阅读说明：本技术 一种高稳定单原子铂基催化材料及制备方法和在含氧挥发烃净化中的应用 (High-stability monatomic platinum-based catalytic material, preparation method and application in purification of oxygen-containing volatile hydrocarbon ) 是由 何炽 姜泽宇 建艳飞 董瑞 武雅妮 于 2020-05-21 设计创作，主要内容包括：一种高稳定单原子铂基催化材料及制备方法和在含氧挥发烃净化中的应用,以高稳定碳化钼为载体,通过水热碱浸法在载体表面构筑丰富的表面羟基。使得单原子铂活性相通过与表面羟基的强相互作用而稳定的分散于碳化钼载体表面。该发明所制备的单原子铂基催化材料具有优异的低温催化活性和稳定性,能够在温度100-135℃、反应空速36000-45000h<Sup>-1</Sup>、氧气浓度10-20vol.％的条件下实现工业源排放挥发性含氧烃的深度净化。本发明极大地提升了该单原子催化材料的低温催化效率。在一定程度上解决了负载型贵金属成本昂贵的问题,具有较好的应用普适性。(A high-stability monatomic platinum-based catalytic material, a preparation method and an application in purification of oxygen-containing volatile hydrocarbon are disclosed, wherein high-stability molybdenum carbide is used as a carrier, and abundant surface hydroxyl groups are constructed on the surface of the carrier through a hydrothermal alkaline leaching method. So that the monoatomic platinum active phase is stably dispersed on the surface of the molybdenum carbide carrier through strong interaction with surface hydroxyl. The monoatomic platinum-based catalytic material prepared by the invention has excellent low-temperature catalytic activity and stabilityThe reaction can be carried out at the temperature of 100 ℃ plus 135 ℃ and the reaction space velocity of 36000h plus 45000h ‑1 And the oxygen concentration is 10-20 vol.% to realize deep purification of volatile oxygen-containing hydrocarbon discharged from industrial sources. The invention greatly improves the low-temperature catalysis efficiency of the monatomic catalytic material. The problem of high cost of the load type noble metal is solved to a certain extent, and the method has better application universality.)

1. A preparation method of a high-stability monatomic platinum-based catalytic material is characterized in that a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is added into an ammonium molybdate tetrahydrate aqueous solution, after uniform stirring, cis-oil-based primary amine is added dropwise, and uniform stirring is carried out to form a light yellow transparent solution; then adjusting the pH value to 3.5-4, continuously stirring to obtain a mixed solution, carrying out heating reflux reaction on the mixed solution in a microwave generator, centrifuging after complete reaction, and roasting for one time to obtain powder; putting the powder into a potassium hydroxide solution, uniformly stirring, and then putting the powder into a hydrothermal reaction kettle for crystallization to obtain a solid; dispersing the solid in ethanol, adding polyvinylpyrrolidone, stirring uniformly, then dropwise adding a chloroplatinic acid hexahydrate-ethanol solution, heating, stirring, filtering, washing, drying, and roasting for the second time to obtain the high-stability monatomic platinum-based catalytic material.

2. The method for preparing a highly stable monatomic platinum-based catalytic material of claim 1, wherein the aqueous ammonium molybdate tetrahydrate solution is prepared by dissolving ammonium molybdate tetrahydrate in deionized water, wherein the ratio of ammonium molybdate tetrahydrate to deionized water is 15 to 35 mmoL: 75-95 mL.

3. The method for preparing a high-stability monatomic platinum-based catalytic material according to claim 1, wherein the ratio of ammonium molybdate tetrahydrate, the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and the cis-oleyl primary amine is 15 to 35 mmoL: 0.53-0.75 g: 15-23 mL.

4. The preparation method of the high-stability monatomic platinum-based catalytic material according to claim 1, characterized in that 1mol/L hydrochloric acid is adopted to adjust the pH value to 3.5-4, and the stirring is continued for 30 min; the power of the microwave generator is set to 850W, the temperature of the reflux reaction is 120-135 ℃, and the time is 30-45 min.

