High-water-resistance Co-Cu-CeO2 solid solution oxide catalyst for catalytic oxidation degradation of styrene

Abstract

The invention relates to the technical field of waste gas treatment, in particular to a high-water-resistance Co-Cu-CeO2 solid solution oxide catalyst for catalytic oxidation degradation of styrene. A catalyst obtained by a conventional method and used for catalytic oxidative degradation of styrene is poor in water resistance, and when a styrene reaction raw material contains a small amount of water, the conversion rate of styrene can be remarkably reduced. In order to solve the problems, the invention provides the high-water-resistance Co-Cu-CeO2 solid solution oxide catalyst for catalytic oxidation degradation of styrene, and during preparation of the catalyst, water-soluble salts such as cobalt nitrate hydrate, cerium nitrate hydrate and copper nitrate hydrate are dissolved in deionized water to obtain a ternary mixed solution, the ternary mixed solution is atomized to form aerosol, and then the aerosol is added into the mixed solution to prepare the high-water-resistance Co-Cu-CeO2 solid solution oxide catalyst for catalytic oxidation degradation of styrene. And performing thermal decomposition and solid-phase reaction through a high-temperature decomposition tube. The catalyst is excellent in water resistance and can still keep good catalytic activity in a water-containing environment. The styrene catalytic oxidation degradation method adopting the catalyst can efficiently and stably degrade styrene, effectively solves the problems of poor water resistance and the like of the existing catalyst, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of waste gas treatment technology, specifically to a highly water-resistant Co-Cu-CeO2 solid solution oxide catalyst for the catalytic oxidation and degradation of styrene. Background Technology

[0002] With the continuous development of the petrochemical industry, the impact of volatile organic compounds (VOCs) on the atmospheric environment has become increasingly significant, attracting public attention. VOCs not only threaten human health, but are also key precursors to summer photochemical smog, urban haze, fine particulate matter (PM2.5), and ozone formation. They are major factors contributing to photochemical pollution, ozone layer depletion, and the greenhouse effect, and urgently require effective control and treatment.

[0003] VOCs are diverse, with olefins playing a crucial role in atmospheric chemical processes due to their high reactivity. Styrene (C8H8), a typical olefin and aromatic hydrocarbon VOC, is widely used in industries such as plastics and rubber, making its emission control a key focus of environmental governance.

[0004] Traditional VOCs treatment methods, such as activated carbon adsorption, direct combustion, and biodegradation, suffer from high energy consumption, low treatment efficiency, and the potential for secondary pollution. Therefore, developing efficient and green VOCs purification technologies has become an important topic in the field of environmental science.

[0005] In recent years, catalytic oxidation technology has attracted much attention due to its excellent performance in the treatment of olefin VOCs such as styrene. This technology has advantages such as high degradation efficiency, low ignition temperature, and clean final products, making it suitable for highly reactive pollutants like styrene. Catalyst performance is crucial in catalytic oxidation systems, directly affecting pollutant degradation efficiency, byproduct formation, and system energy utilization. Given the scarcity and high cost of precious metal resources, developing cost-effective non-precious metal or low-precious metal supported catalysts has become a research trend.

[0006] However, existing catalysts have many shortcomings. The noble metal Pd supported catalyst in patent CN114011391A, using cerium dioxide (CeO2) as a support and loading 0.5-1.5 wt.% of noble metal Pd as the main active component, can achieve a 90% conversion rate in the catalytic oxidation of styrene, but requires a relatively high temperature (T). 90 The temperature is approximately 260-280℃, and it has poor water resistance; after introducing 3 vol.% water vapor, the styrene conversion rate decreases by more than 25 percentage points. The manganese-based oxide catalyst (Mn3O4 / CeO2) in patent number CN113578512A, prepared by co-precipitation, improves the Tconversion of styrene under completely dry conditions. 90The catalytic activity is approximately 250℃, but its main drawback is its poor water resistance. When the reaction atmosphere contains 2 vol.% water vapor, the catalytic activity decreases significantly, with styrene conversion decreasing by about 40%, limiting its application in humid environments. The Cu-Mn-Al ternary composite oxide catalyst in patent number CN112774812A exhibits high intrinsic activity for propylene, with a Tg of propylene at a space velocity of 20000 mL / (g·h). 90 The temperature was approximately 240°C, but no improvement in water resistance was mentioned. Based on the data from the examples, it can be inferred that the catalytic efficiency and stability would deteriorate sharply under high space velocity or water-containing conditions, making it difficult to adapt to complex industrial waste gas environments.

