A confined CoCeO x @ZSM-5 Materials, Preparation Methods, and Applications

Abstract

This invention discloses a confined CoCeO x The invention relates to @ZSM-5 materials, preparation methods, and applications, including the following steps: Step 1: Add Ce(NO3)2 and Co(NO3)2 to a bromobrown trimethylammonium solution and stir until homogeneous to form solution A; Step 2: Add 2-methylimidazole to a solvent to form solution B; Step 3: Under vacuum, add ZSM-5 to solution A, then dropwise add solution B to the above liquid and stir, followed by aging; Step 4: Centrifuge, wash, and dry to obtain the CoCeOx@ZSM-5 precursor; Step 5: Calcine the product obtained in Step 4 to obtain the CoCeOx@ZSM-5 material catalyst. The CoCeOx@ZSM-5 catalyst prepared by this invention... x The @ZSM-5 catalyst exhibits significantly improved catalytic combustion activity of 1,2-dichlorobenzene compared to single Co3O4 / ZSM-5, Co3O4@ZSM-5, and CeO2@ZSM-5 catalysts.

Description

Technical Field

[0001] This invention relates to the field of catalytic oxidation nanomaterial preparation and catalytic oxidation decomposition of CVOCs, specifically to a confined CoCeO₂ nanomaterial. x @ZSM-5 material, preparation method and application. Background Technology

[0002] Chlorinated volatile organic compounds (CVOCs), commonly used chemical intermediates and solvents in pesticides and pharmaceuticals, are highly toxic and persistent pollutants, posing serious harm to humans and the environment. Therefore, the complete degradation of CVOCs has attracted continuous attention. Catalytic combustion technology is considered one of the most effective methods for the complete degradation of CVOCs in industry.

[0003] The activity and structural stability of a catalyst are the main factors affecting the catalytic removal of CVOCs, determining the removal efficiency. Currently, catalysts mainly fall into two categories: noble metal catalysts and transition metal oxides. Noble metal catalysts exhibit the best catalytic activity, but their high cost and susceptibility to deactivation limit their application. Transition metal oxide catalysts have attracted widespread attention due to their low cost, high activity, thermal stability, and resistance to poisoning. The current challenge lies in achieving high activity and high structural stability at low temperatures without adding noble metals. Furthermore, the aggregation of active components on the catalyst surface is one of the reasons for low catalyst activity and poor stability. Therefore, the preparation of catalysts with dispersed active components and stable structures is crucial. Summary of the Invention

[0004] To address the above problems, this invention provides a confined CoCeO x @ZSM-5 material, preparation method and application.

[0005] The present invention adopts the following technical solution:

[0006] A confined CoCeO x The preparation method of @ZSM-5 material is characterized by including the following steps:

[0007] Step 1: Add Ce(NO3)2 and Co(NO3)2 to the bromobrown trimethylammonium solution and stir until homogeneous to form solution A; Step 2: Add 2-methylimidazole to the solvent to form solution B;

[0008] Step 3: Under vacuum, add ZSM-5 to solution A, then add solution B dropwise to the above liquid and stir, then let stand;

[0009] Step 4: Centrifuge, wash, and dry to obtain CoCeO x @ZSM-5 precursor;

[0010] Step 5: Calcine the product obtained in Step 4 to obtain CoCeO x @ZSM-5 material.

[0011] Furthermore, in step 1, the ratio of bromobrown trimethylammonium: Co(NO3)2: Ce(NO3)2 is 1:10-60:10-60.

[0012] Furthermore, in step 2, the concentration of 2-methylimidazole is 0.001-30 g / ml.

[0013] Furthermore, in step 3, ZSM-5 and Co + Ce + The dosage ratio is 1:0.001-0.4, the vacuum degree is -0.1 to -0.8 MPa, the treatment time under vacuum is 0.5-6 h, and the temperature is 30-45℃.

[0014] Furthermore, in step 4, the washing is performed with a mixture of water and ethanol in any proportion.

[0015] Furthermore, in step 5, the calcination conditions are calcination at 300–550°C for 2–10 hours, with a heating rate of 1–15°C / min.

[0016] Another aspect of the present invention provides a CoCeO x @ZSM-5 material.

