CN115138367A

CN115138367A - Ozone oxidation catalyst and preparation method and application thereof

Info

Publication number: CN115138367A
Application number: CN202110343677.5A
Authority: CN
Inventors: 王宏伟; 张庆民; 赵冬炎; 吴晓峰; 张冰鑫; 王天来; 苗磊; 庄立波
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2021-03-30
Filing date: 2021-03-30
Publication date: 2022-10-04

Abstract

The invention provides an ozone oxidation catalyst and a preparation method and application thereof. The preparation method comprises the following steps: s1, mixing copper nitrate, lanthanum nitrate, an auxiliary dispersing agent and an auxiliary binding agent to obtain a steeping liquor; s2, immersing the modified gamma-activated alumina carrier into an impregnating solution to obtain a catalyst precursor; and S3, drying and roasting the catalyst precursor to obtain the ozone oxidation catalyst. Wherein the auxiliary dispersing agent is a mixed solution of beta-cyclodextrin and ethanol, and the auxiliary binding agent is ammonia water. The ozone oxidation catalyst is prepared by an impregnation method, modified gamma-activated alumina is used as a carrier, copper oxide and lanthanum oxide are used as active components, an ethanol mixed solution of a co-dispersant beta-cyclodextrin and an ammonia water as a co-binder are introduced, so that the catalytic activity and the stability of the ozone oxidation catalyst are better through synergistic interaction, and when the ozone oxidation catalyst is subsequently applied to the oxidation process of biochemically treated sewage, the capacity of treating complex sewage is better, and the COD removal rate is higher.

Description

Ozone oxidation catalyst and preparation method and application thereof

Technical Field

The invention relates to the field of catalysts, and particularly relates to an ozone oxidation catalyst and a preparation method and application thereof.

Background

The chemical comprehensive sewage is formed by gathering a plurality of strands of chemical sewage, the water quality is complex due to the diversity of the sources, the characteristic pollutants are numerous, and furthermore, the residual organic matters and organic matter fragments in the effluent after biochemical reaction treatment are more complex. In order to realize the standard discharge of the final effluent of the sewage plant, the biochemical effluent needs to be subjected to advanced treatment.

Ozone is an allotrope of oxygen, has an oxidation-reduction potential of 2.07V in a standard state, is a very strong oxidant, and is widely applied to the fields of domestic sewage treatment and industrial sewage treatment. In order to overcome the problems of selective oxidation, large ozone consumption and high energy consumption of the single ozone oxidation technology, a catalyst is introduced into a reaction system. Under the action of the catalyst, the efficiency of ozone oxidation can be greatly improved, the dosage of ozone is reduced, and the catalytic ozone oxidation reaction is nonselective. Therefore, the ozone catalytic oxidation technology becomes an important chemical comprehensive advanced sewage treatment technology. In the ozone catalytic oxidation of sewage treatment, the traditional homogeneous catalyst has the problems that the catalyst cannot be recovered, secondary pollution is introduced, and the treatment cost is high. The heterogeneous catalytic ozonation technology has three phases of solid, liquid and gas in a reaction system, the catalyst is solid, reactants and products are liquid or gaseous, the separation and reutilization of the catalyst are convenient, secondary pollution of effluent is not caused, and the heterogeneous catalytic ozonation technology becomes a mainstream technology of a sewage deep treatment technology.