[0007] Furthermore, while catalytic oxidation technology for treating VOCs offers advantages such as high efficiency and clean final products, it also has limitations. On one hand, energy consumption is significant. When treating low-concentration, high-volume waste gas, maintaining catalyst activity requires continuous preheating of the waste gas to the catalytic ignition temperature (typically 200-400℃), resulting in high fuel costs and impacting economic efficiency. On the other hand, the catalytic oxidation process may generate secondary pollution. Improper control of reaction conditions (such as insufficient temperature, excessively high space velocity, or catalyst deactivation) may lead to incomplete oxidation of VOCs such as styrene, generating harmful intermediate byproducts such as aldehydes and ketones. If the waste gas contains nitrogen, nitrogen oxides (NOx) may also be generated under certain conditions. x Existing non-precious metal catalysts have shortcomings in terms of water resistance, low-temperature activity, and by-product control. Their stability is challenged when treating complex waste gases, and conventional preparation methods make it difficult to precisely control the microstructure and surface properties of the catalyst, resulting in low accessibility of active sites and difficulty in controlling reaction pathways.

[0008] In summary, developing a non-precious metal catalyst that combines high and low temperature catalytic activity, excellent water resistance, wide reaction window, and low by-product formation, along with a simple and controllable preparation process, to achieve efficient, economical, and stable degradation of styrene waste gas, has become an urgent problem to be solved in this field. Summary of the Invention

[0009] A problem with existing technologies is that catalysts obtained by conventional methods for the catalytic oxidative degradation of styrene have poor water resistance; when the styrene reactant contains a small amount of water, the conversion rate of styrene decreases significantly. To address this problem, this invention provides a highly water-resistant Co-Cu-CeO2 solid solution oxide catalyst for the catalytic oxidative degradation of styrene, the preparation method of which includes the following steps: (1) Dissolve the cobalt source, cerium source and copper source in deionized water to obtain a ternary mixed solution; (2) The above ternary mixed solution is atomized, and the resulting atomized gas enters the heat-insulated pipe under the action of the carrier gas (the water in the atomized gas evaporates) to form an aerosol; (3) The obtained aerosol enters the high-temperature decomposition tube with the carrier gas and undergoes thermal decomposition and solid-phase reaction, finally obtaining Co-Cu-CeO2 solid solution oxide catalyst.

[0010] Preferably, the cobalt source, cerium source, and copper source are water-soluble cobalt salt, water-soluble cerium salt, and water-soluble copper salt, respectively.

[0011] Preferably, the water-soluble cobalt salt, water-soluble cerium salt, and water-soluble copper salt are hydrated cobalt nitrate, hydrated cerium nitrate, and hydrated copper nitrate, respectively.

[0012] Preferably, the carrier gas is nitrogen or an inert gas.

[0013] Preferably, the molar ratio of elements Co, Ce, and Cu in the cobalt source, cerium source, and copper source is 6:6:0.5.

[0014] Preferably, the temperature in the insulated pipe is 60-70℃.

[0015] Preferably, the temperature in the high-temperature decomposition tube is 500-800℃.