5. The preparation method of the high-stability monatomic platinum-based catalytic material according to claim 1, characterized in that the specific conditions of the primary calcination are as follows: the process is carried out in nitrogen atmosphere, the temperature of primary roasting is 600 ℃, and the time of primary roasting is 4-5 h.

6. The method for preparing a high-stability monatomic platinum-based catalytic material according to claim 1, wherein the concentration of the potassium hydroxide solution is 0.1 to 1 mol/L; the crystallization temperature is 80-100 ℃, and the crystallization time is 2.5-3.5 h; when the solid was dispersed in ethanol, the ratio of solid to polyvinylpyrrolidone was 1 g: 0.05-0.1 g.

7. The method for preparing a high-stability monatomic platinum-based catalytic material according to claim 1, wherein the concentration of the chloroplatinic acid hexahydrate-ethanol solution is 1.5-4.0mg Pt/mL; the specific conditions of the secondary roasting are as follows: the process is carried out in nitrogen atmosphere, the temperature of secondary roasting is 200 ℃, and the time of secondary roasting is 2-3.5 h.

8. A high stable monatomic platinum-based catalytic material prepared by the method according to any one of claims 1 to 7, characterized in that the high stable monatomic platinum-based catalytic material has a specific surface area of 236.8 to 275.4m²Per g, the pore volume of the micropores is 0.14-0.29cm³/g。

9. Use of a highly stable monatomic platinum-based catalytic material prepared according to the method of any of claims 1 to 8 in the purification of volatile oxygen-containing hydrocarbons.

10. The use as claimed in claim 9, wherein the use as claimed in claim 13, is characterized in that the highly stable monatomic platinum-based catalytic material is used at a temperature of 100 ℃ and a space velocity of 36000 ℃ and 45000h^-1And the volume concentration of the oxygen is 10-20%, and the purification of the methanol with the volume concentration of 0.08% is realized.

Technical Field

The invention belongs to the technical field of air pollution treatment, and particularly relates to a high-stability monatomic platinum-based catalytic material, a preparation method and application thereof in purification of oxygen-containing volatile hydrocarbon.

Background

Volatile Organic Compounds (VOCs) are a generic term for all Organic Compounds that have a boiling point below 260 ℃ at atmospheric pressure or have a saturated vapor pressure above 133.32Pa at room temperature (25 ℃) and are emitted into the air in gaseous molecular form. VOCs are in various types, and mainly comprise aliphatic hydrocarbons, oxygen-containing hydrocarbons, aromatic hydrocarbons and derivatives thereof, halogen-containing hydrocarbons, nitrogen-containing hydrocarbons, sulfur-containing hydrocarbons and the like. VOCs have high atmospheric chemical reaction activity and are a key factor for enhancing atmospheric oxidation. In recent years, the total amount of VOCs discharged in China is gradually increased, and the problems of photochemical smog, urban dust haze and other composite atmospheric pollution caused by the VOCs are increasingly serious. The emission of a large amount of VOCs not only causes the atmospheric quality to be reduced, but also produces great harm to the functions of the immune system, the kidney and the respiratory system of the human body, and increases the carcinogenic risk of the tissues and organs of the human body (brain, pancreas, lymph, hematopoiesis, stomach and the like). After dust removal, desulfurization, denitration and motor vehicle exhaust pollution treatment, VOCs pollution control becomes one of the priority directions of atmospheric pollution control in China. According to related requirements, the reduction and emission reduction of volatile hydrocarbons emitted by key industries (parks) are currently carried out in China, emission reduction measures in the emission process combined with sources are emphasized and developed, and efficient control technology and process equipment are formed. Therefore, the efficient emission reduction control of the VOCs has important significance for improving the quality of the atmospheric environment in China. Oxygen-containing volatile organic pollutants (such as formaldehyde, acetone, ethyl acetate and the like) which are taken as representatives of heteroatom hydrocarbons can be discharged into the environment by various ways such as furniture decoration, coating, packaging printing, electronic chemical industry and the like, and cause extremely serious negative effects on the production and the life of human beings. The catalytic oxidation technology has the advantages of high efficiency, energy conservation, environmental protection and the like, and is one of the most effective means for purifying low-concentration volatile hydrocarbons at present. The supported noble metal catalyst has good activity and strong regenerability, and is widely used for removing oxygen-containing hydrocarbons. However, the noble metal is expensive, and the active center is easy to agglomerate and is easy to inactivate, so that the prospect of further industrial application is limited. Therefore, there is an urgent need to develop a monatomic catalyst with high activity and high stability according to the emission characteristics and molecular characteristics of volatile oxygen-containing hydrocarbons so as to improve the conversion rate of pollutants on a unit platinum atom, reduce the cost of catalytic materials and maintain higher activity and stability. The invention has important application prospect in the field of low-temperature purification of volatile organic pollutants.