The invention patent CN106964333A discloses a rare earth supported catalyst for treating sewage, a preparation method and application thereof, and a method for treating sewage by ozone catalytic oxidation. The invention patent CN107008449A discloses a preparation method of an ozone heterogeneous oxidation solid catalyst. The catalyst is used for heterogeneous reaction, the carrier is porous mazzite, garnet, medical stone, wollastonite, potash feldspar and boromagnesite, the auxiliary agent is organic salt containing scandium, yttrium, lanthanum and lutetium, and the active components are elements such as titanium, vanadium, osmium and the like. The invention patent CN107758971A is a domestic sewage treatment process based on a magnetic particle photocatalyst. The catalyst comprises magnetic nanoparticles, titanium dioxide, graphene, aluminum oxide and carboxymethyl-beta-cyclodextrin. The invention patent CN108499574A discloses a catalyst for catalyzing ozone to oxidize low-concentration volatile organic compounds, namely MnO _x -CeO _x -LaO _x -CuO _x Aluminum oxide, manganese nitrate, cerium nitrate, lanthanum nitrate and copper nitrate are used as main raw materials. The catalyst is applied to the field of ozone catalytic oxidation treatment of low-concentration volatile organic compounds, and belongs to the field of gas purification. The invention patent CN103586026A discloses a carbon-supported catalyst for ozone oxidation, and a preparation method and application thereof. The catalyst consists of active carbon supported iron, copper, nickel or manganese transition metal active components and a cerium, lanthanum or potassium cocatalyst. 0.5 to 10.0 percent of active component, 0.00 to 0.50 percent of cocatalyst and the balance of carrier. The catalyst is a water treatment universal ozone catalyst, and the carrier is modified activated carbon.

The existing ozone heterogeneous catalytic oxidation technology has the problems of single pollutant removal, poor capability of treating complex sewage and low COD removal efficiency.

Disclosure of Invention

The invention mainly aims to provide an ozone oxidation catalyst, and a preparation method and application thereof, so as to solve the problems of poor capability of treating complex sewage and low COD removal efficiency of the ozone oxidation catalyst in the prior art.

In order to achieve the above object, according to one aspect of the present invention, there is provided a method for preparing an ozone oxidation catalyst, the method comprising the steps of: s1, mixing copper nitrate, lanthanum nitrate, an auxiliary dispersing agent and an auxiliary binding agent to obtain a steeping liquor; s2, immersing the modified gamma-activated alumina carrier into an impregnating solution to obtain a catalyst precursor; s3, drying and roasting the catalyst precursor to obtain an ozone oxidation catalyst; wherein the auxiliary dispersing agent is a mixed solution of beta-cyclodextrin and ethanol, and the auxiliary binding agent is ammonia water.

Further, the weight ratio of the modified gamma-activated alumina carrier to the impregnating solution is (3-4): (10 to 20).

Furthermore, the molar ratio of copper ions in the copper nitrate to ammonia in the ammonia water is 1 (6-8). Preferably, the molar concentration of the ammonia water is 0.1 to 2mol/L.

Furthermore, the weight concentration of the beta-cyclodextrin in the impregnation liquid is 0.05-1.5%.

Further, the molar ratio of copper ions in copper nitrate to lanthanum ions in lanthanum nitrate in the impregnation solution was (14 to 8): 1.

Further, the weight ratio of the ethanol to the beta-cyclodextrin is (10-8): (1-2).

Further, the roasting treatment process comprises the steps of heating the dried catalyst precursor to 280-320 ℃ at the speed of 8-20 ℃/min and roasting for 1-3 h, and then heating to 390-510 ℃ at the speed of 3-8 ℃/min and roasting for 6-15 h to obtain the ozone oxidation catalyst.

In order to achieve the above object, according to one aspect of the present invention, there is provided an ozone oxidation catalyst produced by the above-described method for producing an ozone oxidation catalyst.

In order to achieve the above object, according to one aspect of the present invention, there is provided a use of an ozone oxidation catalyst in a process of oxidizing biochemically treated sewage, the ozone oxidation catalyst being prepared by the above method for preparing an ozone oxidation catalyst.

Furthermore, the COD of the sewage is 75.2-90.0 mg/L.

The ozone oxidation catalyst is prepared by an impregnation method, modified gamma-activated alumina is used as a carrier, copper oxide and lanthanum oxide are used as active components, and the catalytic activity and stability of the ozone oxidation catalyst are promoted to be better by introducing ethanol mixed liquor of a dispersion aid agent beta-cyclodextrin and ammonia water serving as a binding aid in a synergistic manner. Meanwhile, the preparation method is simpler and the preparation cost is lower.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.

As described in the background section, the ozone oxidation catalyst in the prior art has poor capability of treating complex sewage and low COD removal efficiency.

