving cerium nitrate in anhydrous ethanol to obtain a cerium nitrate-ethanol solution;

[0006] 2. dissolving niobium pentachloride in anhydrous ethanol to obtain a niobium pentachloride-ethanol solution;

[0007] 3. Add the niobium pentachloride-ethanol solution dropwise into the cerium nitrate-ethanol solution and stir thoroughly to obtain a mixed salt-ethanol solution, wherein the ratio of the amount of niobium pentachloride to the amount of cerium nitrate is m:3-m;

[0008] 4. dissolving hexamethylenetetramine in distilled water to obtain a hexamethylenetetramine-water solution, wherein the molar ratio of the sum of the moles of niobium pentachloride and cerium nitrate to the mole of hexamethylenetetramine is 1:(1-5);

[0009] 5. Heat the mixed salt-ethanol solution to 75°C, add the hexamethylenetetramine-water solution dropwise to the mixed salt-ethanol solution under constant stirring, continue stirring at 75°C for 4 hours after the addition is complete, gradually generate solid precipitate, filter the solid precipitate, wash it 3 times with distilled water, wash it once with anhydrous ethanol, put it in an oven, keep it in an oven at 110°C for 10 hours, and obtain a dry solid;

[0010] 6. After the dried solid is ground into powder, it is placed in a muffle furnace and heated to 500°C at a heating rate of 10°C / min. It is treated at high temperature in the muffle furnace at 500°C for 5 hours, cooled naturally to room temperature, and then ground, tableted, and granulated to obtain Nb m Ce 3-m O x Composite metal oxide catalyst, Nb m Ce 3-m O x The molecular formula of the composite metal oxide catalyst is Nb m Ce 3-m O x , where m is 0.05~0.4.

[0011] The Nb m Ce 3-m O x Application of composite metal oxide catalysts, the Nb m Ce 3-m O x The composite metal oxide type catalyst eliminates nitrogen oxides and toluene simultaneously within the same temperature window.

[0012] The Nb prepared by the present invention m Ce 3-m O x The composite metal oxide catalyst can perform selective catalytic reduction of ammonia to eliminate NO, can also catalytically oxidize toluene, and can also perform selective catalytic reduction of ammonia to eliminate NO and catalytically oxidize toluene simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a comparison chart of NH3-SCR denitration performance of composite metal oxide type catalysts prepared in Experiments 1 to 5;

[0014] Figure 2 This is a comparison chart of the catalytic oxidation performance of toluene by the composite metal oxide catalysts prepared in Experiments 1 to 5;

[0015] Figure 3 It is the Nb prepared in Experiment 2 0.1 Ce 2.9 O x Comparison of the catalytic performance of the catalysts for the simultaneous catalytic elimination of NO and toluene in the absence of water or in the presence of water; (A) represents the NO conversion rate, and (B) represents the toluene conversion rate;

[0016] Figure 4 CeO2, Nb prepared in Experiment 2 0.1 Ce 2.9 O x and Nb prepared in Experiment 5 0.4 Ce 2.6 O x Temperature-programmed desorption of ammonia NH3-TPD spectrum of the catalyst;

[0017] Figure 5 CeO2, Nb prepared in Experiment 2 0.1 Ce 2.9 O x and Nb prepared in Experiment 5 0.4 Ce 2.6 O x Hydrogen temperature-programmed reduction H2-TPR spectrum of the catalyst;

[0018] Figure 6 CeO2, Nb prepared in Experiment 2 0.1 Ce 2.9 O x and Nb prepared in Experiment 5 0.4 Ce 2.6 O x Oxygen temperature-programmed desorption O2-TPD spectrum of the catalyst. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0020] Specific implementation method 1: This implementation method Nb m Ce 3-m O x The preparation method of the composite metal oxide catalyst is carried out according to the following steps:

[0021] 1. dissolving cerium nitrate in anhydrous ethanol to obtain a cerium nitrate-ethanol solution;

[0022] 2. dissolving niobium pentachloride in anhydrous ethanol to obtain a niobium pentachloride-ethanol solution;

[0023] 3. Add the niobium pentachloride-ethanol solution dropwise into the cerium nitrate-ethanol solution and stir thoroughly to obtain a mixed salt-ethanol solution, wherein the ratio of the amount of niobium pentachloride to the amount of cerium nitrate is m:3-m;