[0016] Beneficial effects: (1) In the prior art, many catalysts used for the catalytic oxidation and degradation of styrene have serious defects in water resistance. However, the Co-Cu-CeO2 solid solution oxide catalyst obtained in Example 1 of this invention exhibits excellent water resistance. In practical applications, industrial waste gas often contains a certain amount of water vapor. This catalyst can maintain stable catalytic activity in complex water-containing environments, effectively avoiding the problem of a significant reduction in catalytic efficiency caused by the presence of water vapor. This greatly broadens the application scenarios of the catalyst, making it more suitable for actual industrial waste gas treatment, especially for the treatment of styrene waste gas in humid environments. (2) T 90 Reaction temperature is one of the important indicators for evaluating catalyst performance; a lower T... 90 Reaction temperature signifies a faster attainment of higher conversion rates in catalytic oxidation reactions, thereby reducing energy consumption and improving economic efficiency. Traditional catalytic oxidation technologies for VOCs require continuous preheating of the waste gas to the catalytic ignition temperature to maintain catalyst activity, making fuel consumption particularly costly when treating low-concentration, high-volume waste gas. The Co-Cu-CeO2 solid solution oxide catalyst obtained in Example 1 of this invention exhibits higher T values ​​during the catalytic oxidation degradation of styrene. 90The reaction temperature is relatively low. Under suitable reaction conditions, styrene can be efficiently converted at a lower temperature, reducing the energy consumption required to preheat the waste gas to a high temperature and lowering operating costs. At the same time, the lower reaction temperature also helps to reduce side reactions that may occur at high temperatures, reducing the probability of the formation of harmful intermediate by-products (such as aldehydes, ketones, etc.) and nitrogen oxides (NOx, when the waste gas contains nitrogen), further improving the environmental friendliness and safety of the catalytic oxidation process; (3) The Co-Cu-CeO2 solid solution oxide catalyst obtained in Example 1 of this invention has excellent water resistance and low T 90 The reaction temperature has a significant advantage in the field of styrene waste gas treatment, providing a better solution for efficient, economical and stable treatment of styrene waste gas, and has broad market application prospects and promotion value. Attached Figure Description

[0017] Figure 1 Example 1: Schematic diagram of the preparation process of the high water-resistant Co-Cu-CeO2 solid solution oxide catalyst.

[0018] Figure 2 Example 1: Schematic diagram of the apparatus used to prepare the high water-resistant Co-Cu-CeO2 solid solution oxide catalyst.

[0019] Figure 3 SEM image of the water-resistant Co-Cu-CeO2 solid solution oxide catalyst obtained in Example 1.

[0020] Figure 4 TEM image of the water-resistant Co-Cu-CeO2 solid solution oxide catalyst obtained in Example 1.

[0021] Figure 5 XRD pattern of the water-resistant Co-Cu-CeO2 solid solution oxide catalyst obtained in Example 1.

[0022] Figure 6 Mapping analysis diagram of the highly water-resistant Co-Cu-CeO2 solid solution oxide catalyst obtained in Example 1.

[0023] Figure 7 When the reactants are styrene or a mixture of styrene and water (1% water, 2% water), the relationship between the styrene conversion rate and the reaction temperature and the CO content of the catalyst obtained in Comparative Example 1 are investigated. X A graph showing the relationship between selectivity and reaction temperature.

[0024] Figure 8 When the reactants are styrene or a mixture of styrene and water (1% water, 2% water), the relationship between the styrene conversion rate and the reaction temperature and the CO content of the catalyst obtained in Comparative Example 2 are investigated.X A graph showing the relationship between selectivity and reaction temperature.

[0025] Figure 9 When the reactants are styrene or a mixture of styrene and water (1% water, 2% water), the relationship between the styrene conversion rate and the reaction temperature and the CO content of the catalyst obtained in Comparative Example 3 are investigated. X A graph showing the relationship between selectivity and reaction temperature.

[0026] Figure 10 When the reactants are styrene or a mixture of styrene and water (1% water, 2% water), the relationship between the styrene conversion rate and the reaction temperature and the CO2 conversion rate of the catalyst obtained in Example 1 are as follows: X A graph showing the relationship between selectivity and reaction temperature.

[0027] Figure 11 When the reactants are styrene or a mixture of styrene and water (1% water, 2% water), the relationship between the styrene conversion rate and the reaction temperature and the CO content of the catalyst obtained in Comparative Example 4 are investigated. X A graph showing the relationship between selectivity and reaction temperature.