In order to solve the problem, the invention provides a preparation method of an ozone oxidation catalyst. The preparation method comprises the following steps: s1, mixing copper nitrate, lanthanum nitrate, an auxiliary dispersing agent and an auxiliary binding agent to obtain a steeping liquor; s2, immersing the modified gamma-activated alumina carrier into an impregnating solution to obtain a catalyst precursor; and S3, drying and roasting the catalyst precursor to obtain the ozone oxidation catalyst. Wherein the auxiliary dispersing agent is a mixed solution of beta-cyclodextrin and ethanol, and the auxiliary binding agent is ammonia water.

The method comprises the steps of putting a modified gamma-activated alumina carrier into a liquid containing active substances of copper nitrate and lanthanum nitrate, an auxiliary dispersing agent beta-cyclodextrin, ethanol and an auxiliary binding agent ammonia water for impregnation, gradually adsorbing the active substances on the surface of the carrier, obtaining a catalyst precursor after the impregnation balance, and drying and roasting the catalyst precursor to obtain the ozone oxidation catalyst, wherein the active components in the ozone oxidation catalyst are copper oxide and lanthanum oxide. The modified gamma-activated alumina is used as a carrier, and the high specific surface area and pore volume of the carrier can improve the dispersibility of active components on the carrier, so that the catalytic activity of the catalyst is improved. The mixed solution of beta-cyclodextrin and ethanol is used as the dispersion aid, so that the utilization rate of the active components can be improved, and the catalytic activity of the catalyst can be further improved. Ammonia water is used as a bonding assistant, and the weak alkalinity of the ammonia water can improve the acid strength distribution on the surface of the carrier, promote the bonding strength of the active component and the carrier to be higher, and further improve the stability of the catalyst. The catalytic activity and the stability of the ozone oxidation catalyst are promoted to be better by introducing the beta-cyclodextrin, the ethanol and the ammonia water in a synergistic manner, and when the catalyst is subsequently applied to the oxidation process of the sewage subjected to biochemical treatment, the capacity of treating complex sewage is better, and the COD removal rate is higher. Meanwhile, the preparation method is simpler and has lower cost.

In addition, the specific surface area of the carrier gamma-activated alumina adopted by the invention is about 177m ² The grain diameter is 2 mm-4 mm, the pore volume is 0.40 mL/g. gamma-Al ₂ O ₃ The preparation method comprises the following steps: 1000mL of alumina was washed with distilled water 3 times to remove floating ash. And (2) placing the alumina in 1200mL of 0.1mol/L citric acid, soaking at 80 ℃ for 4 hours, draining residual liquid, airing at a ventilated place at room temperature in a dark place, placing the aired carrier in a forced air drying box, and drying at 120 ℃ for 5 hours to obtain the gamma-activated alumina carrier.

Preferably, the weight ratio of the modified gamma-activated alumina carrier to the impregnating solution is (3-4): (10-20). Within the range, the dispersion effect of the active component in the impregnation liquid is better, and the utilization rate of the active component can be improved due to good dispersibility. Meanwhile, the bonding strength of the active component and the carrier is stronger, and the active component is more uniformly distributed on the carrier, so that the high catalytic activity and the high stability of the catalyst can be further balanced.

Preferably, the molar ratio of copper ions in the copper nitrate to ammonia in the ammonia water is 1 (6-8). Within this range, the bonding strength of the active component to the carrier can be further improved, and the stability of the catalyst can be promoted to be better. More preferably, the molar concentration of ammonia water is 0.1 to 2mol/L, based on which the acid strength distribution on the support surface can be more effectively improved.

In a preferred embodiment, the impregnation solution has a beta-cyclodextrin concentration by weight of 0.05 to 1.5%. Therefore, the dispersion effect of the active substance in the impregnation liquid can be promoted to be better, the utilization rate of the active component is higher, and the catalytic activity of the catalyst is promoted to be better.

For the purpose of promoting better catalytic activity of the catalyst, the molar ratio of copper ions in copper nitrate and lanthanum ions in lanthanum nitrate in the impregnation liquid is (14-8): 1.

Based on the purpose of further promoting better dispersion effect and higher utilization rate of active substances in the impregnation liquid, in the dispersion aid, the weight ratio of beta-cyclodextrin to ethanol is (10-8): (1-2).

