Application of Dual-Atom Copper-Cobalt / Graphdiyne Catalyst in Catalytic Oxidation of Volatile Organic Compounds

Abstract

The present invention discloses the application of a dual-atom copper-cobalt / graphdiyne catalyst in the catalytic oxidation of volatile organic compounds, belonging to the technical field of catalytic oxidation. The application of the dual-atom copper-cobalt / graphdiyne catalyst in the catalytic oxidation of volatile organic compounds. This catalyst has a synergistic effect between the bimetallic atoms, enabling it to effectively activate molecular oxygen and thus effectively remove volatile organic pollutants.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic oxidation, and particularly to the application of a dual-atom copper-cobalt / graphdiyne catalyst in the catalytic oxidation of volatile organic compounds. Background Art

[0002] Volatile organic compounds (VOCs) generally refer to compounds with a boiling point below 250 °C at room temperature and atmospheric pressure. According to their different chemical structures, they can be further classified into the following categories: alkanes, aromatic hydrocarbons, alkenes, halogenated hydrocarbons, esters, aldehydes, ketones, etc. For example, propylene has a high photochemical ozone formation potential and plays an important role in the formation of O3 and photochemical smog. Due to the increasing people's needs for a better life, it is of great significance to efficiently remove VOCs, achieve ecological sustainability and protect human health. Research shows that in the process of low-temperature catalytic oxidation, the adsorption of VOCs molecules and the activation of oxygen are the key steps of catalytic oxidation. Therefore, developing a catalyst that can promote the efficient activation of molecular oxygen is an important scientific issue. Summary of the Invention

[0003] Dual-atom catalysts have synergistic atomic interactions and tunable electronic structures. The unique structure of dual-atom catalysts endows them with the ability to effectively adsorb and activate molecular oxygen during the catalytic process. Graphdiyne has characteristics such as a uniformly distributed pore structure and an easily adjustable electronic structure, making graphdiyne suitable for anchoring bimetallic atoms. Research shows that graphdiyne-based atomic catalysts can efficiently activate molecular oxygen and exhibit good low-temperature catalytic oxidation activity. The sp-hybridized carbon atoms of graphdiyne can effectively adsorb O2 and transfer electrons to the 2π* orbital of O2. The molecular O2 is activated by obtaining electrons and can be used in the low-temperature oxidation process. However, at present, there are still few reports on the mechanism of molecular oxygen activation involving highly efficient graphdiyne-based catalysts.

[0004] Based on the structural advantages of the above-mentioned dual-atom and graphdiyne materials, it is expected to achieve the efficient activation of molecular oxygen. Therefore, we explored the application of a dual-atom copper-cobalt / graphdiyne catalyst in the catalytic oxidation of volatile organic compounds.

[0005] The purpose of the present invention is to overcome the above technical deficiencies, provide an application of a dual-atom copper-cobalt / graphdiyne catalyst in the catalytic oxidation of volatile organic compounds, and solve the technical problem of how to promote the efficient activation of molecular oxygen in the prior art.

[0006] To achieve the above technical purpose, the technical solution of the present invention provides an application of a dual-atom copper-cobalt / graphdiyne catalyst in the catalytic oxidation of volatile organic compounds.

[0007] Further, the volatile organic compound is one or more of methanol, propylene, and ethyl acetate.

[0008] Furthermore, the reaction atmosphere is 200-1000 ppm volatile organic compounds, 5%-12% O2, N2 balance gas, and the mass space velocity is 750-60000 mL·g -1 ·h -1 .

[0009] Furthermore, the amount of the catalyst used is 100 mg-300 mg.

[0010] Furthermore, the reaction temperature is 40-250°C.

[0011] Furthermore, when the volatile organic compound is propylene, the temperature of the catalytic reaction is 200-250°C.

[0012] Further, the temperature is increased from 40-60° C. to 200-250° C. at a heating rate of 5-10° C. / min.

[0013] Furthermore, the method further comprises heating the temperature in sections of 5-20°C and keeping each section warm for 25-50 minutes.

[0014] Furthermore, the diatomic copper cobalt / graphdiyne catalyst is prepared by the following steps:

[0015] S1. Dispersing graphyne nanosheets and copper nitrate trihydrate in an aqueous ammonia solution to obtain a first mixed solution, drying the first mixed solution, and then instantaneously calcining the mixed solution at 200-400° C. under an inert atmosphere to obtain a first mixture;

[0016] S2. Dispersing the first mixture and cobalt nitrate hexahydrate in an ethanol solution to obtain a second mixed solution, drying the second mixed solution, and then instantaneously calcining the second mixed solution at 200-400° C. under an inert atmosphere to obtain a diatomic copper cobalt / graphdiyne catalyst.

