High-entropy alloy catalyst for coal chemical industry wastewater treatment and preparation method of high-entropy alloy catalyst

Abstract

The invention provides a high-entropy alloy catalyst for coal chemical wastewater treatment and a preparation method thereof, and belongs to the technical field of catalysts. The preparation method comprises the following steps: taking hard shells as a raw material, crushing, introducing carbon dioxide into a tubular furnace for calcining and activating, cooling and sieving to obtain an activated carbon carrier with a high specific surface area; the preparation method comprises the following steps: performing acid modification on the prepared high-specific-surface-area activated carbon by using a nitric acid solution to increase the average pore size, total pore volume and mesopore volume of the activated carbon, soaking the modified carrier in a nitrate solution, and roasting to load cobalt oxide, manganese oxide and the like on the surface of the carrier; the high-entropy metal oxide enables metal ions to generate a synergistic effect, and the oxidation-reduction capability of the catalyst is enhanced, so that the degradation efficiency and the stability of the catalyst are improved; the prepared catalyst is stable in effect, especially has an excellent degradation effect on coal chemical wastewater, and has a wide market prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and relates to a high-entropy alloy catalyst for coal chemical wastewater treatment and a preparation method thereof. Background Art

[0002] The exploitation and processing of coal enterprises have increased the discharge of coal chemical wastewater. Different from other industrial wastewaters, coal chemical wastewater contains a large amount of toxic and harmful substances, and has characteristics such as high-concentration oil pollution and high-concentration COD. Therefore, it has become a recognized type of difficult-to-treat industrial wastewater at home and abroad. As a new and efficient water treatment technology, the ozone catalytic oxidation technology has been widely used in the treatment of organic wastewater due to its environmental friendliness, no secondary pollution, etc. This technology catalyzes ozone by using an ozone catalyst to generate strongly oxidizing reactive oxygen species, such as hydroxyl radicals, superoxide radicals, etc., to kill germs, degrade and even mineralize organic pollutants.

[0003] Currently, in the existing technologies, there have been many preparation methods of ozone catalysts proposed. Patent CN201910389530.2 provides a preparation method of a three-dimensional pore structure Co / Ce bimetallic MOF-based ozone catalyst prepared by a simple ultrasonic-calcination synthesis method, which can effectively solve the problems of conventional ozone catalysts in the process of industrial wastewater treatment. The ultrasonic-calcination synthesis method is also relatively simple, but in practical applications, it is difficult to accurately control the preparation parameters, and there are deficiencies in terms of stability and reliability. Patent CN200510086948.4 discloses a Ru / Al2O3 ozone catalytic oxidation catalyst. The RuCl3 solution and the Al2O3 carrier are mixed in equal volume by the equal-volume impregnation method, impregnated in a shaking table, and then the finished catalyst is obtained through steps such as drying and microwave heating. This catalyst has good removal effects on phenolic substances and small molecular acid substances. However, the raw materials selected are precious metals, the preparation cost is too high, and the microwave method is difficult to implement in actual industrial production. CN201811557283.4 provides a preparation and application method of a magnetic nano-ozone catalyst CoFe2O4. During the ozonation treatment of organic wastewater, CoFe2O4 has good removal rates for both organic pollutant substrates and COD, and it is measured that the metal ion leaching rate of CoFe2O4 is low and the stability is good. However, the powdery nanoparticles are extremely fine and are prone to inactivation and aggregation in water, and the treatment effect is affected by this.

[0004] Although the above-mentioned catalysts all have certain treatment effects, there are still problems such as low stability, complex preparation process and high cost. Therefore, inventing an ozone catalyst with high stability, low cost and excellent treatment effect is still a problem to be solved. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a high-entropy alloy catalyst for coal chemical wastewater treatment and a preparation method thereof. In the present invention, hard fruit shells are used as raw materials to prepare a high specific surface area activated carbon carrier, which is modified by nitric acid to increase its average pore diameter, total pore volume and mesopore volume; finally, metal oxides cobalt oxide, magnesium oxide, manganese oxide, cerium oxide and copper oxide are loaded on its surface, thereby improving the degradation efficiency and catalyst stability.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a preparation method of a high-entropy alloy catalyst for coal chemical wastewater treatment, and the preparation method of the high-entropy alloy catalyst for coal chemical wastewater treatment includes:

[0008] S1: Crush and dry the hard fruit shells to obtain pretreated hard fruit shells, soak them in a potassium carbonate solution, filter and dry them to obtain waste residues; place the waste residues in a tubular furnace, heat them up for calcination activation in a carbon dioxide atmosphere and then cool them to room temperature, and obtain high specific surface area activated carbon after sieving;

[0009] S2: Add the high specific surface area activated carbon to an acidic solution, perform constant temperature treatment, wash and dry it after cooling to obtain a modified carrier;

[0010] S3: Prepare a nitrate solution, immerse the modified carrier in the nitrate solution, dry it after impregnation to obtain a primary product, and place it in a tubular furnace, heat it up for roasting in a nitrogen atmosphere to obtain a high-entropy alloy catalyst for coal chemical wastewater treatment.

[0011] As a preferred technical solution of the present invention, in step S1, the hard fruit shells are one or any combination of coconut shells, palm shells, and walnut shells.

[0012] As a preferred technical solution of the present invention, in step S1, the mass ratio of the pretreated hard fruit shells to the potassium carbonate solution is 1:(3 - 5).

[0013] As a preferred technical solution of the present invention, in step S1, the mass fraction of the potassium carbonate solution is 30 wt.%.

[0014] As a preferred technical solution of the present invention, in step S1, the temperature for drying the pretreated hard fruit shells after soaking in the potassium carbonate solution is 110°C and the time is 4 h.

[0015] As a preferred technical solution of the present invention, in step S1, the temperature for calcination activation of the waste residues in the tubular furnace is 850°C; the time is 8 h; the heating rate of the tubular furnace is 5°C / min.

[0016] As a preferred technical solution of the present invention, in step S2, the acidic solution is nitric acid, and the concentration of the acidic solution is 10-20%.

[0017] As a preferred technical solution of the present invention, in step S2, the temperature of the high specific surface area activated carbon stirred at a constant temperature in the acidic solution is 60°C, and the time is 2 h.

[0018] As a preferred technical solution of the present invention, in step S3, the nitrates are cobalt nitrate, manganese nitrate, magnesium nitrate, cerium nitrate and copper nitrate, and their mass ratio is (1-1.5):(1.5-2):(1.5-2.5):(1.5-2.5):(1-2).

[0019] As a preferred technical solution of the present invention, in step S3, the temperature for drying after impregnation of the modified carrier in the nitrate solution is 105°C, and the time is 12 h.

[0020] As a preferred technical solution of the present invention, in step S3, the temperature for calcining the initial product is 400°C; the time is 5 h; the heating rate of the tubular furnace is 5°C / min.

[0021] Second, the present invention provides a high-entropy alloy catalyst for coal chemical wastewater treatment.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) The activated carbon prepared by this method has a simple process, does not involve steps such as pickling, and there are no problems such as equipment corrosion and environmental pollution. The prepared activated carbon has a very high specific surface area and microporous structure, making it have excellent adsorption performance.

[0024] (2) After the prepared activated carbon is modified by nitric acid, the proportion of its mesopore volume increases, which is more conducive to adsorbing macromolecular organic substances.

[0025] (3) Loading multiple metal oxides not only enables the metal ions to produce a synergistic effect to promote more redox reactions and reduce the ion leaching rate, but also can increase the acidic active sites and improve the chemical adsorption rate, thereby improving the degradation efficiency and catalyst stability. Description of the Drawings

[0026] Figure 1 COD degradation efficiency of the high-entropy alloy catalyst for coal chemical wastewater treatment in Examples 1-3 and Comparative Examples 1-3 of the present invention for coal chemical wastewater;

[0027] Figure 2 Chromaticity degradation efficiency of the high-entropy alloy catalyst for coal chemical wastewater treatment in Examples 1-3 and Comparative Examples 1-3 of the present invention for coal chemical wastewater. Specific Embodiments

[0028] The technical solution of the present invention will be described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments described herein are specific specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are all explanatory and exemplary and should not be construed as limiting the embodiments of the present invention and the protection scope of the present invention. Except for the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that make any obvious substitutions and modifications to the embodiments described herein.

