Composite catalyst, preparation method thereof and application of composite catalyst in irradiation degradation of coal chemical wastewater

Abstract

The present application belongs to the technical field of catalyst preparation and irradiation degradation, and particularly relates to a composite catalyst, a preparation method thereof and application of the composite catalyst in irradiation degradation of coal chemical industry wastewater. Specifically, the present application successfully prepares a compound composite catalyst containing La, Co, Bi and Ti four kinds of metals. The compound composite catalyst can be used as an electron beam irradiation catalyst to improve the degradation effect on high-concentration organic compounds, refractory, long-chain polymer organic matters and the like, can completely degrade organic pollutants to meet the emission standard, is good in economy, and has no new hazardous waste and salinity risk, and therefore has good practical application value.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalyst preparation and irradiation degradation technology, and particularly relates to a composite catalyst, a preparation method thereof and application of the composite catalyst in irradiation degradation of coal chemical industry wastewater. BACKGROUND

[0002] The information disclosed in this BACKGROUND section is only for the purpose of increasing the understanding of the background of the present application and should not be taken as an acknowledgement or any form of suggestion that this information forms prior art that is publicly known.

[0003] Coal chemical industry is one of the key fields of energy industry in China. However, during the production process of coal chemical industry, a large amount of wastewater is discharged, which has become an urgent environmental problem. These wastewaters contain various harmful substances such as heavy metals, organic matter and suspended solids, which pose a potential threat to the surrounding environment and water resources. Therefore, coal chemical wastewater treatment urgently needs to be paid attention to and solved to ensure the sustainability of industrial development and the health of the environment. Environmental protection: coal chemical wastewater contains a large amount of harmful substances, direct discharge will cause soil and water pollution, threaten the ecological balance. Implementing effective wastewater treatment is an important means to protect the environment and maintain the ecological balance.

[0004] Coal chemical wastewater may contain some difficult-to-treat high-difficulty organic matter and heavy metals, such as benzene series substances, cyanide, etc., which are difficult to completely remove by traditional treatment methods, and more efficient treatment technology is needed. The introduction of advanced wastewater treatment technology requires high investment cost, and some enterprises may not be willing or difficult to implement advanced wastewater treatment equipment due to economic considerations, which may become an obstacle to promote technology upgrading.

[0005] Electron beam irradiation as a new type of wastewater treatment technology has been widely applied and concerned. Electron beam irradiation realizes rapid degradation of organic pollutants by generating hydroxyl radicals, and is a highly efficient industrial wastewater treatment and purification method. Compared with traditional biochemical, physical and chemical treatment methods, electron beam irradiation has higher treatment efficiency and shorter treatment period, and does not need to add additional chemical reagents. Therefore, under the goal of zero discharge and wastewater reuse, electron beam irradiation technology has become one of the important directions of current wastewater treatment technology improvement. However, the inventors found that electron beam irradiation for wastewater degradation treatment has the problems of high treatment cost and the pollution treatment effect still needs to be improved. SUMMARY

[0006] To address the shortcomings of the existing technologies, this invention provides a composite catalyst, its preparation method, and its application in the irradiation degradation of coal chemical wastewater. Specifically, this invention successfully prepared a compound composite catalyst containing four metals: La, Co, Bi, and Ti. Experimental verification shows that it can be used as an electron beam irradiation catalyst to improve the degradation effect on high-concentration organic compounds, recalcitrant and long-chain polymeric organic matter, etc., and can completely degrade organic pollutants to emission standards. It is economical and does not generate new hazardous waste or salinity risks. Therefore, based on the above research results, this invention was completed.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a composite catalyst, said composite catalyst being a compound comprising at least four metals: La, Co, Bi, and Ti, wherein the LaCoO3 powder and Bi4Ti3O 12 The mass ratio of the nanosheets is 0.5-5:2-10.

[0009] A second aspect of the present invention provides a method for preparing the above-mentioned composite catalyst, the method comprising:

[0010] S1, Bi4T i3 O 12 Nanosheet preparation: Bi2O3 and TiO2 are mixed and pulverized, and the resulting mixture is calcined, cooled and dried to obtain the nanosheet.

[0011] Preparation of S2 and LaCoO3 powders: Lanthanum source and cobalt source are added to water and heated, then citric acid is added and allowed to stand until a gel is formed; the resulting gel is then calcined to obtain the powder.

