A ruthenium- and vanadium-doped cerium-manganese catalyst for denitration and VOCs removal, as well as its preparation method and application

Abstract

The present invention discloses a ruthenium and vanadium dual-doped cerium manganese catalyst for denitrification and VOCs removal, as well as its preparation method and application. The catalyst uses cerium and manganese oxides as carriers and ruthenium and vanadium as active components. The ruthenium and vanadium dual-doped cerium manganese catalyst obtained by coprecipitation method has more active centers and excellent redox ability. The catalyst can achieve NO removal under medium and low temperature conditions. x , VOCs synergistic catalytic removal, the catalyst has strong sulfur resistance and water resistance, which is beneficial to simplify the treatment process of industrial tail gas purification, improve process purification efficiency and reduce flue gas treatment costs.

Description

Technical Field

[0001] The present invention provides a ruthenium- and vanadium-doped cerium-manganese catalyst for denitration and removal of VOCs, and a preparation method and application thereof, belonging to the field of environmentally friendly catalytic materials and air pollution control. Background Art

[0002] In recent years, with the rapid development of my country's economy and society, environmental problems have become increasingly prominent. Volatile organic compounds (VOCs) and nitrogen oxides (NO x ) are two common air pollutants. Controlling and reducing their emissions has become one of the key processes in solving the problem of air pollution. VOCs is a general term for various organic compounds with a boiling point of 50-260°C at room temperature. The amount of VOCs emitted in the environment is second only to atmospheric particulate matter and is considered the second largest category of air pollutants. These compounds not only damage the ozone layer and intensify the greenhouse effect, but also cause secondary pollution. NO in the atmosphere x The sources of NO are mainly divided into natural sources and human-generated sources. Compared with natural processes, NO generated by human factors x It is the main source of air pollution, most of which comes from the emissions after the combustion of fossil fuels. In actual production and life, VOCs and NO x The two pollutants often exist at the same time, so the research on VOCs and NO x Comprehensive and coordinated control of the two pollutants is of great significance to improving environmental pollution problems.

[0003] Thermal catalytic technology is currently commonly used for synergistic removal of NO x and VOCs, selective catalytic reduction reaction (SCR) and catalytic oxidation (CO) all require catalysts to have high redox properties. Among the existing patents for catalytic removal of VOCs, patent CN202310938297 discloses a catalyst with copper oxide and vanadium pentoxide as active components. The catalyst adopts a three-step synthesis process of solvent hydrothermal-impregnation-carbonization. First, ZSM5 molecular sieve is added to N, N diethylbenzamide solution for hydrothermal reaction, followed by centrifugation and washing operations. The obtained white solid is carbonized to obtain a hollow ZSM5 molecular sieve; ammonium metavanadate and copper nitrate solution are added to the hollow molecular sieve, stirred, impregnated, and carbonized to obtain a catalyst. Patent CN202310983347 provides a precious metal-embedded mesoporous CeO2 hollow sphere composite material and a preparation method thereof. The preparation method of the reaction solution is to add organic acid, alcohol organic solvent, cerium salt and precious metal salt into pure water solution, stir thoroughly, let it stand at about 200℃, wash, and dry the precipitate; the dried product is calcined at 200-300℃ to finally obtain the catalyst. Among the existing denitrification patents, patent CN202111087108 provides a method for NO xA catalyst for the synergistic removal of VOCs and VOCs and a preparation method thereof, wherein vanadium is doped as an active component in the lattice of a CeO2 matrix. The catalysts prepared in the above patents either use precious metals or have a cumbersome preparation process, resulting in significant market limitations. Summary of the Invention

[0004] The present invention is aimed at the current VOCs and NO x The research status and existing problems of synergistic removal process and catalysts provide a ruthenium and vanadium dual-doped denitrification and VOCs removal cerium manganese catalyst, which can achieve VOCs oxidation while NO x It has a synergistic removal effect, removing NO x and VOCs are catalytically decomposed into N2, CO2, H2O and other components. In addition, the catalyst of the present invention can truly achieve NO x The reduction and harmlessness of VOCs have important economic and social value.

