阅读说明：本技术 一种用于催化臭氧氧化含氯挥发性有机物的催化剂制备方法 (Preparation method of catalyst for catalyzing ozone to oxidize chlorine-containing volatile organic compounds ) 是由 徐仲均 庄院院 陈少博 张喜荣 于 2021-09-09 设计创作，主要内容包括：本发明公开了一种用于催化臭氧氧化含氯挥发性有机物(CVOCs)的催化剂制备方法。该催化剂主要以MnCeO-(x)为活性组分,采用模板法-真空干燥法制得。制备流程简单,原料易得,且本方法不仅能够有效的利用模板剂使锰铈固溶体形成特定结构,增大其比表面积；还可以改善两种过渡金属氧化物体表面乃至内部分布的均一性,形成较多Mn-Ce-O键,使氯物种以HCl、Cl-(2)的形式脱除。本发明制备的催化剂可在室温下催化臭氧氧化CVOCs为CO-(2)、H-(2)O、HCl、Cl-(2)等物质,具有优异的低温氧化还原活性、抗氯中毒性能以及较高的CO-(2)选择性。(The invention discloses a preparation method of a catalyst for catalyzing ozone to oxidize chlorine-Containing Volatile Organic Compounds (CVOCs). The catalyst mainly comprises MnCeO x Is prepared from active component through template process and vacuum drying process. The preparation process is simple, the raw materials are easy to obtain, and the method can effectively utilize the template agent to enable the manganese-cerium solid solution to form a specific structure and increase the specific surface area of the manganese-cerium solid solution; the surface and even the inner part of the two transition metal oxides can be improvedUniformity of the cloth, more Mn-Ce-O bonds are formed, chlorine species are made to react with HCl and Cl 2 Is removed in the form of (1). The catalyst prepared by the invention can catalyze ozone to oxidize CVOCs into CO at room temperature 2 、H 2 O、HCl、Cl 2 And the like, has excellent low-temperature redox activity, chlorine poisoning resistance and higher CO 2 And (4) selectivity.)

1. A preparation method of a catalyst for catalyzing ozone oxidation of chlorine-containing volatile organic compounds is characterized in that the catalyst is of a mesoporous manganese-cerium solid solution structure and is prepared by adopting a template method-vacuum drying method, and the preparation method comprises the following steps:

(1) adding manganese salt and cerium salt into pure water, and stirring and dissolving to obtain manganese-cerium salt mixed solution;

(2) soaking the mesoporous silicon template agent in a manganese-cerium salt mixed solution, and then centrifuging to remove a soaking solution;

(3) drying the impregnated product obtained in the step (2) in vacuum and then calcining to obtain a manganese-cerium solid solution precursor;

(4) adopting an alkali solution to dip the manganese-cerium solid solution precursor obtained in the step (3), dissolving a template agent in the manganese-cerium solid solution precursor, filtering, and washing a filter cake to be neutral by pure water;

(5) and drying the filter cake in vacuum to obtain the mesoporous manganese-cerium solid solution catalyst.

2. The preparation method of the catalyst according to claim 1, wherein the manganese salt in the step (1) is one or more of manganese chloride, manganese sulfate, manganese acetate and manganese nitrate; the cerium salt is one or a mixture of cerium chloride, cerium sulfate and cerium nitrate; the molar ratio of manganese to cerium is from 1:4 to 4: 1.

3. The method for preparing the catalyst according to claim 1, wherein the template in the step (2) is one or more of SBA-15, SBA-16, KIT-6 and MCM-41, and the mass ratio of the template to the transition metal salt is 5:4 to 5: 1; the dipping condition is magnetic stirring for 4-10 hours.

4. The method for preparing a catalyst according to claim 1, wherein the vacuum drying temperature in the step (3) is 60 to 100 ℃ for 5 to 14 hours; the calcination temperature is 200-600 ℃ and the calcination time is 4-10 hours.

5. The method for preparing the catalyst according to claim 1, wherein the alkali solution in the step (4) is one or a mixture of sodium hydroxide and potassium hydroxide, and the concentration is 1-3 mol/L; the dipping condition is magnetic stirring for 4-10 hours.

