AU2019421318A1

AU2019421318A1 - Method for preparing ozone catalyst by means of stepped gradient temperature elevation calcination method and use thereof

Info

Publication number: AU2019421318A1
Application number: AU2019421318A
Authority: AU
Inventors: Weilin BIAN; Yue Cheng; Jianjun DAI; Aimin Li; Miaoyue LI; Jinnan Wang; Wei Zhang
Original assignee: Nanjing University Yancheng Environmental Protection Technology and Engineering Research Institute
Current assignee: Nanjing University Yancheng Environmental Protection Technology and Engineering Research Institute
Priority date: 2019-01-11
Filing date: 2019-12-25
Publication date: 2021-06-24
Also published as: CN109718749B; AU2019101810A4; CN109718749A; WO2020143450A1

Abstract

Disclosed are a method for preparing an ozone catalyst by means of a stepped gradient temperature elevation calcination method and a use thereof, belonging to the field of environmentally friendly materials. The method comprises: adding water to an aluminum-based precursor material and stirring same until uniform to obtain an active precursor material; drying the active precursor material to obtain an active material; and calcinating the active material to obtain an ozone catalyst, wherein the calcination method is a programmed stepped gradient temperature elevation calcination method. In the preparation method, the efficiency of the ozone catalyst removing TOC in wastewater can be efficiently improved; and using the method to prepare the catalyst involves simple steps, is easy to control, and is more conducive to the mass production of a highly efficient ozone catalyst.

Description

SPECIFICATION METHOD FOR PREPARING OZONE CATALYST BY USING STEPPED-GRADIENT HEATING CALCINATION METHOD AND APPLICATION THEREOF TECHNICAL FIELD

The present invention relates to the field of environmental protection materials, and in particular,

relates to a method for preparing an ozone catalyst by using a stepped-gradient heating calcination

method and an application thereof.

BACKGROUND

With the development of reform and opening up, the chemical industry has sprung up like

mushrooms, but a series of environmental pollution problems have become increasingly serious. The

pesticide industry is one of the typical representatives of the fine chemical industry. Pesticide

wastewater has become an urgent problem to be solved by chemical enterprises due to its large total

COD amount, high content of toxic substances, poor biodegradability, etc. Ozone has a strong

oxidizing ability, and can directly mineralize organic matter into substances with a smaller molecular

weight. However, ozone has strong oxidation selectivity, and as a result, organic pollutants cannot be

fully mineralized into C02 and H20, causing a decrease in the utilization rate of ozone, and also

reducing the efficiency of removal of organic pollutants. To improve this phenomenon, a catalyst is

added to an ozone oxidation system, because the catalyst can decompose ozone into •OH with strong

catalytic ability to catalyze the oxidation of organic pollutants in water so as to mineralize organic

matter.

Heterogeneous ozone catalysts are widely used in ozone catalysts because of their advantages

of being easy to separate from a liquid and causing no pollution of active metal ions on which the

treatment requires additional investment. However, the low catalytic activity and incomplete

degradation of organic matter are common, which restricts the development of ozone catalysts against

pesticide wastewater.

Prior art of publication No. CN105366846A discloses a method for treating paraquat pesticide

wastewater, which adopts a process of micro-electrolysis + advanced ozone oxidation + biochar

SPECIFICATION adsorption to treat pesticide wastewater, requires a relatively large dosage of pure ozone, and cannot

fully mineralize organic matter in pesticide wastewater due to high selectivity of ozone oxidation.

Prior art of publication No. CN108097231A discloses an ozone catalytic oxidation catalyst and

a preparation method and an application thereof. The method includes mixing active components of

p-alumina and zinc oxide with water to prepare spherical pellets with a particle size of 1-9 mm;

subjecting the pellets to constant-temperature treatment at 60-90°C for 10-24 h, and then calcining

and activating the pellets at 450-550°C for 2-5 hours to obtain an ozone oxidation catalyst. Organic

phenol wastewater and sodium oxalate wastewater involved in implementation cases thereof are

relatively easily degradable wastewater, and ozone decomposition can also achieve high organic

removal efficiency, and therefore it is difficult to fully reflect the catalytic degradation ability of the

catalyst, and it is also difficult to fully explain that the method for preparing a catalyst by loading the

active components can be applied to wastewater of other chemical enterprises.