[0024] 4. dissolving hexamethylenetetramine in distilled water to obtain a hexamethylenetetramine-water solution, wherein the molar ratio of the sum of the moles of niobium pentachloride and cerium nitrate to the mole of hexamethylenetetramine is 1:(1-5);

[0025] 5. Heat the mixed salt-ethanol solution to 75°C, add the hexamethylenetetramine-water solution dropwise to the mixed salt-ethanol solution under constant stirring, continue stirring at 75°C for 4 hours after the addition is complete, gradually generate solid precipitate, filter the solid precipitate, wash it 3 times with distilled water, wash it once with anhydrous ethanol, put it in an oven, keep it in an oven at 110°C for 10 hours, and obtain a dry solid;

[0026] 6. After the dried solid is ground into powder, it is placed in a muffle furnace and heated to 500°C at a heating rate of 10°C / min. It is treated at high temperature in the muffle furnace at 500°C for 5 hours, cooled naturally to room temperature, and then ground, tableted, and granulated to obtain Nb m Ce 3-m O x Composite metal oxide catalyst, Nb m Ce 3-m O x The molecular formula of the composite metal oxide catalyst is Nb m Ce 3-m O x , where m is 0.05~0.4.

[0027] Specific implementation method 2: This implementation method is different from the specific implementation method 1 in that m in step 6 is 0.05. The rest is the same as the specific implementation method 1.

[0028] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that m in step 6 is 0.1. The rest is the same as specific implementation method 1 or 2.

[0029] Specific implementation method 4: This implementation method is different from specific implementation methods 1 to 3 in that m in step 6 is 0.15. The rest is the same as specific implementation methods 1 to 3.

[0030] Specific implementation mode 5: This implementation mode is different from specific implementation modes 1 to 4 in that m is 0.2 in step 6. The rest is the same as specific implementation modes 1 to 4.

[0031] Specific implementation method 6: This implementation method is different from specific implementation methods 1 to 5 in that m is 0.4 in step 6. The rest is the same as specific implementation methods 1 to 5.

[0032] Specific implementation method 7: Nb described in specific implementation methods 1 to 6 m Ce 3-m O x Application of composite metal oxide catalysts, the Nb m Ce 3-m O x The composite metal oxide type catalyst eliminates nitrogen oxides and toluene simultaneously within the same temperature window.

[0033] The following experiments were used to verify the effect of the present invention:

[0034] Experiment 1:

[0035] Nb 0.05 Ce 2.95 O x The preparation method of the composite metal oxide catalyst is carried out according to the following steps:

[0036] 1. Dissolve 12.8 g of cerium nitrate in anhydrous ethanol to obtain a cerium nitrate-ethanol solution;

[0037] 2. dissolving 0.135 g of niobium pentachloride in anhydrous ethanol to obtain a niobium pentachloride-ethanol solution;

[0038] 3. Add the niobium pentachloride-ethanol solution dropwise into the cerium nitrate-ethanol solution and stir thoroughly to obtain a mixed salt-ethanol solution, wherein the ratio of the amount of niobium pentachloride to the amount of cerium nitrate is 0.5:2.95;

[0039] 4. Take 13g of hexamethylenetetramine and dissolve it in distilled water to obtain a hexamethylenetetramine-water solution, wherein the molar ratio of the sum of the moles of niobium pentachloride and cerium nitrate to the mole of hexamethylenetetramine is 1:3;

[0040] 5. Heat the mixed salt-ethanol solution to 75°C, add the hexamethylenetetramine-water solution dropwise to the mixed salt-ethanol solution under constant stirring, continue stirring at 75°C for 4 hours after the addition is complete, gradually generate solid precipitate, filter the solid precipitate, wash it 3 times with distilled water, wash it once with anhydrous ethanol, put it in an oven, keep it in an oven at 110°C for 10 hours, and obtain a dry solid;

[0041] 6. After the dried solid is ground into powder, it is placed in a muffle furnace and heated to 500°C at a heating rate of 10°C / min. It is treated at high temperature in the muffle furnace at 500°C for 5 hours, cooled naturally to room temperature, and ground, pressed into tablets, and granulated to obtain a composite metal oxide catalyst Nb 0.05 Ce 2.95 O x .

