Process for the preparation of modified manganese slag catalysts for catalyzing vocs
By modifying manganese slag to prepare catalysts, the problems of high cost of VOCs degradation and pollution from manganese slag treatment are solved, achieving efficient VOCs degradation and resource utilization, and reducing energy consumption and costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUIZHOU INST OF TECH
- Filing Date
- 2025-05-20
- Publication Date
- 2026-07-31
AI Technical Summary
Existing VOCs degradation methods are costly, energy-intensive, and may generate secondary pollution. Furthermore, manganese slag is mainly disposed of through landfill or stockpiling, which occupies land and may pollute the environment.
The catalyst was prepared by modifying manganese slag, including steps such as crushing, sieving, acid treatment, pH adjustment, and calcination, to form a mesoporous structure to improve specific surface area and catalytic activity.
It achieves efficient degradation of VOCs, reduces reaction temperature and energy consumption, utilizes manganese slag as a resource, reduces environmental pollution, and lowers catalyst costs.
Smart Images
Figure CN120515437B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of industrial solid waste resource utilization and air pollution control technology, specifically relating to a method for preparing a catalytic oxidation catalyst for volatile organic compounds (VOCs) using manganese slag as raw material. Background Technology
[0002] Volatile organic compounds (VOCs) are a general term for a class of organic chemical substances with high saturated vapor pressure and high volatility. They are widely present in various fields such as industrial production, transportation, and consumer goods. VOC emissions have caused serious harm to the environment and human health, such as forming photochemical smog, damaging the ozone layer, exacerbating the greenhouse effect, and causing respiratory diseases. How to effectively degrade VOCs has become an urgent environmental problem to be solved.
[0003] Traditional VOCs degradation methods include adsorption, combustion, and biological methods. While adsorption is simple to operate, the adsorbent requires regular replacement and regeneration, resulting in high costs. Combustion requires high temperatures, consumes a lot of energy, and may generate secondary pollution. Biological methods have strict requirements on the type and concentration of VOCs and have relatively low treatment efficiency. In recent years, catalytic oxidation has received widespread attention due to its advantages such as high efficiency, energy saving, and environmental friendliness. However, commonly used catalysts, such as precious metal catalysts (e.g., platinum, palladium), are expensive, while non-precious metal catalysts (e.g., titanium dioxide, alumina) have shortcomings in terms of activity and stability.
[0004] Manganese slag is a solid waste generated during the smelting of ferromanganese. Its main components include manganese oxides such as manganese dioxide and manganese tetroxide, as well as small amounts of metal oxides such as iron and aluminum. Currently, the main methods for treating manganese slag are landfilling or stockpiling, which not only occupies a large amount of land resources but also may pollute soil and water bodies. Developing a highly efficient VOCs catalytic degradation method for the resource utilization of manganese slag, achieving the goal of treating waste with waste, has significant environmental and economic benefits. Summary of the Invention
[0005] To address the aforementioned problems, this invention aims to provide a method for preparing a modified manganese slag catalyst for catalyzing VOCs.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] 1) After crushing the manganese slag, sieve it to below 40 mesh to obtain manganese slag powder;
[0008] 2) Disperse the manganese slag powder in 300 mL of water at a solid-liquid ratio of 1:15, and stir evenly with ultrasonication to obtain a suspension.
[0009] 3) Add 150-200 ml of 6 mol / L acid solution to the suspension, heat in a water bath at 60-80°C and stir until homogeneous, let stand at room temperature for 1-3 hours to obtain the reaction solution; the acid solution is one of hydrochloric acid, nitric acid, and oxalic acid, or a combination of two or three.
[0010] 4) Add ammonia or sodium hydroxide to the reaction solution to adjust the pH to 8-9 and age for 1.5 hours; filter and wash the filter cake repeatedly with ethanol and water until neutral;
[0011] 5) After the filter cake is dried, it is calcined at 500℃ for 3-4 hours, ground, and passed through a 20-40 mesh sieve.
