A catalyst with high dispersion of active components, its preparation method and application

Abstract

The application discloses a kind of active component highly dispersed catalyst, which is prepared by the following method: copper salt, cerium salt, aminocarboxylic acid salt, water and ethanol are mixed, ultrasonic, obtain impregnation solution, granular carrier is placed in the above impregnation solution, vacuum rotary evaporation impregnation is carried out in rotary evaporator until liquid is completely evaporated;Drying, calcination, to obtain the catalyst.The preparation method of the present application is simple and fast, the active metal is a non-transition metal with lower cost, and the oxidation performance of the catalyst is improved by doping with rare earth metal cerium, and batch production can be realized;The addition of aminocarboxylic acid salt and the vacuum rotary impregnation step synergistically realize the high dispersion of copper active center, avoid the agglomeration of active metal, and have better catalytic activity.The catalyst is used for ozone catalytic oxidation reaction, and the TOC removal rate can reach more than 80%.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, specifically to a method for preparing a catalyst with highly dispersed active components, and the application of the catalyst in the field of wastewater treatment. Background Technology

[0002] Ozone oxidation technology has the advantages of strong oxidation capacity, fast reaction rate, and convenient control, and has been widely used in the field of wastewater treatment. However, the ozone oxidation capacity alone is limited, and it needs to be used in conjunction with a catalyst to achieve better treatment results. Catalysts with copper as the active component have excellent catalytic activity, and therefore have been the subject of extensive research by scholars.

[0003] CN109107582A discloses a method for preparing a high-efficiency ozone catalyst, comprising the following steps: 1) Weighing an active support material, granulating it, drying it, and calcining it at 500~700℃ under nitrogen protection to prepare an active support; the active support material is a mixture of activated clay, bamboo charcoal, and graphite; 2) Loading manganese compounds and copper compounds onto the active support using impregnation or spraying methods; 3) Drying the active support loaded with manganese compounds and copper compounds and then drying it at 180~280℃ for 2~6 hours to complete the catalyst reactivation and molding, thereby obtaining a high-efficiency ozone catalyst; the catalyst of the present invention can be used in wastewater treatment according to single-phase and multi-phase catalytic oxidation processes, and can also be adapted to static water decontamination and dynamic water decontamination, and has the effect of removing oil stains and decolorizing polluted water sources.

[0004] CN110270329A discloses an ozone catalyst for treating recalcitrant organic pollutants in water and its preparation method. The catalyst is an alumina catalyst composite material supported on copper oxides. The method includes: Step 1, pretreatment: washing activated alumina microspheres with deionized water and then thoroughly drying them; Step 2, impregnation treatment: thoroughly impregnating the dried activated alumina microspheres from Step 1 in a pre-prepared copper nitrate precursor solution, followed by thorough washing and drying to obtain activated alumina microspheres supported on the copper nitrate precursor; Step 3, calcination treatment: calcining the activated alumina microspheres supported on the copper nitrate precursor obtained in Step 2 at high temperature. The resulting copper oxide-supported alumina catalyst composite material is the ozone catalyst for treating recalcitrant organic pollutants in water. This invention features simple equipment, strong operability, and is suitable for large-scale production.

[0005] However, the above catalyst preparation process mainly involves impregnating the catalyst support with a conventional metal inorganic salt solution and then calcining it to complete the catalyst preparation. Catalysts prepared by this method have the disadvantage of uneven distribution of active components, which can easily cause agglomeration of active components and reduce the catalytic activity of the catalyst. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing a catalyst with highly dispersed active components. By employing specific technical means, the high dispersion of active metals is achieved. The catalyst has advantages such as simple preparation, good stability, good catalytic activity, and low cost, and can be mass-produced, showing promising application prospects.

[0007] To achieve the above technical objectives, the technical solution adopted by this invention is as follows:

[0008] A method for preparing a catalyst with highly dispersed active components includes the following steps:

[0009] Copper salt, cerium salt, aminocarboxylate, water and ethanol are mixed and sonicated to obtain an impregnation solution. A particulate carrier is placed in the above impregnation solution and impregnated by vacuum rotary evaporation in a rotary evaporator until the liquid is completely evaporated. The mixture is then dried and calcined to obtain the catalyst.

[0010] Furthermore, the aminocarboxylate is selected from one or more of sodium aminotriacetate (NTA), ethylenediaminetetraacetate (EDTA disodium or tetrasodium) and diethylenetriaminepentacarboxylate (DTPA).

[0011] Furthermore, the volume ratio of water to ethanol in the impregnation solution is 1:1-10.

