CN111250087B

CN111250087B - Preparation method and application of catalyst for catalyzing ozone oxidation

Info

Publication number: CN111250087B
Application number: CN201811459901.1A
Authority: CN
Inventors: 赵颖; 孙承林; 卫皇曌; 顾彬; 张如玉; 荣欣
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2018-11-30
Filing date: 2018-11-30
Publication date: 2021-04-23
Anticipated expiration: 2038-11-30
Also published as: CN111250087A

Abstract

The application discloses a preparation method of a catalyst, which comprises the following steps: a) obtaining aluminum sol; b) and (3) soaking the formed honeycomb carrier in the alumina sol, drying and roasting to obtain the catalyst. The prepared catalyst can be used for carrying out catalytic ozone oxidation treatment on organic wastewater, and has the advantages of high removal efficiency, high ozone utilization rate, good catalyst stability, less loss of active components and the like.

Description

Preparation method and application of catalyst for catalyzing ozone oxidation

Technical Field

The application relates to a preparation method of a catalytic ozonation catalyst and application of the catalytic ozonation catalyst in organic wastewater treatment, and belongs to the fields of wastewater treatment technologies and environmental functional materials.

Background

The present waste water end treatment method mainly adopts biochemical method, Fenton oxidation method, etc. to reduce COD of discharged waste water to below 50mg/L, but its defects are that its efficiency is slow, active component is lost and pollutes environment, and the catalytic ozone oxidation method (CWOO) is used for treating refractory waste water by utilizing the property of that ozone can produce active particles of hydroxyl radical [. OH ] and monatomic oxygen [ O ] with strong oxidation power under the action of catalyst. The technology is one of advanced oxidation technologies, has decomposition effects on organic and inorganic pollutant pollutants which are difficult to degrade, such as benzene, phenol and derivatives thereof, cyanide, sulfide, iron and humic acid, pesticides, herbicides and the like, and has the effects of decoloring, deodorizing and sterilizing.

The current commonly used catalytic ozonation catalyst carriers include alumina, molecular sieves, zeolites, activated carbon, honeycomb ceramics and the like. The conventional carrier has particle property, and the friction of the fluid disturbance to the catalyst causes partial loss of the active component. The honeycomb ceramic can be widely applied to various environmental protection fields due to the specific properties of high strength, high temperature resistance, corrosion resistance, wear resistance and the like, and can be made into an integral module, thereby being beneficial to the loading of active components and avoiding the loss of the active components. Because the honeycomb ceramics generally have macroscopic pores, in order to ensure the effective load of active components, a surface alumina sol coating method can be adopted to improve the surface property of the honeycomb ceramics. Currently, researchers have evolved honeycomb ceramics as CWOO catalyst supports. Stability of the engineering wastewater treatment catalyst. The patent CN 101811049 has good mineralization rate for catalyzing ozone oxidation of 2, 4-dichlorophenoxyacetic acid by loading pseudo-boehmite and an active component Co on the surface of honeycomb ceramic; patent 201610950671.3 discloses that a ceramic membrane is used as a substrate, iron sesquioxide-nickel oxide-cerium dioxide is loaded by a layer-by-layer deposition heat treatment method, and the obtained catalyst can solve the problem of water pollution such as high organic matter content, high COD concentration and the like. The aluminum sol prepared by the aluminum foil is adopted to carry out surface coating on the honeycomb ceramic, and the transition metal is loaded in a common mode or in a fractional mode, so that the obtained catalyst has good catalytic ozonation activity and stability, the preparation process is simple, and the engineering can be realized. The effluent treated by the catalyst can directly reach the standard and be discharged or reclaimed.

Disclosure of Invention

According to one aspect of the present application, a catalyst is provided, which has the advantages of high pollutant removal rate, good catalyst stability, less loss of active components, and the like.

The catalyst is an ozone oxidation catalyst, honeycomb ceramics is used as a carrier, aluminum sol is loaded by a coating method, and the prepared ozone oxidation catalyst loaded or co-doped by transition metal salt solutions of Fe, Mn, Cu, Zn and the like is prepared.

The catalyst for catalyzing ozone oxidation is characterized by comprising a formed honeycomb ceramic carrier;

after the surface of the carrier is contacted with an aluminum-containing sol and a liquid containing a transition metal element, drying and roasting are carried out to obtain the catalyst;

the loading amount of the transition metal element on the catalyst is 0.5-5 wt.%; the supporting amount of the transition metal element on the catalyst is based on the mass of the transition metal element.

Optionally, the loading amount of the transition metal element on the catalyst is 2-4 wt.%.

Optionally, the transition metal element comprises at least one of Fe, Mn, Cu, Zn.