Prior art of publication No. CN106345450A discloses an ozone oxidation catalyst for wastewater

treatment, which is a supported ozone oxidation catalyst with y-alumina as a carrier and SnO2 and

TiO2 as active components. A method for preparing the catalyst includes carrier particle pretreatment,

gel solution preparation, impregnation, calcination and repeated treatment, where the first step

"carrier particle pretreatment" includes: placing alumina particles in a mixed solution of ethanol and

acetone for ultrasonic vibration to remove organic matter on the surface; then, placing the alumina

particles having undergone vibration in HNO3 for boiling, to remove an oxide layer on the surface;

taking out the acid-treated alumina particles and washing the particles with ultrapure water to be

neutral, and drying at 90-150°C; the second step "gel solution preparation" includes: dissolving tin

salt in a mixed solution of hydrochloric acid and absolute ethanol and then adding a stabilizer, adding

a titanium-based compound to the above mixed solution, slowly adding ultrapure water dropwise

with stirring, and obtaining a transparent and stable gel solution after uniform stirring; the third step

"impregnation" includes: placing the alumina particles treated in the first step into the gel solution

prepared in the second step, performing impregnation for 1-12 h with vibration, and filtering out an

impregnation liquid and then drying the obtained particle material at 85-100°C for 4-6 h; the fourth

step "calcination" includes: placing the particle material prepared in the third step in a muffle furnace,

and heating the particle material at a heating rate of 5°C/min, performing constant-temperature

calcination for 1-8 h, and heating to 400-990°C at a constant heating rate to obtain a supported ozone

oxidation catalytic material having undergone primary treatment, with y-alumina as the carrier and

SPECIFICATION tin and titanium bimetal oxides SnO2and TiO2as the active components; and the fifth step "repeated treatment" includes: repeatedly performing the third step and the fourth step several times on the supported ozone oxidation catalytic material having undergone primary treatment to obtain a supported ozone oxidation catalyst. The supported ozone oxidation catalyst can be used to perform ozone catalytic oxidation treatment on antibiotic wastewater such as chloramphenicol wastewater, penicillin wastewater, erythromycin wastewater, streptomycin wastewater, vancomycin wastewater, and pipemidic acid wastewater, and has the advantages of high removal efficiency, a high ozone utilization rate, no need for additional chemicals, etc.

SUMMARY

1. To-be-resolved Problem In view of the problem of how to further improve the activity of an ozone catalyst, the present invention provides a method for preparing an ozone catalyst by using a gradient heating calcination method and an application thereof.

2. Technical Solutions In order to solve the foregoing problems, the technical solutions adopted by the present invention are as follows: A method for preparing an ozone catalyst by using a stepped-gradient heating calcination method includes the following steps: (1): adding water to an aluminum-based precursor material and stirring evenly to obtain an active precursor material; (2): drying the active precursor material to obtain an active material; and (3) calcining the active material to obtain an ozone catalyst, where the calcination method is a programmed stepped-gradient heating calcination method. Preferably, the programmed stepped-gradient heating calcination method in step (3) includes: stage I: a stage from room temperature until cold air is discharged to form a precursor calcination atmosphere; stage II: a temperature stage in which an active crystalline phase structure of alumina is generated; stage III: a temperature stage of calcination and forming of active components; and stage IV: a cooling stage.

SPECIFICATION Preferably, in stage I, heating is performed at 5-10°C/min to 90-110°C and then the temperature

is kept for 1 h; in stageII, heating is performed at 3-5°C/min to 200-300°C and then the temperature

is kept for 2-4 h; and in stageIII, heating is performed at3C/min to 500-600°C and then the

temperature is kept for 4-8 h.

Preferably, in step IV, cooling is performed at 1-2°C/min to 200-300°C and then the temperature

is lowered to room temperature.

Preferably, in step (2), drying is performed at a temperature of 105-120°C.

Preferably, the aluminum-based precursor material further includes dextrose anhydrate or

dextrose monohydrate.

Preferably, a method for preparing the aluminum-based precursor material includes: mixing

aluminum-containing salt and dextrose anhydrate or dextrose monohydrate in the aluminum-based

precursor material at an amount-of-substance ratio of (1.5-50):1, stirring evenly at 25-35°C, and

drying in an oven at 105-120°C.

Preferably, the active precursor material further includes active components, and the active

components include one of nitrates, sulfates, hydrochlorides, acetates, oxalates, and persulfates

containing Mn, Cu, Fe, Co, and Zn components or a combination of several thereof.

