A low-temperature simultaneous removal of NO x Supported catalyst for toluene and preparation method and application thereof

Abstract

The present invention belongs to the field of environmental protection and environmental catalysis, and specifically relates to a method for simultaneously removing NO at low temperature. x The preparation method of the catalyst adopts an ethanol dispersion method, uses ethanol as a solvent to prepare a metal salt solution containing a cerium source and a zirconium source, mixes and stirs the metal salt solution with a CuSAPO-34 carrier, loads the Ce salt and the Zr salt on the CuSAPO-34 carrier, and calcines in an oxygen atmosphere to obtain a supported CeZrO x / CuSAPO‑34 catalyst. The obtained catalyst has a high activity for NO x It has the advantages of wide removal temperature window, high removal activity and stable removal performance.

Description

Technical Field

[0001] The present invention belongs to the field of environmental protection and environmental catalysis, and specifically relates to a method for simultaneously removing NO at low temperature. x A supported catalyst for the synthesis of toluene and toluene, and a preparation method and application thereof. Background Art

[0002] In recent years, my country's atmospheric pollution is still severe. x ) and volatile organic pollutants (VOCs) account for nearly 30% of anthropogenic emissions. Among atmospheric pollutants, NO x and VOCs are the main pollutants and are also important precursors to the formation of fine particles and ozone (O3). x There is a considerable level of treatment, but the VOCs in the flue gas have not been effectively treated. SCR devices can be used to synergistically catalytically remove NO x No additional treatment equipment is required, which can reduce costs and save construction space. Under the action of the catalyst, NO can be achieved in the low temperature range. x and VOCs are controlled in coordination, among which NO x The most typical example is the synergistic removal of toluene. The key to achieving this synergistic removal technology is to develop a low-temperature denitrification synergistic control VOCs catalyst with high efficiency and strong resistance to deactivation.

[0003] The catalyst removes NO at low temperature x The key to the technology of NO and toluene is to develop NO based on the characteristics of SCR catalyst. x The catalyst for the synergistic removal of toluene has a series of problems such as narrow temperature window for simultaneous removal, low activity, and poor stability, making it difficult to be applied in actual industry. The currently in-situ synthesized CuSAPO-34 molecular sieve has a wide denitration temperature window, excellent denitration catalytic activity, hydrothermal stability, and high N2 selectivity, but poor catalytic oxidation activity for toluene.

[0004] Based on this, a novel method for NO x It is very important to have a catalyst with a wide temperature window, high activity and stability for the simultaneous removal of toluene and toluene. Summary of the invention

[0005] In order to solve the shortcomings and deficiencies of the prior art, the first object of the present invention is to provide a low temperature and simultaneous removal of NO x A method for preparing a supported catalyst for NO and toluene, wherein the preparation process involved in the method is easy to operate, the raw materials are environmentally friendly and readily available, and the prepared catalyst has good x It has excellent removal activity and stability for both 2-nitrogen and toluene.

[0006] The second object of the present invention is to provide a method for simultaneously removing NO at low temperature prepared by the above method. x and toluene supported catalyst, the provided catalyst for NO x It has excellent removal activity and stability for both 2-nitrogen and toluene.

[0007] The third object of the present invention is to provide the above catalyst for removing NO x and VOCs systems, the activity evaluation test shows that the catalyst provided by the present application has a x It has excellent removal activity and stability for both NO and toluene, and can be used for simultaneous removal of NO x and VOCs systems.

[0008] In order to achieve the first object of the present invention, the technical solution provided by the present invention is: a method for simultaneously removing NO at low temperature x The invention discloses a method for preparing a supported catalyst of CeZrO2 and toluene, wherein a metal salt solution containing a cerium source and a zirconium source is prepared by an ethanol dispersion method using ethanol as a solvent, the metal salt solution is mixed with a CuSAPO-34 carrier and stirred, so that Ce ions and Zr ions are loaded on the CuSAPO-34 carrier, and the supported CeZrO2 is obtained by calcining in an oxygen atmosphere. x / CuSAPO-34 catalyst;

[0009] In the catalyst, the mass percentage of [Ce]+[Zr] / CuSAPO-34 is 10-30%, and the molar ratio of Ce to Zr is 1:0.2-0.35.

