阅读说明：本技术 一种用于光热催化净化VOCs的Co-MOF衍生物光热催化剂及制备方法与应用 (Co-MOF derivative photo-thermal catalyst for photo-thermal catalytic purification of VOCs, and preparation method and application thereof ) 是由 胡芸 曾译葵 钟金平 王煌彬 毛慧阳 叶代启 付名利 于 2021-07-16 设计创作，主要内容包括：本发明公开了一种用于光热催化净化VOCs的Co-MOF衍生物光热催化剂及制备方法与应用。该方法包括：(1)以吡啶-3,5-二羧酸、硝酸钴和氢氧化钠为原料,通过室温搅拌法制备Co-MOFs；(2)将所述Co-MOFs在N-(2)惰性气氛下热解得Co/CoO-(x)/NC光热催化剂。本发明所制备的光热催化剂可同时吸收全光谱并转化成热能,从而诱发光热催化净化VOCs的反应。由于等离子体金属Co、CoO-(x)和多孔碳的耦合增强光热效应,光热催化剂在太阳光的照射下,表现出高效VOCs氧化性能,且稳定性好。本发明工艺简单可行,催化效率高,催化过程能耗低,直接利用太阳能作为光和热的来源,在环境能源领域具有广泛的应用前景。(The invention discloses a Co-MOF derivative photo-thermal catalyst for photo-thermal catalytic purification of VOCs, and a preparation method and application thereof. The method comprises the following steps: (1) preparing Co-MOFs by taking pyridine-3, 5-dicarboxylic acid, cobalt nitrate and sodium hydroxide as raw materials through a room-temperature stirring method; (2) setting the Co-MOFs at N 2 Pyrolyzing under inert atmosphere to obtain Co/CoO x a/NC photo-thermal catalyst. The photo-thermal catalyst prepared by the invention can simultaneously absorb full spectrum and convert the full spectrum into heat energy, thereby inducing the reaction of photo-thermal catalytic purification of VOCs. Due to plasma metal Co, CoO x And the photo-thermal effect is enhanced by coupling of porous carbon, and the photo-thermal catalyst shows high-efficiency VOCs oxidation performance under the irradiation of sunlight and has good stability. The invention has simple and feasible process, high catalytic efficiency and low energy consumption in the catalytic processThe solar energy is directly used as a light and heat source, and the solar energy heat source has wide application prospect in the field of environmental energy.)

1. Preparation of Co-MOF derivative photo-thermal catalyst for photo-thermal catalytic purification of VOCsThe preparation method is characterized in that pyridine-3, 5-dicarboxylic acid, cobalt nitrate and sodium hydroxide are placed in an organic solvent, and the Co/CoO is prepared by stirring at room temperature, centrifugally washing, vacuum drying and calcining in a tube furnace_x(ii) a/NC photothermal catalyst; the photo-thermal catalyst can absorb full spectrum and convert the full spectrum into heat energy, so that the reaction of photo-thermal catalytic purification of VOCs is induced.

2. The method of claim 1, wherein the method comprises the steps of:

(1) preparation of Co-MOF:

mixing water and an organic solvent to obtain a solution A, stirring at room temperature, adding cobalt nitrate into the solution A, and mixing and stirring until the cobalt nitrate is dissolved to obtain a solution B; then, mixing water and an organic solvent to obtain a solution C, stirring at room temperature, adding sodium hydroxide into the solution C, mixing and stirring until the sodium hydroxide is dissolved to obtain a solution D, adding pyridine-3, 5-dicarboxylic acid into the solution D, and then uniformly mixing by ultrasound to obtain a solution E; transferring the solution B into the solution E, stirring at room temperature to obtain a solution F, filtering to obtain pink precipitates, centrifugally washing the precipitates with deionized water and ethanol, and drying to obtain Co-MOF;

(2)Co/CoO_xpreparation of/NC:

drying the Co-MOF prepared in the step (1) in an oven, then placing the Co-MOF in a tube furnace, calcining for 3-6 h at a constant heating rate of 400-600 ℃ in an inert atmosphere, and naturally cooling to room temperature to obtain Co/CoO_xNC photo-thermal catalytic material.