Preferably, the active precursor material obtained by adding water to the aluminum-based

precursor material and the active components and mixing evenly is dried at a drying temperature of

60-120°C to obtain the active material. Drying at this temperature ensures that the active components

in the active precursor material, i.e., metal salts, are supported on the aluminum-based precursor

material.

Preferably, the aluminum-based precursor material includes aluminum isopropoxide, aluminum

nitrate, sodium metaaluminate, aluminum nitrate nonahydrate, and alumina spherical particle

materials.

Preferably, the active component of the alumina spherical particulate material is y-alumina which

has a size of 2-4 mm and is ground to10-400 meshes.

Preferably, the ozone catalyst obtained in step 3) is washed with deionized water for 3 to 5 times,

so as to remove excess metal ions and oxides thereof on the surface of the catalyst particles.

Preferably, the washed material is dried in an oven at 105-110°C, and placed in a drying oven

for use.

Preferably, the active material in step (3) is calcined twice according to the programmed stepped

A

SPECIFICATION gradient heating calcination method to obtain the ozone catalyst. Provided is an application of an ozone catalyst prepared by using the above method, which is used in the field of TOC removal from pesticide wastewater. 3. Beneficial Effects Compared with the prior art, the present invention has the following beneficial effects: (1) The ozone catalyst prepared by using the programmed stepped-gradient heating calcination method in the present invention shows excellent catalytic effects in the process of degrading pesticide wastewater. Compared with a catalyst obtained through calcination at a certain high temperature by using a one-step heating method used in the prior art, the catalyst calcined by using the method of the present invention significantly improves the TOC removal rate under the same conditions. (2) In the programmed stepped-gradient heating calcination method of the present invention, stage II is set as a temperature stage in which an active crystalline phase structure of alumina is generated, and heating is performed at 3-5°C/min to 200-300°C; during this heating stage, alumina crystal is continuously formed and crystal surface shrinkage and pore channel collapse occur, forming a tiny porous framework structure, which is conducive to the loading of active components to improve the activity of the catalyst; and keeping the temperature for 2-4 hours in this stage has the function of maintaining the crystal structure of the active catalyst and maintaining the loading strength of the active components. Stage III is set as a temperature stage of calcination and forming of active components, and active sites with active catalytic components are evenly distributed on the surface of the alumina carrier; the framework structure formed by alumina at high temperature has a certain steric hindrance effect, which makes the active components evenly distributed not easily subjected to aggregation and sintering, improves the contact between the carrier and the active components, increases the forming efficiency and stability of the catalyst, and maintains the dispersion; heating at a rate of3C/min makes the active components slowly and evenly form a metal oxide layer on the alumina surface, maintains the dispersion of the material on the surface of the carrier, and improves active sites; and keeping the temperature at 500-600°C for 4-8 h has the function of maintaining a high-active crystalline phase structure and maintaining the uniform distribution of active sites, maintains the highly dispersed active component site distribution structure and maintains the high degradation activity of the catalyst. (3) In the present invention, the active material is calcined twice according to the programmed stepped-gradient heating calcination method. Compared with the ozone catalyst calcined once, the

SPECIFICATION obtained ozone catalyst further improves the catalytic effect under the same conditions. This is

because compared with primary calcination, the secondary calcination further activates the active

components that have not been fully activated, increases the dispersion of the material and improves

the active site of the material.

(4) Using the method of the present invention to prepare the catalyst has simple steps and is easy

to control and more conducive to mass production of high-efficiency ozone catalysts.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a stepped-gradient heating calcination method adopted in

Embodiment 4; and

FIG. 2 is a schematic diagram of a one-step heating method adopted in Comparative Example 4.

DESCRIPTION OF EMBODIMENTS

The present invention is further described below with reference to specific embodiments.

Embodiment 1

An aluminum-based precursor material used in this embodiment includes: aluminum

isopropoxide and dextrose anhydrate.

14.4 g of aluminum isopropoxide was dissolve in 100 mL of deionized water, 5 g of dextrose

anhydrate was added, and the solution was stirred in a stirrer at 35°C at a speed of 400 r/min for 6 h

for full and uniform stirring; the evenly-stirred material was placed in an oven at 105°C for drying to

a constant weight, and then the material was taken out for use.