[0005] A method for preparing a ruthenium- and vanadium-doped cerium-manganese catalyst for denitration and VOCs removal, the preparation method of the catalyst is as follows:

[0006] (1) Preparation of Mn-MOF

[0007] Manganese salt and polymer are dissolved in a solvent to form solution A. 1,3,5-benzoic acid solution is slowly added to solution A and allowed to stand for 10 to 16 hours. The precipitate is collected, washed, and dried. The resulting sample is labeled Mn-MOF.

[0008] (2)Mn μ CeO x Catalyst preparation

[0009] The Mn-MOF powder is added to the cerium salt solution and mixed, and then centrifuged, washed, dried and calcined in sequence to obtain Mn μ CeO x catalyst, where μ represents the molar ratio of Mn / Ce;

[0010] (3) Ru, V dual doping

[0011] Mn μ CeO x The catalyst is added to the solvent and mixed to obtain a suspension. The vanadium salt and ruthenium salt are then added to the suspension and mixed again. After mixing, the mixture is dried and calcined twice to obtain the final product RuV / Mn μ CeO x .

[0012] In the above preparation method: the high molecular polymer described in step (1) is polyvinyl pyrrolidone, and the mass ratio of manganese salt, high molecular polymer and 1,3,5-benzoic acid is 0.1-1:1-4:0.5-1.5.

[0013] In the above preparation method: in step (1), the drying is carried out in a vacuum drying oven, the drying temperature is 70-90° C., and the drying time is 10-14 h.

[0014] In the above preparation method: in step (2), the calcination temperature is 300-600° C., and the calcination time is 2-4 hours.

[0015] In the above preparation method: in step (3), the first drying temperature is 40-70° C., the calcination time is 2-4 h, the calcination temperature is 250-400° C., and the calcination atmosphere is 5-15% H 2 / Ar atmosphere.

[0016] In the above preparation method: in step (3), the second drying temperature is 40-70° C., the calcination time is 2-4 h, the calcination temperature is 600-800° C., and the calcination atmosphere is 5-15% H2 / Ar atmosphere.

[0017] In the above preparation method: the manganese salt described in step (1) is Mn(OAc)2·4H2O, and the cerium salt is Ce(NO3)3·6H2O; the vanadium salt described in step (3) is NH4VO3, and the ruthenium salt is Rucl3·3H2O.

[0018] In the above preparation method: RuV / Mn μ CeO x The mass ratio of cerium oxide, manganese oxide, ruthenium oxide and vanadium oxide is 1-5:1-5:0.1-5:0.1-5.

[0019] In some preferred technical solutions, the mass ratio of cerium oxide, manganese oxide, ruthenium oxide and vanadium oxide is 1-5:1-3:0.1-1.5:0.1-1.

[0020] A ruthenium- and vanadium-doped cerium-manganese catalyst for denitration and VOCs removal is prepared by the above method.

[0021] In the technical solution of the present invention, the catalyst prepared by the above method is used as a catalyst to synergistically remove VOCs and NO x Application in this area.

[0022] Beneficial effects:

[0023] (1) Metal-organic frameworks (MOFs) have potential applications in various fields due to their unique structure and function. The cerium-manganese catalyst with a MOF structure prepared by the coprecipitation method of the present invention has more active centers and excellent redox ability.

[0024] (2) Effect of cerium (Ce) oxide content on the MnCeO x The micromorphology and crystal structure of the catalyst, as well as the adsorption and activation of o-DCB molecules, are extensively affected. Modification of manganese (Mn) oxides can provide more oxygen vacancies, enhancing the catalyst's low-temperature denitrification performance. Ruthenium (Ru) composite oxides can maintain stability under VOC oxidation conditions in the presence of water vapor, improving the catalyst's water resistance and thus extending its service life. Vanadium (V) oxides can enhance the catalyst's redox capacity and surface active oxygen adsorption capacity.