Specifically, the catalyst for catalytic ozonation is characterized in that: the method comprises the steps of taking the formed honeycomb ceramic as a carrier, and coating and impregnating aluminum sol and a transition metal salt solution on the surface, wherein the loading amount of the transition metal is 0.5-5 wt.%.

Optionally, the catalyst takes the formed honeycomb ceramic as a carrier, the surface of the catalyst is coated with an impregnated alumina sol and a transition metal salt solution, the transition metal is preferably Fe, Mn, Cu and Zn, and the loading amount is preferably 2-4 wt.%.

According to yet another aspect of the present application, there is provided a method for preparing the catalyst.

The method comprises the following steps:

a) obtaining an alumina sol containing a transition metal element;

b) and (3) impregnating the formed honeycomb ceramic carrier with alumina sol containing transition metal elements, drying and roasting to obtain the catalyst.

Optionally, the method comprises the steps of:

a) obtaining aluminum sol;

b) impregnating the formed honeycomb ceramic carrier with the alumina sol, and drying and roasting to obtain a precursor;

c) and (3) dipping the precursor by using a solution containing a transition metal element, drying and roasting to obtain the catalyst.

Optionally, the transition metal element-containing alumina sol in the step a) is prepared by adding a transition metal salt after reacting an aluminum foil with hydrochloric acid;

wherein the molar ratio of the aluminum foil to the hydrochloric acid is 1.3-1.8;

the solid content of the aluminum sol containing the transition metal elements is 20-30 wt.%, and the density is 1.2-1.4 g/ml.

Optionally, the alumina sol in step a) is prepared by reacting aluminum foil with hydrochloric acid;

the solid content of the aluminum sol is 20-30 wt.%, and the density is 1.2-1.4 g/ml.

Optionally, the roasting temperature in the step b) and the step c) is 480-560 ℃, and the roasting time is 2-5 h.

Optionally, the roasting temperature is 500-550 ℃.

The drying temperature is 100-200 ℃, and the drying time is 3-8 h.

Optionally, the upper limit of the temperature of the firing is selected from 500 ℃, 520 ℃, 540 ℃, 550 ℃, or 560 ℃; the lower limit is selected from 480 ℃, 500 ℃, 520 ℃, 540 ℃ or 550 ℃.

Optionally, the upper limit of the time of the calcination is selected from 3h, 4h or 5 h; the lower limit is selected from 2h, 3h or 4 h;

alternatively, the impregnation in step b) and step c) are both equal volume impregnation.

Specifically, the preparation method of the catalyst for catalyzing ozone oxidation mainly comprises the following steps:

1) preparing a transition metal salt solution/transition metal aluminum sol mixed solution: calculating the mass of transition metal needing to be subjected to corresponding mass fraction according to the water absorption of the formed honeycomb ceramic, and dissolving the transition metal into deionized water/aluminum sol with corresponding volume to obtain a transition metal salt solution/transition metal aluminum sol mixed solution;

2) soaking an aluminum sol or a transition metal aluminum sol mixed solution on a formed honeycomb ceramic carrier by using the formed honeycomb ceramic as the carrier by an isometric impregnation method to obtain a TAl or a TAlM;

3) drying the TAl or the TAlM at 120 ℃ for 3-8 h, and roasting at 480-560 ℃ for 2-5 h in an air atmosphere to obtain cat-TAl or cat-TAlM;

4) and (3) according to the water absorption rate of TA1, dipping TA1 into a transition metal salt solution by an equal-volume dipping method, and repeating the step 3) to obtain cat-TA 1-M.

The aluminum sol in the step 1) is prepared by reacting aluminum foil and hydrochloric acid, wherein the molar ratio of the aluminum foil to the hydrochloric acid is 1.3-1.8, the solid content of the aluminum sol is 20-30 wt.%, and the density of the aluminum sol is 1.2-1.4 g/ml; the transition metal salt solution is a nitrate solution and a sulfate solution of transition metal, the equivalent volume impregnation method in the step 2) is that the pore volume of the carrier is consistent with the volume of impregnation liquid, the impregnation liquid just can completely enter the pores, the drying time in the step 3) is preferably 3-5 h, and the roasting temperature is preferably 500-550 ℃.

The invention provides application of the catalyst for catalyzing ozone oxidation as a catalyst in a catalytic ozone oxidation technology.

The invention provides a catalyst for catalyzing ozone oxidation, which is used for treating wastewater, wherein the COD (chemical oxygen demand) is 50-500 mg/L, and the reaction conditions are as follows: normal temperature and pressure, initial pH of waste water is 5-10, and O₃(mg/L):COD(mg/L)＝1.0～3.0，O₃The concentration is 10-130 mg/L, and the volume airspeed of the wastewater is as follows: 2 to 10 hours^-1。

According to another aspect of the present application, there is provided a method for treating wastewater by catalytic ozonation, characterized in that the wastewater is introduced into a reactor containing a catalyst, and reacted in the presence of ozone;

the catalyst is selected from at least one of the catalyst and the catalyst prepared by the method.