6. The method for preparing a catalyst according to claim 1, wherein the vacuum drying temperature in the step (5) is 60 to 100 ℃ for 5 to 14 hours.

Technical Field

The invention relates to the technical field of environment, in particular to a preparation method of a catalyst for catalyzing ozone to oxidize chlorine-containing volatile organic compounds.

Background

Volatile Organic Compounds (VOCs) are organic chemical substances with high vapor pressure and volatility at normal temperature and normal pressure, and are important precursors for forming atmospheric pollution such as haze, photochemical smog and the like. chlorine-Containing Volatile Organic Compounds (CVOCs) are a class with a high content of VOCs and are widely used as production raw materials, solvents, refrigerants and the like. Most CVOCs have the characteristics of strong volatility, poor degradability, high toxicity and the like, and partial CVOCs even have the effect of causing three causes, so that the environmental quality is seriously influenced, and the human health is also greatly threatened. Therefore, it is urgent to find a practical and effective technique for controlling CVOCs.

The chlorine-containing volatile organic compounds have chlorine atoms which are difficult to convert in the environment, and are liable to cause catalyst poisoning and deactivation. In order to solve the problem of chlorine poisoning of the catalyst, scholars at home and abroad make a great deal of research work and develop a series of composite metal (or oxide) chlorine-resistant catalysts. CN 112588289A discloses a high CO₂The selective CVOCs removing catalyst is prepared with titanium oxide as carrier, transition metal oxide as active component and noble metal Pd as modifying component. CN 101402047A discloses a catalyst for CVOCs catalytic combustion and a preparation method thereof, the cerium titanium nanotube catalyst prepared by the method can effectively remove dichloroethane and has strong chlorine poisoning resistance.

In recent years, the technology of catalyzing ozone to oxidize VOCs has attracted much attention because of the advantages of high purification efficiency, no secondary pollution, no need of auxiliary heating, etc. However, few studies on this technology have been reported to deal with CVOCs. The invention prepares a mesoporous manganese-cerium solid solution catalyst by utilizing a template method and a vacuum drying method. The preparation process is simple, the raw materials are easy to obtain, and the method can effectively utilize the template agent to enable the manganese-cerium solid solution to form a specific structure and increase the specific surface area of the manganese-cerium solid solution; can also improve the uniformity of the surface and even internal distribution of two transition metal oxides, form more Mn-Ce-O bonds, and make chlorine species adopt HCl and Cl₂Is removed in the form of (1). Catalyst prepared by the inventionThe oxidant can catalyze ozone to oxidize CVOCs into CO at room temperature₂、H₂O、HCl、Cl₂And the like, has excellent low-temperature redox activity, chlorine poisoning resistance and higher CO₂And (4) selectivity.

Disclosure of Invention

The invention discloses a preparation method of a catalyst for catalyzing ozone to oxidize chlorine-containing volatile organic compounds. Aims to degrade CVOCs into CO by improving the deep oxidation of ozone to the CVOCs and the chlorine poisoning resistance of the catalyst₂、H₂O、HCl、Cl₂And the like.

The preparation method of the manganese-cerium solid solution catalyst comprises the following steps:

(1) adding manganese salt and cerium salt into pure water, and stirring and dissolving to obtain manganese-cerium salt mixed solution;

(2) soaking the mesoporous silicon template agent in a manganese-cerium salt mixed solution, and then centrifuging to remove a soaking solution;

(3) drying the impregnated product obtained in the step (2) in vacuum and then calcining to obtain a manganese-cerium solid solution precursor;

(4) adopting an alkali solution to dip the manganese-cerium solid solution precursor obtained in the step (3), dissolving a template agent in the manganese-cerium solid solution precursor, filtering, and washing a filter cake to be neutral by pure water;

(5) and drying the filter cake in vacuum to obtain the mesoporous manganese-cerium solid solution catalyst.