[0025] (3) Compared with single metal catalysts, the synergistic effect of mixed metals gives the catalyst excellent stability and oxidation performance, and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the removal rate of NO by the catalyst in Examples 1 to 3 and Comparative Examples 1 to 3.

[0027] Figure 2 It is the removal rate of o-dichlorobenzene by the catalyst in Examples 1 to 3 and Comparative Examples 1 to 3.

[0028] Specific embodiment

[0029] The present invention will be further described below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto:

[0030] Example 1

[0031] (1) Preparation of Mn-MOF catalyst

[0032] 0.48 g Mn(OAc)2·4H2O and 2 g polyvinylpyrrolidone (PVP) were dissolved in 100 mL of a mixture of ethanol and deionized water (V 乙醇 :V 水 =2:1) ​​to form solution A. 0.9 g of 1,3,5-benzoic acid was dissolved in 30 ml of a mixed solution of ethanol and deionized water (V 乙醇 :V 水 =2:1) ​​to form Solution B. Solution B was slowly dripped into Solution A and allowed to stand for 12 hours. The white precipitate was then washed three times with methanol, collected, centrifuged, and dried in a vacuum oven at 80°C for 12 hours. The resulting sample was labeled Mn-MOF.

[0033] (2)Mn μ CeO x Catalyst preparation

[0034] First, 0.326g of Ce(NO3)3·6H2O was dissolved in 15ml of ethanol solution. 1.28g of Mn-MOF prepared in step (1) was dispersed in the solution and ultrasonicated for 30min. The solution was then stirred at room temperature for 1h, washed three times with methanol, and dried. Finally, the sample was calcined at 450°C for 3h to produce the cerium-manganese-based catalyst.

[0035] (3) Ru, V dual doping

[0036] First, the catalyst prepared in step (2) was added to 20 ml of deionized water and then ultrasonically treated for 30 minutes. 7.02 mg of NH4VO3 and 26.1 mg of RuCl3 were added to the suspension and ultrasonically treated again for 30 minutes. Then, the suspension was placed in a 50°C water bath and kept stirring continuously until the solvent evaporated. The sample was dried in a vacuum oven at 60°C overnight, and then the sample was transferred to a tube furnace and reacted at 300°C for 3 hours under a 10% H2 / Ar atmosphere. After that, the prepared sample was repeatedly washed with deionized water and centrifuged to wash away residual ions, and then dried in a vacuum oven at 60°C overnight. The sample was then transferred to a tube furnace and reacted at 700°C for 3 hours under a 10% H2 / Ar atmosphere to finally prepare a ruthenium and vanadium dual-doped cerium-manganese-based catalyst (the mass ratio of cerium oxide, manganese oxide, ruthenium oxide and vanadium oxide was 3.12:1.56:0.16:0.35).

[0037] (4) Catalyst activity test

[0038] The prepared catalyst was weighed and loaded into a catalyst performance evaluation reactor, with a mass of 1.936 g. The quartz tube in the evaluation reactor had an inner diameter of 30 mm, and simulated gas was introduced for activity evaluation. The simulated gas composition was: NO (400 ppm), NH3 (400 ppm), o-dichlorobenzene (40 ppm), O2 (11%), and N2 as a carrier gas, with a total gas flow rate of 1000 mL / min. The catalytic reaction was tested at a temperature range of 200-400°C. The test results showed that at 200°C, after 15 minutes, the NO removal efficiency was 85.7%, and the o-dichlorobenzene removal efficiency was 80.6%. After two hours of reaction, the catalyst gained 0.132 g, a weight gain of 6.8%.

[0039] Example 2

[0040] (1) The preparation of Mn-MOF catalyst was the same as in Example 1.