[0029] The chemical reagents used in the embodiments and comparative examples of the present invention are all commercially available products and have not been further purified or processed.

[0030] Example 1

[0031] This example provides a high-entropy alloy catalyst for coal chemical wastewater treatment and a preparation method thereof. The preparation method of the high-entropy alloy catalyst for coal chemical wastewater treatment specifically includes the following steps:

[0032] S1: Crush 10 g of coconut shell to less than 200 μm and then dry it at 110 °C for 4 h to obtain pretreated hard fruit shell. Immerse it in 30 mL of potassium carbonate solution with a mass fraction of 30 wt.%, soak for 12 h, filter, and dry to obtain waste residue. Place the waste residue in a tubular furnace, heat it to 850 °C at a rate of 5 °C / min under a carbon dioxide atmosphere, calcine and activate for 8 h, then cool to room temperature, and pass through a 100-mesh sieve to obtain high specific surface area activated carbon;

[0033] S2: Add the high specific surface area activated carbon to 200 mL of nitric acid solution with a concentration of 10%, treat it at a constant temperature of 60 °C for 2 h, cool, wash, and dry to obtain a modified carrier;

[0034] S3: Weigh 1 g of cobalt nitrate, 1.8 g of manganese nitrate, 2.1 g of magnesium nitrate, 1.5 g of cerium nitrate, and 1.2 g of copper nitrate, add them to 50 mL of water to obtain a nitrate solution. Immerse the modified carrier in the nitrate solution for 12 h, dry it at 105 °C for 12 h after impregnation to obtain a primary product, place it in a tubular furnace, heat it to 400 °C at a rate of 5 °C / min under a nitrogen atmosphere, and calcine for 5 h to obtain a high-entropy alloy catalyst for coal chemical wastewater treatment.

[0035] The test results show that after 4 h of reaction, the COD content of the wastewater is 148 mg / L, and the removal rate reaches 91.19%; the chromaticity drops from 500 degrees to 70 degrees.

[0036] Example 2

[0037] This embodiment provides a high-entropy alloy catalyst for coal chemical wastewater treatment and a preparation method thereof. The preparation method of the high-entropy alloy catalyst for coal chemical wastewater treatment specifically includes the following steps:

[0038] S1: Crush 10 g of walnut shells to below 200 μm, dry them at 110 °C for 4 h to obtain pretreated hard fruit shells, soak them in 40 mL of a potassium carbonate solution with a mass fraction of 30 wt.%, filter and dry to obtain waste residues; place the waste residues in a tubular furnace, heat them to 850 °C at a rate of 5 °C / min under a carbon dioxide atmosphere, calcine and activate them for 8 h, then cool to room temperature, and sieve through a 100-mesh sieve to obtain high-specific-surface-area activated carbon;

[0039] S2: Add the high-specific-surface-area activated carbon to 200 mL of a nitric acid solution with a concentration of 15%, treat it at a constant temperature of 60 °C for 2 h, wash and dry it after cooling to obtain a modified carrier;

[0040] S3: Weigh 1.2 g of cobalt nitrate, 1.5 g of manganese nitrate, 2.4 g of magnesium nitrate, 1.7 g of cerium nitrate and 1.5 g of copper nitrate, add them to 50 mL of water to obtain a nitrate solution, immerse the modified carrier in the nitrate solution for 12 h, dry it at 105 °C for 12 h after immersion to obtain a primary product, place it in a tubular furnace, heat it to 400 °C at a rate of 5 °C / min under a nitrogen atmosphere, and calcine it for 5 h to obtain a high-entropy alloy catalyst for coal chemical wastewater treatment.

[0041] The test results show that after 4 h of reaction, the COD content of the wastewater is 62 mg / L, and the removal rate reaches 96.29%; the chromaticity drops from 500 degrees to 35 degrees.

