Preparation method and application of irregular honeycomb-shaped ozone catalytic oxidation catalyst

Abstract

The present invention provides a preparation method and application of an irregular honeycomb ozone catalytic oxidation catalyst. The catalyst preparation method is as follows: pumice is selected as a carrier and then perforated to make the pumice surface transparent; the carrier is rinsed with deionized water, the pH value of the rinsed honeycomb carrier is adjusted to 2-3 with hydrochloric acid, and then washed with deionized water until it is nearly neutral; the pH value of the honeycomb carrier is adjusted to 11 with sodium hydroxide, and then washed with deionized water until it is nearly neutral; the obtained pumice is filtered and dried; the obtained pumice is immersed in an aqueous solution of manganese nitrate and cerium nitrate, the pumice is dried, and then immersed in the aqueous solution of manganese nitrate and cerium nitrate again; the pumice is dried twice to obtain an ozone catalytic oxidation catalyst with an irregular surface; the catalyst presents a honeycomb shape, which greatly increases the contact area between ozone and the catalyst and improves the catalytic oxidation COD removal efficiency.

Description

Technical Field

[0001] The present invention relates to the fields of environmental engineering and water treatment technology, in particular to a preparation method and application of an irregular honeycomb ozone catalytic oxidation catalyst. Background Art

[0002] Ozone can act as both a nucleophilic agent and an electrophilic agent to participate in the reaction. It is a highly oxidizing agent, and its decomposition product is oxygen, which does not cause secondary pollution. Therefore, it is widely used in the removal of COD in many fields such as petrochemical wastewater, printing and dyeing wastewater, and pharmaceutical wastewater. However, the ozone oxidation reaction in water bodies is slow to remove COD and has strong selectivity. Therefore, many scientific researchers have tried to use a variety of metal oxides as ozone oxidation catalysts to further improve the catalytic efficiency. Common metal oxides include Fe3O4, MgO, CuO, TiO2, MnO, Co3O4, ZnO, Al2O3, Ni2O3 and some other transition metals, rare earth metal oxides, etc. as ozone catalytic oxidation catalysts. However, whether used alone or in combination, the cost of making the catalyst is high, which limits the research on different types of catalysts to treat different types of wastewater in the laboratory.

[0003] Given this, numerous studies have focused on loading metal oxides onto various supports. A suitable support provides a reaction site for ozone and organic matter in the liquid phase. Selecting a support with good thermal stability and mechanical strength is crucial to effectively prevent the loss of the catalyst's active components during the reaction. Currently, the most commonly used supports include γ-Al2O3, silicon-based materials, activated carbon, as well as volcanic rock, TiO2, and CeO2. However, the catalyst production process is complex and costly, with commercially available catalysts typically costing over 10,000 yuan per ton. During use, problems arise, such as scaling and deformation of the catalyst support skeleton under acidic or alkaline conditions, and the inability to recycle. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the existing technology and provide a preparation method and application of an irregular honeycomb ozone catalytic oxidation catalyst with a COD removal rate increased by at least 30%, an acid-resistant and alkali-resistant carrier, and recyclable, and a production cost saving of more than 50%.

[0005] The technical problem to be solved by the present invention is achieved through the following technical solution, and the catalyst preparation method is as follows:

[0006] Step (1): pumice is selected as a carrier, crushed to a particle size of less than 1 cm, and then mechanically perforated on the pumice to penetrate the surface of the pumice;

[0007] Step (2): Rinse the honeycomb carrier prepared in step (1) with deionized water, adjust the pH value of the washed honeycomb carrier to 2-3 with hydrochloric acid, soak it in ultrasound for 12 hours to 36 hours, and then wash the honeycomb carrier with deionized water until it is nearly neutral; adjust the pH value of the honeycomb carrier to 11 with sodium hydroxide, soak it in ultrasound for 12 hours to 36 hours, and then wash it with deionized water until it is nearly neutral; filter the obtained pumice and dry it at a drying temperature of 100° C. to 105° C. for 6 hours to 8 hours;

[0008] Step (3): immersing the pumice obtained in step (2) in an aqueous solution of manganese nitrate and cerium nitrate for 18 to 48 hours, with intermittent ultrasonic vibration;

[0009] Step (4): drying the pumice in step (3) at a temperature of 100° C. to 105° C., and then immersing it again in the aqueous solution of manganese nitrate and cerium nitrate prepared in step (3) for 12 h to 24 h;

[0010] Step (5): drying the pumice obtained in step (4) twice, the first drying temperature being 100°C-105°C and the drying time being 6h-8h, and the second drying temperature being 200°C-550°C and the drying time being 4h-12h, to obtain an ozone catalytic oxidation catalyst with an irregular surface honeycomb.