[0028] Figure 12 When the reactants are a mixture of styrene and water (1% water), the relationship between styrene conversion and reaction temperature and CO for the catalysts obtained in Example 1 and Comparative Examples 1-4 are as follows: X The relationship between selectivity and reaction temperature.

[0029] Figure 13 When the reactants are a mixture of styrene and water (2% water), the relationship between styrene conversion and reaction temperature, and CO2 conversion rates for the catalysts obtained in Examples 1 and Comparative Examples 1-4 are as follows: X The relationship between selectivity and reaction temperature. Detailed Implementation

[0030] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.

[0031] Example 1

[0032] A method for preparing a highly water-resistant Co-Cu-CeO2 solid solution oxide catalyst for the catalytic oxidative degradation of styrene (a schematic diagram of the preparation process is attached to the instruction manual). Figure 1 As shown, the apparatus used for the preparation is as per the attached instruction manual. Figure 2 As shown below: S1: Weigh out cobalt nitrate (Co(N)) according to a molar ratio of 6:6:0.5. ·6 O), cerium nitrate (Ce(N) ·6 O) and copper nitrate (Cu(N) Dissolve 10g of the product in deionized water and bring the volume up to 50 mL. Shake well and place in a nebulizer bottle. S2: Start the ultrasonic nebulizer to atomize the solution in the nebulization bottle. The generated mist is carried by the carrier gas. The atomized gas enters the insulated pipe at a flow rate of 0.8 L / min. The pipe temperature is maintained at 70℃. The length of the insulated pipe is 50cm. Moisture in the atomized gas evaporates inside the insulated pipe to form aerosol particles (precursor salt compounds). S3: Aerosol particles continue to flow with the carrier gas after exiting the insulated pipe. Upon entering the high-temperature decomposition tube preheated to 600°C, the precursor salt compounds rapidly thermally decompose and undergo a solid-phase reaction, ultimately producing Co-Cu-Ce. Solid solution oxide particles; S4: Co-Cu-Ce The solid solution oxide particles continued to enter the absorption bottle containing deionized water along with the carrier gas, Co-Cu-Ce The solid solution oxide particles were introduced into deionized water. After the reaction was completed, the collected liquid in the absorption bottle was centrifuged (8000 rpm, 3 minutes) and dried (80℃, 12 hours) to obtain a highly water-resistant Co-Cu-CeO2 solid solution oxide catalyst.

[0033] The characterization data of the water-resistant Co-Cu-CeO2 solid solution oxide catalyst obtained in Example 1 are as follows: SEM analysis (as per the instruction manual) Figure 3 As shown in the image, the catalyst exhibits typical open and closed plum-shaped and broken hollow spherical structures, with particle sizes ranging from tens of nanometers to several micrometers. This morphology helps prevent particle agglomeration and sintering, and increases the specific surface area and the number of active sites.

[0034] TEM analysis (as per the instruction manual) Figure 4 As shown): Ce can be clearly observed in the high-resolution TEM image. (111) crystal plane striations and belonging to C (311) crystal plane stripes. The presence of blurred or distorted lattice stripes in the figure indicates the presence of abundant lattice defects in the catalyst, which usually facilitates the formation of oxygen vacancies and enhances catalytic activity.

[0035] XRD analysis (as per the instruction manual) Figure 5 As shown): The spectrum is mainly composed of Ce The structural diffraction peaks are dominant, C The characteristic peaks are weak and broad, indicating that Co species are highly dispersed or partially doped into Ce. Crystal lattice. Due to the low Cu doping concentration, no obvious CuO characteristic diffraction peaks were observed.

[0036] Mapping analysis (as per the instruction manual) Figure 6 As shown in the figure): Elemental surface scan analysis showed that Co, Ce and Cu were uniformly distributed on the catalyst particles, confirming the successful multi-element doping and composite.