[0010] It should be noted that [Ce] and [Zr] in [Ce]+[Zr] / [CuSAPO-34] are calculated based on the mass of Ce and Zr elements.

[0011] According to some preferred embodiments, in the catalyst, the mass percentage of [Ce]+[Zr] / CuSAPO-34 is 20%, and the molar ratio of Ce to Zr is 1:0.25.

[0012] According to some preferred embodiments, the metal salt solution further contains hexadecyltrimethylammonium bromide, and the added amount of the hexadecyltrimethylammonium bromide is 0.05-0.1 g / ml ethanol.

[0013] According to some preferred embodiments, the preparation method comprises the following steps:

[0014] (1) Preparation of metal salt solution: dissolving a certain proportion of copper source, cerium source and hexadecyltrimethylammonium bromide in anhydrous ethanol;

[0015] (2) Dispersion treatment: adding the CuSAPO-34 molecular sieve carrier to the metal salt solution obtained in step (1) and performing a dispersion and stirring treatment;

[0016] (3) evaporating the solvent: evaporating the dispersion obtained in step (2) to remove the solvent in the dispersion;

[0017] (4) Calcination: The sample obtained in step (3) is dried and activated by calcination in air to obtain CeZrO x / CuSAPO-34 catalyst.

[0018] According to some preferred embodiments, the dispersion and stirring treatment time in step (2) is 0.5 to 1.5 hours; preferably, the dispersion and stirring treatment time is 1 hour.

[0019] According to some preferred embodiments, the evaporation method in step (3) is carried out in a water bath, and the evaporation temperature is 60 to 90° C.

[0020] Preferably, the evaporation temperature is 80°C.

[0021] According to some preferred embodiments, the calcination temperature in step (4) is 350-450°C, and the holding time is 1-3 h;

[0022] Preferably, the calcination temperature is 400° C. and the holding time is 2 h.

[0023] According to some preferred embodiments, the CuSAPO-34 molecular sieve carrier in step (2) is prepared by an in-situ synthesis method, and the raw materials for preparing the in-situ synthesized CuSAPO-34 catalyst are calculated based on the effective ingredients, C6H 15 The molar ratios of N, Al2O3, H3PO4, SiO2, Cu(CH3COO)2·H2O, H2O, and PEG600 are 3.1:1:2:0.6:0.15:68:0.04.

[0024] The above CeZrO x / Preparation method of CuSAPO-34 catalyst, CeZr metal oxide is loaded on acidic CuSAPO-34 molecular sieve carrier by CTAB-assisted ethanol impregnation method, so that CeZrO x / CuSAPO-34-CTAB has higher dispersion and higher concentration of Ce 3+ The redox and acidity of the catalyst are coordinated and unified, which can achieve NO x The reduction and catalytic oxidation of toluene with organic synergistic catalysts.

[0025] In order to achieve the above second purpose, the technical solution provided by the present invention is to provide a low temperature and NO removal x The prepared CeZrO x / CuSAPO-34 catalyst in the temperature range of 265~350℃, NO x Conversion rate and toluene conversion rate> 80%, with good low temperature and simultaneous removal of NO x and toluene, and can be well applied to remove NO at low temperature x and toluene system.

[0026] In order to achieve the third purpose, the technical solution provided by the present invention is: providing the above catalyst to remove NO x and applications in VOCs systems;

[0027] Preferably, NO is removed simultaneously x and the VOCs system is a fixed bed reactor; and / or, the removal condition is a gas flow rate of 500 mL∙min -1 ~2000mL∙min -1 , the reaction space velocity is 70,000 mL∙g -1 ∙h -1 ~80,000 mL∙g -1 ∙h -1 .

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The technical solution of the present invention improves the dispersibility of CeZr metal oxide by introducing cationic surfactant hexadecyltrimethylammonium bromide (CTAB), enhances the interaction between Ce, Zr and CuSAPO-34, regulates the redox ability of the catalyst, and enables the catalyst to have good low-temperature and simultaneous NO removal x and toluene activity and stability, suitable for simultaneous removal of NO in SCR devices x and toluene.