[0011] The above-mentioned irregular honeycomb ozone catalytic oxidation catalyst preparation method, its further preferred technical solution is: the pumice stone is natural pumice stone with a rough and irregular surface, the particle size is 2cm-6cm, the porosity is ≥40%, the compressive strength is ≥5Mpa, the specific surface area is ≥15m 2 / g.

[0012] A further preferred technical solution of the above-mentioned method for preparing the irregular honeycomb-shaped ozone catalytic oxidation catalyst is that the pore diameter formed by mechanical perforation of the pumice stone is 1-2 mm.

[0013] A further preferred technical solution of the above-mentioned method for preparing the irregular honeycomb-shaped ozone catalytic oxidation catalyst is as follows: the mass fraction of hydrochloric acid is ≥30%, and the mass fraction of sodium hydroxide is ≥30%.

[0014] A further preferred technical solution of the above-mentioned method for preparing the irregular honeycomb-shaped ozone catalytic oxidation catalyst is that the molar amounts of manganese nitrate and cerium nitrate in the aqueous solution of manganese nitrate and cerium nitrate are the same.

[0015] A further preferred technical solution of the above-mentioned method for preparing the irregular honeycomb-shaped ozone catalytic oxidation catalyst is that the mass fraction of manganese nitrate and cerium nitrate in the aqueous solution of manganese nitrate and cerium nitrate is 3% to 15%.

[0016] A further preferred technical solution of the above-mentioned method for preparing the irregular honeycomb-shaped ozone catalytic oxidation catalyst is that the volume ratio of the aqueous solution of manganese nitrate and cerium nitrate to pumice is 1:1-2.

[0017] A further preferred technical solution of the above-mentioned method for preparing the irregular honeycomb ozone catalytic oxidation catalyst is that the pumice is immersed in the manganese nitrate and cerium nitrate aqueous solution for the first time for 18 hours to 36 hours, and the second time for 12 hours to 24 hours.

[0018] The preparation method of the irregular honeycomb ozone catalytic oxidation catalyst described above has a further preferred technical solution: the second drying is a staged calcination, and the pumice after the first drying is calcined at 200℃-300℃ and maintained for 1h-4h, calcined at 300℃-400℃ and maintained for 1h-4h, and calcined at 400℃-550℃ and maintained for 1h-4h.

[0019] A further preferred technical solution of the above-mentioned method for preparing the irregular honeycomb-shaped ozone catalytic oxidation catalyst is that the catalyst prepared by the above-mentioned method for preparing the irregular honeycomb-shaped ozone catalytic oxidation catalyst has the function of being a catalytic oxidation catalyst for sewage treatment.

[0020] Compared with the prior art, the beneficial technical effects of the present invention are:

[0021] (1) The catalyst is honeycomb-shaped, which greatly increases the contact area between ozone and catalyst, and improves the catalytic oxidation COD removal efficiency;

[0022] (2) The raw material of the catalyst carrier is natural pumice, which is inexpensive, costing about RMB 500 per ton. It is acid-resistant, alkali-resistant, recyclable, and has a rough surface, making it very suitable for use as a catalyst carrier. Pumice can be suspended in water or sink to the bottom of a pool, providing a variety of application scenarios for industrial applications.

[0023] (3) The prepared catalyst undergoes two-stage impregnation and staged calcination. The catalyst loading is large and uniform, and a variety of metal loadings can be used, which has wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a reference for the catalyst morphology of the irregular honeycomb ozone catalytic oxidation catalyst of the present invention;

[0025] Figure 2 This is an electron microscope image of the pumice before loading;

[0026] Figure 3 This is an electron microscope image of the pumice loaded in the present invention. DETAILED DESCRIPTION

[0027] The specific technical solutions of the present invention are further described below with reference to the accompanying drawings to help those skilled in the art further understand the present invention without limiting the rights thereof.