Disclosure of Invention

The invention aims to provide a high-stability monatomic platinum-based catalytic material, a preparation method and application in purification of oxygen-containing volatile hydrocarbon.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a preparation method of a high-stability monatomic platinum-based catalytic material comprises the steps of adding a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer into an ammonium molybdate tetrahydrate aqueous solution, stirring uniformly, then dropwise adding cis-oil-based primary amine, and stirring uniformly to form a light yellow transparent solution; then adjusting the pH value to 3.5-4, continuously stirring to obtain a mixed solution, carrying out heating reflux reaction on the mixed solution in a microwave generator, centrifuging after complete reaction, and roasting for one time to obtain powder; putting the powder into a potassium hydroxide solution, uniformly stirring, and then putting the powder into a hydrothermal reaction kettle for crystallization to obtain a solid; dispersing the solid in ethanol, adding polyvinylpyrrolidone, stirring uniformly, then dropwise adding a chloroplatinic acid hexahydrate-ethanol solution, heating, stirring, filtering, washing, drying, and roasting for the second time to obtain the high-stability monatomic platinum-based catalytic material.

In a further improvement of the invention, the aqueous ammonium molybdate tetrahydrate solution is prepared by dissolving ammonium molybdate tetrahydrate in deionized water, wherein the ratio of ammonium molybdate tetrahydrate to deionized water is 15-35 mmoL: 75-95 mL.

A further improvement of the invention is that the ratio of ammonium molybdate tetrahydrate, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer to cis-oleyl primary amine is 15 to 35 mmoL: 0.53-0.75 g: 15-23 mL.

The further improvement of the invention is that 1mol/L hydrochloric acid is adopted to adjust the pH value to 3.5-4, and the stirring is continued for 30 min; the power of the microwave generator is set to 850W, the temperature of the reflux reaction is 120-135 ℃, and the time is 30-45 min.

The further improvement of the invention is that the specific conditions of the primary roasting are as follows: the process is carried out in nitrogen atmosphere, the temperature of primary roasting is 600 ℃, and the time of primary roasting is 4-5 h.

The further improvement of the invention is that the concentration of the potassium hydroxide solution is 0.1-1 mol/L; the crystallization temperature is 80-100 ℃, and the crystallization time is 2.5-3.5 h; when the solid was dispersed in ethanol, the ratio of solid to polyvinylpyrrolidone was 1 g: 0.05-0.1 g.

The further improvement of the invention is that the concentration of the chloroplatinic acid hexahydrate-ethanol solution is 1.5-4.0mg Pt/mL; the specific conditions of the secondary roasting are as follows: the process is carried out in nitrogen atmosphere, the temperature of secondary roasting is 200 ℃, and the time of secondary roasting is 2-3.5 h.

The specific surface area of the high-stability monatomic platinum-based catalytic material is 236.8-275.4m²Per g, the pore volume of the micropores is 0.14-0.29cm³/g。

An application of high-stability monatomic platinum-based catalytic material in the purification of volatile oxygen-containing hydrocarbons.

The further improvement of the present invention is the use according to claim 13, wherein the high-stability monatomic platinum-based catalytic material is at a temperature of 100-^-1And the volume concentration of the oxygen is 10-20%, and the purification of the methanol with the volume concentration of 0.08% is realized.

A further improvement of the invention is that the volatile oxygen-containing hydrocarbon is methanol.