[0017] Another aspect of the present invention provides a CoCeO x Application of ZSM-5 material in catalysts.

[0018] Furthermore, its application in the catalytic combustion of 1,2-dichlorobenzene.

[0019] The beneficial effects of this invention are:

[0020] 1. The raw materials used in this method are all common chemical reagents, which are widely available, inexpensive, and readily available. The preparation process of this invention is simple, requires less equipment, and can rapidly synthesize CoCeO. x @ZSM-5 catalyst, simple process, and highly controllable reaction conditions.

[0021] 2. The vacuum degree selected by the method is -0.1 to -0.8 MPa, the treatment time under vacuum is 0.5-6 h and the treatment temperature is 30-45℃. Within this range, the active components can be highly dispersed in the pores of the mesoporous support, thereby achieving high dispersion of the active components and improving the activity and structural stability of the catalyst.

[0022] 3. The obtained CoCeO xThe ZSM-5 catalyst exhibits excellent reducibility, and its suitable mesoporous structure is beneficial for enhancing the adsorption and activation of reactants.

[0023] 4. The obtained CoCeO x The @ZSM-5 catalyst exhibits significantly improved catalytic combustion activity of 1,2-dichlorobenzene compared to single Co3O4 / ZSM-5, Co3O4@ZSM-5, and CeO2@ZSM-5 catalysts. This is because the CoCeO2 catalyst... x @ZSM-5 catalyst contains CoCeO x The formation of a solid solution and the strong interaction between Co and Ce promote its degradation activity for 1,2-dichlorobenzene. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0025] Figure 1 The diagram shows the catalytic combustion 1,2-dichlorobenzene determination apparatus of Example 1 and Comparative Examples 1-3 of the present invention;

[0026] Figure 2 The XRD patterns are those of Embodiment 1 and Comparative Examples 1-2 of the present invention;

[0027] Figure 3 This is a TEM image of Embodiment 1 of the present invention;

[0028] Figure 4 The stability diagrams of 1,2-dichlorobenzene under catalytic combustion in Example 1 and Comparative Examples 1 and 3 of this invention are shown.

[0029] Figure 5 The diagram shows the catalytic activity of 1,2-dichlorobenzene during combustion in Example 1 and Comparative Examples 1-3 of this invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] A confined CoCeO xThe preparation method of @ZSM-5 material includes the following steps:

[0033] Step 1: Add Ce(NO3)2 and Co(NO3)2 to the bromobrown trimethylammonium solution and stir until homogeneous to form solution A.

[0034] In step 1, the ratio of bromobrown trimethylammonium: Co(NO3)2: Ce(NO3)2 is 1:10-60:10-60.

[0035] Step 2: Add 2-methylimidazole to the solvent to form solution B.

[0036] In step 2, the concentration of 2-methylimidazole is 0.001-30 g / ml.

[0037] Step 3: Under vacuum, add ZSM-5 to solution A, then add solution B dropwise to the above liquid and stir, then let stand.

[0038] In step 3, ZSM-5 and Co + Ce + The dosage was 1:0.001-0.4, the vacuum degree was -0.1 to -0.8 MPa, the treatment time under vacuum was 0.5-6 h, and the temperature was 30-45℃. Step 4: Centrifugation, washing, and drying to obtain CoCeO. x @ZSM-5 precursor.

[0039] Step 4: Centrifuge, wash, and dry to obtain CoCeO x @ZSM-5 precursor.

[0040] In step 4, the washing is performed with a mixture of water and ethanol in any proportion.

[0041] Step 5: Calcine the product obtained in Step 4 to obtain CoCeO x @ZSM-5 material.

[0042] In step 5, the calcination conditions are calcination at 300-550℃ for 2-10 hours, with a heating rate of 1-15℃ / min.

[0043] This invention uses the above preparation method to obtain a CoCeO x The application of ZSM-5 material in catalysts, specifically in the catalytic combustion of 1,2-dichlorobenzene.