[0028] Example 1, reference Figure 1-3 , a method for preparing an irregular honeycomb ozone catalytic oxidation catalyst, the catalyst preparation method is as follows:

[0029] Step (1): Use pumice as carrier. The pumice is natural pumice with rough and irregular surface, particle size 2cm, porosity 40%, compressive strength 5Mpa, specific surface area 15m 2 / g, crushed it to a particle size of 1 cm, and then mechanically perforated on the pumice. The pore size formed after mechanical perforation of the pumice is 2 mm, penetrating the surface of the pumice;

[0030] Step (2): Rinse the honeycomb carrier prepared in step (1) with deionized water, adjust the pH value of the washed honeycomb carrier to 2 with hydrochloric acid (mass fraction of hydrochloric acid is 30%), ultrasonically soak the carrier for 12 hours, and then wash the honeycomb carrier with deionized water until it is nearly neutral; adjust the pH value of the honeycomb carrier to 11 with sodium hydroxide (mass fraction of sodium hydroxide is 30%), ultrasonically soak the carrier for 12 hours, and then wash the honeycomb carrier with deionized water until it is nearly neutral; filter the obtained pumice and dry it at a drying temperature of 100° C. for 6 hours;

[0031] Step (3): immersing the pumice obtained in step (2) in an aqueous solution of manganese nitrate and cerium nitrate, wherein the molar amounts of manganese nitrate and cerium nitrate in the aqueous solution of manganese nitrate and cerium nitrate are the same, the mass fraction of manganese nitrate and cerium nitrate in the aqueous solution of manganese nitrate and cerium nitrate is 3%, and the volume ratio of the aqueous solution of manganese nitrate and cerium nitrate to the pumice is 1:1, and immersing for 18 hours, during which ultrasonic vibration is applied intermittently;

[0032] Step (4): drying the pumice in step (3) at a drying temperature of 100° C., and immersing it again in the aqueous solution of manganese nitrate and cerium nitrate prepared in step (3) for 12 hours;

[0033] Step (5): drying the pumice obtained in step (4) twice, the first drying temperature is 100°C, the drying time is 6 hours, and the second drying temperature is staged calcination, and the pumice after the first drying is calcined at 200°C and kept for 1 hour, calcined at 300°C and kept for 1 hour, and calcined at 400°C and kept for 1 hour in sequence to obtain an irregular surface honeycomb ozone catalytic oxidation catalyst.

[0034] Example 2, a method for preparing an irregular honeycomb-shaped ozone catalytic oxidation catalyst, the catalyst preparation method is as follows:

[0035] Step (1): pumice is selected as the carrier. The pumice is natural pumice with a rough and irregular surface, a particle size of 4 cm, a porosity of 50%, a compressive strength of 7 MPa, and a specific surface area of ​​18 m 2 / g, crushed to a particle size of 0.8cm, and then mechanically perforated on the pumice. The pore size formed after mechanical perforation of the pumice is 1mm, penetrating the surface of the pumice;

[0036] Step (2): Rinse the honeycomb carrier prepared in step (1) with deionized water, adjust the pH value of the washed honeycomb carrier to 3 with hydrochloric acid (mass fraction of 40%), ultrasonically soak the carrier for 18 hours, and then wash the honeycomb carrier with deionized water until it is nearly neutral; adjust the pH value of the honeycomb carrier to 11 with sodium hydroxide (mass fraction of 40%), ultrasonically soak the carrier for 18 hours, and then wash the honeycomb carrier with deionized water until it is nearly neutral; filter the obtained pumice and dry it at a drying temperature of 105° C. and a drying time of 7 hours;

[0037] Step (3): The pumice obtained in step (2) is immersed in an aqueous solution of manganese nitrate and cerium nitrate, wherein the molar amount of manganese nitrate and cerium nitrate in the aqueous solution of manganese nitrate and cerium nitrate is the same, the mass fraction of manganese nitrate and cerium nitrate in the aqueous solution of manganese nitrate and cerium nitrate is 10%, and the volume ratio of the aqueous solution of manganese nitrate and cerium nitrate to the pumice is 1:1.5. The pumice is immersed for 24 hours, and ultrasonic vibration is applied intermittently during the period.