Compared with the prior art, the invention has the following beneficial effects:

according to the method, ammonium molybdate tetrahydrate is hydrolyzed and then is easily subjected to rapid complexation with cis-form oil-based primary amine to form a precursor of rod-shaped molybdenum carbide, and the complexation degree of the precursor is improved and the pore volume and the specific surface area of a molybdenum carbide carrier are increased by pre-adding a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer. The formation of the high-stability crystal form of the molybdenum carbide carrier can be further promoted by dropwise adding low-concentration hydrochloric acid into the mixed solution to adjust the pH of the solution. In the invention, the molybdenum carbide carrier is further modified by a hydrothermal alkaline leaching method, so that abundant surface hydroxyl groups are constructed on the surface of the carrier. The capture and stabilization of the carrier to the monoatomic platinum precursor are realized by utilizing the non-localization effect of the hydroxyl on the surface of the high-stability carrier. Further, through the strong interaction of the monatomic platinum active phase and the surface hydroxyl, the charge balance process between the carrier and the noble metal is accelerated, and the low-temperature catalysis efficiency and the stability of the monatomic catalysis material are greatly improved. The synthesis method constructed by microwave-assisted hydrothermal alkaline leaching greatly shortens the synthesis time and energy consumption, solves the problem of high cost of the supported noble metal to a certain extent, overcomes the technical defects of complex preparation process and low yield of the existing monatomic catalytic material, and has the prospect of universal application.

The high-stability monatomic platinum-based catalytic material prepared by the invention is widely applied to the purification of volatile oxygen-containing hydrocarbon, and abundant surface hydroxyl groups are constructed on the surface of a carrier by taking high-stability molybdenum carbide as the carrier and a hydrothermal alkaline leaching method. So that the monoatomic platinum active phase is stably dispersed on the surface of the molybdenum carbide carrier through strong interaction with surface hydroxyl. The high-stability monatomic platinum-based catalytic material prepared by the invention is prepared at the temperature of 100 ℃ plus 135 ℃ at the space velocity of 36000h plus 45000h^-1And the deep purification of the methanol with the volume concentration of 0.08 percent is realized under the condition that the volume concentration of the oxygen is 10 to 20 percent. The invention has important application prospect in the field of low-temperature purification of volatile organic pollutants.

Drawings

FIG. 1 is a field emission scanning electron microscope image of a highly stable single-atom platinum-based catalytic material according to the present invention; wherein (a) is high and (b) is low.

FIG. 2 is an EDS-mapping picture of a high-stability single-atom platinum-based catalytic material in a high-angle annular dark field image mode.

FIG. 3 is a spherical aberration electron microscope image of the high-stability single-atom platinum-based catalytic material of the present invention. Wherein (a) is low multiple, (b) is medium multiple, and (c) is high multiple.

FIG. 4 is a graph showing the purification efficiency of a highly stable single-atom platinum-based catalytic material for methanol in the present invention.

Fig. 5 is a water resistance test of the highly stable single-atom platinum-based catalytic material of the present invention.

FIG. 6 is an XRD spectrum of a highly stable single-atom platinum-based catalytic material according to the present invention.

FIG. 7 is a solid-phase nuclear magnetic resonance test spectrum of the high-stability single-atom platinum-based catalytic material of the invention.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and examples.

The invention adopts a microwave-assisted synthesis method to prepare a high-stability porous molybdenum carbide carrier, utilizes the fact that ammonium molybdate tetrahydrate is hydrolyzed and then is easily rapidly complexed with cis-form oil-based primary amine to form a precursor of rod-shaped molybdenum carbide, and improves the complexation degree of the precursor and increases the pore volume and the specific surface area of the molybdenum carbide carrier by pre-adding a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer. The formation of the high-stability crystal form of the molybdenum carbide carrier can be further promoted by dropwise adding low-concentration hydrochloric acid into the mixed solution to adjust the pH of the solution. In the invention, the molybdenum carbide carrier is further modified by a hydrothermal alkaline leaching method, so that abundant surface hydroxyl groups are constructed on the surface of the carrier. The capture and stabilization of the carrier to the monoatomic platinum precursor are realized by utilizing the non-localization effect of the hydroxyl on the surface of the high-stability carrier. Further, through the strong interaction of the monatomic platinum active phase and the surface hydroxyl, the charge balance process between the carrier and the noble metal is accelerated, and the low-temperature catalysis efficiency and the stability of the monatomic catalysis material are greatly improved. The synthesis method constructed by microwave-assisted hydrothermal alkaline leaching greatly shortens the synthesis time and energy consumption, solves the problem of high cost of the supported noble metal to a certain extent, overcomes the technical defects of complex preparation process and low yield of the existing monatomic catalytic material, and has the prospect of universal application. The high-stability monatomic platinum-based catalytic material prepared by the method has abundant surface hydroxyl groups, and shows excellent stability for low-temperature purification of methanol.