Optionally, the COD of the wastewater is 50-500 mg/L;

the reaction conditions are as follows: normal temperature and pressure, initial pH of waste water is 5-10, and O₃(mg/L)：COD(mg/L)＝1.0～3.0，O₃The concentration is 10-130 mg/L, and the volume space velocity of the wastewater is as follows: 2 to 10 hours^-1。

In the present application, "equal volume impregnation" means that the pore volume of the carrier is the same as the volume of the impregnation solution, and the impregnation solution can just completely enter the pores.

The beneficial effects that this application can produce include:

1) the catalyst, the shape-normalized catalyst, and the monolithic catalyst provided by the application can be directly used

The reactor is filled, so that the mutual friction of the surfaces of the catalysts in the transportation and use processes is avoided, and the catalyst can be ensured

Protecting the effective catalytic component formed by surface modification;

2) the catalyst provided by the application has higher initial activity in the catalytic ozone oxidation technology

And the catalyst is a novel reliable and good catalyst for industrial application.

Drawings

FIG. 1 is a flow diagram of a wastewater treatment plant according to the present application.

1: a source of oxygen; 2: a pressure reducing device; 3: a mass flow meter; 4: an ozone generator; 5: an ozone detector; 6: a mass flow meter; 7: a mass flow meter; 8: a catalytic ozonation reactor; 9: a catalytic ozonation reactor; 10: a water inlet tank; 11: a water outlet tank; 12: a water inlet tank; 13: a water outlet tank; 14: a tail gas absorption tower; 15: a centrifugal pump; 16: a centrifugal pump.

The wastewater treatment process of the equipment shown in the figure 1 comprises the following steps:

the catalytic ozonation reactor comprises an air outlet arranged at the top of the tower body, an ozone inlet at the bottom of the tower body and an upper water outlet and a lower water inlet arranged on the side wall of the tower body, ozone after being split flows into the catalytic ozonation reactor ozone inlet connected in parallel through a mass flow meter, waste water in a water inlet tank is input into the lower water inlet of the catalytic ozonation reactor through a centrifugal pump, the water outlet is connected with a water outlet tank, a gas distributor is arranged at the bottom of the catalytic ozonation reactor and communicated with the ozone inlet, the upper air outlet is connected with a tail gas absorption system, outlet water after reaction flows out through the upper water outlet of the ozone reactor, tail gas passes through an ozone detector through the upper air outlet and is connected with the lower end of a tail gas absorption tower, and the upper end of.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

Unless otherwise specified, the raw materials and catalysts in the examples of the present application were all purchased commercially.

The analysis method in the examples of the present application is as follows:

TOC (Total organic carbon) was measured using a TOC-VCPH/CPN analyzer manufactured by Shimadzu corporation, Japan; the pH is measured by a thunder magnetic PHS-3C precision pH meter; measuring the content of m-cresol by HPLC; the application of the prepared catalyst in the catalytic ozone oxidation technology is evaluated by using a fixed bed continuous reaction evaluation device.

The water quality of the m-cresol wastewater of 100ppm adopted in the experiment is as follows: 78mg/L of TOC and 6.7 of pH. And (3) continuous reaction: normal temperature and pressure, initial pH 6.7, O₃(mg/L) 1.0-3.0 COD (mg/L) and 2-10 h airspeed^-1The reaction time was 5 h.

In the examples, the preparation method of the aluminum sol a: and stirring and mixing the aluminum foil and the hydrochloric acid at a molar ratio of 1.3 to obtain the aluminum sol with a solid content of 23 wt.% and a density of 1.3 g/ml.

The preparation method of the aluminum sol b comprises the following steps: the molar ratio of the aluminum foil to the hydrochloric acid is 1.6, the aluminum foil and the hydrochloric acid are stirred and mixed, the solid content of the aluminum sol is 23 wt.%, and the density is 1.4 g/ml.

Example 1

1) Dissolving 20.46g of ferric nitrate nonahydrate in the aluminum sol a, and continuously metering the volume to 50ml to obtain an iron-aluminum sol mixed solution a;

2) soaking the iron-aluminum sol mixed solution a on a formed honeycomb ceramic carrier by an isometric impregnation method by taking the formed honeycomb ceramic as the carrier to obtain TAlM-a;

3) drying the TAlM-a at 120 ℃ for 3h, and then roasting at 520 ℃ for 3h in an air atmosphere to obtain cat-TAlFe-a.