3. The method for preparing a Co-MOF derivative photothermal catalyst for photothermal catalytic purification of VOCs according to claim 2, wherein in step (1), the organic solvent is acetonitrile.

4. The method for preparing a Co-MOF derivative photothermal catalyst for photothermal catalytic purification of VOCs according to claim 2, wherein in the step (1), the addition amount of water and the organic solvent in the solution A satisfies the following conditions: the addition amount of water is: 45-55 mL of water; the addition amount of the organic solvent is as follows: 45-55 mL; in the solution B, the addition amount of cobalt nitrate is as follows: 6.5-7.5 g.

5. The method for preparing a Co-MOF derivative photothermal catalyst for photothermal catalytic purification of VOCs according to claim 2, wherein in the step (1), the addition amount of water and the organic solvent in the solution C satisfies the following condition: the addition amount of water is: 145-155 mL of water; the addition amount of the organic solvent is as follows: 145-155 mL.

6. The preparation method of the Co-MOF derivative photothermal catalyst for photothermal catalytic purification of VOCs according to claim 2, wherein in the step (1), the addition amount of sodium hydroxide is 0.7-1.7 g; the amount of pyridine-3, 5-dicarboxylic acid added is 1.9 to 2.9 g.

7. The preparation method of the Co-MOF derivative photothermal catalyst for photothermal catalytic purification of VOCs according to claim 2, wherein in the step (1), the temperature of stirring at room temperature is 25-35 ℃; the stirring speed is 50-100 r/min; when the solution B and the solution D are prepared, the stirring time is 5-10 min; when the solution F is prepared, the stirring time is 10-14 h;

the ultrasonic time is 0.5-1 h, and the ultrasonic temperature is 25-35 ℃; the ultrasonic frequency is 35-40 KHz, and the ultrasonic power is 520-560W; the centrifugal rate of the product is 3500-4500 rpm; the drying temperature is 60-80 ℃, and the drying time is 4-6 h.

8. The preparation method of the Co-MOF derivative photothermal catalyst for photothermal catalytic purification of VOCs according to claim 2, wherein in the step (2), the inert atmosphere is nitrogen, the temperature rise rate is 0.5-1.5 ℃/min, and the temperature drop rate is 1-10 ℃/min.

9. A Co-MOF derivative photo-thermal catalyst for photo-thermal catalytic purification of VOCs is prepared by the preparation method of any one of claims 1-8.

10. The application of Co-MOF derivative photo-thermal catalyst for photo-thermal catalytic purification of VOCs in the field of degradation of volatile organic compounds as claimed in claim 5, wherein Co/CoO_xthe/NC photo-thermal catalyst can stably degrade volatile organic compounds under full spectrum without consuming secondary energy such as electric energy for heat supply.

Technical Field

The invention belongs to the technical field of environment function materials, and particularly relates to a Co-MOF derivative photo-thermal catalyst for photo-thermal catalytic purification of VOCs, and a preparation method and application thereof.

Background

Volatile Organic Compounds (VOCs) are important precursors causing air pollution, can participate in atmospheric photochemical reactions, cause formation of ozone, photochemical smog and secondary aerosol in atmospheric environment, seriously harm human health and sustainable development of society, and therefore are receiving wide attention. At present, the traditional thermal catalysis has high efficiency in removing VOCs, but mainly relies on electric energy to provide working temperature, and has huge energy consumption. The photocatalysis technology is a technology for degrading pollutants by utilizing clean solar drive, but the light energy utilization rate is low, and the oxidation is not thorough, so that the wide practical application of the photocatalysis technology is greatly limited. Therefore, it is urgently needed to develop a green technology which perfectly combines the high degradation efficiency of thermal catalysis and the low energy consumption of photocatalysis to realize the green and low-energy-consumption treatment of the VOCs.