[0038] Step (4): drying the pumice in step (3) at a drying temperature of 105° C., and immersing it again in the aqueous solution of manganese nitrate and cerium nitrate prepared in step (3) for 18 hours;

[0039] Step (5): drying the pumice obtained in step (4) twice, the first drying temperature is 105°C, the drying time is 8 hours, and the second drying temperature is staged calcination, and the pumice after the first drying is calcined at 250°C and kept for 2 hours, calcined at 400°C and kept for 2 hours, and calcined at 500°C and kept for 2 hours in sequence to obtain an irregular surface honeycomb ozone catalytic oxidation catalyst.

[0040] Example 3, a method for preparing an irregular honeycomb-shaped ozone catalytic oxidation catalyst, the catalyst preparation method is as follows:

[0041] Step (1): pumice is selected as the carrier. The pumice is natural pumice with a rough and irregular surface, a particle size of 6 cm, a porosity of 40%, a compressive strength of 5 MPa, and a specific surface area of ​​15 m 2 / g, crushed it to a particle size of 1 cm, and then mechanically perforated on the pumice. The pore size formed after mechanical perforation of the pumice is 2 mm, penetrating the surface of the pumice;

[0042] Step (2): Rinse the honeycomb carrier prepared in step (1) with deionized water, adjust the pH value of the washed honeycomb carrier to 3 with hydrochloric acid (mass fraction of 30%), soak it in ultrasound for 36 hours, and then wash the honeycomb carrier with deionized water until it is nearly neutral; adjust the pH value of the honeycomb carrier to 11 with sodium hydroxide (mass fraction of 30%), soak it in ultrasound for 36 hours, and then wash it with deionized water until it is nearly neutral; filter the obtained pumice and dry it at a drying temperature of 105° C. and a drying time of 8 hours;

[0043] Step (3): The pumice obtained in step (2) is immersed in an aqueous solution of manganese nitrate and cerium nitrate, wherein the molar amounts of manganese nitrate and cerium nitrate in the aqueous solution of manganese nitrate and cerium nitrate are the same, the mass fraction of manganese nitrate and cerium nitrate in the aqueous solution of manganese nitrate and cerium nitrate is 15%, and the volume ratio of the aqueous solution of manganese nitrate and cerium nitrate to the pumice is 1:2. The pumice is immersed for 36 hours, and ultrasonic vibration is applied intermittently during the period.

[0044] Step (4): drying the pumice in step (3) at a drying temperature of 105° C., and immersing it again in the aqueous solution of manganese nitrate and cerium nitrate prepared in step (3) for 24 hours;

[0045] Step (5): drying the pumice obtained in step (4) twice, the first drying temperature is 105°C, the drying time is 8 hours, and the second drying temperature is staged calcination, and the pumice after the first drying is calcined at 300°C and maintained for 4 hours, calcined at 400°C and maintained for 4 hours, and calcined at 550°C and maintained for 4 hours in sequence to obtain an irregular surface honeycomb ozone catalytic oxidation catalyst.

[0046] Example 4: The pumice in Examples 1-3 is a natural pumice sample from a mining company in Hebei Province, with a particle size of 2 cm to 3 cm, brick red color, and a rough surface. The test indicators are as follows:

[0047]

[0048] Example 5: Using concentrated water prepared from a high-density effluent from a high-salinity circulating water sequence at a certain location as raw water, and referring to the process parameters for the first-level ozone catalysis of the RO concentrated water from the second phase of recycled water (ozone dosage 200 mg / L, residence time 60 min, continuous water inflow), the experimental results are shown in the table:

[0049]

[0050] The average influent COD dropped from 238 mg / L to 122 mg / L, with an average COD removal rate of 48.7% and an O / C ratio of 1.72. The experimental conditions and results of the commercially available catalyst (O / C ratio = 2.3) are as follows:

[0051] 1. Experimental conditions:

[0052] (1) Effective volume: 1 column, inner diameter of single column 22 cm, height 120 cm, effective volume of single column 42 L;

[0053] (2) Residence time: Set the water inlet volume to approximately 41.5 L, the residence time to 61 minutes, and continuous water inlet.