[0042] Example 3

[0043] This embodiment provides a high-entropy alloy catalyst for coal chemical wastewater treatment and a preparation method thereof. The preparation method of the high-entropy alloy catalyst for coal chemical wastewater treatment specifically includes the following steps:

[0044] S1: Crush 10 g of palm shells to below 200 μm, dry them at 110 °C for 4 h to obtain pretreated hard fruit shells, soak them in 50 mL of a potassium carbonate solution with a mass fraction of 30 wt.%, filter and dry to obtain waste residues; place the waste residues in a tubular furnace, heat them to 850 °C at a rate of 5 °C / min under a carbon dioxide atmosphere, calcine and activate them for 8 h, then cool to room temperature, and sieve through a 100-mesh sieve to obtain high-specific-surface-area activated carbon;

[0045] S2: Add the high-specific-surface-area activated carbon to 200 mL of a nitric acid solution with a concentration of 20%, treat it at a constant temperature of 60 °C for 2 h, wash and dry it after cooling to obtain a modified carrier;

[0046] S3: Weigh 1.5 g of cobalt nitrate, 1.6 g of manganese nitrate, 2.2 g of magnesium nitrate, 2 g of cerium nitrate and 1.5 g of copper nitrate, add them to 50 mL of water to obtain a nitrate solution. Immerse the modified carrier in the nitrate solution for 12 h, and after immersion, dry it at 105 °C for 12 h to obtain a preliminary product. Place it in a tubular furnace, and under a nitrogen atmosphere, heat it to 400 °C at a rate of 5 °C / min and calcine it for 5 h to obtain a high-entropy alloy catalyst for coal chemical wastewater treatment.

[0047] The test results show that after 4 h of reaction, the COD content of the wastewater is 279 mg / L, and the removal rate reaches 83.38%; the chromaticity drops from 500 degrees to 96 degrees.

[0048] Comparative Example 1

[0049] This comparative example provides a high-entropy alloy catalyst for coal chemical wastewater treatment. The difference from Example 1 is that the high specific surface area activated carbon is not soaked in the nitric acid solution in S2, and other operation steps and process parameters are exactly the same as those in Example 1.

[0050] Comparative Example 2

[0051] This comparative example provides a high-entropy alloy catalyst for coal chemical wastewater treatment. The difference from Example 1 is that the modified carrier is not soaked in the nitrate solution in S3, and other operation steps and process parameters are exactly the same as those in Example 1.

[0052] Comparative Example 3

[0053] This comparative example provides a high-entropy alloy catalyst for coal chemical wastewater treatment. The difference from Example 1 is that only cobalt nitrate is used in the nitrate in S3, and other operation steps and process parameters are exactly the same as those in Example 1.

[0054] Perform performance tests on the high-entropy alloy catalysts for coal chemical wastewater treatment in the above Examples 1-3 and Comparative Examples 1-3. The specific process is as follows:

[0055] Load the catalyst into the performance evaluation reaction device. The test device mainly consists of an oxygen pipe, an ozone generator, a reaction glass column, and a tail gas recovery device. A sampling port is provided in the middle of the glass column. Load 500 mL of coal chemical wastewater with a total COD of 1680 mg / L into the glass beads, and at the same time, the flow rate of the ozone generator is 0.5 L / min. Take samples every 1 h, analyze the COD concentration at each time point with a water quality analyzer, and measure the chromaticity with a spectrophotometer.

[0056] The test results are as Figure 1 、 Figure 2 shown.

[0057] From the test results of Example 1 and Comparative Example 1, it can be seen that without soaking the high specific surface area activated carbon in nitric acid solution, the average pore diameter, total pore volume and mesopore volume of the prepared carrier are reduced, weakening the degradation ability of macromolecular substances and resulting in a decrease in the catalytic effect of the catalyst.

[0058] From the test results of Example 1 and Comparative Example 2, it can be seen that without loading the active component on the modified carrier, the active sites of the modified carrier are reduced, and its stability is decreased, resulting in a decrease in the catalytic effect of the catalyst.