The dried material was placed in a muffle furnace, heated to 90°C at 5°C/min in an air

atmosphere, and then the temperature was kept for 1 h; further, the material was heated to 200°C at

3°C/min, and then the temperature was kept for 2 h; further, the material was heated to 550°C at

3°C/min, and the temperature was kept for 4 h; the material was cooled to room temperature at

2°C/min; and the prepared catalyst was washed 3 times with deionized water to remove excess metal

ions and oxides thereof on the surface of the catalyst particles. The washed material was placed in an

oven at 105°C for drying, and placed in a drying oven for use. The obtained ozone catalyst was

denoted as Y-Al-1.

Comparative Example 1

Other conditions of this comparative example are the same as those of Embodiment 1, except

K2

SPECIFICATION that: a material calcined by directly heating to 550°C in one step at 5°C/min was used as a blank

control, and the obtained ozone catalyst was denoted as Y-Al-0.

2,4-dichlorophenoxyacetic acid (hereinafter referred to as 2,4-D), which is a typical

representative substance in pesticide wastewater, was selected as a tested organic pollutant. Under

the conditions of a catalyst dosage of 2.5 g/L, an ozone dosage of 3 g/h, and a reaction time of 80

min, removal efficiency data is as follows:

Table 1 Comparison of TOC removal efficiency of the ozone catalyst Sample Initial TOC 10 min 40 min 60 min 80 min Removal rate mg/L mg/L mg/L mg/L mg/L

% Y-Al-0 37.26 27.41 11.40 8.79 7.71 79.3 Y-Al-1 44 32.11 7.33 4.62 4.79 89.1

Experimental data showed that the TOC removal rate of the ozone catalyst prepared by using

the direct heating method of Comparative Example 1 was slightly lower than that of the catalyst

prepared by using the stepped-gradient heating calcination method of this procedure. When the

reaction time was 80 min, the TOC removal rates of the two methods were 79.3% and 89.1%,

respectively. It can be seen that the ozone catalyst material prepared by stepped heating in

Embodiment 1 has a better catalytic effect.

Embodiment 2

An aluminum-based precursor material used in this embodiment is aluminum nitrate.

7.5 g of aluminum nitrate nonahydrate was weighed and placed in a 250 mL beaker, 60 mL of

deionized water was added for dissolution, and the solution was stirred at room temperature at 350

r/min for 6 h; the evenly-stirred material was placed in an oven at 105°C for drying to a constant

weight, and then the material was taken out for use.

The dried material was placed in a muffle furnace, heated to 90°C at 5°C/min, and then the

temperature was kept for 1 h; further, the material was heated to 200°C at 3°C/min, and then the

temperature was kept for 2 h; further, the material was heated to 550°C at 3°C/min, and the

temperature was kept for 4 h; the material was cooled to room temperature at 2°C/min; and the

prepared catalyst was washed 5 times with deionized water to remove excess metal ions and oxides

thereof on the surface of the catalyst particles. The washed material was placed in an oven at110°C

for drying, and placed in a drying oven for use. The obtained ozone catalyst was denoted as X-Al-1.

Comparative Example 2

SPECIFICATION Other conditions of this comparative Example are the same as those of Embodiment 2, except

that: a material calcined by directly heating to 550°C in one step at 5°C/min was used as a blank

control, and the obtained ozone catalyst was denoted as X-Al-0.

the conditions of a catalyst dosage of 2 g/L, an ozone flow of 2 L/min, an ozone dosage of 3 g/h, and

a reaction time of 80 min, removal efficiency data is as follows:

Table 2 Comparison of TOC removal efficiency of the ozone catalyst Sample Initial TOC 10 min 40 min 60 min 80 min Removal rate mg/L mg/L mg/L mg/L mg/L

% X-Al-0 38.33 27.59 15.13 13.28 11.84 69.1 X-Al-1 41.2 31.65 15.44 13.37 9.31 77.4

From the data analysis, it can be seen that the removal effect of the material prepared by using

the stepped-gradient heating calcination method was increased by 8.3% compared with that of the

material prepared by using the one-step heating method. Compared with a control group, the material

prepared by using this method has a faster degradation rate in the first 40 minutes, indicating that the

material prepared by using this method has a better catalytic effect.

Embodiment 3

In this embodiment, an aluminum-based precursor material used is alumina particles, and an

active component is copper nitrate trihydrate.