In recent years, the emerging photo-thermal catalytic oxidation is a technology for efficiently purifying VOCs by utilizing solar energy to store, convert and drive catalytic reaction. The method is not limited by the spectrum range any more, can effectively utilize full spectrum energy, particularly infrared light, and can obtain high-efficiency durable catalytic performance equivalent to that of thermal catalysis without secondary energy input. However, most of the current photo-thermal catalysts have narrow solar absorption spectrum and low photo-thermal conversion efficiency, and the catalytic efficiency is still not ideal compared with the traditional thermal catalysis and photo-catalysis technologies. Therefore, it becomes a challenge to develop a photo-thermal catalyst with high activity and high full-spectrum light absorption capability, improve the photo-thermal conversion efficiency, and realize the efficient degradation of VOCs. In addition, due to the high cost of noble metal-based catalysts, there is increasing interest in transition metal catalysts that are cost-effective. The transition metal has strong Localized Surface Plasmon Resonance (LSPR) effect and can drive redox reaction under the irradiation of sunlight. While the carbon-based MOFs (metal organic frameworks) derivative porous material obtained by taking MOFs as a precursor has high gas adsorption capacity, full spectrum light absorption capacity and enhanced chemical stability, and is concerned.

In view of the above, the invention firstly prepares Co-MOFs by taking pyridine-3, 5-dicarboxylic acid, cobalt nitrate and sodium hydroxide as raw materials through a room-temperature stirring self-assembly method; then, the Co-MOFs is added into N₂Pyrolyzing the mixture in inert atmosphere to obtain Co and CoO_xN-doped C-composition composite material (named Co/CoO)_x/NC). Such Co/CoO_xthe/NC material has a unique mixed interface structure, so that the plasma metal Co and CoO_xThe N-doped C has strong interaction with N atoms, so that the light absorption range of the N-doped C can be expanded to an infrared region, and the key problems of narrow sunlight absorption spectrum, low photothermal conversion efficiency and the like of the conventional photothermal catalyst for photothermal catalysis can be effectively solved. Meanwhile, the highly dispersed Co-N-C sites of the material are easy to adsorb and enrich VOCs molecules to active sites of the material, and efficient adsorption-catalysis integration is realized. The invention provides a new idea for the fields of preparation of high-efficiency solar-driven environmental purification catalysts, atmospheric pollution control and the like.

Disclosure of Invention

The invention aims to overcome the problems of narrow sunlight absorption spectrum, low photothermal conversion efficiency and the like of a photothermal catalyst, and provides Co/CoO with light absorption capacity, high activity and controllable structure_xPreparation method and application of/NC photo-thermal catalyst. Compared with the original Co-MOFs, the prepared photo-thermal catalyst has obviously improved performances such as sunlight absorption capacity, photo-thermal conversion efficiency, catalytic activity, catalytic stability and the like.

The purpose of the invention is realized by the following technical scheme:

is used forA preparation method of a Co-MOF derivative photo-thermal catalyst for photo-thermal catalytic purification of VOCs is characterized in that pyridine-3, 5-dicarboxylic acid, cobalt nitrate and sodium hydroxide are placed in an organic solvent, and the Co/CoO is prepared by stirring at room temperature, centrifugal washing, vacuum drying and calcining in a tubular furnace_x(ii) a/NC photothermal catalyst; the photo-thermal catalyst has a unique mixed interface structure, and under the irradiation of sunlight, plasma metal Co and CoO_xThe N-doped C has strong interaction with N atoms, and can efficiently absorb full-spectrum energy and convert the full-spectrum energy into heat energy, so that the reaction of purifying VOCs by photo-thermal catalysis is induced, and the reaction rate and the catalytic performance are improved.

The preparation method comprises the following steps:

(1) preparation of Co-MOF:

mixing 45-55 mL of water with 45-55 mL of organic solution to obtain a solution A, stirring at room temperature for 5-10 min, adding 6.5-7.5 g of cobalt nitrate to the solution A, and mixing and stirring until the cobalt nitrate is dissolved to obtain a solution B; then, mixing 145-155 mL of water with 145-155 mL of organic solution to obtain a solution C, stirring at room temperature for 5-10 min, adding 0.7-1.7 g of sodium hydroxide to the solution C, mixing and stirring until the sodium hydroxide is dissolved to obtain a solution D, adding 1.9-2.9 g of pyridine-3, 5-dicarboxylic acid to the solution D, and then performing ultrasonic mixing uniformly to obtain a solution E; transferring the solution B into the solution E, stirring at room temperature for 10-14h to obtain a solution F, filtering to obtain pink precipitates, centrifugally washing the precipitates with deionized water and ethanol, and drying to obtain Co-MOF;