[0059] From the test results of Example 1 and Comparative Example 3, it can be seen that when only a single metal oxide is loaded on the modified carrier, the active sites provided by the single metal oxide are single, restricting its catalytic performance in the treatment process and weakening the catalytic effect of the catalyst.

[0060] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of within the technical scope disclosed by the present invention by those skilled in the art all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A preparation method of a high-entropy alloy catalyst for coal chemical wastewater treatment, characterized in that, The preparation method includes: S1: Crush the hard fruit shell and dry it to obtain pretreated hard fruit shell, soak it in potassium carbonate solution, filter and dry it to obtain waste residue; place the waste residue in a tubular furnace, heat it up for calcination activation in a carbon dioxide atmosphere and then cool it to room temperature, and obtain high specific surface area activated carbon after sieving; S2: Add the high specific surface area activated carbon to an acidic solution, perform constant temperature treatment, wash and dry it after cooling to obtain a modified carrier; S3: Prepare a nitrate solution, immerse the modified carrier in the nitrate solution, dry it after immersion to obtain a primary product, place it in a tubular furnace, heat it up for roasting in a nitrogen atmosphere to obtain a high-entropy alloy catalyst for coal chemical wastewater treatment.

2. The preparation method of a high-entropy alloy catalyst for coal chemical wastewater treatment according to claim 1, wherein, In S1: The hard fruit shell is one or any combination of coconut shell, palm shell, and walnut shell; The hard fruit shell is crushed to a diameter of less than 200 μm.

3. The preparation method of a high-entropy alloy catalyst for coal chemical wastewater treatment according to claim 1, characterized in that, In S1: The mass ratio of the pretreated hard fruit shell to the potassium carbonate solution is 1:(3 - 5); The mass fraction of the potassium carbonate solution is 30 wt.%; The soaking time of the pretreated hard fruit shell in the potassium carbonate solution is 12 h.

4. The preparation method of a high-entropy alloy catalyst for coal chemical wastewater treatment according to claim 1, characterized in that, In S1: The drying temperature of the pretreated hard fruit shell after soaking in the potassium carbonate solution is 110 °C; The drying time of the pretreated hard fruit shell after soaking in the potassium carbonate solution is 4 h; The calcination activation temperature of the waste residue in the tubular furnace is 850 °C; The calcination activation time of the waste residue in the tubular furnace is 8 h; The heating rate of the tubular furnace is 5 °C / min.

5. The preparation method of a high-entropy alloy catalyst for coal chemical wastewater treatment according to claim 1, characterized in that, In S1: The waste residue is sieved through a 100-mesh sieve after calcination activation.

6. The preparation method of a high-entropy alloy catalyst for coal chemical wastewater treatment according to claim 1, characterized in that, In S2: The acidic solution is nitric acid, and the concentration of the acidic solution is 10 - 20%.

7. The preparation method of a high-entropy alloy catalyst for coal chemical wastewater treatment according to claim 1, characterized in that, In S2: The constant temperature stirring temperature of the high specific surface area activated carbon in the acidic solution is 60 °C; The constant temperature stirring time of the high specific surface area activated carbon in the acidic solution is 2 h.

8. The preparation method of a high-entropy alloy catalyst for coal chemical wastewater treatment according to claim 1, characterized in that, In S3: The nitrates are cobalt nitrate, manganese nitrate, magnesium nitrate, cerium nitrate, and copper nitrate, and their mass ratio is (1 - 1.5):(1.5 - 2):(1.5 - 2.5):(1.5 - 2.5):(1 - 2).

9. The preparation method of a high-entropy alloy catalyst for coal chemical wastewater treatment according to claim 1, wherein, In S3: The drying temperature of the modified carrier after immersion in the nitrate solution is 105 °C; The drying time of the modified carrier after immersion in the nitrate solution is 12 h.

10. The preparation method of a high-entropy alloy catalyst for coal chemical wastewater treatment according to claim 1, characterized in that, In S3: The roasting temperature of the primary product is 400 °C; The roasting time of the primary product is 5 h; The heating rate of the tubular furnace is 5 °C / min.

11. A high-entropy alloy catalyst for coal chemical wastewater treatment prepared by the preparation method described in any one of claims 1 - 10.

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