In the preparation method, the manganese salt in the step (1) is one or a mixture of more of manganese chloride, manganese sulfate, manganese acetate and manganese nitrate; the cerium salt is one or a mixture of cerium chloride, cerium sulfate and cerium nitrate; the molar ratio of manganese to cerium is from 1:4 to 4: 1.

In the preparation method, the template agent in the step (2) is one or a mixture of more of SBA-15, SBA-16, KIT-6 and MCM-41, and the mass ratio of the template agent to the transition metal salt is 5:4 to 5: 1; the dipping condition is magnetic stirring for 4-10 hours.

In the step (3), the vacuum drying temperature is 60-100 ℃, and the time is 5-14 hours; the calcination temperature is 200-600 ℃ and the calcination time is 4-10 hours.

The alkali solution in the step (4) of the preparation method is one or two mixed solutions of sodium hydroxide and potassium hydroxide, and the concentration is 1-3 mol/L; the dipping condition is magnetic stirring for 4-10 hours.

In the step (5), the vacuum drying temperature is 60-100 ℃, and the time is 5-14 hours.

Drawings

Fig. 1 is a flowchart of a method for preparing a mesoporous manganese-cerium solid solution catalyst according to an embodiment of the present invention;

FIG. 2 is a transmission electron micrograph of a catalyst made according to an embodiment of the invention.

Detailed Description

Example 1: 20g of 50% manganese nitrate solution and 12g of cerium nitrate hexahydrate were dissolved in 130ml of pure water by thoroughly stirring for 30 min. Adding 6g of SBA-15 template agent into the manganese-cerium salt mixed solution, magnetically stirring and soaking at room temperature for 10 hours, and centrifuging to obtain a white solid. And (3) putting the white solid in a vacuum drying oven, drying for 12 hours at the temperature of 60 ℃, and then calcining for 4 hours in a muffle furnace at the temperature of 400 ℃ to obtain a brown manganese-cerium solid solution precursor. Dissolving the manganese-cerium solid solution precursor in 150ml of 2mol/L sodium hydroxide solution, stirring, soaking for 6 hours, filtering, washing a filter cake to pH 7 with pure water, and drying the filter cake in a vacuum drying oven at 60 ℃ for 12 hours to obtain the mesoporous manganese-cerium solid solution catalyst for catalyzing ozone oxidation CVOCs. Evaluation of catalyst Performance: the mass of the catalyst was 0.5g, the gas flow was 125ml/min, and the inlet concentration of dichloroethane was 150mg/m³The ozone concentration at the inlet is 1000mg/m³When the purification rate of dichloroethane is 85%, the selectivity of carbon dioxide is 70%, no ozone is detected at the outlet, the operation lasts for 15 hours, and the performance of the catalyst is stable.

Example 2: 10g of 50% manganese nitrate solution and 24g of cerium nitrate hexahydrate were dissolved in 130ml of pure water by thoroughly stirring for 30 min. Soaking 6g of SBA-15 template agent in the manganese-cerium salt mixed solution, magnetically stirring and soaking at room temperature for 10 hours, and centrifuging to obtain a white solid. The white solid was dried in a vacuum oven at 60 ℃ for 12 hours and then calcined in a muffle furnace at 400 ℃ for 4 hours to give a brown colorThe precursor of manganese-cerium solid solution. Dissolving the manganese-cerium solid solution precursor in 150ml of 2mol/L sodium hydroxide solution, stirring, soaking for 6 hours, filtering, washing a filter cake to pH 7 with pure water, and drying the filter cake in a vacuum drying oven at 60 ℃ for 12 hours to obtain the mesoporous manganese-cerium solid solution catalyst for catalyzing ozone oxidation CVOCs. Evaluation of catalyst Performance: the mass of the catalyst was 0.5g, the gas flow was 125ml/min, and the inlet concentration of dichloroethane was 150mg/m³The ozone concentration at the inlet is 1000mg/m³The measured dichloroethane purification rate is 96%, the carbon dioxide selectivity is 82%, no ozone is detected at the outlet, the operation is carried out for 15 hours, and the catalyst performance is stable.