[0042] Experiment 2:

[0043] Nb 0.1 Ce 2.9 O x The preparation method of the composite metal oxide catalyst is carried out according to the following steps:

[0044] 1. Dissolve 12.6 g of cerium nitrate in anhydrous ethanol to obtain a cerium nitrate-ethanol solution;

[0045] 2. dissolving 0.27 g of niobium pentachloride in anhydrous ethanol to obtain a niobium pentachloride-ethanol solution;

[0046] 3. Add the niobium pentachloride-ethanol solution dropwise into the cerium nitrate-ethanol solution and stir thoroughly to obtain a mixed salt-ethanol solution, wherein the ratio of the amount of niobium pentachloride to the amount of cerium nitrate is 1:2.9;

[0047] 4. Take 13g of hexamethylenetetramine and dissolve it in distilled water to obtain a hexamethylenetetramine-water solution, wherein the molar ratio of the sum of the moles of niobium pentachloride and cerium nitrate to the mole of hexamethylenetetramine is 1:3;

[0048] 5. Heat the mixed salt-ethanol solution to 75°C, add the hexamethylenetetramine-water solution dropwise to the mixed salt-ethanol solution under constant stirring, continue stirring at 75°C for 4 hours after the addition is complete, gradually generate solid precipitate, filter the solid precipitate, wash it 3 times with distilled water, wash it once with anhydrous ethanol, put it in an oven, keep it in an oven at 110°C for 10 hours, and obtain a dry solid;

[0049] 6. After the dried solid is ground into powder, it is placed in a muffle furnace and heated to 500°C at a heating rate of 10°C / min. It is treated at high temperature in the muffle furnace at 500°C for 5 hours, cooled naturally to room temperature, and ground, pressed into tablets, and granulated to obtain a composite metal oxide catalyst Nb 0.1 Ce 2.9 O x .

[0050] Experiment 3:

[0051] Nb 0.15 Ce 2.85 O xThe preparation method of the composite metal oxide catalyst is carried out according to the following steps:

[0052] 1. Dissolve 12.4 g of cerium nitrate in anhydrous ethanol to obtain a cerium nitrate-ethanol solution;

[0053] 2. dissolving 0.405 g of niobium pentachloride in anhydrous ethanol to obtain a niobium pentachloride-ethanol solution;

[0054] 3. Add the niobium pentachloride-ethanol solution dropwise into the cerium nitrate-ethanol solution and stir thoroughly to obtain a mixed salt-ethanol solution, wherein the ratio of the amount of niobium pentachloride to the amount of cerium nitrate is 0.15:2.85;

[0055] 4. Take 13g of hexamethylenetetramine and dissolve it in distilled water to obtain a hexamethylenetetramine-water solution, wherein the molar ratio of the sum of the moles of niobium pentachloride and cerium nitrate to the mole of hexamethylenetetramine is 1:3;

[0056] 5. Heat the mixed salt-ethanol solution to 75°C, add the hexamethylenetetramine-water solution dropwise to the mixed salt-ethanol solution under constant stirring, continue stirring at 75°C for 4 hours after the addition is complete, gradually generate solid precipitate, filter the solid precipitate, wash it 3 times with distilled water, wash it once with anhydrous ethanol, put it in an oven, keep it in an oven at 110°C for 10 hours, and obtain a dry solid;

[0057] 6. After the dried solid is ground into powder, it is placed in a muffle furnace and heated to 500°C at a heating rate of 10°C / min. It is treated at high temperature in the muffle furnace at 500°C for 5 hours, cooled naturally to room temperature, and ground, pressed into tablets, and granulated to obtain a composite metal oxide catalyst Nb 0.15 Ce 2.85 O x .