[0037] Comparative Example 1 is the same as Example 1, except that in Comparative Example 1, step S1 involves weighing cobalt nitrate (Co(N)) at a molar ratio of 1:1. ·6 O), cerium nitrate (Ce(N) ·6 Dissolve 10g of O in deionized water and bring the volume up to 50mL.

[0038] Comparative Example 2 is the same as Example 1, except that in Comparative Example 2, step S1 involves weighing cobalt nitrate (Co(N)) in a molar ratio of 6:6:1. ·6 O), cerium nitrate (Ce(N) ·6 Dissolve 10g of O in deionized water and bring the volume up to 50 mL.

[0039] Comparative Example 3 is the same as Example 1, except that in Comparative Example 3, step S1 involves weighing cobalt nitrate (Co(N)) in a molar ratio of 5:5:1. ·6 O), cerium nitrate (Ce(N) ·6 Dissolve 10g of O in deionized water and bring the volume up to 50 mL.

[0040] Comparative Example 4 is the same as Example 1, except that in Comparative Example 4, step S1 involves weighing cobalt nitrate (Co(N)) in a molar ratio of 6:6:0.25. ·6 O), cerium nitrate (Ce(N) ·6 Dissolve 10g of O in deionized water and bring the volume up to 50 mL.

[0041] The catalytic activity of the catalysts obtained in Example 1 and Comparative Examples 1-4 was tested, and the specific test methods are as follows: Take 0.2 g of catalyst (sieved to 60 mesh) and pack it into the isothermal zone (220℃) of a continuous flow quartz reactor. The carrier gas is supplied by... and The mixture is prepared at a volume ratio of 8:2, with a total flow rate of 100 mL / min and a corresponding weight hourly space velocity (WHSV) of 30000 mL / (g·h). Liquid styrene or a liquid mixture of styrene and water (with a water mass percentage of 1% or 2%, denoted as 1% water or 2% water, respectively) is injected into the vaporization chamber via a micro-injection pump. After vaporization, it enters the reactor. The flow rate of styrene in the reactants is controlled to 0.30 μl / min by adjusting the injection pump rate. The reaction time is determined based on the hourly space velocity (HSV), which is 30000 mL / (g·h) (HHSV = total flow rate of the reaction mixture (mL / h) / catalyst loading mass (g). This parameter is inversely proportional to the apparent contact time of the reactants in the catalyst bed. HSV is a standardized parameter for measuring catalyst processing efficiency and reaction conditions). The reactor temperature is controlled by a programmable temperature-controlled furnace. The styrene and COx (C2O3) in the reaction tail gas are... The concentrations of styrene and COx were analyzed using online gas chromatography, and the conversion rates of styrene and COx were calculated using the following formula: ; ; ; .

[0042] In the above calculation formula, the unit of concentration C is ppm. in C represents the initial concentration of styrene. out C represents the concentration of styrene and COx in the gaseous products. CO2 C represents the concentration of CO2 in the gaseous products. CO This indicates the concentration of CO in the gaseous products.

[0043] The specific test results are shown in Table 1.

[0044] Table 1

[0045] The catalysts obtained in Example 1 and Comparative Examples 1-4 were tested under the same test conditions for the catalytic oxidation of styrene and a mixture of styrene and water (1% water, 2% water). The relationship between the styrene conversion rate and the reaction temperature, and the CO2 conversion rate of the catalysts obtained in Example 1 and Comparative Examples 1-4 were also tested. X The relationship between selectivity and reaction temperature is shown in the attached instructions. Figure 7 As shown in (Comparative Example 1), 8 (Comparative Example 2), 9 (Comparative Example 3), 10 (Example 1), and 11 (Comparative Example 4).

[0046] The catalysts obtained in Example 1 and Comparative Examples 1-4 were tested under the same test conditions for catalytic oxidation of a mixture of styrene and water (1% water). The relationship between the styrene conversion rate and the reaction temperature, and the CO2 conversion rate of the catalysts obtained in Example 1 and Comparative Examples 1-4 were analyzed. X The relationship between selectivity and reaction temperature is shown in the attached instruction manual. Figure 12 As shown in the figure. Test results indicate that a Co / Ce / Cu atomic molar ratio of 6:6:0.5 can significantly improve the water resistance and CO2 degradation resistance of styrene. X Selectivity.