[0017] Furthermore, in step S1, the copper nitrate trihydrate is mixed with the graphyne nanosheets according to a mass ratio of Cu to C of 4%-10%; in step S2, the cobalt nitrate hexahydrate is mixed with the graphyne nanosheets according to a mass ratio of Co to C of 4%-10%.

[0018] Compared with the prior art, the beneficial effects of the present invention include: the application of the diatomic copper-cobalt / graphene catalyst proposed by the present invention in the catalytic oxidation of volatile organic compounds, the catalyst uses graphene as a carrier and loads dimetallic copper-cobalt atoms, the catalyst has a large number of active sites, and at the same time has a synergistic effect between the dimetallic atoms, so that it can effectively activate molecular oxygen and thus effectively remove volatile organic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1(a) Theoretical model diagram and (b) aberration-corrected high-angle annular dark-field scanning transmission electron microscopy image (Ac-HAADF-STEM) of the Cu-Co / GDY catalyst.

[0020] Figure 2 (a) Top view and side view of the adsorption configuration of O2 on the Cu-Co / GDY catalyst, and (b) O 1s XPS spectrum.

[0021] Figure 3 EPR spectrum of radical capture of the Cu-Co / GDY catalyst using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO).

[0022] Figure 4 Propylene catalytic oxidation activity diagrams of the Cu-Co / GDY catalyst and the CuNP-CoNP / GDY catalyst in Example 1.

[0023] Figure 5 Methanol catalytic oxidation activity diagrams of the Cu-Co / GDY catalyst and the CuNP-CoNP / GDY catalyst in Example 2.

[0024] Figure 6 Ethyl acetate catalytic oxidation activity diagrams of the Cu-Co / GDY catalyst and the CuNP-CoNP / GDY catalyst in Example 3. Detailed implementation mode

[0025] This detailed implementation mode provides an application of a dual-atom copper-cobalt / graphdiyne catalyst in the catalytic oxidation of volatile organic compounds; the volatile organic compounds are one or more of methanol, propylene, and ethyl acetate; the reaction atmosphere is 200 - 1000 ppm volatile organic compounds, 5% - 12% O2, N2 balance gas, and the mass space velocity is 750 - 60000 ml / (g*h); the dosage of the catalyst is 100 mg - 300 mg; the reaction temperature is 40 - 250 °C; when the volatile organic compound is propylene, the catalytic reaction temperature is 200 - 250 °C; heat up from 40 - 60 °C to 200 - 250 °C at a heating rate of 5 - 10 °C / min, with each 5 - 20 °C increase as a temperature segment, and each temperature segment is held for 25 - 50 min.

[0026] In some embodiments, the dual-atom copper-cobalt / graphdiyne catalyst is prepared by the following steps:

[0027] S1. Disperse graphdiyne nanosheets and copper nitrate trihydrate in an ammonia aqueous solution to obtain a first mixed solution. Dry the first mixed solution, and then instantaneously calcine it at 200 - 400 °C under the protection of an inert atmosphere to obtain a first mixture; the copper nitrate trihydrate and the graphdiyne nanosheets are mixed according to the mass ratio of Cu to C of 4% - 10%;

[0028] S2. Disperse the first mixture and cobalt nitrate hexahydrate in an ethanol solution to obtain a second mixed solution. Dry the second mixed solution, and then instantaneously calcine it at 200 - 400 °C under the protection of an inert atmosphere to obtain a dual-atom copper-cobalt / graphdiyne catalyst; the cobalt nitrate hexahydrate and the graphdiyne nanosheets are mixed according to the mass ratio of Co to C of 4% - 10%.

[0029] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] The dual-atom copper-cobalt / graphdiyne catalyst in the following embodiments is prepared by the following steps:

[0031] T1. Disperse 100 mg of graphdiyne nanosheets and 19.05 mg of copper nitrate trihydrate in an ammonia aqueous solution to obtain a first mixed solution. Stir and disperse the first mixed solution for more than 30 minutes, then transfer it to a constant-temperature drying oven at 40 °C and dry it until the ammonia aqueous solution completely volatilizes. Then continue to calcine it at 300 °C for 1 min under the protection of an inert atmosphere of argon to obtain a first mixture;

[0032] T2. Disperse the first mixture and 24.69 mg of cobalt nitrate hexahydrate in a beaker containing an ethanol solution to obtain a second mixed solution. Stir and disperse the second mixed solution for more than 30 minutes, then transfer it to a constant-temperature drying oven at 40 °C and dry it until the ethanol solution completely volatilizes. Then continue to calcine it at 300 °C for 1 min under the protection of an inert atmosphere of argon to obtain a graphdiyne-based dual-atom copper-cobalt catalyst (named Cu-Co / GDY catalyst).