[0012] Furthermore, the copper salt and cerium salt are selected from one or more soluble nitrates, sulfates, chlorides, phosphates, and acetates. The mass fractions of the copper salt and cerium salt in the impregnation solution are 1-10% and 0.5-3%, respectively.

[0013] Furthermore, the ratio of aminocarboxylate to copper salt is 1:1-6 in terms of molar amount.

[0014] Furthermore, the particulate carrier is selected from at least one of 30-80 mesh activated carbon, alumina, titanium dioxide, and molecular sieve.

[0015] Furthermore, the temperature of the vacuum rotary evaporation impregnation is 50-80℃, and the pressure is (-0.1MPa)-(-0.3MPa).

[0016] Furthermore, the air-drying time is 6-8 hours.

[0017] Furthermore, the calcination temperature is 300-900℃, the heating rate from room temperature to the calcination temperature is 1-5℃ / min, and the time is 1-4h.

[0018] Furthermore, the calcination is carried out in an inert atmosphere, which is nitrogen or an inert gas.

[0019] The technical objective of the second aspect of this invention is to provide a catalyst prepared by the above-described preparation method.

[0020] The technical objective of a third aspect of the present invention is to provide an application of the catalyst for ozone catalytic oxidation reactions.

[0021] Furthermore, the ozone dosage in the ozone catalytic oxidation reaction is 50-160 mg / L, and the wastewater retention time is 0.5-3 h.

[0022] The technical solution of the present invention has the following advantages:

[0023] (1) The preparation method of the present invention is simple and quick, the active metal is a non-transition metal with low cost, and the oxidation performance of the catalyst is improved by doping with rare earth metal cerium, which can realize batch preparation;

[0024] (2) In the preparation method of the present invention, the addition of aminocarboxylate and the vacuum rotary impregnation step synergistically achieve high dispersion of copper active centers, avoid the agglomeration of active metals, and have better catalytic activity.

[0025] (3) The catalyst prepared by the present invention can achieve a TOC removal rate of not less than 40% and up to 80% when used in ozone catalytic oxidation reaction.

[0026] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0027] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0028] In the following examples, the total organic carbon of the samples was determined using a TOC analyzer.

[0029] Example 1

[0030] (1) Preparation of impregnation solution: Weigh 4g copper nitrate, 1g cerium nitrate and 3.72g sodium ethylenediaminetetraacetate, add them to a mixture of 10mL distilled water and 20mL ethanol, and mix them evenly by ultrasonication;

[0031] (2) Vacuum evaporation impregnation: Add 50g of 60-mesh coconut shell carbon to the impregnation solution, transfer the mixture to a vacuum rotary evaporator, set the temperature to 70℃ and the pressure to -0.16MPa, and perform rotary evaporation impregnation until the liquid is completely evaporated;

[0032] (3) Drying: Take out the solid from step (3) and let it air dry for 6 hours.

[0033] (4) Calcination: Take out the solid from step (3) and place it in an inert atmosphere furnace for calcination. The flow rate of the inert gas is 100 mL / min, the temperature of the atmosphere furnace is set to 600℃, and the time is 2 h to obtain the catalyst.

[0034] The prepared catalyst was used for ozone catalytic oxidation: using 300 mg / L LDEA wastewater as the degradation substrate, the catalyst dosage was 1 g / L, the ozone dosage was 100 mg / L, and the residence time was 1 h. The TOC removal rate was found to be 84.5%.

[0035] Example 2

[0036] Unlike Example 1, the mass of copper nitrate was 6g, but the other steps were the same.

[0037] The prepared catalyst was used for ozone catalytic oxidation: using 300 mg / L LDEA wastewater as the degradation substrate, the catalyst dosage was 1 g / L, the ozone dosage was 100 mg / L, and the residence time was 1 h. The TOC removal rate was measured to be 89.6%.

[0038] Example 3

[0039] Unlike Example 1, the mass of cerium nitrate was 1.5g, but the other steps were the same.

[0040] The prepared catalyst was used for ozone catalytic oxidation: using 300 mg / L LDEA wastewater as the degradation substrate, the catalyst dosage was 1 g / L, the ozone dosage was 100 mg / L, and the residence time was 1 h. The TOC removal rate was found to be 86.0%.

[0041] Example 4

[0042] Unlike Example 1, the amount of sodium ethylenediaminetetraacetate was 1.86 g, while the other steps were the same.

[0043] The prepared catalyst was used for ozone catalytic oxidation: using 300 mg / L LDEA wastewater as the degradation substrate, the catalyst dosage was 1 g / L, the ozone dosage was 100 mg / L, and the residence time was 1 h. The TOC removal rate was found to be 80.5%.