[0041] (2)Mn μ CeO x Catalyst preparation

[0042] First, 0.0978g of Ce(NO3)3·6H2O was dissolved in 15ml of ethanol. 1.28g of the Mn-MOF prepared in step (1) was dispersed in the solution and ultrasonicated for 30min. The solution was then stirred at room temperature for 1h, washed three times with methanol, and dried. Finally, the sample was calcined at 450°C for 3h to produce the cerium-manganese-based catalyst.

[0043] (3) Ru, V dual doping

[0044] First, the catalyst prepared in step (2) was added to 20 ml of deionized water and then ultrasonically treated for 30 minutes. 11.7 mg of NH4VO3 and 15.6 mg of RuCl3 were added to the suspension and ultrasonically treated again for 30 minutes. Then, the suspension was placed in a 50°C water bath and kept stirring continuously until the solvent evaporated. The sample was dried in a vacuum oven at 60°C overnight and then reduced at 300°C in a 10% H2 / Ar atmosphere for 3 hours. Afterwards, the prepared sample was repeatedly washed with deionized water and centrifuged to wash away residual ions, and then dried in a vacuum oven at 60°C overnight. Finally, the sample was reduced at 700°C in a 10% H2 / Ar atmosphere for 3 hours to prepare a ruthenium and vanadium dual-doped cerium-manganese-based catalyst (the mass ratio of cerium oxide, manganese oxide, ruthenium oxide and vanadium oxide was 3.37:1.03:0.53:0.61).

[0045] (4) Catalyst activity test

[0046] The prepared catalyst was weighed and loaded into a catalyst performance evaluation reactor, with a mass of 1.072 g. The quartz tube in the evaluation reactor had an inner diameter of 30 mm, and simulated gas was introduced for activity evaluation. The simulated gas composition was: NO (400 ppm), NH3 (400 ppm), o-dichlorobenzene (40 ppm), O2 (11%), and N2 as a carrier gas. The total gas flow rate was 1000 mL / min. The catalytic reaction test temperature range was 200-400°C. The test results showed that at 200°C, after 15 minutes, the NO removal efficiency was 90.5%, and the o-dichlorobenzene removal efficiency was 83.5%. After two hours of reaction, the catalyst weight increased by 0.161 g, with a weight gain ratio of 15.0%.

[0047] Example 3

[0048] (1) Preparation of Mn-MOF catalyst

[0049] 0.84 g Mn(OAc)2·4H2O and 2 g polyvinylpyrrolidone (PVP) were dissolved in 100 mL of a mixture of ethanol and deionized water (V 乙醇 :V 水=2:1) ​​to form solution A. 0.9 g of 1,3,5-benzoic acid was dissolved in 30 ml of a mixed solution of ethanol and deionized water (V 乙醇 :V 水 =2:1) ​​to form Solution B. Solution B was slowly dripped into Solution A and allowed to stand for 12 hours. The white precipitate was then washed three times with methanol, collected, centrifuged, and dried in a vacuum oven at 80°C for 12 hours. The resulting sample was labeled Mn-MOF.

[0050] (2)Mn μ CeO x Catalyst preparation

[0051] First, 0.627 g of Ce(NO₃)₃·6H₂O was dissolved in 15 ml of ethanol. 1.62 g of the Mn-MOF prepared in step (1) was dispersed in the solution and ultrasonicated for 30 min. The solution was then stirred at room temperature for 1 h, washed three times with methanol, and dried. Finally, the sample was calcined at 450°C for 3 h to produce the cerium-manganese-based catalyst.

[0052] (3) Ru, V dual doping

[0053] First, the catalyst prepared in step (2) was added to 20 ml of deionized water and then ultrasonically treated for 30 minutes. 26.3 mg of NH4VO3 and 47.8 mg of RuCl3 were added to the suspension and ultrasonically treated again for 30 minutes. Then, the suspension was placed in a 50°C water bath and kept stirring continuously until the solvent evaporated. The sample was dried in a vacuum oven at 60°C overnight and then reduced at 300°C for 3 hours under 10% H2 / Ar. After that, the prepared sample was repeatedly washed with deionized water and centrifuged to wash away residual ions, and then dried in a vacuum oven at 60°C overnight. Finally, the sample was reduced at 700°C for 3 hours in a 10% H2 / Ar atmosphere to finally prepare a ruthenium and vanadium dual-doped cerium-manganese-based catalyst (the mass ratio of cerium oxide, manganese oxide, ruthenium oxide and vanadium oxide was 3.84:1.87:0.96:0.73).