The commercially available alumina particle catalyst with a particle size of 2-4 mm was taken,

and the particles were ground into fine particles of 30-60 meshes by a grinder; 30 g of catalyst was

weighed, 6.42 g of copper nitrate trihydrate was added, and the solution was fully and evenly stirred

and then the supported catalyst was placed in an oven at 110°C for drying, and then the material was

taken out and placed in a ceramic crucible; the material was placed in a muffle furnace, heated to

90°C at 5°C/min, and then the temperature was kept for 1 h; further, the material was heated to 200°C

at 3°C/min, and then the temperature was kept for 2 h; further, the material was heated to 550°C at

2°C/min; and the prepared catalyst was washed 4 times with deionized water to remove excess metal

oven at 110°C for drying, and placed in a drying oven for use. The catalyst was denoted as K-Al-1.

Q

SPECIFICATION Comparative Example 3

Other conditions of this comparative example are the same as those of Embodiment 3, except

control denoted as K-Al-10.

the conditions of a catalyst dosage of 2.5 g/L, an ozone flow of 2 L/min, an ozone dosage of 3 g/h,

and a reaction time of 80 min, removal efficiency data is as follows:

Table 3 Comparison of TOC removal efficiency of the ozone catalyst Sample Initial TOC 10 min 40 min 60 min 80 min Removal rate mg/L mg/L mg/L mg/L mg/L

% K-Al-0 37.71 29.07 12.43 9.03 6.86 81.8 K-Al-1 43.3 26.22 7.48 5.93 5.38 87.6

From the comparison of experimental data, it can be known that the catalyst prepared by using

the stepped-gradient heating calcination method in Embodiment 3 had a TOC removal rate of 87.6%

in 80 min, which was 5.8% higher than the removal rate of the material prepared by using the one

step method in Comparative Example 3, and had a relatively faster TOC degradation rate in the first

40 min, indicating that the catalyst prepared by using the method in Embodiment 3 has a better

catalytic effect.

Embodiment 4

In this embodiment, an aluminum-based precursor material used includes aluminum

isopropoxide and dextrose monohydrate, and an active component is cobalt nitrate heptahydrate.

14.4 g of aluminum isopropoxide was weighed and dissolved in 100 mL of deionized water, 5 g

of dextrose monohydrate was added, then 4.2 g of cobalt nitrate heptahydrate was added, and the

solution was stirred evenly at 25°C, and placed in an oven at 120°C for drying to a constant weight;

and the material was placed in a ceramic crucible and calcined in a muffle furnace. The calcination

method adopted is the programmed stepped-gradient heating calcination method. The specific steps

were as follows:

As shown in FIG. 1, the material was heated to 90°C at 5°C/min, and then the temperature was

kept for 1 h; further, the material was heated to 200°C at 3°C/min, and then the temperature was kept

for 2 h; further, the material was heated to 550°C at 3°C/min, and the temperature was kept for 5 h;

SPECIFICATION the material was cooled to room temperature at 2°C/min; and the prepared catalyst was washed 3

times with deionized water to remove excess metal ions and oxides thereof on the surface of the

catalyst particles. The washed material was placed in an oven at 105°C for drying, and placed in a

drying oven for use. The obtained ozone catalyst was denoted as Y-Al-11.

Comparative Example 4

Other conditions of this comparative example are the same as those of Embodiment 4, except

control, to obtain an ozone catalyst denoted as Y-Al-02. The heating process is shown in FIG. 2.

and a reaction time of 80 min, removal efficiency data is as follows:

Table 4 Comparison of TOC removal efficiency of the ozone catalyst Sample Initial TOC 10 min 40 min 60 min 80 min Removal rate mg/L mg/L mg/L mg/L mg/L

% Y-Al-02 39.37 31.3 13.54 8.19 6.83 82.6 Y-Al-11 41.54 30.57 6.70 2.77 2.22 94.6

According to the comparison of test data, after the active component Co was loaded, the catalyst

prepared by using the method of the present invention shows better catalytic performance, improves

the TOC removal rate by 12% compared with the one-step heating method in Comparative Example

4, and has a relatively faster degradation rate in first 40 min, which is close to about twice the

degradation rate of the one-step heating method, thereby shortening the degradation reaction time.

This shows that the catalyst prepared by using the method of the present invention has a certain

superior performance.