[0012] S3. Preparation of composite catalyst: Bi4Ti3O 12 The nanosheets and LaCoO3 powder are dispersed in methanol, mixed evenly, and dried to obtain the final product.

[0013] A third aspect of the present invention provides the application of the above-described composite catalyst in the treatment of irradiated degradation wastewater.

[0014] The wastewater mentioned can be wastewater from coal chemical industry.

[0015] Compared with existing technical solutions, one or more of the above technical solutions have the following beneficial effects:

[0016] The above technical solution provides a compound composite catalyst containing four metals: La, Co, Bi, and Ti. Experimental verification shows that it can efficiently degrade high molecular weight organic compounds in aqueous solution using irradiation energy. At the same time, it can effectively achieve repeated recycling of the catalyst and has good stability, further promoting the industrialization of irradiation decontamination. Therefore, it has good practical application value. Attached Figure Description

[0017] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0018] Figure 1 This is an electron micrograph of the composite catalyst prepared in Example 1 of the present invention; wherein, 1-LaCoO3, 2-Bi4Ti3O 12 . Detailed Implementation

[0019] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0020] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0021] In a typical embodiment of the present invention, a composite catalyst is provided, wherein the composite catalyst is a compound containing at least four metals: La, Co, Bi, and Ti. Specifically, it is composed of LaCoO3 powder and Bi4Ti. i3 O 12 The nanosheets were obtained by combining the LaCoO3 powder with Bi4Ti3O4. 12 The mass ratio of nanosheets is 0.5-5:2-10; further, 1-2:3-5; and even further, 1.28:4.01.

[0022] In another specific embodiment of the present invention, a method for preparing the above-mentioned composite catalyst is provided, the method comprising:

[0023] S1, Bi4T i3 O 12Nanosheet preparation: Bi2O3 and TiO2 are mixed and pulverized, and the resulting mixture is calcined, cooled and dried to obtain the nanosheet.

[0024] Preparation of S2 and LaCoO3 powders: Lanthanum source and cobalt source are added to water and heated, then citric acid is added and allowed to stand until a gel is formed; the resulting gel is then calcined to obtain the powder.

[0025] S3. Preparation of composite catalyst: Bi4Ti3O 12 The nanosheets and LaCoO3 powder are dispersed in methanol, mixed evenly, and dried to obtain the final product.

[0026] In step S1, the mass ratio of Bi2O3 to TiO2 is 2-10:0.5-3, further 4-7:1-3, and even further 6:2.76. The pulverization can be carried out by grinding. In order to improve the particle dispersion during the grinding process, promote the uniform mixing of raw materials, and / or play a fluxing role during calcination, the present invention further adds an additive to Bi2O3 and TiO2. The additive can be at least one of sodium salt, potassium salt, lithium salt, or ammonium salt. Further, the additive is NaCl or KCl. The amount of additive added is controlled to be 1-10% (w / w) of the mixture.

[0027] The specific conditions for calcination are as follows: the heating rate is controlled at 2-5℃ / min, the final calcination temperature is controlled at 700-900℃, and more preferably 800-900℃, and the final temperature is maintained for 2-4 hours.

[0028] In step S2, the lanthanum source and cobalt source are at least one of oxides, chlorides, nitrates, carbonates, etc. of lanthanum and cobalt; further, lanthanum nitrate (La(NO3)3·6H2O) and cobalt nitrate (Co(NO3)2·6H2O) are selected as the lanthanum source and cobalt source, respectively.

[0029] The mass ratio of the lanthanum source, cobalt source, and citric acid is 10-30:1-5:10-20, and more specifically 20.71:3.17:16.80.

[0030] The specific calcination conditions include: pre-calcining at 200-300℃ (preferably 250℃) for 3-5 hours, then increasing the temperature at a rate of 5-10℃ / min, with the final calcination temperature being 700-900℃ (preferably 800-900℃), and maintaining the final temperature for 3-5 hours (preferably 4-5 hours).

[0031] In step S3, the LaCoO3 powder and Bi4Ti3O 12 The mass ratio of nanosheets is 0.5-5:2-10; further, 1-2:3-5; and even further, 1.28:4.01.

[0032] In another specific embodiment of the present invention, the application of the above-mentioned composite catalyst in irradiation degradation wastewater treatment is provided.

[0033] The wastewater mentioned can be wastewater from coal chemical industry.

[0034] Specifically, the application method includes: adding the above-mentioned composite catalyst into coal chemical wastewater and irradiating it with an electron beam.

