Cu with plasmonic effect 2-x S / carbon / MnO2 / attapulgite composite catalyst and application thereof

Abstract

The application belongs to the technical field of catalyst preparation, and particularly discloses a Cu 2‑x The application discloses a preparation method and application of an S / carbon / MnO2 / attapulgite composite catalyst. Attapulgite is used as a carrier, and is reacted with thiophene and potassium permanganate to uniformly load flaky manganese dioxide on the attapulgite carrier, and simultaneously, the thiophene is oxidized into a polymer to prepare polythiophene / MnO2 / attapulgite. A copper source is added, and complexation and coordination occur between sulfur atoms (S) in the thiophene and copper ions (Cu 2+ ), so that the copper ions are adsorbed in situ to the surface of the polythiophene / MnO2 / attapulgite composite, and Cu 2‑x S / carbon / MnO2 / attapulgite is prepared by pyrolysis. The prepared catalyst has both thermal catalysis function and plasmonic photothermal effect, greatly reduces the reaction temperature when the catalyst catalyzes and oxidizes VOCs, and realizes the purpose of coupling and catalyzing and oxidizing VOCs under low-temperature conditions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalyst preparation, and particularly relates to a Cu 2-x Preparation method and application of S / carbon / MnO2 / attapulgite composite catalyst. BACKGROUND

[0002] Volatile organic compounds (VOCs) are one of the main atmospheric pollutants, which are the main cause of the formation of secondary organic aerosols, atmospheric photochemical smog and ozone destruction. Among them, aromatic VOCs including benzene, toluene, o-xylene and chlorobenzene have high toxicity and "carcinogenic-mutagenic-teratogenic" effects on human health. Catalytic oxidation method is widely used due to its high treatment efficiency, no secondary pollution and relatively low light-off temperature. Catalyst is the core of catalytic oxidation technology, and non-noble metal has attracted widespread attention due to its advantages of abundant resources and low price. MnO2, as a typical non-noble metal catalyst, has the advantages of relatively low catalytic activity, wide raw material sources and simple preparation process, and is used in the field of catalytic treatment of VOCs. Flaky MnO2 has the advantages of large specific surface area and large number of active sites, and has become a research hotspot. Chinese patent (CN115744995A) discloses a continuous flow microwave method for preparing flaky manganese dioxide. A divalent manganese salt, a heptavalent manganese salt, a base and water are mixed to obtain a mixed solution. The mixed solution is injected into a microwave chemical reactor for continuous flow microwave reaction, flows out of the microwave chemical reactor, and is filtered and dried to obtain the flaky manganese dioxide. The flaky manganese dioxide prepared by this method has serious stacking and agglomeration problems, which greatly reduces the catalytic oxidation performance of the manganese-based catalyst. How to solve the agglomeration of manganese dioxide is a key technical problem to be solved.

[0003] At present, the Mn-based catalysts still need a thermal catalytic temperature of more than 300 DEG C for catalyzing benzene series (such as benzene, toluene, xylene, etc.). In order to further reduce the catalytic reaction temperature, coupling of light-driven catalysts with thermal catalysts for photocatalytic oxidation of VOCs is a catalytic oxidation technology with the advantages of mild reaction conditions, low energy consumption and environmental friendliness. Under light conditions, nano materials with local surface plasmon resonance effect will produce hot electrons with higher energy (much higher than the energy of electrons in thermodynamic equilibrium state). In recent years, compared with noble metal catalysts such as platinum and gold, non-noble metal nano catalysts have become a research hotspot due to their low price. In particular, non-stoichiometric Cu 2-x S is widely used in the field of photo-thermal catalysis due to its simple preparation process, strong local surface plasmon resonance (LSPR) effect and excellent visible-near infrared light absorption capacity. SUMMARY

[0004] To solve the two problems in the background art, the application provides a Cu 2-x The application aims at: on the one hand, using palygorskite as a carrier, loading flaky MnO2 on the palygorskite carrier to prepare the MnO2 / palygorskite catalyst, so as to overcome the problems of easy agglomeration and stacking of the flaky MnO2 catalyst, thereby improving the specific surface area and active sites of the MnO2 catalyst; on the other hand, loading Cu 2-x S with plasmonic effect on the surface of the flaky MnO2 to form a strong photothermal effect, thereby further reducing the reaction temperature of the MnO2 catalyst in the thermal catalysis of VOCs, and solving the problem of high activity temperature of the Mn-based thermal catalyst.

[0005] The application provides a Cu 2-x S / Carbon / MnO2 / palygorskite catalyst, and the specific steps are as follows:

[0006] 1. While stirring, thienyl and palygorskite are dispersed into an acetone solvent, after uniform stirring, potassium permanganate is continuously added into the solution, and ozone (O3) gas with a flow rate of 3-6 mL / min is continuously introduced into the system through a flow meter (MCR-500SLPMM, American Alikate Company), after ultrasonic reaction for 1-3 h, the gas is stopped, and the polythienyl / MnO2 / palygorskite composite filter cake is prepared by filtering and washing with deionized water;

[0007] In step 1, the mass ratio of thienyl to acetone is 0.02-0.05:1, and the molar ratio of thienyl to potassium permanganate is 0.8-1.2:1; wherein the mass ratio of manganese dioxide (theoretical value) to palygorskite is 0.5-1.2:1.