[0044] Example 1

[0045] 20 mg of trimethylammonium bromobrown was weighed and dissolved in 30 mL of deionized water at room temperature. The solution was then mixed thoroughly with 0.5 g of Co(NO3)2 and 0.48 g of Ce(NO3)2 to obtain solution A. 9.08 g of 2-methylimidazole was weighed and added to 100 mL of deionized water to obtain solution B. Under vacuum, 0.5 g of ZSM-5 was added to solution A, and then solution B was added dropwise to the above solution with stirring. The mixture was then aged. After centrifugation and washing with deionized water and ethanol, the solution was dried at 80 °C for 6 hours to obtain CoCeO. x @ZSM-5 precursor; calcined at 550℃ for 6 hours to obtain CoCeO x @ZSM-5 catalyst.

[0046] Comparative Example 1

[0047] 20 mg of bromobrown trimethylammonium was weighed and dissolved in 30 mL of deionized water at room temperature and mixed thoroughly. Then, 0.9 g of Co(NO3)2 was added and stirred thoroughly to obtain solution A. 9.08 g of 2-methylimidazole was weighed and added to 100 mL of deionized water to obtain solution B. 0.5 g of ZSM-5 was added to solution A under vacuum, and then solution B was added dropwise to the above liquid and stirred. The mixture was then aged. After centrifugation and washing, the mixture was washed with deionized water and ethanol and dried at 80 °C for 6 hours to obtain the Co3O4@ZSM-5 precursor. The precursor was calcined at 550 °C for 6 hours to obtain the Co3O4@ZSM-5 catalyst.

[0048] Comparative Example 2

[0049] 20 mg of trimethylammonium bromide was weighed and dissolved in 30 mL of deionized water at room temperature and mixed thoroughly. Then, 1.02 g of Ce(NO3)2 was added and stirred thoroughly to obtain solution A. 9.08 g of 2-methylimidazole was weighed and added to 100 mL of deionized water to obtain solution B. 0.5 g of ZSM-5 was added to solution A under vacuum, and then solution B was added dropwise to the above liquid and stirred. The mixture was then aged. After centrifugation and washing, the solution was washed with deionized water and ethanol and dried at 80 °C for 6 hours to obtain the CeO2@ZSM-5 precursor. The precursor was calcined at 550 °C for 6 hours to obtain the CeO2@ZSM-5 catalyst.

[0050] Comparative Example 3

[0051] 0.9 g of Co(NO3)2 was weighed and dissolved in 20 ml of ultrapure water at room temperature and stirred continuously to form solution A. While stirring solution A, 0.5 g of ZSM-5 was added to solution A and stirring was continued for 6 h. The resulting product was dried and calcined in air at 450 °C for 6 h to obtain the Co3O4 / ZSM-5 catalyst.

[0052] Test case

[0053] 1. Schematic diagram of the catalytic activity testing device

[0054] like Figure 1 As shown, the catalytic activity was determined in a fixed-bed continuous flow microreactor. The method of preparation was as follows: 400 mg of catalyst (20–60 mesh) was mixed with 500 mg of quartz sand (20–60 mesh) and placed in a quartz tube reactor with an inner diameter of 10 mm. 1000 ppm of 1,2-dichlorobenzene (also known as o-dichlorobenzene, denoted as o-DCB) was mixed with dry air in a mixing bottle, preheated by a preheater, and then introduced into the quartz tube. The catalyst reacted in the electrically heated quartz tube. The temperature range of the quartz tube was 100–450 °C, and the gas hourly space velocity (GHSV) was 15000 h⁻¹. -1 The reacted gas was passed through a GC-7900 gas chromatograph and FID flame ionization detector from Shanghai Tianmei Chemical Co., Ltd. to determine the concentration of 1,2-dichlorobenzene. A 50m × 0.32mm (ID) × 1.0μm TM-1 capillary column was used. A standard curve for 1,2-dichlorobenzene concentration was established using the external standard method in chromatographic quantitative analysis to calculate the actual concentration of 1,2-dichlorobenzene. The exhaust gas was treated with AC and ethanol before being discharged.

[0055] The catalytic oxidation activity of the catalyst is expressed as the conversion rate of 1,2-dichlorobenzene, and the calculation formula is x = (C in -C out ) / C in *100%, where x is the conversion rate of 1,2-dichlorobenzene, C in and C out The values ​​are the concentrations of 1,2-dichlorobenzene in the gas before and after the reaction, respectively, in ppm.