[0035] The dosage of the composite catalyst is 0.01-0.1 g / L, and further 0.5 g / L.

[0036] The specific conditions for irradiation treatment are as follows: electron beam irradiation energy of 1-10 MeV (preferably 1-5 MeV), irradiation beam current intensity of 10-200 mA (preferably 10-100 mA), irradiation dose of 0.5-30 kGy, and irradiation treatment time of 0.5-1 min.

[0037] The coal chemical wastewater refers to industrial wastewater generated during coal chemical production processes. The treatment process of this invention can significantly reduce the COD of the coal chemical wastewater. Simultaneously, the iron-based metal-organic framework / titanium dioxide composite material prepared above is recyclable, exhibits good stability, further reduces treatment costs, and promotes the industrialization of irradiation decontamination.

[0038] The present invention will be further illustrated below with specific examples. These examples are for illustrative purposes only and do not limit the scope of the invention. Any simple modifications, equivalent variations, and alterations made to the embodiments based on the technical essence of the present invention are within the scope of the present invention. All embodiments use the same batch of coal chemical wastewater with an initial COD of 630 mg / L.

[0039] Example 1

[0040] (1) Bi4Ti3O 12 Nanosheet preparation: 6.0 g of Bi₂O₃ and 2.76 g of TiO₂ were mixed, and 0.88 g of NaCl additive was added before grinding for 2 h. The mixture was then calcined at a heating rate of 2 °C / min to a final temperature of 800 °C, which was maintained for 2 h. After cooling, Bi₄Ti₃O₃ was filtered out. 12 Nanosheets were prepared and dried at 60°C.

[0041] (2) Preparation of LaCoO3 powder. 20.71 g of La(NO3)3·6H2O and 3.17 g of Co(NO3)3·6H2O were added to 100 ml of water, heated to 60 °C and stirred. Then, 16.80 g of citric acid monohydrate was added to the reaction system, and the mixture was allowed to stand until a gel formed. The gel was calcined. First, the gel was pre-calcined in a muffle furnace at 250 °C for 4 h, then the temperature was increased at a rate of 5 °C / min, and the final calcination temperature was 800 °C, which was maintained for 4 h. After calcination, black solid LaCoO3 powder was obtained.

[0042] (3) Preparation of composite catalyst. 1.28g LaCoO3 powder and 4.01g Bi4Ti3O were mixed. 12 Nanosheets were dispersed in 20 ml of methanol and mixed evenly. After stirring at room temperature, the mixture was dried in an oven at 60 °C for 12 h to obtain a compound catalyst containing four metals: La, Co, Bi, and Ti.

[0043] (4) The composite material powder was added to the pretreated coal chemical wastewater with a COD of 630 mg / L and an addition amount of 0.05 g / L. Electron beam irradiation was then carried out at an energy of 5 MeV, a beam current of 10 mA, an absorbed dose of 5 kGy, and an irradiation time of 60 seconds.

[0044] Example 2

[0045] The procedure was carried out according to Example 1, except that in step 1, TiO2 was changed from 2.76g to 5.52g, and the other steps were the same as in Example 1.

[0046] Example 3

[0047] The procedure was carried out according to Example 1, except that in step 2, the gel was not pre-calcined; instead, the temperature was increased directly at a rate of 5°C / min, and the final calcination temperature was 800°C, which was maintained for 4 hours. After calcination, a black solid powder, LaCoO3 powder, was obtained. All other steps were the same as in Example 1.

[0048] Example 4

[0049] The procedure was carried out according to Example 1, except that in step 3, Bi4Ti3O 12 The mass of the nanosheets changed from 4.01g to 10.03g, and the other steps were the same as in Example 1.

[0050] Example 5

[0051] The procedure was carried out according to Example 1, except that in step 2, Bi4Ti3O 12The calcination temperature of the nanosheets was adjusted differently, with a heating rate of 3℃ / min and a final calcination temperature of 680℃. The final temperature was maintained for 2 hours, and the rest was the same as in Example 1.

[0052] Example 6

[0053] The procedure was carried out according to Example 1, except that in step 2, the mass of citric acid monohydrate added was different, being 1 g. Everything else was the same as in Example 1.

[0054] Example 7

[0055] Without adding a catalyst, the biological wastewater was subjected to the same irradiation process as step 4 in Example 1.