[0030] 2. CeZrO provided by this application x / The preparation method of CuSAPO-34 catalyst involves simple and easy preparation steps, environmentally friendly raw materials, and cheap and easy to obtain. The prepared catalyst is effective for removing NO x It has excellent removal activity and stability for both 2-nitrogen and toluene, and has very good industrial application and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0032] Figure 1The catalysts in Examples 1 to 2 and Comparative Examples 1 to 3 simultaneously remove NO x NO under toluene flue gas conditions x Remove active test graph;

[0033] Figure 2 The catalysts in Examples 1 to 2 and Comparative Examples 1 to 3 simultaneously remove NO x Toluene removal activity test diagram under toluene flue gas conditions;

[0034] Figure 3 The catalyst in Examples 1-2 removes NO at the same time x Removal of NO in toluene atmosphere x Stability test diagram;

[0035] Figure 4 The catalyst in Examples 1-2 removes NO at the same time x Stability test diagram of removing toluene in toluene atmosphere;

[0036] Figure 5 The XRD patterns of the catalysts in Comparative Example 1 and Examples 1 to 2 are shown in FIG.

[0037] Figure 6 It is the EDS-mapping spectrum of the catalyst in Examples 1-2. DETAILED DESCRIPTION

[0038] The present invention provides a method for simultaneously removing NO at low temperature. x The invention is further described in conjunction with a specific embodiment of the invention. However, the embodiments of the invention are not limited thereto. If there are process parameters not specifically noted, conventional techniques may be used.

[0039] Example 1

[0040] (1) Preparation of CuSAPO-34 carrier: The raw material molar composition of the in situ synthesized CuSAPO-34 catalyst is 3.1C6H 15N: 1 Al2O3: 2 H3PO4: 0.6 SiO2: 0.15 Cu(CH3COO)2·H2O: 68 H2O: 0.04PEG600. The raw material mole ratio of the catalyst was reduced by 0.06 times year-on-year. After 13.83 g phosphoric acid (H3PO4, 85 wt%) and 20.00 g deionized water were mixed evenly, 8.88 g pseudo-thin mother diaspore (A12O3, 68.9 wt%) was added to the above solution. After stirring for one hour, 7.21 g silica sol (SiO2, 30 wt%) was added thereto and stirred for half an hour. 1.80 g copper acetate (Cu(CH3COO)2·H2O, 99 wt%) was dissolved in 20.00 g deionized water and added dropwise to the above solution. After stirring for 0.5 hours, 18.82 g template triethylamine (C6H 15 N, 99 wt%) and the remaining deionized water, and continue stirring for 2 hours, then add PEG600 and stir for another 4 hours. The obtained gel was transferred into a 100 mL stainless steel synthesis kettle with a polytetrafluoroethylene liner, sealed, transferred into an oven, and aged for 1 hour. Then, the temperature was raised to 200°C at a rate of 3°C / min, crystallized at 200°C for 48 hours, filtered, washed with deionized water until neutral, dried at 110°C for 12 hours, and calcined at 30°C in air at a rate of 1°C / min to 550°C for 6 hours to remove the organic template.

[0041] (2) Ce 0.8 Zr 0.2 O x / CuSAPO-34-CTAB (abbreviated as Ce 0.8 Zr 0.2 Preparation of CeO-ZrO / CuA34-C: CeO-ZrO / CuA34-C was prepared by ethanol dispersion method assisted by surfactant CTAB. x Loaded on the surface of CuSAPO-34. First, 0.5330 g Ce(NO3)3·6H2O, 0.0710 g ZrO(NO3)2 and 0.30 g CTAB were completely dissolved in 40 mL ethanol and stirred for 0.5 h, 1.0 g CuSAPO-34 was weighed and added to the above solution, stirred for another 1 h, and then placed in a water bath at 80°C and stirred dry. The obtained solid was placed in an oven at 100°C for 12 h, and after grinding, it was placed in a tube furnace and calcined at 400°C for 2 h under aerobic conditions, with a heating rate of 5°C / min.