[0047] The catalysts obtained in Example 1 and Comparative Examples 1-4 were tested under the same test conditions for catalytic oxidation of a mixture of styrene and water (2% water). The relationship between the styrene conversion rate and the reaction temperature, and the CO2 conversion rate of the catalysts obtained in Example 1 and Comparative Examples 1-4 were analyzed. X The relationship between selectivity and reaction temperature is shown in the attached instruction manual. Figure 13 As shown. Test results indicate that Co-Ce without Cu doping... The catalyst (Comparative Example 1) exhibited high activity under dry conditions but extremely poor water resistance. Introducing an appropriate amount of Cu significantly improved the catalyst's water resistance and carbon oxide selectivity. Example 1 (Co:Ce:Cu = 1:1:0.083) demonstrated the best overall performance, maintaining a high styrene conversion rate under both dry and aqueous conditions, indicating that this atomic molar ratio is key to optimizing catalyst activity and water resistance.

[0048] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A highly water-resistant Co-Cu-CeO2 solid solution oxide catalyst for the catalytic oxidative degradation of styrene, characterized in that, The preparation method includes the following steps: (1) Dissolve the cobalt source, cerium source and copper source in deionized water to obtain a ternary mixed solution; (2) The above ternary mixed solution is atomized, and the resulting atomized gas enters the heat-insulated pipe under the action of the carrier gas (the water in the atomized gas evaporates) to form an aerosol; (3) The obtained aerosol enters the high-temperature decomposition tube with the carrier gas and undergoes thermal decomposition and solid-phase reaction, finally obtaining Co-Cu-CeO2 solid solution oxide catalyst.

2. The highly water-resistant Co-Cu-CeO2 solid solution oxide catalyst for the catalytic oxidative degradation of styrene according to claim 1, characterized in that, The cobalt source, cerium source, and copper source are water-soluble cobalt salt, water-soluble cerium salt, and water-soluble copper salt, respectively.

3. The highly water-resistant Co-Cu-CeO2 solid solution oxide catalyst for the catalytic oxidative degradation of styrene according to claim 2, characterized in that, The water-soluble cobalt salt, water-soluble cerium salt, and water-soluble copper salt are hydrated cobalt nitrate, hydrated cerium nitrate, and hydrated copper nitrate, respectively.

4. The highly water-resistant Co-Cu-CeO2 solid solution oxide catalyst for the catalytic oxidative degradation of styrene according to claim 1, characterized in that, The carrier gas is nitrogen or an inert gas.

5. The highly water-resistant Co-Cu-CeO2 solid solution oxide catalyst for the catalytic oxidative degradation of styrene according to claim 1, characterized in that, The molar ratio of elements Co, Ce, and Cu in the cobalt, cerium, and copper sources is 6:6:0.

5.

6. The highly water-resistant Co-Cu-CeO2 solid solution oxide catalyst for the catalytic oxidative degradation of styrene according to claim 1, characterized in that, The temperature inside the insulated pipe is 60-70℃.

7. The highly water-resistant Co-Cu-CeO2 solid solution oxide catalyst for the catalytic oxidative degradation of styrene according to claim 1, characterized in that, The temperature in the high-temperature decomposition tube is 500-800℃.

8. A method for the catalytic oxidative degradation of styrene, characterized in that, The Co-Cu-CeO2 solid solution oxide catalyst according to any one of claims 1-7 is used as the catalytically active material for the reaction.

9. The method for catalytic oxidative degradation of styrene according to claim 8, characterized in that, The sieve particle size range of the Co-Cu-CeO2 solid solution oxide catalyst is 40-60 mesh.

10. The method for catalytic oxidative degradation of styrene according to claim 8, characterized in that, The reaction temperature is ≥230℃.

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