Embodiment 5

active component is manganese nitrate.

and the catalyst was ground into fine particles of 10-20 meshes by a grinder. 30 g of catalyst was

weighed, 4.53 mL of 50% manganese nitrate was added, and the solution was fully and evenly stirred

In

SPECIFICATION taken out and placed in a ceramic crucible; the material was placed in a muffle furnace, heated to 90°C at 5°C/min, and then the temperature was kept for 1 h; further, the material was heated to 200°C at 3°C/min, and then the temperature was kept for 2 h; further, the material was heated to 550°C at 3°C/min, and the temperature was kept for 6 h; the material was cooled to room temperature at 2°C/min; and the prepared catalyst was washed 3 times with deionized water to remove excess metal ions and oxides thereof on the surface of the catalyst particles. The washed material was placed in an oven at 105°C for drying, and placed in a drying oven for use. The obtained ozone catalyst was denoted as K-Al-11. Comparative Example 5

Other conditions of this comparative example are the same as those of Embodiment 5, except that: a material calcined by directly heating to 550°C in one step at 5°C/min was used as a blank control, and the obtained ozone catalyst was denoted as K-Al-00. 2,4-dichlorophenoxyacetic acid (hereinafter referred to as 2,4-D), which is a typical representative substance in pesticide wastewater, was selected as a tested organic pollutant. Under the conditions of a catalyst dosage of 2.5 g/L, an ozone flow of 2 L/min, an ozone dosage of 3 g/h, and a reaction time of 80 min, removal efficiency data is as follows: Table 5 Comparison of TOC removal efficiency of the ozone catalyst Sample Initial TOC 10 min 40 min 60 min 80 min Removal rate mg/L mg/L mg/L mg/L mg/L

% Y-Al-00 39.77 33.41 11.30 8.38 6.95 82.5 Y-Al-11 41.02 34.14 11.06 8.79 5.37 86.9

The TOC removal rate of the ozone catalyst prepared by using the staged heating method of Embodiment 5 is increased by 4.4% compared with that of Comparative Example 5 by using the one step heating method, indicating that the degree of mineralization of organic matter is more thorough after the reaction, and indicating that the catalyst is more suitable for the degradation of pesticide wastewater.

Embodiment 6 The calcined catalyst in Embodiment 3 was calcined for the second time according to the calcination method in Embodiment 3, and the obtained ozone catalyst was denoted as K-Al-2. 2,4 dichlorophenoxyacetic acid (hereinafter referred to as 2,4-D), which is a typical representative substance in pesticide wastewater, was selected as a tested organic pollutant. Under the conditions of a catalyst dosage of 2.5 g/L, an ozone flow of 2 L/min, an ozone dosage of 3 g/h, and a reaction time

SPECIFICATION of 80 min, removal efficiency data is as follows:

Table 6 Comparison of TOC removal efficiency of the ozone catalyst Sample Initial TOC 10 min 40 min 60 min 80 min Removal rate mg/L mg/L mg/L mg/L mg/L

% K-Al-0 37.71 29.07 12.43 9.03 6.86 81.8 K-Al-1 43.3 26.22 7.48 5.93 5.38 87.6 K-Al-2 42.87 25.31 6.82 5.12 4.55 89.4

Through data comparison, it is found that in the process of this embodiment, the same secondary

programmed stepped-gradient heating method used for the material further improves the TOC

removal rate in degrading the same wastewater, which shows that the catalyst prepared by using this

method has excellent recycling performance, and can be used as a means to increase the activity of

the catalyst after the catalyst activity decreases upon repeated use.

Embodiment 7

Other conditions of this embodiment are the same as those of Embodiment 1, except that: the

adding amount of dextrose anhydrate was 8.5 g, and the stepped heating method includes: placing the

dried material in a muffle furnace, and heating at 10°C/min to 90°C, and keeping the temperature for

1 h; further, heating at 5°C/min to 300°C, and keeping the temperature for 4 h; further, heating at

3°C/min to 600°C, keeping the temperature for 8 h, and cooling at 1.6°C/min to room temperature to

obtain an ozone catalyst. The catalyst has the same TOC removal rate in degrading the same

wastewater under the same conditions as the catalyst in Embodiment 1.

Embodiment 8

adding amount of dextrose anhydrate was 0.25 g, and the stepped heating method includes: placing

the dried material in a muffle furnace, and heating at 8°C/min to 90°C, and keeping the temperature

for 1 h; further, heating at 4°C/min to 250°C, and keeping the temperature for 3 h; further, heating at

3°C/min to 500°C, keeping the temperature for 6 h, and cooling at 2°C/min to room temperature to

wastewater under the same conditions as the catalyst in Embodiment 1.