[0054] (3) Catalyst: a catalyst (the catalyst in Examples 1-3), the loading amount of a single column being about 40% of the effective volume of the single column;

[0055] (4) Time: 15:00, December 9, 2022 to 16:30, December 10, 2022, for a total of 26:30.

[0056] (5) Sampling frequency: Continuous water intake starts at 15:00 and sampling is conducted every 4 hours.

[0057] (6) Test items: COD / TOC / UV254;

[0058] (7) Raw water: COD 145 mg / L, TOC 61.7 mg / L;

[0059] (8) Ozone: Use on-site ozone with an ozone concentration of 140 mg / L and an ozone dosage of 200 mg / L.

[0060] 2. Experimental Results

[0061]

[0062] Example 6, application experiment of irregular honeycomb ozone catalytic oxidation catalyst for sewage treatment:

[0063] Refer to the process parameters of a high-salt circulating water sequence ozone contact oxidation tank in a certain place, with an ozone dosage of 130 mg / L, a residence time of 2 hours, and continuous water inflow. The experimental results under different conditions are compared as follows:

[0064] (1) The catalytic effect of the catalyst of the present invention when hydrogen peroxide is added and the amount of hydrogen peroxide added is about 28% to 30% of the ozone addition concentration is as follows:

[0065]

[0066] When hydrogen peroxide is added simultaneously with the catalyst of the present invention, the average influent COD is reduced from 64.3 mg / L to 27.9 mg / L, the average COD removal rate is 56.6%, and the average O / C is 3.6, which is lower than the current engineering operation O / C≈4-5.

[0067] (2) The catalytic effect of the catalyst of the present invention without adding hydrogen peroxide is as follows:

[0068]

[0069] When hydrogen peroxide is added simultaneously with the catalyst of the present invention, the average influent COD is reduced from 67 mg / L to 43.46 mg / L without the addition of hydrogen peroxide, and the average O / C is 5.7, slightly lower than the engineering operation O / C≈6-7.

[0070] (3) The catalytic effect of using only hydrogen peroxide without adding the catalyst of the present invention is as follows:

[0071]

[0072] When only hydrogen peroxide was added without using the catalyst of the present invention, the average influent COD dropped from 63.3 mg / L to 37.2 mg / L, the average COD removal rate was 41.2%, and the average O / C was 4.98. The laboratory experimental results were basically consistent with the actual engineering results.

[0073] (4) The effects when no catalyst of the present invention and no hydrogen peroxide are added are as follows:

[0074]

[0075] When the catalyst of the present invention is not used and hydrogen peroxide is not added, the average influent COD is reduced from 60.8 mg / L to 44.7 mg / L, the average COD removal rate is 26.5%, the average O / C is 8, and the ozone contact oxidation effect is not good.

[0076] From (1) to (4), it can be seen that the catalytic effect is better when hydrogen peroxide is added to the catalyst of the present invention and the amount of hydrogen peroxide added is about 28% to 30% of the ozone addition concentration.

[0077] Example 6: Take the effluent from a high-salt secondary high-density pool in a certain chemical industry, refer to the process parameters of the chemical high-salt ozone oxidation tower, ozone dosage 70mg / L, residence time 1h, water inflow 4.6L / h; continuous water inflow; compare the experimental results with and without catalyst, as follows:

[0078] (1) The ozone oxidation effect when using the catalyst of the present invention is as follows:

[0079]

[0080] When the catalyst of the present invention is used, the average influent COD is reduced from 85.7 mg / L to 56 mg / L, the average COD removal rate is 34.6%, and the average O / C is 2.4, which is slightly better than the actual O / C of 3 in the project.

[0081] (2) The ozone oxidation effect when the catalyst of the present invention is not used is as follows:

[0082]

[0083] Without catalyst, the average influent COD dropped from 85 mg / L to 63.1 mg / L, the average COD removal rate was 25.7%, and the average O / C was 3.2, which is basically consistent with the current project operation (O / C = 3 to 3.5).