[0012] Compared with the prior art, the present invention has the following advantages:
[0013] 1) Highly efficient VOCs degradation: After modification, the manganese slag has a more open pore structure, refined pore size, and becomes mesoporous, increasing the specific surface area, promoting the catalytic oxidation of chlorobenzene molecules, and improving the catalytic activity of the catalyst. The degradation efficiency of VOCs can reach over 90%.
[0014] 2) Energy saving and consumption reduction: Compared with traditional VOCs degradation methods such as combustion, the reaction temperature of the method of the present invention is lower (300-350℃), energy consumption is significantly reduced, and it has a better energy saving effect.
[0015] 3) Resource utilization of manganese slag: This invention transforms manganese slag, an industrial solid waste, into a highly efficient VOCs catalyst, realizing the resource utilization of manganese slag, reducing the pollution of manganese slag to the environment, and reducing the cost of the catalyst. Attached Figure Description
[0016] Figure 1 It is a graph showing the conversion rate of chlorobenzene to modified manganese slag catalyst;
[0017] Figure 2 This is a comparison diagram of the pore size of the catalyst of this invention and the pore size of the original manganese slag. Detailed Implementation
[0018] The present invention will be further described below with reference to specific embodiments in conjunction with the accompanying drawings:
[0019] Example 1
[0020] 1) After crushing the manganese slag, sieve it to below 40 mesh to obtain manganese slag powder;
[0021] 2) Disperse 20g of manganese slag powder in 300mL of water at a solid-liquid ratio of 1:15, and stir evenly with ultrasonication to obtain a suspension.
[0022] 3) Add 150 mL of 6 mol / L nitric acid to the suspension, heat in a water bath at 60-80°C and stir at 250 r / min for 1 h, and let stand at room temperature for 1-3 h to obtain the reaction solution;
[0023] 4) Slowly add ammonia or sodium hydroxide to the reaction solution to adjust the pH to 8-9, and age for 1.5 hours; filter, and wash the filter cake repeatedly with ethanol and water until neutral;
[0024] 5) Place the filter cake in a 110℃ forced-air drying oven and dry for 4 hours until constant weight;
[0025] 6) Place the dried filter cake in a muffle furnace and calcine it at 500℃ for 3-4 hours at a rate of 5℃ / min. Then cool, grind, and sieve to 20-40 mesh to obtain the modified manganese slag catalyst.
[0026] Example 2 follows the same steps as Example 1. However, in step 3), the nitric acid is replaced with 200 mL of 6 mol / L hydrochloric acid.
[0027] Example 3 follows the same steps as Example 1. However, in step 3), the nitric acid is replaced by 175 mL of 6 mol / L oxalic acid.
[0028] Example 4, the steps are the same as in Example 1. Except that the nitric acid in step 3) is replaced by 150 mL of acid solution with a concentration of 6 mol / L, which is a mixture of nitric acid and hydrochloric acid.
[0029] Example 5, the steps are the same as in Example 4. In step 3), the acid solution is 200 mL, and the acid solution is a mixture of hydrochloric acid and oxalic acid.
[0030] Example 6, the steps are the same as in Example 4. In step 3), the acid solution is 175 mL, and the acid solution is a mixture of nitric acid and oxalic acid.
[0031] Example 7 follows the same steps as Example 1. However, in step 3), the nitric acid is replaced by 150 mL of a 6 mol / L acid solution, which is a mixture of hydrochloric acid, nitric acid, and oxalic acid.
[0032] Example 8, the steps are the same as in Example 7. Except that the acid solution in step 3) is 200 mL.
[0033] Example 9, the steps are the same as in Example 7. Among them, the acid solution in step 3) is 175 mL.
[0034] Test example:
[0035] The modified manganese slag catalyst product prepared in Example 1 was used to evaluate the catalytic activity of a typical representative of volatile organic compounds (chlorobenzene).