[0042] Example 2

[0043] (1) Preparation of carrier CuSAPO-34, the preparation method is the same as step (1) of Example 1;

[0044] (2) Ce0.8 Zr 0.2 O x / CuSAPO-34 (abbreviated as Ce 0.8 Zr 0.2 Preparation of / CuA34): First, 0.5330 g Ce(NO3)3·6H2O and 0.0710 g ZrO(NO3)2 were completely dissolved in 40 mL ethanol and stirred for 0.5 h. 1.0 g CuSAPO-34 was weighed and added to the above solution, stirred for 1 h, and then placed in a water bath at 80°C and stirred to dry. The obtained solid was placed in an oven at 100°C for 12 h, ground and placed in a tubular furnace and calcined at 400°C for 2 h under aerobic conditions with a heating rate of 5°C / min.

[0045] Comparative Example 1

[0046] In this comparative example, CuSAPO-34 without Ce and Zr loading is used as the catalyst (CuA34 for short), and its preparation method is the same as step (1) of Example 1.

[0047] Comparative Example 2

[0048] (1) Preparation of carrier CuSAPO-34, the preparation method is the same as step (1) of Example 1;

[0049] (2) Ce 0.9 Zr 0.1 O x / CuSAPO-34 (abbreviated as Ce 0.9 Zr 0.1 Preparation of / CuA34): First, 0.5780 g Ce(NO3)3·6H2O and 0.0342 g ZrO(NO3)2 were completely dissolved in 40 mL ethanol and stirred for 0.5 h. 1.0 g CuSAPO-34 was weighed and added to the above solution, stirred for 1 h, and then placed in a water bath at 80°C and stirred dry. The obtained solid was placed in an oven at 100°C for 12 h, ground and placed in a tubular furnace and calcined at 400°C for 2 h under aerobic conditions with a heating rate of 5°C / min.

[0050] Comparative Example 3

[0051] (1) Preparation of carrier CuSAPO-34, the preparation method is the same as step (1) of Example 1;

[0052] (2) Ce 0.7 Zr 0.3 O x / CuSAPO-34 (abbreviated as Ce 0.7 Zr 0.3Preparation of CuSAPO-34: First, 0.4846 g Ce(NO3)3·6H2O and 0.1106 g ZrO(NO3)2 were completely dissolved in 40 mL ethanol and stirred for 0.5 h. 1.0 g CuSAPO-34 was weighed and added to the above solution, stirred for 1 h, and then placed in a water bath at 80°C and stirred dry. The obtained solid was placed in an oven at 100°C for 12 h, ground and placed in a tubular furnace and calcined at 400°C for 2 h under aerobic conditions with a heating rate of 5°C / min.

[0053] Test Example 1: Activity Evaluation Test

[0054] The catalysts prepared in the examples and comparative examples were placed in a quartz tube fixed bed reactor for activity evaluation using laboratory simulated flue gas conditions. Toluene atmosphere was introduced into the SCR denitration system using a liquid phase stripping method. The amount of toluene added was controlled by adjusting the flow rate of stripping N2 and the temperature of the thermostatic bath. The solid catalyst bed was 0.8 g (40-60 mesh). In the experiment, the simulated atmosphere composition was 500 ppm NH3, 500 ppm NO, 5 vol.% O2, 100 ppm C7H8, N2 was used as a balance gas, and the gas flow rate was 1000 mL∙min -1 , the reaction space velocity is 75,000 mL∙g -1 ∙h -1 The NO, N2O, and NO2 in the gas before and after the reaction were detected by the GASMET DX4000 flue gas analyzer, and C7H8 was detected by the hydrogen flame ionization detector (FID Ⅱ) in the gas chromatograph (GC9790Ⅱ). The results are shown in Tables 1-2 and Figures 1-2 As shown:

[0055] Table 1 Denitrification activity evaluation results of the examples and comparative examples

[0056]