[0033] For the convenience of comparison, another catalyst is also used in the following embodiments for the following catalytic reaction. This catalyst is prepared by the following steps:

[0034] T1. Disperse 100 mg of graphdiyne nanosheets and 91.86 mg of cobalt phthalocyanine in an anhydrous ethanol solution to obtain a first mixed solution. Stir and disperse the first mixed solution for more than 30 minutes, then transfer it to a constant-temperature drying oven at 40 °C and dry it until the ethanol solution completely volatilizes. Then continue to calcine it at 800 °C for 1 h under the protection of an inert atmosphere of argon to obtain a first mixture;

[0035] T2. Disperse the first mixture and 1.43 mL (7.03 mL / g) of copper nanoparticle suspension in a beaker containing an ethanol solution to obtain a second mixed solution. Stir and disperse the second mixed solution for more than 30 minutes, then transfer it to a constant-temperature drying oven at 40 °C and dry it until the ethanol solution completely evaporates. Then continue to calcine it at 300 °C for 1 min under the protection of an inert argon atmosphere to obtain a graphdiyne-based double-nanoparticle copper-cobalt catalyst (named CuNP-CoNP / GDY).

[0036] Figure 1 (a) Theoretical model diagram and (b) aberration-corrected high-angle annular dark-field scanning transmission electron microscopy image (Ac-HAADF-STEM) of the Cu-Co / GDY catalyst; it can be clearly observed from the figure that the dual atoms Cu and Co are successfully anchored on the surface of GDY.

[0037] Figure 2 (a) Top view and side view of the adsorption configuration of O2 on the Cu-Co / GDY catalyst. In the figure, red represents O atoms, blue represents Cu atoms, magenta represents Co atoms, and brown represents C atoms. (b) O 1s XPS spectrum; as Figure 2 shown in a, according to DFT calculations, it can be known that O2 gains 0.87e-, and the O-O bond length stretches from to and is activated. Further, the O 1s of the XPS of the Cu-Co / GDY catalyst and the CuNP-CoNP / GDY catalyst are deconvoluted. As Figure 2 shown in b, the chemical adsorption oxygen is at a binding energy of 532.9 eV, and the peaks of hydroxyl oxygen and water molecule oxygen are at a binding energy of 533.9 eV. A larger peak area of chemical adsorption oxygen can be observed in the Cu-Co / GDY catalyst, indicating that the surface of the Cu-Co / GDY catalyst contains more chemical adsorption oxygen.

[0038] Example 1

[0039] This example presents an application of a catalyst in the catalytic oxidation of propylene. The propylene catalytic oxidation activities of the Cu-Co / GDY catalyst and the CuNP-CoNP / GDY catalyst are tested respectively. Specifically, it includes: in a quartz tube fixed-bed reactor with a diameter of 6 mm, first load 200 mg of catalyst powder in the middle of the quartz tube, then place the quartz tube loaded with the catalyst in the tube furnace at the correct position, adopt a programmed temperature rise mode, heat from 60 °C to 240 °C at a heating rate of 5 °C / min, with each 10 °C temperature rise as a temperature segment, and keep the temperature for 25 min in each temperature segment. The reaction atmosphere is 1000 ppm C3H6, 12% O2, N2 balance gas, and the mass space velocity is 2500 mL·g -1 ·h -1 , and the total flow rate is 25 / 3 ml / min.

[0040] Example 2

[0041] This example presents the application of a catalyst in the catalytic oxidation of methanol. The methanol catalytic oxidation activities of the Cu-Co / GDY catalyst and the CuNP-CoNP / GDY catalyst were tested respectively. Specifically, 100 mg of the catalyst powder was weighed and sealed in the middle of a horizontal quartz tube with quartz wool. The temperature-programmed mode was adopted, and it was heated from 60 °C to 240 °C at a heating rate of 5 °C / min. Each 10 °C increase was taken as a temperature segment, and each temperature segment was kept warm for 50 min. The reaction atmosphere was 1000 ppm CH3OH, 5% O2, and N2 balance gas, and the corresponding gas mass space velocity was about 60000 mL·g -1 ·h -1 , and the total flow rate was 100 mL / min.