(2)Co/CoO_xpreparation of/NC:

drying the Co-MOF prepared in the step (1) in an oven, then placing the Co-MOF in a tube furnace, calcining for 3-6 h at a constant heating rate of 400-600 ℃ in an inert atmosphere, and naturally cooling to room temperature to obtain Co/CoO_xNC photo-thermal catalytic material.

Further, in the step (1), the organic solvent is acetonitrile;

further, in the step (1), the stirring temperature at room temperature is 25-35 ℃; the stirring speed is 50-100 r/min; the ultrasonic time is 0.5-1 h, and the ultrasonic temperature is 25-35 ℃; the ultrasonic frequency is 35-40 KHz, and the ultrasonic power is 520-560W; the centrifugal rate of the product is 3500-4500 rpm; the drying temperature is 60-80 ℃, and the drying time is 4-6 h;

further, in the step (2), the inert atmosphere is nitrogen, the heating rate is 0.5-1.5 ℃/min, and the cooling rate is 1-10 ℃/min.

A Co-MOF derivative photo-thermal catalyst for photo-thermal catalytic purification of VOCs is applied to the field of degradation of volatile organic compounds. Co/CoO_xthe/NC photo-thermal catalyst can stably degrade volatile organic compounds under full spectrum without consuming secondary energy such as electric energy for heat supply.

The material prepared by the invention is essentially different from the existing material, and the Co-MOFs is prepared by a room temperature stirring method and then calcined in a tubular furnace under the inert atmosphere to obtain Co/CoO with high sunlight absorption capacity_xa/NC photo-thermal catalyst. The photo-thermal catalyst has a unique mixed interface structure, and under the irradiation of sunlight, plasma metal Co and CoO_xThe catalyst has strong interaction with C doped with N atoms, can widen the light absorption range of the material and improve the photo-thermal conversion efficiency, and simultaneously, Co-N-C is used as a target active site of the photo-thermal catalytic oxidation reaction of VOCs to realize the catalytic performance with high efficiency and high stability.

Therefore, compared with the prior art, the invention has the advantages that:

Co/CoO of the invention_xThe preparation method of the/NC has the advantages of simple and convenient operation, simple process, good repeatability and the like. In addition, the prepared material has high-dispersion Co-N-C sites, VOCs molecules are easy to adsorb and enrich to active sites of the material, and simultaneously, plasma metal Co and CoO are adopted_xThe mixed interface of the N-doped C increases the absorption of sunlight and improves the photo-thermal conversion efficiency, so that Co/CoO_xthe/NC hybrid material realizes high-efficiency and long-time stable catalytic performance in the reaction of degrading VOCs by photo-thermal catalysis completely depending on solar energy.

Drawings

FIG. 1 is a graph showing UV-VIS-IR absorption spectra of photothermal catalysts prepared in examples 1, 2 and 3 of the present invention;

FIG. 2 shows the photo-thermal catalyst prepared by the method 1, 2, 3 at 300mW/cm²A material thermal effect diagram under the irradiation of a full-spectrum xenon lamp light source;

FIG. 3 shows the photo-thermal catalyst prepared in examples 1, 2 and 3 of the present invention at 300mW/cm²And (3) an activity comparison graph of the catalyst on the photo-thermal catalytic oxidation of the methanol under the irradiation of a full-spectrum xenon lamp light source.

FIG. 4 shows the photo-thermal catalyst prepared in example 2 of the present invention at 300mW/cm²And (3) a stability graph of the catalyst on the photo-thermal catalytic oxidation of the methanol under the condition of irradiating for 50 hours by a full-spectrum xenon lamp light source.

Detailed Description

The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention are not limited thereto, and may be carried out with reference to conventional techniques for process parameters not particularly noted.