Preferably, the roasting treatment process comprises the steps of heating the dried catalyst precursor to 280-320 ℃ at the speed of 8-20 ℃/min and roasting for 1-3 h, and then heating to 390-510 ℃ at the speed of 3-8 ℃/min and roasting for 6-15 h to obtain the ozone oxidation catalyst. By doing so, the performance of the active component in the catalyst during calcination can be promoted to be more uniform and stable.

The invention also provides an ozone oxidation catalyst, which is prepared by the preparation method of the ozone oxidation catalyst.

Based on the reasons, the catalytic activity and the stability of the ozone oxidation catalyst are better, and when the ozone oxidation catalyst is subsequently applied to the oxidation process of sewage after biochemical treatment, the capacity of treating complex sewage is better, and the COD removal rate is higher.

The invention also provides an application of the ozone oxidation catalyst in the process of oxidizing the biochemically treated sewage, and the ozone oxidation catalyst is prepared by the preparation method of the ozone oxidation catalyst. In a preferred embodiment, the COD of the wastewater is in the range of 75.2 to 90.0mg/L.

Based on the reasons, the catalytic activity and the stability of the ozone oxidation catalyst are better, and particularly when the ozone oxidation catalyst is applied to the oxidation process of sewage after biochemical treatment, the capacity of treating complex sewage is better, and the COD removal rate is higher.

The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.

Example 1

Preparation of modified gamma-active alumina carrier

700g of alumina was put into a 3000mL beaker, and washed 3 times with distilled water to remove fly ash. And then soaking the carrier in 1200mL of 0.1mol/L citric acid at 80 ℃ for 4h, draining residual liquid, airing the carrier at a ventilation place at room temperature in a dark place, putting the aired carrier into an air-blast drying oven, and drying the carrier at 120 ℃ for 5h to obtain the modified gamma-activated alumina carrier.

Example 2

Taking analytically pure copper nitrate to prepare 1mol/L copper nitrate mother liquor. Preparing 1mol/L lanthanum nitrate mother liquor from analytically pure lanthanum nitrate. And (3) preparing a steeping liquor by using the prepared copper nitrate mother liquor, lanthanum nitrate mother liquor, analytically pure ammonia water, anhydrous ethanol and analytically pure beta-cyclodextrin. The formula of the impregnation liquid is as follows: the molar concentration of copper nitrate was 0.6mol/L. The molar ratio of copper nitrate to lanthanum nitrate is 10:1, the molar ratio of copper nitrate to ammonia water is 1:6, the weight concentration of the beta-cyclodextrin in the impregnation liquid is 0.5%, and in the dispersion aid, the weight ratio of ethanol to the beta-cyclodextrin is 10:1.

150g of the modified gamma-activated alumina carrier prepared in example 1 was immersed in 600g of the impregnation solution and stirred once every 0.5 h. Soaking for 4h, draining residual liquid, airing at a ventilation position at room temperature in a dark place, putting the aired catalyst precursor into a blast drying oven, drying at 120 ℃ for 6h, putting into a muffle furnace, carrying out temperature programming roasting, rapidly heating to 300 ℃ at the heating rate of 20 ℃/min, carrying out constant temperature roasting for 2h, heating to 450 ℃ at the heating rate of 5 ℃/min, and carrying out constant temperature roasting for 6h to obtain the catalyst. Wherein, the weight ratio of the modified alumina carrier to the impregnating solution is 1:4.

example 3

The difference from the example 2 is that the mole ratio of the copper nitrate to the lanthanum nitrate in the impregnation solution is 14:1.

example 4

The difference from the example 2 is that the mole ratio of the copper nitrate and the lanthanum nitrate in the impregnation liquid is 8:1.

example 5

The difference from example 2 is that the weight concentration of beta-cyclodextrin in the impregnation solution was 0.05%.

Example 6

The difference from example 2 is that the weight concentration of beta-cyclodextrin in the impregnation solution is 1.5%.

Example 7

The difference from the embodiment 2 is that during the temperature programming roasting, the temperature is rapidly raised to 280 ℃ at the temperature raising rate of 20 ℃/min, the roasting is carried out for 2 hours at the constant temperature, and then the temperature is raised to 450 ℃ at the temperature raising rate of 5 ℃/min, and the roasting is carried out for 6 hours at the constant temperature.