[0042] Example 3

[0043] This example presents the application of a catalyst in the catalytic oxidation of ethyl acetate (i.e., EA). The catalytic oxidation activities of the Cu-Co / GDY catalyst and the CuNP-CoNP / GDY catalyst in ethyl acetate were tested respectively. 100 mg of the catalyst powder was weighed and sealed in the middle of a horizontal quartz tube with quartz wool. The temperature-programmed mode was adopted, and it was heated from 40 °C to 220 °C at a heating rate of 5 °C / min. Each 10 °C increase was taken as a temperature segment, and each temperature segment was kept warm for 50 min. The reaction atmosphere was 200 ppm EA, 5% O2, and N2 balance gas, and the corresponding gas mass space velocity was about 7500 mL·g -1 ·h -1 , and the total flow rate was 25 mL / min.

[0044] Figure 3 Figure is the EPR spectrum of radical capture of the Cu-Co / GDY catalyst using DMPO; it can be known from the radical capture using DMPO that the Cu-Co / GDY catalyst is more likely to activate molecular oxygen into ·O2 - .

[0045] Figure 4 Figure is the propylene catalytic oxidation activity diagram of the Cu-Co / GDY catalyst and the CuNP-CoNP / GDY catalyst in Example 1; under the conditions of 1000 ppm C3H6, 12% O2, N2 balance gas, and a mass space velocity of 2500 mL·g -1 ·h -1 , the test results of the propylene catalytic oxidation activity show that the Cu-Co / GDY catalyst has more excellent catalytic oxidation activity. It reaches 90% conversion at 203 °C, while the CuNP-CoNP / GDY catalyst reaches 90% conversion only at 224 °C.

[0046] Figure 5 Catalytic oxidation activity diagrams of the Cu-Co / GDY catalyst and the CuNP-CoNP / GDY catalyst in Example 2. Under the conditions of 1000 ppm CH3OH, 5% O2, N2 balance gas, and a mass space velocity of 60000 mL·g -1 ·h -1 The results of the methanol catalytic oxidation activity test show that the Cu-Co / GDY catalyst has more excellent catalytic oxidation activity. It reaches a conversion rate of 90% at 140 °C, while the CuNP-CoNP / GDY catalyst reaches a conversion rate of 90% only at 234 °C.

[0047] Figure 6 Catalytic oxidation activity diagrams of the Cu-Co / GDY catalyst and the CuNP-CoNP / GDY catalyst in Example 3. Under the conditions of 200 ppm EA, 5% O2, N2 balance gas, and a mass space velocity of 7500 mL·g -1 ·h -1 The results of the ethyl acetate catalytic oxidation activity test show that the Cu-Co / GDY catalyst has more excellent catalytic oxidation activity. It reaches a conversion rate of 90% at 194 °C, while the CuNP-CoNP / GDY catalyst has a conversion rate of less than 20% at around 200 °C.

[0048] The specific embodiments of the present invention described above do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. Application of a dual-atom copper-cobalt / graphdiyne catalyst in catalytic oxidation of volatile organic compounds; the dual-atom copper-cobalt / graphdiyne catalyst is prepared by the following steps: S1. Dispersing graphdiyne nanosheets and copper nitrate trihydrate in an ammonia aqueous solution to obtain a first mixed solution, drying the first mixed solution, and then instantaneously calcining at 200-400 °C under the protection of an inert atmosphere to obtain a first mixture; S2. Dispersing the first mixture and cobalt nitrate hexahydrate in an ethanol solution to obtain a second mixed solution, drying the second mixed solution, and then instantaneously calcining at 200-400 °C under the protection of an inert atmosphere to obtain a dual-atom copper-cobalt / graphdiyne catalyst.

2. The application according to claim 1, characterized in that The volatile organic compound is one or more of methanol, propylene, and ethyl acetate.

3. The application according to claim 1, wherein, The reaction atmosphere is 200 - 1000 ppm volatile organic compounds, 5% - 12% O2, with N2 as the balance gas, and the mass space velocity is 750 - 60000 mL·g -1 ·h -1 .

4. The application according to claim 3, characterized in that, The dosage of the catalyst is 100 mg - 300 mg.

5. The application according to claim 3, wherein The reaction temperature is 40-250 °C.

6. The application according to claim 5, characterized in that, When the volatile organic compound is propylene, the temperature of the catalytic reaction is 200-250 °C.

7. The application according to claim 6, characterized in that, Raise the temperature from 40-60 °C to 200-250 °C at a heating rate of 5-10 °C / min.

8. The application according to claim 7, wherein It also includes that every 5-20 °C increase in temperature is a temperature segment, and each temperature segment is kept warm for 25-50 min.

9. The application according to claim 1, wherein In step S1, the copper nitrate trihydrate and the graphdiyne nanosheets are mixed according to the mass ratio of Cu to C of 4%-10%; in step S2, the cobalt nitrate hexahydrate and the graphdiyne nanosheets are mixed according to the mass ratio of Co to C of 4%-10%.

Images