[0054] (4) Catalyst activity test

[0055] The prepared catalyst was weighed and loaded into a catalyst performance evaluation reactor, with a mass of 2.113 g. The quartz tube in the evaluation reactor had an inner diameter of 30 mm, and simulated gas was introduced for activity evaluation. The simulated gas composition consisted of NO (400 ppm), NH3 (400 ppm), o-dichlorobenzene (40 ppm), O2 (11%), and N2 as a carrier gas, with a total gas flow rate of 1000 mL / min. The catalytic reaction was tested at a temperature range of 200-400°C. Test results showed that at 200°C, after 15 minutes, the NO removal efficiency was 93.7%, and the o-dichlorobenzene removal efficiency was 87.2%. After two hours of reaction, the catalyst weight increased by 0.225 g, representing a weight gain of 10.6%.

[0056] Comparative Example 1

[0057] (1) Preparation of Mn-MOF catalyst

[0058] The conditions are the same as step (1) in Example 1;

[0059] (2)Mn μ CeO x Catalyst preparation

[0060] The conditions are the same as step (2) in Example 1;

[0061] (3) Catalyst activity test

[0062] The test conditions were the same as those in step (4) of Example 1, and the catalyst weighed 2.472 g. The test results showed that within the temperature range of 200-400°C, the NO removal efficiency ranged from a minimum of 60.2% to a maximum of 75.3%. The o-dichlorobenzene removal efficiency ranged from a minimum of 52.6% to a maximum of 67.1%. After two hours of reaction, the catalyst gained 1.284 g, a weight gain of 51.94%.

[0063] (4) Contrast effect

[0064] Compared to Example 1, the sample without ruthenium and vanadium dual doping exhibited significant decreases in NO removal and o-dichlorobenzene removal efficiency. This is likely due to the lack of ruthenium and vanadium dual doping, which reduced the number of active sites and led to decreased catalyst activity. Furthermore, the catalyst's hydrophobicity decreased, leading to significant weight gain after two hours of reaction.

[0065] Comparative Example 2

[0066] (1) Preparation of Mn-MOF catalyst

[0067] The conditions are the same as step (1) in Example 1;

[0068] (2)Mn μ CeO x Catalyst preparation

[0069] The conditions are the same as step (2) in Example 1;

[0070] (3) Ru doping

[0071] In step (3), NH4VO3 was not added, and other conditions were the same as those in step (3) of Example 1;

[0072] (4) Catalyst activity test

[0073] The test conditions were the same as those in step (4) of Example 1, and the catalyst weighed 1.812 g. The test results showed that within the temperature range of 200-400°C, the NO removal efficiency ranged from a minimum of 63.3% to a maximum of 75.3%. The o-dichlorobenzene removal efficiency ranged from a minimum of 59.6% to a maximum of 70.3%. After two hours of reaction, the catalyst gained 0.338 g, a weight gain of 18.4%.

[0074] (5) Contrast effect

[0075] Compared with Example 1, the catalyst prepared was only doped with Ru. The NO conversion rate of the sample reached over 70%, and the o-dichlorobenzene removal efficiency decreased significantly, which may be due to the lack of vanadium doping, which reduced the active sites and led to the decline in catalyst activity.