[0058] Experiment 4:

[0059] Nb 0.2 Ce 2.8 O x The preparation method of the composite metal oxide catalyst is carried out according to the following steps:

[0060] 1. Dissolve 12.2 g of cerium nitrate in anhydrous ethanol to obtain a cerium nitrate-ethanol solution;

[0061] 2. dissolving 0.54 g of niobium pentachloride in anhydrous ethanol to obtain a niobium pentachloride-ethanol solution;

[0062] 3. Add the niobium pentachloride-ethanol solution dropwise into the cerium nitrate-ethanol solution and stir thoroughly to obtain a mixed salt-ethanol solution, wherein the ratio of the amount of niobium pentachloride to the amount of cerium nitrate is 0.2:2.8;

[0063] 4. Take 13g of hexamethylenetetramine and dissolve it in distilled water to obtain a hexamethylenetetramine-water solution, wherein the molar ratio of the sum of the moles of niobium pentachloride and cerium nitrate to the mole of hexamethylenetetramine is 1:3;

[0064] 5. Heat the mixed salt-ethanol solution to 75°C, add the hexamethylenetetramine-water solution dropwise to the mixed salt-ethanol solution under constant stirring, continue stirring at 75°C for 4 hours after the addition is complete, gradually generate solid precipitate, filter the solid precipitate, wash it 3 times with distilled water, wash it once with anhydrous ethanol, put it in an oven, keep it in an oven at 110°C for 10 hours, and obtain a dry solid;

[0065] 6. After the dried solid is ground into powder, it is placed in a muffle furnace and heated to 500°C at a heating rate of 10°C / min. It is treated at high temperature in the muffle furnace at 500°C for 5 hours, cooled naturally to room temperature, and ground, pressed into tablets, and granulated to obtain a composite metal oxide catalyst Nb 0.2 Ce 2.8 O x .

[0066] Experiment 5:

[0067] Nb 0.4 Ce 2.6 O x The preparation method of the composite metal oxide catalyst is carried out according to the following steps:

[0068] 1. Dissolve 11.3 g of cerium nitrate in anhydrous ethanol to obtain a cerium nitrate-ethanol solution;

[0069] 2. dissolving 1.08 g of niobium pentachloride in anhydrous ethanol to obtain a niobium pentachloride-ethanol solution;

[0070] 3. Add the niobium pentachloride-ethanol solution dropwise into the cerium nitrate-ethanol solution and stir thoroughly to obtain a mixed salt-ethanol solution, wherein the ratio of the amount of niobium pentachloride to the amount of cerium nitrate is 0.4:2.6;

[0071] 4. Take 13g of hexamethylenetetramine and dissolve it in distilled water to obtain a hexamethylenetetramine-water solution, wherein the molar ratio of the sum of the moles of niobium pentachloride and cerium nitrate to the mole of hexamethylenetetramine is 1:3;

[0072] 5. Heat the mixed salt-ethanol solution to 75°C, add the hexamethylenetetramine-water solution dropwise to the mixed salt-ethanol solution under constant stirring, continue stirring at 75°C for 4 hours after the addition is complete, gradually generate solid precipitate, filter the solid precipitate, wash it 3 times with distilled water, wash it once with anhydrous ethanol, put it in an oven, keep it in an oven at 110°C for 10 hours, and obtain a dry solid;

[0073] 6. After the dried solid is ground into powder, it is placed in a muffle furnace and heated to 500°C at a heating rate of 10°C / min. It is treated at high temperature in the muffle furnace at 500°C for 5 hours, cooled naturally to room temperature, and ground, pressed into tablets, and granulated to obtain a composite metal oxide catalyst Nb 0.4 Ce 2.6 O x .

[0074] The composite metal oxide catalysts prepared in experiments 1 to 5 were heated in an atmosphere of 1000 ppm NO, 1000 ppm NH, 3% O, 40,000 h / min gas and N2 as the balance gas. -1 The denitrification performance test was carried out under the condition of test temperature of 120~450℃. The test results are shown in Table 1:

[0075] Table 1 NO conversion rate of different catalysts

[0076]

[0077] The composite metal oxide catalysts prepared in experiments 1 to 5 were heated in an atmosphere with a toluene concentration of 1000 ppm, an O2 volume concentration of 18%, N2 as the balance gas, and a space velocity of 20,000 h -1 The catalytic oxidation toluene performance test was carried out under the condition of test temperature of 120-300°C. The test results are shown in Table 2:

[0078] Table 2 Toluene conversion of different catalysts

[0079]

[0080] The Nb prepared in Experiment 2 0.1 Ce 2.9 O x Catalyst concentration: 1000ppm NO, 1000ppm NH, 1000ppm toluene, 18% O, 5% H, N2 as balance gas, space velocity: 20,000h -1 The performance test of catalytic elimination of NO and toluene was carried out at a test temperature of 120-420°C. The test results are shown in Table 3:

[0081] Table 3Nb 0.1 Ce 2.9 O x Catalytic performance of catalyst for simultaneous removal of NO and toluene

[0082]

[0083]

[0084] Figure 1 The NH3-SCR denitration performance of the composite metal oxide catalysts prepared in Experiments 1 to 5 is given. When the Nb doping amount is zero, the denitration performance of the CeO2 catalyst is poor, and the maximum NO conversion rate does not exceed 50%. m Ce 3-m O x (m = 0.05 ~ 0.4) The NO conversion rate of the catalyst is significantly improved and the active temperature window is significantly widened. 0.1 Ce 2.9 O x The catalyst exhibited good denitrification ability, with a NO conversion rate of more than 90% in the temperature range of 190 to 420°C.

[0085] Figure 2 The catalytic oxidation performance of toluene is given. When the Nb doping amount is zero, the CeO2 catalyst has a certain catalytic performance for toluene. However, its toluene conversion temperature is high, and the toluene conversion rate exceeds 90% at 220℃. m Ce 3-m O x (m=0.05~0.4) The performance of the catalyst for toluene oxidation first increases and then decreases with the Nb doping amount. 0.1 Ce 2.9 O x The catalyst exhibits excellent toluene elimination capabilities, with a toluene conversion rate greater than 90% at 202°C, and a toluene conversion rate of more than 99% at temperatures above 215°C.

[0086] Figure 3 Given Nb 0.1 Ce 2.9 O x Catalytic performance of the catalyst for simultaneous removal of NO and toluene. 0.1 Ce 2.9 O x The catalyst exhibits excellent catalytic performance in the simultaneous elimination of multiple pollutants (NO and toluene). In the temperature range of 203-403°C, the NO conversion rate is greater than 90%. When the temperature is higher than 210°C, the toluene conversion rate exceeds 90%. The catalytic performance of the simultaneous elimination of NO and toluene in the presence of 5 vol% H2O was tested. The test results show that Nb 0.1 Ce 2.9 O x The catalyst still has a wide active temperature window even in the presence of water. 0.1 Ce 2.9 O x The catalyst can achieve a conversion rate of more than 90% for NO and toluene in the temperature range of 215-400°C.0.1 Ce 2.9 O x The catalyst has multiple uses, a wide active temperature window and resistance to water poisoning.

[0087] Figure 4 CeO2, Nb 0.1 Ce 2.9 O x and Nb 0.4 Ce 2.6 O x Ammonia temperature programmed desorption (NH3-TPD) spectrum of the catalyst. 0.1 Ce 2.9 O x and Nb 0.1 Ce 2.9 O x The acidity of the catalyst is significantly higher than that of CeO2, which indicates that Nb doping can significantly improve the ability of catalytic adsorption of ammonia and increase the surface acidity of the catalyst. m Ce 3-m O x (m=0.05~0.4) is an important factor in improving the NH3-SCR denitrification performance of the catalyst.

[0088] Figure 5 CeO2, Nb 0.1 Ce 2.9 O x and Nb 0.4 Ce 2.6 O x Hydrogen temperature programmed reduction (H2-TPR) spectrum of the catalyst. 0.1 Ce 2.9 O x The oxidation ability of the lattice oxygen on the catalyst surface is enhanced to a certain extent, indicating that a small amount of Nb doping can improve the oxidation ability of the lattice oxygen on the catalyst surface. 0.4 Ce 2.6 O x The lattice oxygen oxidation ability of the catalyst surface is significantly reduced, indicating that excessive Nb will inhibit the oxidizability of the catalyst. This is consistent with the catalytic oxidation activity of the catalyst for toluene.

[0089] Figure 6 CeO2, Nb 0.1 Ce 2.9 O x and Nb 0.4 Ce 2.6 O x O2-TPD spectrum of oxygen temperature programmed desorption of catalyst. Nb 0.1 Ce2.9 O x and Nb 0.4 Ce 2.6 O x After the catalyst is doped with Nb, it will inhibit the oxidizing property of the surface adsorbed oxygen and increase the activity of the surface lattice oxygen and the bulk lattice oxygen. This is an important reason why the catalyst can simultaneously carry out NH3-SCR denitrification and catalytic oxidation of toluene. 0.1 Ce 2.9 O x The catalyst can not only activate NH3, but also inhibit the over-oxidation of NH3 at high temperature. At the same time, the increased activity of lattice oxygen can promote the catalytic oxidation of toluene. 0.1 Ce 2.9 O x The catalyst exhibits excellent NH3-SCR denitrification performance, catalytic oxidation of toluene performance and the ability to catalyze the simultaneous elimination of multiple pollutants (NO and toluene).