[0057] Table 2 Evaluation results of detoluene activity of the embodiments and comparative examples

[0058]

[0059] From Tables 1 and 2, Figure 1 , 2 It can be seen that Comparative Example 1 has excellent denitration activity, but its toluene oxidation performance is poor. Example 2, Comparative Examples 2 and 3 are different ratios of CeZr, among which Ce 0.8 Zr 0.2 O x / CuSAPO-34 simultaneous removal of NO x The temperature window of Ce and toluene is the widest. Thus, it has good simultaneous removal activity.0.8 Zr 0.2 O x / CuSAPO-34-CTAB and Ce prepared without CTAB 0.8 Zr 0.2 O x / CuSAPO-34 catalyst samples all achieved good low-temperature denitrification activity, reaching nearly 100% NO x The toluene conversion rate of Example 1 was 80% at 265°C, while the toluene removal performance of Example 2 (293°C to 80% T) was significantly different. 80 ) is significantly worse than that in Example 1, which further indicates that CTAB as a surfactant improves the activity of the catalyst in low-temperature catalytic oxidation of toluene, and the denitrification activity remains relatively stable, broadening the scope of simultaneous removal of toluene and NO x reaction temperature window.

[0060] Test Example 2: Stability Performance Test

[0061] Testing the catalyst for simultaneous removal of NO x The stability of the reaction with toluene was studied to study whether the catalyst could maintain stable and continuous synergistic catalytic efficiency at low temperatures. The stability test was carried out at 275°C. In the experiment, the simulated atmosphere composition was 500ppm NH3, 500ppm NO, 5vol.% O2, 100ppm C7H8, N2 as the balance gas, and the total gas flow rate was 1000mL∙min -1 , the reaction space velocity is 75,000 mL∙g -1 ∙h -1 At 275℃, the removal of NO was first tested. x The reaction stability of the catalyst was then tested for the removal of toluene. The reaction lasted for several hours and the catalyst was observed to be stable in NO x NO of the catalyst under the same atmosphere as toluene x and toluene removal stability, and continuously record the reaction data for each period of time, including NO x The activity evaluation data under the simultaneous atmosphere of toluene and ethanol are as follows. NO, N2O, and NO2 in the gas before and after the reaction are detected by GASMET DX4000 flue gas analyzer, and C7H8 is detected by hydrogen flame ionization detector (FID Ⅱ) in gas chromatograph (GC9790Ⅱ). The specific data are shown in Tables 3-4 and Figures 3-4 :

[0062] Table 3 Removal of NO in the examples x Stability test

[0063]

[0064] Table 4 Toluene removal stability test of the embodiment

[0065]

[0066] From Tables 3 to 4 and Figures 3-4 It can be seen that Example 1 and Example 2 have x The toluene and toluene atmospheres all maintained excellent denitration stability. In Example 1, the toluene conversion rate was >85% within 6 hours, and the NO x The conversion rate is about 100%, while the toluene conversion rate of Example 2 is only about 60%, which shows that after CTAB modification, while improving its catalytic oxidation activity of toluene, it also maintains excellent denitration stability.

[0067] according to Figure 5 It can be seen that for Comparative Example 1, typical diffraction peaks related to SAPO-34 were detected in the 2θ range of 5° to 35° (PDF: 00-047-0429). With the addition of Ce and Zr, the diffraction peaks of SAPO-34 were significantly reduced. This is due to the coverage of the crystal structure. The diffraction peaks of SAPO-34 in Example 1 are weaker than those in Example 2. This may be because the assistance of CTAB reduces the agglomeration of metal oxides on the molecular sieve, making CeO2, ZrO x The dispersion on CuSAPO-34 is more uniform, covering the diffraction peak of SAPO-34.

[0068] Figure 6 The EDS mapping of Example 2 (a) and Example 1 (b) shows that Example 2 is loaded with CeO by ethanol dispersion method. x -ZrO x Afterwards, there are many aggregations of metal oxide particles. Example 1 is a catalyst sample modified with CTAB. It can be seen that the Cu and Ce elements in Example 1 are more evenly dispersed, indicating that the preparation method of the present invention improves the dispersibility of the active components.