[0084] Example 7, the catalyst morphology of the irregular honeycomb ozone catalytic oxidation catalyst in Examples 1-3 is shown in the accompanying drawings of the specification. Figure 1 .

[0085] Example 8: The elemental analysis results of the irregular honeycomb ozone catalytic oxidation catalysts in Examples 1-3 are as follows:

[0086]

[0087] Example 9, the irregular honeycomb ozone catalytic oxidation catalyst in Example 1-3 is prepared into 1m 3 The cost bill of materials is as follows:

[0088]

[0089] It can be seen from Example 9 that the catalyst has low manufacturing cost and low price.

Claims

1. A method for preparing an irregular honeycomb-shaped ozone catalytic oxidation catalyst, characterized in that: The catalyst preparation method is as follows: Step (1): pumice is selected as a carrier, crushed to a particle size of less than 1 cm, and then mechanically perforated on the pumice to penetrate the surface of the pumice; Step (2): Rinse the honeycomb carrier prepared in step (1) with deionized water, adjust the pH value of the washed honeycomb carrier to 2-3 with hydrochloric acid, soak it in ultrasound for 12 hours to 36 hours, and then wash the honeycomb carrier with deionized water until it is nearly neutral; adjust the pH value of the honeycomb carrier to 11 with sodium hydroxide, soak it in ultrasound for 12 hours to 36 hours, and then wash it with deionized water until it is nearly neutral; filter the obtained pumice and dry it at a drying temperature of 100°C to 105°C and a drying time of 6 hours to 8 hours; Step (3): soaking the pumice obtained in step (2) in an aqueous solution of manganese nitrate and cerium nitrate for 18-36 hours, with intermittent ultrasonic vibration; Step (4): drying the pumice in step (3) at a temperature of 100°C to 105°C, and immersing it again in the aqueous solution of manganese nitrate and cerium nitrate prepared in step (3) for 12 h to 24 h; Step (5): drying the pumice obtained in step (4) twice, the first drying temperature is 100°C-105°C, the drying time is 6h-8h, and the second drying is staged calcination, the pumice after the first drying is calcined at 200°C-300°C and kept for 1h-4h, calcined at 300°C-400°C and kept for 1h-4h, and calcined at 400°C-550°C and kept for 1h-4h, to obtain an irregular surface honeycomb ozone catalytic oxidation catalyst.

2. The method for preparing an irregular honeycomb-shaped ozone catalytic oxidation catalyst according to claim 1, characterized in that: Pumice is made of natural pumice with a rough and irregular surface, a particle size of 2cm-6cm, a porosity of ≥40%, a compressive strength of ≥5Mpa, and a specific surface area of ​​≥15m² / g.

3. The method for preparing an irregular honeycomb-shaped ozone catalytic oxidation catalyst according to claim 1, characterized in that: The pore size formed by mechanical perforation of pumice is 2 mm.

4. The method for preparing an irregular honeycomb-shaped ozone catalytic oxidation catalyst according to claim 1, characterized in that: The mass fraction of hydrochloric acid is ≥30%, and the mass fraction of sodium hydroxide is ≥30%.

5. The method for preparing an irregular honeycomb-shaped ozone catalytic oxidation catalyst according to claim 1, characterized in that: The molar amounts of manganese nitrate and cerium nitrate in the aqueous solution of manganese nitrate and cerium nitrate are the same.

6. The method for preparing an irregular honeycomb-shaped ozone catalytic oxidation catalyst according to claim 1, characterized in that: The mass fractions of manganese nitrate and cerium nitrate in the manganese nitrate and cerium nitrate aqueous solution are 3% to 15%.

7. The method for preparing an irregular honeycomb-shaped ozone catalytic oxidation catalyst according to claim 1, characterized in that: The volume ratio of the aqueous solution of manganese nitrate and cerium nitrate to pumice is 1:1~2.

8. Use of the catalyst prepared by the method for preparing the irregular honeycomb ozone catalytic oxidation catalyst according to any one of claims 1 to 7 as a catalytic oxidation catalyst for sewage treatment.

Images