[0056] Table 1 Comparison of wastewater degradation rates in the examples

[0057] Case COD (mg / L) COD degradation rate raw sewage 630 / Example 1 238 62.2％ Example 2 293 53.5％ Example 3 254 59.7％ Example 4 296 53.0％ Example 5 286 54.6％ Example 6 268 57.5％ Example 7 427 32.2％

[0058] As can be seen from the COD removal rates of wastewater in Table 1, the composite catalyst obtained in Example 1 exhibits the best catalytic activity, significantly improving COD degradation compared to single electron beam irradiation. The composite catalyst prepared in Example 1 of this invention can be reused more than 20 times. After catalyst recovery, drying, and repeated sintering, it can be recycled more than 20 times.

[0059] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. The application of composite catalysts in the treatment of wastewater from coal chemical industry by irradiation degradation, characterized in that, The composite catalyst is a compound containing at least four metals: La, Co, Bi, and Ti, and is composed of LaCoO3 powder and Bi4Ti3O. 12 The nanosheets were obtained by combining LaCoO3 powder and Bi4Ti3O4. 12 The mass ratio of the nanosheets is 0.5-5:2-10; The specific method of the application includes: adding the composite catalyst into coal chemical wastewater and irradiating it with an electron beam; The specific conditions for irradiation treatment are as follows: electron beam irradiation energy of 1-10 MeV, irradiation beam current intensity of 10-200 mA, irradiation dose of 5-30 kGy, and irradiation treatment time of 0.5-1 min.

2. The application as described in claim 1, characterized in that, The dosage of the composite catalyst is 0.01-0.1 g / L.

3. The application as described in claim 1, characterized in that, The preparation method of the composite catalyst includes: S1, Bi4T i3 O 12 Nanosheet preparation: Bi2O3 and TiO2 are mixed and pulverized, and the resulting mixture is calcined, cooled and dried to obtain the nanosheet. Preparation of S2 and LaCoO3 powders: Lanthanum source and cobalt source are added to water and heated, then citric acid is added and allowed to stand until a gel is formed; the resulting gel is then calcined to obtain the powder. S3. Preparation of composite catalyst: Bi4Ti3O 12 The nanosheets and LaCoO3 powder are dispersed in methanol, mixed evenly, and dried to obtain the final product.

4. The application as described in claim 3, characterized in that, In step S1, the mass ratio of Bi2O3 to TiO2 is 2-10:0.5-3; the pulverization is carried out by a grinding process.

5. The application as described in claim 3, characterized in that, In step S1, an additive is added to Bi2O3 and TiO2, wherein the additive is at least one of sodium salt, potassium salt, lithium salt, or ammonium salt; the amount of the additive added is controlled to be 1-10% of the mixture. The specific conditions for calcination are as follows: the heating rate is controlled at 2-5℃ / min, the final calcination temperature is controlled at 700-900℃, and the final temperature is maintained for 2-4 hours.

6. The application as described in claim 5, characterized in that, The additive is NaCl or KCl.

7. The application as described in claim 3, characterized in that, In step S2, the lanthanum source and cobalt source are at least one of lanthanum and cobalt oxides, chlorides, nitrates, and carbonates.

8. The application as described in claim 7, characterized in that, Lanthanum nitrate and cobalt nitrate were selected as the lanthanum source and cobalt source, respectively.

9. The application as described in claim 3, characterized in that, In step S2, the mass ratio of the lanthanum source, cobalt source, and citric acid is 10-30:1-5:10-20.

10. The application as described in claim 9, characterized in that, The mass ratio of the lanthanum source, cobalt source, and citric acid is 20.71:3.17:16.

80.

11. The application as described in claim 3, characterized in that, In step S2, the specific calcination conditions include: pre-calcining at 200-300℃ for 3-5 hours, then increasing the temperature at a rate of 5-10℃ / min, with the final calcination temperature being 700-900℃, and maintaining the final temperature for 3-5 hours.

12. The application as described in claim 3, characterized in that, In step S3, the LaCoO3 powder and Bi4Ti3O 12 The mass ratio of the nanosheets is 0.5-5:2-10.

13. The application as described in claim 12, characterized in that, The LaCoO3 powder and Bi4Ti3O 12 The mass ratio of the nanosheets is 1-2:3-5.

14. The application as described in claim 13, characterized in that, The LaCoO3 powder and Bi4Ti3O 12 The mass ratio of nanosheets is 1.28:4.01.

Images