The preparation method comprises the following steps:

(1) preparation of Co-MOF:

mixing 45-55 mL of water with 45-55 mL of organic solution to obtain a solution A, stirring at room temperature for 5-10 min, adding 6.5-7.5 g of cobalt nitrate to the solution A, and mixing and stirring until the cobalt nitrate is dissolved to obtain a solution B; then, mixing 145-155 mL of water with 145-155 mL of organic solution to obtain a solution C, stirring at room temperature for 5-10 min, adding 0.7-1.7 g of sodium hydroxide to the solution C, mixing and stirring until the sodium hydroxide is dissolved to obtain a solution D, adding 1.9-2.9 g of pyridine-3, 5-dicarboxylic acid to the solution D, and then performing ultrasonic mixing uniformly to obtain a solution E; transferring the solution B into the solution E, stirring at room temperature for 10-14h to obtain a solution F, filtering to obtain pink precipitates, centrifugally washing the precipitates with deionized water and ethanol, and drying to obtain Co-MOF;

(2)Co/CoO_xpreparation of/NC:

drying the Co-MOF prepared in the step (1) in an oven, then placing the Co-MOF in a tube furnace, calcining for 3-6 h at a constant heating rate of 400-600 ℃ in an inert atmosphere, and naturally cooling to room temperature to obtain Co/CoO_xNC photo-thermal catalytic material.

In the step (1), the organic solvent is acetonitrile.

In the step (1), the stirring temperature at room temperature is 25-35 ℃; the stirring speed is 50-100 r/min; the ultrasonic time is 0.5-1 h, and the ultrasonic temperature is 25-35 ℃; the ultrasonic frequency is 35-40 KHz, and the ultrasonic power is 520-560W; the centrifugal rate of the product is 3500-4500 rpm; the drying temperature is 60-80 ℃, and the drying time is 4-6 h.

Further, in the step (2), the inert atmosphere is nitrogen, the heating rate is 0.5-1.5 ℃/min, and the cooling rate is 1-10 ℃/min.

Example 1

Preparation of Co-MOF: mixing 50mL of water and 50mL of acetonitrile to obtain a solution A, stirring at room temperature for 5-10 min, adding 7g of cobalt nitrate into the solution A, and mixing and stirring until the cobalt nitrate is dissolved to obtain a solution B; then, mixing 150mL of water with 150mL of acetonitrile to obtain a solution C, stirring for 5min at room temperature, adding 1.2g of sodium hydroxide into the solution C, mixing and stirring until the sodium hydroxide is dissolved to obtain a solution D, adding 2.4g of pyridine-3, 5-dicarboxylic acid into the solution D, and then performing ultrasonic mixing uniformly to obtain a solution E; and transferring the solution B into the solution E, stirring at room temperature for 12h to obtain a solution F, filtering to obtain pink precipitate, centrifugally washing the precipitate with deionized water and ethanol, and drying to obtain Co-MOF.

Co/CoO_xPreparation of/NC-400: the prepared Co-MOF was dried in an oven, and then 1.2g of Co-MOF was placed in a tube furnace under N₂Calcining at the temperature rising rate of 1 ℃/min to 400 ℃ for 4h in the atmosphere, and naturally cooling to room temperature to obtain Co/CoO_xNC-400 photo-thermal catalytic material.

Example 2

Preparation of Co-MOF: mixing 50mL of water and 50mL of acetonitrile to obtain a solution A, stirring at room temperature for 5-10 min, adding 7g of cobalt nitrate into the solution A, and mixing and stirring until the cobalt nitrate is dissolved to obtain a solution B; then, mixing 150mL of water with 150mL of acetonitrile to obtain a solution C, stirring for 5min at room temperature, adding 1.2g of sodium hydroxide into the solution C, mixing and stirring until the sodium hydroxide is dissolved to obtain a solution D, adding 2.4g of pyridine-3, 5-dicarboxylic acid into the solution D, and then performing ultrasonic mixing uniformly to obtain a solution E; and transferring the solution B into the solution E, stirring at room temperature for 12h to obtain a solution F, filtering to obtain pink precipitate, centrifugally washing the precipitate with deionized water and ethanol, and drying to obtain Co-MOF.