[0090] Catalyst Nb 0.1 Ce 2.9 O x It exhibits excellent NH3-SCR denitrification performance, catalytic oxidation of toluene performance and simultaneous elimination of multiple pollutants (NO and toluene). 0.1 Ce 2.9 O x The catalyst has multiple functional uses, a wide pollutant elimination active temperature window and the catalyst's resistance to water poisoning. This is due to the following reasons. Nb doping can promote the ability of catalytic adsorption of ammonia and increase the surface acidity of the catalyst, thereby increasing the Nb m Ce 3-m O x (m = 0.05 ~ 0.4) Catalyst NH3-SCR denitrification performance. A small amount of Nb doping can improve the surface lattice oxygen oxidation ability, thereby promoting the catalytic oxidation of toluene. 0.1 Ce 2.9 O x The catalyst can not only oxidize and activate NH3, but also inhibit the over-oxidation of NH3 at high temperature. At the same time, the increased activity of lattice oxygen can promote the catalytic oxidation of toluene.

Claims

1. Nb m Ce 3-m O x A method for preparing a composite metal oxide catalyst, characterized in that The Nb m Ce 3-m O x The preparation method of the composite metal oxide catalyst is carried out according to the following steps:

1. dissolving cerium nitrate in anhydrous ethanol to obtain a cerium nitrate-ethanol solution; 2. dissolving niobium pentachloride in anhydrous ethanol to obtain a niobium pentachloride-ethanol solution; 3. Add the niobium pentachloride-ethanol solution dropwise into the cerium nitrate-ethanol solution and stir thoroughly to obtain a mixed salt-ethanol solution, wherein the ratio of the amount of niobium pentachloride to the amount of cerium nitrate is m:3-m; 4. dissolving hexamethylenetetramine in distilled water to obtain a hexamethylenetetramine-water solution, wherein the molar ratio of the sum of the moles of niobium pentachloride and cerium nitrate to the mole of hexamethylenetetramine is 1:(1-5); 5. Heat the mixed salt-ethanol solution to 75°C, add the hexamethylenetetramine-water solution dropwise to the mixed salt-ethanol solution under constant stirring, continue stirring at 75°C for 4 hours after the addition is complete, gradually generate solid precipitate, filter the solid precipitate, wash it 3 times with distilled water, wash it once with anhydrous ethanol, put it in an oven, keep it in an oven at 110°C for 10 hours, and obtain a dry solid; 6. After the dried solid is ground into powder, it is placed in a muffle furnace and heated to 500°C at a heating rate of 10°C / min. It is treated at high temperature in the muffle furnace at 500°C for 5 hours, cooled naturally to room temperature, and then ground, tableted, and granulated to obtain Nb m Ce 3-m O x Composite metal oxide catalyst, Nb m Ce 3-m O x The molecular formula of the composite metal oxide catalyst is Nb m Ce 3-m O x , where m is 0.05~0.

4.

2. According to claim 1, Nb m Ce 3-m O x Composite metal oxide catalyst, characterized in that In step 6, m is 0.

05.

3. Nb according to claim 1 m Ce 3-m O x Composite metal oxide catalyst, characterized in that In step 6, m is 0.

1.

4. Nb according to claim 1 m Ce 3-m O x Composite metal oxide catalyst, characterized in that In step 6, m is 0.

15.

5. Nb according to claim 1 m Ce 3-m O x Composite metal oxide catalyst, characterized in that In step 6, m is 0.

2.

6. Nb according to claim 1 m Ce 3-m O x Composite metal oxide catalyst, characterized in that In step 6, m is 0.

4.

7. Nb according to claim 1 m Ce 3-m O x Application of composite metal oxide catalyst, characterized in that The Nb m Ce 3- m O x The composite metal oxide type catalyst eliminates nitrogen oxides and toluene simultaneously within the same temperature window.

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