[0036] I. Test Conditions
[0037] The experimental gas was chlorobenzene, and air was used as the carrier gas. Chlorobenzene was purged using a bubbling method and then thoroughly mixed with air in a mixing bottle (both the chlorobenzene generator and the mixing bottle were placed in a constant-temperature water bath), yielding a chlorobenzene concentration of 3000 mg / m³. 3 A mixed gas with a total flow rate of 2 L / min enters the reactor. The reaction tube is a quartz glass tube with an inner diameter of 18 mm and a wall thickness of 1 mm. The isothermal zone is 80 mm long. 4 ml of catalyst is used, and the catalyst is supported and fixed in the reaction tube by high-temperature resistant quartz wool. The catalytic reaction is carried out at atmospheric pressure with a space velocity (GHSV) of 30,000 h⁻¹. -1 The temperature was controlled by a vertical tubular furnace, and the temperature of the catalytic bed was monitored by a thermocouple inserted into the center of the reaction tube. The catalytic section was placed in the constant temperature zone of the tubular furnace, and the catalytic activity was tested in the range of 200–400°C. The concentration of chlorobenzene was determined using an Agilent GC7890 gas chromatograph.
[0038] II. Test Steps
[0039] 1. Grind 4 mL (about 2 g) of the catalyst of this invention to 40-60 mesh and place it in the constant temperature zone of the reactor to ensure that the height of the catalyst bed is 15-16 mm;
[0040] 2. Place the thermocouple on top of the catalyst bed;
[0041] 3. Heat the reactor to 100-400℃ using a temperature controller at a heating rate of 5℃ / min;
[0042] 4. Using clean air as the carrier gas, the chlorobenzene generator bottle was purged to produce saturated chlorobenzene vapor, yielding a chlorobenzene concentration of 3000 mg / m³. 3 The chlorobenzene waste gas was passed through the catalyst bed at a total flow rate of 2 L / min; the space velocity was 60000 mL / (g·h);
[0043] 5. The concentrations of chlorobenzene at the reactor inlet and outlet were determined using an Agilent GC7890 gas chromatograph (see [reference]). Figure 1 ).
[0044] from Figure 1 It can be seen that the original manganese slag has low catalytic activity; the chlorobenzene conversion rate is 1.39% at a catalytic temperature of 300℃ and 84.9% at 500℃. After modification using the method of this invention, the catalytic activity of the original manganese slag is significantly improved. The chlorobenzene conversion rate is 11.3% at a catalytic temperature of 280℃ and 100% at 400℃. This indicates that the modified manganese slag catalyst prepared by the method of this invention has excellent catalytic performance for chlorobenzene.
[0045] from Figure 2 It can be seen that, compared with the original manganese slag, the modified manganese slag catalyst has a significantly increased mesopore content, exhibiting a dense distribution within the 2–20 nm mesopore range. Mesopores provide specific surface area and pore capacity for the reaction, offering more active reaction sites and facilitating diffusion and mass transfer reactions; thus improving the overall catalytic performance of the modified manganese slag catalyst. This indicates that the modified manganese slag catalyst prepared using the invented method possesses more mesopores, which is more conducive to the catalytic reaction, resulting in a significantly enhanced catalytic activity compared to the original manganese slag.
Claims
1. A method for preparing a modified manganese slag catalyst for catalyzing VOCs, characterized in that... The method is as follows: 1) After crushing the manganese slag, sieve it to below 40 mesh to obtain manganese slag powder; 2) Disperse the manganese slag powder in 300 mL of water at a solid-liquid ratio of 1:15, and stir evenly with ultrasonication to obtain a suspension. 3) Add 150-200 ml of 6 mol / L acid solution to the suspension, heat in a water bath at 60-80°C and stir until homogeneous, let stand at room temperature for 1-3 hours to obtain the reaction solution; the acid solution is one of hydrochloric acid, nitric acid, and oxalic acid, or a combination of two or three. 4) Add ammonia or sodium hydroxide to the reaction solution, adjust the pH to 8-9, age for 1.5 hours, filter, and wash the filter cake repeatedly with ethanol and water until neutral. 5) After the filter cake is dried, it is calcined at 500℃ for 3-4 hours, ground, and passed through a 20-40 mesh sieve.