Co/CoO_xPreparation of/NC-500: the prepared Co-MOF was dried in an oven, and then 1.2g of Co-MOF was placed in a tube furnace under N₂Calcining at 1 deg.C/min to 500 deg.C for 4h, and naturally cooling to room temperature to obtain Co/CoO_xNC-500 photo-thermal catalytic material.

Example 3

Preparation of Co-MOF: mixing 50mL of water and 50mL of acetonitrile to obtain a solution A, stirring at room temperature for 5-10 min, adding 7g of cobalt nitrate into the solution A, and mixing and stirring until the cobalt nitrate is dissolved to obtain a solution B; then, mixing 150mL of water with 150mL of acetonitrile to obtain a solution C, stirring for 5min at room temperature, adding 1.2g of sodium hydroxide into the solution C, mixing and stirring until the sodium hydroxide is dissolved to obtain a solution D, adding 2.4g of pyridine-3, 5-dicarboxylic acid into the solution D, and then performing ultrasonic mixing uniformly to obtain a solution E; and transferring the solution B into the solution E, stirring at room temperature for 12h to obtain a solution F, filtering to obtain pink precipitate, centrifugally washing the precipitate with deionized water and ethanol, and drying to obtain Co-MOF.

Co/CoO_xPreparation of/NC-600: the prepared Co-MOF was dried in an oven, and then 1.2g of Co-MOF was placed in a tube furnace under N₂Calcining at a heating rate of 1 ℃/min to 600 ℃ for 4h in the atmosphere, and naturally cooling to room temperature to obtain Co/CoO_xthe/NC-600 photo-thermal catalytic material.

Example 4

And (3) material characterization and analysis: from FIG. 1, it can be observed that the Co-MOF derived Co/CoO of the present invention_x/NC-400，Co/CoO_xNC-500 and Co/CoO_xthe/NC-600 has strong absorption to ultraviolet light, visible light and infrared radiation, and the Co/CoO_xThe absorption of/NC is significantly greater than that of Co-MOF. Co/CoO with increasing calcination temperature_xThe sunlight absorbing ability of/NC gradually increases. Indicating the Co/CoO of the invention_xthe/NC has high full-spectrum light absorption capability.

Evaluation of photothermal catalytic oxidation activity: methanol is used as a probe molecule to explore the photo-thermal catalytic activity of the catalyst. The photothermal catalytic oxidation methanol degradation reaction is carried out on a self-made fixed bed reactor, the light source used in the reaction is PLS-SXE300 full spectrum xenon lamp light source of Beijing Pofely science and technology Limited company, and the reaction light rate density is 300mW/m²The methanol concentration is 200ppm, the catalyst dosage is 100mg, the reaction gas flow rate is 100mL/min, the space velocity is 60000 mL/g.h, and N is₂Is a balance gas; concentration change of methanol during the reaction and final product CO₂The concentration value of (b) is detected on-line by gas chromatography with FID detector. The experimental results according to FIG. 2 show that under simulated solar irradiation, the material reaches high temperature in a short time, Co/CoO_x/NC-400， Co/CoO_xNC-500 and Co/CoO_xThe temperatures of the/NC-600 platforms are 132 ℃, 171 ℃ and 170 ℃ respectively, which shows that the prepared photo-thermal catalyst has higher solar photo-thermal conversion efficiency. From the results of the activity test in FIG. 3, it can be seen that Co/CoO was contained in all the catalysts prepared_xthe/NC-500 shows the best catalytic activity, the conversion rate of the methanol can reach 97 percent, and the high activity is kept in the irradiation process; the activity of Co-MOF is the worst, and the conversion rate of methanol is only about 21%. The long term stability test results according to FIG. 4 show that Co/CoO_xThe performance of the/NC-500 continuous irradiation for 50 hours is almost unchanged, the average conversion rate of the methanol is 97 percent, and the CO content is reduced₂The yield is 95%, which shows that the product has excellent photo-thermal catalytic oxidation stability.

The above examples of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.