[0069] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A low-temperature simultaneous removal of NO x The method for preparing a supported catalyst of toluene and toluene is characterized in that: The metal salt solution containing cerium source and zirconium source was prepared by ethanol dispersion method using ethanol as solvent, and the metal salt solution was mixed with CuSAPO-34 carrier and stirred to load Ce salt and Zr salt onto CuSAPO-34 carrier, and then calcined in oxygen atmosphere to obtain loaded CeZrO x / CuSAPO-34 catalyst; In the catalyst, the mass percentage of [Ce]+[Zr] / CuSAPO-34 is 10-30%, and the molar ratio of Ce to Zr is 1:0.2-0.25; The metal salt solution also contains hexadecyltrimethylammonium bromide, and the amount of hexadecyltrimethylammonium bromide added is 0.05-0.1 g / ml ethanol; The preparation method comprises the following steps: (1) Preparation of metal salt solution: dissolving a certain proportion of copper source, cerium source and hexadecyltrimethylammonium bromide in anhydrous ethanol; (2) Dispersion treatment: adding the CuSAPO-34 molecular sieve carrier to the metal salt solution obtained in step (1) and performing a dispersion and stirring treatment; (3) Evaporating the solvent: evaporating the dispersion obtained in step (2) to remove the solvent in the dispersion; (4) Calcination: The sample obtained in step (3) is dried and activated by calcination in air to obtain CeZrO x / CuSAPO-34 catalyst; The prepared CeZrO x / CuSAPO-34 catalyst in the temperature range of 265~350℃, NO x The conversion rate and toluene conversion rate are >80%.

2. Low temperature simultaneous removal of NO according to claim 1 x The method for preparing a supported catalyst of toluene and toluene is characterized in that: In the catalyst, the mass percentage of [Ce]+[Zr] / CuSAPO-34 is 20%, and the molar ratio of Ce to Zr is 1:0.

25.

3. Low temperature simultaneous removal of NO according to claim 1 x The method for preparing a supported catalyst of toluene and toluene is characterized in that: The time of the dispersion and stirring treatment in step (2) is 0.5 to 1.5 hours.

4. Low temperature simultaneous removal of NO according to claim 3 x The method for preparing a supported catalyst of toluene and toluene is characterized in that: The time for the dispersion and stirring treatment is 1 hour.

5. Low temperature simultaneous removal of NO according to claim 1 x The method for preparing a supported catalyst of toluene and toluene is characterized in that: The evaporation method in step (3) is carried out in a water bath at a temperature of 60 to 90°C.

6. Low temperature simultaneous removal of NO according to claim 5 x The method for preparing a supported catalyst of toluene and toluene is characterized in that: The evaporation temperature is 80°C.

7. Low temperature simultaneous removal of NO according to claim 1 x The method for preparing a supported catalyst of toluene and toluene is characterized in that: The calcination temperature in step (4) is 350-450° C., and the holding time is 1-3 h.

8. Low temperature simultaneous removal of NO according to claim 7 x The method for preparing a supported catalyst of toluene and toluene is characterized in that: The calcination temperature is 400° C. and the holding time is 2 h.

9. Low temperature simultaneous removal of NO according to claim 1 x The method for preparing a supported catalyst of toluene and toluene is characterized in that: The CuSAPO-34 molecular sieve carrier in step (2) is prepared by an in-situ synthesis method. The raw materials for preparing the in-situ synthesized CuSAPO-34 catalyst are calculated based on the effective ingredients, C6H 15 The molar ratio of N, Al2O3, H3PO4, SiO2, Cu(CH3COO)2·H2O, H2O, and PEG600 is 3.1:1:2:0.6:0.15: 68：0.04。 10. A low-temperature simultaneous removal of NO obtained by the preparation method according to any one of claims 1 to 9 x and toluene supported catalyst.

11. A method for simultaneously removing NO at low temperature as claimed in claim 10 x and toluene supported catalyst for simultaneous removal of NO at low temperature x and VOCs systems.

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