Example 2

1) Dissolving 20.46g of ferric nitrate nonahydrate in the aluminum sol b, and continuously metering the volume to 50ml to obtain an iron-aluminum sol mixed solution b;

2) soaking the iron-aluminum sol mixed solution b on the formed honeycomb ceramic carrier by an isometric impregnation method by taking the formed honeycomb ceramic as the carrier to obtain TAlM-b;

3) drying the TAlM-b at 120 ℃ for 3h, and then roasting at 520 ℃ for 3h in an air atmosphere to obtain cat-TAlFe-b.

Example 3

1) Soaking the alumina sol b on the formed honeycomb ceramic carrier by an isometric impregnation method by taking the formed honeycomb ceramic as the carrier to obtain the TAl-b;

2) drying the TAl-b at 120 ℃ for 3h, and then roasting at 520 ℃ for 3h in an air atmosphere to obtain cat-TAl-b;

3) 36.99g of ferric nitrate nonahydrate is dissolved in water, and the volume is continuously determined to 50ml, so that ferric nitrate solution c is obtained;

4) according to the water absorption rate of TA1, 17.82ml of ferric nitrate solution c is subjected to an isometric immersion method of cat-TAl-b, then dried at 120 ℃ for 3h, and roasted at 520 ℃ for 3h in an air atmosphere to obtain cat-TA 1-Fe-b.

Example 4

1) Dissolving 27.22g of ferric nitrate nonahydrate and 4.10g of 50% manganese nitrate solution in the aluminum sol b, and continuously using the aluminum sol b to fix the volume to 50ml to obtain an iron-aluminum sol mixed solution b;

2) soaking the iron-manganese-aluminum sol mixed solution b on the formed honeycomb ceramic carrier by an isometric impregnation method by taking the formed honeycomb ceramic as the carrier to obtain TAlFeMn-b;

3) drying the TAlFeMn-b at 120 ℃ for 3h, and then roasting at 520 ℃ for 3h in the air atmosphere to obtain cat-TAlFeMn-b.

Example 5

1) Dissolving 16.34g of copper nitrate trihydrate into the aluminum sol b, and continuously using the aluminum sol b to fix the volume to 50ml to obtain an iron-aluminum sol mixed solution b;

2) soaking the iron-manganese-aluminum sol mixed solution b on the formed honeycomb ceramic carrier by an isometric impregnation method by taking the formed honeycomb ceramic as the carrier to obtain TAlCu-b;

3) drying the TAlCu-b at 120 ℃ for 3h, and then roasting at 520 ℃ for 3h in an air atmosphere to obtain the cat-TAlCu-b.

Example 6

The catalysts prepared in examples 1 to 5 were subjected to a catalytic ozonation wastewater treatment test, and the test conditions and results are shown in table 1.

TABLE 1

The experimental results show that the stability of the catalyst is better due to the addition of the aluminum sol b obtained from the experiments of the groups 1 and 2, the mixed impregnation effect of the aluminum sol and the metal salt solution is better than that of the single impregnation in times from the experiments of the groups 2 and 3, and the initial activity of the catalyst can be improved due to the addition of Mn and the activity of Fe is better than that of Cu from the experiments of the groups 2, 4 and 5. The prepared alumina sol/transition metal coating honeycomb ceramic catalyst is suitable for treating industrial wastewater by a catalytic ozonation method, belongs to an integral catalyst, reduces the resistance of a bed layer, avoids the loss of active components, and has good application prospect.

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Claims

1. A method for preparing a catalyst for catalyzing ozone oxidation is characterized by comprising the following steps:

a) obtaining an alumina sol containing a transition metal element;

b) impregnating and molding a honeycomb ceramic carrier by using alumina sol containing transition metal elements, and drying and roasting to obtain the catalyst;

2. The method of claim 1, wherein the transition metal element comprises at least one of Fe, Mn, Cu, Zn.

3. The method according to claim 1, wherein the transition metal element-containing alumina sol in step a) is prepared by reacting aluminum foil with hydrochloric acid, and adding a transition metal salt; wherein the molar ratio of the aluminum foil to the hydrochloric acid is 1.3-1.8; the solid content of the aluminum sol containing the transition metal elements is 20-30 wt.%, and the density is 1.2-1.4 g/ml.

4. The method as claimed in claim 1, wherein the roasting temperature in step b) is 480-560 ℃ and the roasting time is 2-5 h.

5. The method of claim 4, wherein the roasting temperature is 500-550 ℃;

the drying temperature is 100-200 ℃, and the drying time is 3-8 h.

6. The method of claim 1, wherein the impregnations in step b) are all equal volume impregnations.

7. A method for treating waste water by catalytic ozonation is characterized in that the waste water is introduced into a reactor filled with a catalyst and reacts in the presence of ozone;

the catalyst is selected from at least one catalyst prepared according to the method of any one of claims 1 to 6.

8. The method according to claim 7, wherein the COD of the wastewater is 50-500 mg/L;