Example 8

The difference from the embodiment 2 is that during the temperature programming roasting, the temperature is rapidly raised to 300 ℃ at the temperature raising rate of 20 ℃/min, the roasting is carried out at the constant temperature for 2h, and then the temperature is raised to 400 ℃ at the temperature raising rate of 5 ℃/min, and the roasting is carried out at the constant temperature for 6h.

Example 9

The difference from the embodiment 2 is that the weight ratio of the modified alumina carrier to the impregnating solution is 3:10.

example 10

The difference from the embodiment 2 is that the weight ratio of the modified alumina carrier to the impregnating solution is 4:20.

example 11

The difference from example 2 is that the beta-cyclodextrin concentration by weight is 3%.

Example 12

The difference from example 2 is that the molar ratio of copper ions in copper nitrate to ammonia in ammoniacal water is 1.

Comparative example 1

The only difference from example 2 is that no mixed solution of co-dispersant absolute ethanol and analytically pure beta-cyclodextrin was added to the impregnation solution.

Comparative example 2

The difference from example 2 is only that no ammonia as a co-binder was added to the impregnation solution.

And (3) performance characterization:

the catalysts prepared in examples 2 to 12, comparative example 1 and comparative example 2 and the carrier prepared in example 1 were used for each 100mL of the catalyst for activity evaluation. The effluent of biochemical reaction (COD is 75.2 mg/L) of a certain sewage plant is used as a water source, and continuous reaction is adopted to carry out activity evaluation. The ozone concentration in the aeration mixed gas is 1.43g/m ³ Evaluation of ActivityAnd (5) sampling for 56h and analyzing every 6h. The evaluation results are shown in the attached Table 1.

TABLE 1

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an ozone oxidation catalyst, comprising the steps of:

s1, mixing copper nitrate, lanthanum nitrate, an auxiliary dispersing agent and an auxiliary binding agent to obtain a steeping liquor;

s2, immersing the modified gamma-activated alumina carrier into the impregnation liquid to obtain a catalyst precursor;

s3, drying and roasting the catalyst precursor to obtain the ozone oxidation catalyst;

the auxiliary dispersing agent is a mixed solution of beta-cyclodextrin and ethanol, and the auxiliary binding agent is ammonia water.

2. The method for preparing an ozone oxidation catalyst according to claim 1, wherein the weight ratio of the modified gamma-activated alumina carrier to the impregnation liquid is (3-4): (10-20).

3. The method for producing an ozone oxidation catalyst according to claim 1 or 2, wherein the molar ratio of copper ions in the copper nitrate to ammonia in the ammonia water is 1 (6 to 8); preferably, the molar concentration of the ammonia water is 0.1-2 mol/L.

4. The method of any one of claims 1 to 3, wherein the weight concentration of the β -cyclodextrin in the impregnation solution is 0.05 to 1.5%.

5. The method of producing an ozone oxidation catalyst according to claim 1, wherein a molar ratio of copper ions in the copper nitrate to lanthanum ions in the lanthanum nitrate in the impregnation liquid is (14 to 8): 1.

6. The method for preparing an ozone oxidation catalyst according to claim 1, wherein the weight ratio of the ethanol to the β -cyclodextrin in the dispersion aid additive is (10 to 8): (1-2).

7. The method of producing an ozone oxidation catalyst according to any one of claims 1 to 6, characterized in that the calcination treatment process includes:

heating the dried catalyst precursor to 280-320 ℃ at the speed of 8-20 ℃/min, roasting for 1-3 h, and then heating to 390-510 ℃ at the speed of 3-8 ℃/min, roasting for 6-15 h, and obtaining the ozone oxidation catalyst.

8. An ozone oxidation catalyst, characterized in that it is produced by the method for producing an ozone oxidation catalyst according to any one of claims 1 to 7.

9. Use of an ozone oxidation catalyst in the oxidation of biochemically treated wastewater, wherein the ozone oxidation catalyst is prepared by the method of any one of claims 1 to 7.

10. The use of the ozonation catalyst according to claim 9 in the oxidation of biochemically treated wastewater, wherein the COD of the wastewater is 75.2-90.0 mg/L.