[0056] 2. X-ray diffraction pattern detection (XRD)

[0057] Figure 2 The XRD patterns of Example 1 and Comparative Examples 1-2 are shown below. Literature review indicates that the XRD results of Example 1 and Comparative Examples 1-2 primarily show characteristic peaks of ZSM-5, suggesting that CoCeO x Co3O4 and CeO2 do not damage the structure of the support. In the XRD results of Comparative Example 2, a characteristic peak belonging to CeO2 crystals was found at an angle of 33.0°, indicating successful loading of CeO2 onto ZSM-5. In Example 1, a characteristic peak belonging to CeO2 crystals was found at an angle of 32.7°, and this peak was shifted from the original CeO2 crystal peak angle of 33.0°, confirming the presence of CoCeO4. x The generation of CoCeO indicates the successful generation of CoCeO. x The sample was loaded onto ZSM-5. The presence of the Co3O4 crystal phase at 36.9° in Comparative Example 1 indicates successful loading of Co3O4 onto ZSM-5. Examples 1 and 2: CoCeOx The peak intensities of Co3O4 and CeO2 are both low, indicating that CoCeO x The high dispersion of Co3O4 and CeO2 on the support surface is beneficial to improving catalytic activity.

[0058] 3. Transmission electron microscopy (TEM) images

[0059] Figure 3 The image shows a TEM image of Example 1, where the active component is highly dispersed inside the support, rather than being loaded on the outer surface of the support.

[0060] 4. Catalytic stability diagram of 1,2-dichlorobenzene during catalytic combustion

[0061] Figure 4 The figures show the stability of 1,2-dichlorobenzene during catalytic combustion in Examples 1, 1, and 3 (Comparative Examples 1 and 3). As can be seen from the figures, Comparative Example 3 exhibited the worst stability within the measured time, with an activity loss of 36% after 900 minutes, indicating severe catalyst sintering. Comparative Example 1, after employing mesoporous confinement, showed improved stability with an activity loss of only 19%, demonstrating that this method is significantly helpful in addressing catalyst sintering. Example 1 showed virtually no activity loss, indicating that adding Ce doping can resolve the catalyst sintering problem.

[0062] Application examples

[0063] The catalytic combustion activity diagrams of 1,2-dichlorobenzene for Examples 1 and Comparative Examples 1-3 are shown in the figure. Figure 4 You can see CoCeO x @ZSM-5 exhibits the best catalytic activity, achieving a 90% conversion rate of 1,2-dichlorobenzene at a temperature of 297℃.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing confined CoCeOx@ZSM-5 material, characterized in that, Includes the following steps: Step 1: Add Ce(NO3)3 and Co(NO3)2 to the bromobrown trimethylammonium solution and stir until homogeneous to form solution A; Step 2: Add 2-methylimidazole to the solvent to form solution B; Step 3: Under vacuum, add ZSM-5 to solution A, then add solution B dropwise to the above liquid and stir, then let stand; ZSM-5 and Co 2+ Ce 3+ The dosage ratio is 1:0.001-0.4, the vacuum degree is -0.1 to -0.8 MPa, the treatment time under vacuum is 0.5-6 h, and the temperature is 30-45℃. Step 4: Centrifuge, wash, and dry to obtain CoCeOx@ZSM-5 precursor; Step 5: Calcine the product obtained in Step 4 to obtain CoCeOx@ZSM-5 material; the calcination conditions are calcination at 300-550℃ for 2-10h, and the heating rate is 1-15℃ / min.

2. The method for preparing a confined CoCeOx@ZSM-5 material according to claim 1, characterized in that, In step 1, the ratio of bromobrown trimethylammonium: Co(NO3)2: Ce(NO3)3 is 1:10-60:10-60.

3. The method for preparing a confined CoCeOx@ZSM-5 material according to claim 1, characterized in that, In step 2, the concentration of 2-methylimidazole is 0.001-30 g / ml.

4. The method for preparing a confined CoCeOx@ZSM-5 material according to claim 1, characterized in that, In step 4, the washing is performed with a mixture of water and ethanol in any proportion.

5. A CoCeOx@ZSM-5 material is obtained by the preparation method described in any one of claims 1-4.

6. The application of the CoCeOx@ZSM-5 material as described in claim 5, characterized in that, Application in the catalytic combustion of 1,2-dichlorobenzene.

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