Embodiment 9

Other conditions of this embodiment are the same as those of Embodiment 3, except that: after

copper nitrate trihydrate was added and stirred evenly, the supported catalyst was placed in an oven

at 60°C for drying, and then the ozone catalyst was obtained by using a stepped heating method. The 11)

SPECIFICATION catalyst has the same removal rate in degrading the same wastewater under the same conditions as

the catalyst in Embodiment 1.

It has been described in detail above that in the process of the present invention, the stepped

heating conditions of the present invention can improve catalytic performances of catalysts prepared

from different raw materials or catalysts loaded with different active components, mineralize organic

matter more thoroughly, and make improvements against the current situation of incomplete catalytic

performance of the ozone catalysts, thereby having a certain function of promoting the ozone catalysts.

It should be noted that those of ordinary skill in the art should recognize that the operation steps

described in the above specific implementation solutions are merely used to illustrate the

implementation cases in the process of the present invention, and are not limited to the present

invention itself, as long as within the scope of the essential spirit of the present invention, changes

and modifications to the above implementation cases fall within the scope of the claims of the present

invention.

Claims

CLAIMS 1. A method for preparing an ozone catalyst by using a stepped-gradient heating calcination

method, comprising the following steps:

(1): adding water to an aluminum-based precursor material and stirring evenly to obtain an active

precursor material;

(2): drying the active precursor material to obtain an active material; and

(3) calcining the active material to obtain an ozone catalyst, wherein the calcination method is a

programmed stepped-gradient heating calcination method.
2. The method for preparing an ozone catalyst by using a stepped-gradient heating calcination

method according to claim 1, wherein the programmed stepped-gradient heating calcination method

in step (3) comprises:

stage I: a stage from room temperature until cold air is discharged to form a precursor calcination

atmosphere;

stage II: a temperature stage in which an active crystalline phase structure of alumina is

generated;

stage III: a temperature stage of calcination and forming of active components; and

stage IV: a cooling stage.
3. The method for preparing an ozone catalyst by using a stepped-gradient heating calcination

method according to claim 2, wherein in stage I, heating is performed at 5-10°C/min to 90-110°C and

then the temperature is kept for 1 h; in stageII, heating is performed at 3-5°C/min to 200-300°C and

then the temperature is kept for 2-4 h; and in stageIII, heating is performed at3C/min to 500-600°C

and then the temperature is kept for 4-8 h.
4. The method for preparing an ozone catalyst by using a gradient heating calcination method

according to claim 3, wherein in step IV, cooling is performed at 1-2°C/min to 200-300°C and then

the temperature is lowered to room temperature.
5. The method for preparing an ozone catalyst by using a stepped-gradient heating calcination

method according to claim 2, wherein the aluminum-based precursor material further comprises

dextrose anhydrate or dextrose monohydrate.
6. The method for preparing an ozone catalyst by using a stepped-gradient heating calcination

method according to claim 5, wherein a method for preparing the aluminum-based precursor material

comprises: mixing aluminum-containing salt and dextrose anhydrate or dextrose monohydrate in the

aluminum-based precursor material at an amount-of-substance ratio of (1.5-50):1, stirring evenly at

CLAIMS -35°C, and drying in an oven at 105-120°C.
7. The method for preparing an ozone catalyst by using a stepped-gradient heating calcination

method according to claim 2 or 5, wherein the active precursor material further comprises active

components, and the active components comprise one of nitrates, sulfates, hydrochlorides, acetates,

oxalates, and persulfates containing Mn, Cu, Fe, Co, and Zn components or a combination of several

thereof.
8. The method for preparing an ozone catalyst by using a stepped-gradient heating calcination

method according to claim 7, wherein the active precursor material obtained by adding water to the

aluminum-based precursor material and the active components and mixing evenly is dried at a drying

temperature of 60-120°C to obtain the active material.
9. The method for preparing an ozone catalyst by using a stepped-gradient heating calcination

method according to any one of claims 1 to 6 or 8, wherein the active material in step (3) is calcined

twice according to the programmed stepped-gradient heating calcination method to obtain the ozone

catalyst.
10. An application of an ozone catalyst prepared by using the method for preparing an ozone

catalyst by using a stepped-gradient heating calcination method according to claim 9, used in the field

of TOC removal from pesticide wastewater.