The invention comprises the following steps:

(1) 15-35mmoL of ammonium molybdate tetrahydrate is dissolved in 75-95mL of deionized water, and is stirred for 10min at the rotating speed of 500-800rpm to be fully dissolved;

(2) adding 0.53-0.75g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) into the transparent solution obtained in the step (1), and stirring at the rotating speed of 800-;

(3) dropwise adding 15-23mL of cis-oil-based primary amine into the transparent solution obtained in the step (2), wherein the step is helpful for accelerating the nucleation process of rod-shaped molybdenum carbide, and then stirring at the rotating speed of 800-1000rpm for 20min to form a light yellow transparent solution;

(4) dropwise adding 1mol/L hydrochloric acid prepared in advance into the yellow transparent solution obtained in the step (3) to adjust the pH value of the solution, so that the final pH value of the solution is between 3.5 and 4, and continuously stirring the solution for 30 min;

(5) placing the mixed solution obtained in the step (4) in a microwave generator for heating reflux reaction, wherein the power of the microwave generator is set to 850W, the temperature of the reflux reaction is 120-135 ℃, and the time is 30-45 min;

(6) after the solution in the step (5) is cooled to room temperature, centrifuging at 4000-;

(7) carrying out roasting on the solid obtained in the step (6) in a nitrogen atmosphere at the roasting temperature of 600 ℃ for 4-5 h;

(8) dispersing the solid powder obtained in the step (7) in 70-100mL of 0.1-1mol/L potassium hydroxide solution, and stirring at the rotating speed of 800-1000rpm for 30min to uniformly mix the solid powder;

(9) placing the mixed solution obtained in the step (8) in a hydrothermal reaction kettle, wherein the temperature in the hydrothermal crystallization process is 80-100 ℃, and the time is 2.5-3.5 h;

(10) after the mixed solution in the step (9) is cooled to room temperature, centrifuging at 4000-;

(11) dispersing the solid obtained in the step (10) in an ethanol solution, and stirring at the rotating speed of 800-;

(12) adding 0.05-0.1g of polyvinylpyrrolidone into the solution obtained in the step (11), and stirring at the rotating speed of 1000rpm of 800-;

(13) dropwise adding 3-8mL of 1.5-4mg Pt/mL chloroplatinic acid hexahydrate-ethanol solution into the mixed solution obtained in the step (12), and stirring at the rotating speed of 800-1000rpm at the temperature of 50 ℃ for 120 min; wherein, the addition amount of the chloroplatinic acid hexahydrate is 12 mg.

(14) After the solution obtained in the step (13) is cooled to room temperature, filtering, washing with deionized water and ethanol, and drying at 80-100 ℃ to obtain black solid powder;

(15) and (4) roasting the solid powder obtained in the step (14) under the nitrogen condition, wherein the roasting temperature is 200 ℃, and the roasting time is 2-3.5 h.

The high-stability monatomic platinum-based catalytic material prepared by the invention has higher specific surface area (236.8-275.4 m)²Per gram) and pore volume (0.14-0.29 cm)³(iv)/g); the high-stability monatomic platinum-based cuprous oxide catalytic material can be applied to the purification of volatile oxygen-containing hydrocarbons. Specifically, the reaction space velocity is 36,000-45,000h at the temperature of 100-135 DEG C^-1Under the condition that the oxygen concentration is 10-20%, the deep purification of the methanol with the volume concentration of 0.08% is realized; the prepared catalytic material has good stability and poisoning resistance.

The following are specific examples.