[0076] Comparative Example 3

[0077] (1) Preparation of Mn-MOF catalyst

[0078] The conditions are the same as step (1) in Example 3;

[0079] (2)Mn μ CeO x Catalyst preparation

[0080] The conditions are the same as step (2) in Example 3;

[0081] (3) V doping

[0082] In step (3), RuCl 3 was not added, and other conditions were the same as those in step (3) of Example 3;

[0083] (4) Catalyst activity test

[0084] The test conditions were the same as those in step (4) of Example 3, and the catalyst weighed 2.483 g. The test results showed that within the temperature range of 200-400°C, the NO removal efficiency ranged from a minimum of 70.5% to a maximum of 82.3%. The o-dichlorobenzene removal efficiency ranged from a minimum of 62.6% to a maximum of 73.2%. After two hours of reaction, the catalyst gained 0.878 g, a weight gain of 35.3%.

[0085] (5) Contrast effect

[0086] Compared with Example 1, the catalyst prepared was only doped with Ru. The NO removal rate and o-dichlorobenzene removal efficiency of the sample decreased significantly, and the catalyst weight increased significantly after the reaction. Analysis showed that the reason for this may be that the lack of Ru doping reduced the hydrophobicity of the catalyst, resulting in reduced catalytic performance.

Claims

1. A method for preparing a ruthenium- and vanadium-doped cerium-manganese catalyst for denitration and VOCs removal, characterized by: The preparation method of the catalyst is as follows: (1) Preparation of Mn-MOF Manganese salt and polymer are dissolved in a solvent to form solution A. 1,3,5-benzoic acid solution is slowly added to solution A and allowed to stand for 10-16 hours. The precipitate is collected, washed, and dried. The resulting sample is labeled Mn-MOF. (2) Mn μ CeO x Catalyst preparation The Mn-MOF powder is added to the cerium salt solution and mixed, and then centrifuged, washed, dried and calcined in sequence to obtain Mn μ CeO x catalyst, wherein μ represents the molar ratio of Mn / Ce; in step (2), the calcination temperature is 300-600° C., and the calcination time is 2-4 h; (3) Ru, V dual doping Mn μ CeO x The catalyst is added to the solvent and mixed to obtain a suspension. The vanadium salt and ruthenium salt are then added to the suspension and mixed again. After mixing, the mixture is dried twice and calcined twice to obtain the final product RuV / Mn μ CeO x ; In step (3), the first drying temperature is 40-70°C; the first calcination time is 2-4 hours, the calcination temperature is 250-400°C, and the calcination atmosphere is 5-15% H2 / Ar atmosphere; The second drying temperature is 40~70℃; the second calcination time is 2~4h, the calcination temperature is 600~800℃, and the calcination atmosphere is 5~15% H2 / Ar atmosphere; RuV / Mn μ CeO x The mass ratio of cerium oxide, manganese oxide, ruthenium oxide and vanadium oxide is 1~5:1~5:0.1~5:0.1~5.

2. The preparation method according to claim 1, wherein: The high molecular weight polymer in step (1) is polyvinyl pyrrolidone, and the mass ratio of manganese salt, high molecular weight polymer and 1,3,5-benzoic acid is 0.1~1:1~4:0.5~1.

5.

3. The preparation method according to claim 1, wherein: In step (1), the drying is carried out in a vacuum drying oven, the drying temperature is 70-90°C, and the drying time is 10-14 hours.

4. The preparation method according to claim 1, wherein: The manganese salt in step (1) is Mn(OAc)2·4H2O, the cerium salt in step (2) is Ce(NO3)3·6H2O; the vanadium salt in step (3) is NH4VO3, and the ruthenium salt is RuCl3·3H2O.

5. The preparation method according to claim 1, wherein: The mass ratio of cerium oxide, manganese oxide, ruthenium oxide and vanadium oxide is 2~4:1~2:0.1~1.5:0.1~1.

6. A ruthenium- and vanadium-doped cerium-manganese catalyst for denitration and VOCs removal, characterized by: The catalyst is prepared by the method according to any one of claims 1 to 5.

7. The catalyst prepared by the method of claim 1 is effective in catalytically removing VOCs and NO x Application in this area.

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