[0044] Example 5

[0045] Unlike Example 1, 6 mL of distilled water and 24 mL of ethanol were placed in a vacuum rotary evaporator at a temperature of 50°C and a pressure of -0.1 MPa. The other steps of rotary evaporation impregnation were the same.

[0046] The prepared catalyst was used for ozone catalytic oxidation: using 300 mg / L LDEA wastewater as the degradation substrate, the catalyst dosage was 1 g / L, the ozone dosage was 100 mg / L, and the residence time was 1 h. The TOC removal rate was measured to be 87.4%.

[0047] Comparative Example 1

[0048] Except for step (1) where sodium ethylenediaminetetraacetate is not added, the rest is the same as in Example 1.

[0049] The catalyst was used for the ozone catalytic oxidation reaction as in Example 1. The TOC removal rate was measured to be 67.6%. During electron microscopy characterization and elemental EDS energy dispersive spectroscopy analysis, it was found that the copper element dispersion in the catalyst prepared in Example 1 was significantly better than that in Comparative Example 1. This indicates that the method of the present invention can promote the high dispersion of copper active metal and improve the catalytic activity of the catalyst.

[0050] Comparative Example 2

[0051] Except for step (1) where cerium nitrate is not added, the rest is the same as in Example 1.

[0052] The catalyst was used for the ozone catalytic oxidation reaction as in Example 1. The TOC removal rate was measured to be 74.3%. These results indicate that cerium oxides, especially cerium dioxide, have strong oxidizing properties, and that tetravalent cerium has a unique 4f electron structure, which can significantly improve the catalytic performance of the catalyst.

[0053] Comparative Example 3

[0054] In step (2), the impregnation solution and the carrier are mixed and then placed in an oven at 70°C and evaporated at normal pressure to remove the impregnation solution. The rest is the same as in Example 1.

[0055] The catalyst was used in the same ozone catalytic oxidation reaction as in Example 1. The TOC removal rate was measured to be 65.8%. These results indicate that the vacuum rotary impregnation process can improve the catalytic activity of the catalyst.

[0056] Comparative Example 4

[0057] Except for step (1), in which the amount of sodium ethylenediaminetetraacetate added is increased to 8.0g, the rest is the same as in Example 1.

[0058] The catalyst was used for the ozone catalytic oxidation reaction as in Example 1. The TOC removal rate was measured to be 55.81%. This result may be because excessive dispersant added during catalyst calcination may produce carbon deposits, covering some of the metal active sites.

Claims

1. A method for preparing a catalyst with high dispersion of active components, comprising the following steps: mixing a copper salt, a cerium salt, an aminocarboxylate, water and ethanol, ultrasonicating to obtain an impregnation solution, placing a granular carrier in the impregnation solution, and performing vacuum rotary evaporation impregnation in a rotary evaporator until the liquid is completely evaporated; drying, calcining to obtain the catalyst; wherein the aminocarboxylate is selected from one or more of sodium nitrilotriacetate, ethylenediaminetetraacetate and diethylenetriaminepentaacetate, the ratio of the aminocarboxylate to the copper salt is 1:1-6 by mole; the copper salt and the cerium salt are selected from one or more of soluble nitrate, sulfate, chloride, phosphate and acetate; the mass fraction of the copper salt and the cerium salt in the impregnation solution is 1-10% and 0.5-3%, respectively. The volume ratio of water to ethanol in the impregnation solution is 1:1-10.

2. The production method according to claim 1, characterized by, The granular carrier is selected from at least one of activated carbon, alumina, titanium dioxide and molecular sieve with a mesh size of 30-80.

3. The production method according to claim 1, characterized by, The temperature of the vacuum rotary evaporation impregnation is 50-80℃, and the pressure is -0.1MPa~ -0.3MPa.

4. The preparation method according to claim 1, characterized in that, The drying time is 6-8 hours.

5. The preparation method according to claim 1, characterized in that, The calcination temperature is 300-900℃, and the time is 1-4h.

6. The method of claim 1, wherein, The calcination is performed in an inert atmosphere, which is nitrogen or an inert gas.

7. The preparation method according to claim 1, characterized in that, 8.The catalyst prepared by the method of any one of claims 1-7. 9.The use of the catalyst of claim 8 in ozone catalytic oxidation. The ozone catalytic oxidation has an ozone dosage of 50-160mg / L and a wastewater residence time of 0.5-3h.

10. Use according to claim 9, characterized in that, ​