[0008] 2. The polythienyl / MnO2 / palygorskite composite filter cake obtained in step 1 is dispersed in deionized water again to prepare a dispersion slurry with a mass percentage concentration of 10%-13%, and a soluble copper salt is added; the obtained dispersion liquid is immersed and adsorbed for 2-4 h under normal temperature conditions, and then is subjected to suction filtration, washing, drying, crushing, pyrolysis of the prepared powder at a temperature of 300-450 DEG C under a nitrogen atmosphere for 1-3 h, and thus a Cu 2-x S / Carbon / MnO2 / palygorskite composite catalyst is obtained.

[0009] The soluble copper salt in step 2 is one of copper sulfate pentahydrate (CuSO4·5H2O), copper chloride dihydrate (CuCl2·2H2O) or copper nitrate trihydrate (Cu(NO3)2·3H2O). The molar ratio of the soluble copper salt to thienyl in step 1 is 1.1-1.3:1.

[0010] The prepared Cu 2-xUnder the light condition, the S / carbon / MnO2 / attapulgite composite catalyst promotes the surface plasmon effect of the catalyst, and the light-heat coupling synergistic effect catalyzes the oxidation of VOCs.

[0011] The beneficial effects of the present application are:

[0012] 1. The present application adopts the reaction of thiophene and potassium permanganate, and the advantages are: ① Thiophene has reducing property, and the reaction with strong oxidizing potassium permanganate promotes the generation of MnO2, and at the same time, thiophene is oxidized into a polymer; ② The sulfur atoms (S) contained in the molecular chain of polythiophene can complex and coordinate with copper ions (Cu 2+ ), and the copper ions are adsorbed to the surface of the polythiophene / MnO2 / attapulgite composite in situ, and then under the condition of high temperature and inert atmosphere, the polythiophene adsorbing copper ions is pyrolyzed to generate active carbon material with high adsorption, which can quickly enrich VOCs gas to the surface of the catalyst, and at the same time, H2S gas is generated and reacts with Cu 2+ to generate Cu 2-x S with plasmonic effect, under the light condition, the generated hot electrons are converted into local heat, and the light-heat efficiency is improved.

[0013] 2. The present application makes full use of the "skeleton" effect of the one-dimensional nanostructure of fibrous or rod-shaped attapulgite clay, so that the lamellar MnO2 can be stably and orderly loaded on the surface in situ, and the stacking and agglomeration of the lamellar MnO2 are effectively prevented, and the specific surface area and the number of active sites of the MnO2 thermal catalyst are improved.

[0014] 3. The present application further loads Cu 2-x S with plasmonic effect on the surface of the lamellar MnO2 to prepare a bifunctional Cu 2-x S / MnO2 / attapulgite composite catalyst, and the catalyst has the dual functions of thermal catalysis and plasmonic light-heat effect, which greatly reduces the reaction temperature of the catalyst in the catalytic oxidation of VOCs, and realizes the purpose of light-heat coupling synergistic catalytic oxidation of VOCs under low temperature condition.

[0015] 4. The introduced ozone gas and potassium permanganate have a synergistic oxidation function, which can oxidize thiophene monomers into polythiophene. In addition, the introduced ozone gas has a bubbling effect, which can more effectively disperse the solid particles in the system and prevent them from settling, which is conducive to the more uniform loading of the active components on the surface of the attapulgite carrier. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 XRD patterns of Example 4 and Comparative Examples 1-2;

[0017] Figure 2 TEM photos of Example 4;

[0018] Figure 3 UV-Vis spectra of Example 4 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0019] The application will be further described in connection with the following specific examples, but the embodiments of the application are not limited to these examples. For the process parameters not specifically mentioned, the conventional techniques can be referred to.

[0020] Example 1

[0021] 1. While stirring, 1.24 g of thiophene and 2.0 g of palygorskite were dispersed into 41.0 g of acetone solvent. After uniform stirring, 2.9 g of potassium permanganate was continuously added into the solution, and at the same time, ozone (O3) gas with a flow rate of 3 mL / min was continuously introduced into the system through a flow meter (MCR-500 SLPMM, Erika Corporation, USA). After ultrasonic reaction for 1 h, the gas was stopped, and the polythiophene / MnO2 / palygorskite composite filter cake was obtained by filtration and deionized water washing.

[0022] 2. The polythiophene / MnO2 / palygorskite composite filter cake obtained in step 1 was re-dispersed in deionized water to prepare a dispersion slurry with a mass percentage concentration of 10%. Then, 4.72 g of copper sulfate pentahydrate was added, and the obtained dispersion liquid was immersed and adsorbed for 2 h at room temperature. After suction filtration, washing, drying, and crushing, the powder was pyrolyzed at a temperature of 450°C for 3 h under a nitrogen atmosphere to obtain a Cu 2-x S / carbon / MnO2 / palygorskite composite catalyst.

[0023] Example 2

[0024] 1. While stirring, 2.78 g of thiophene and 2.0 g of palygorskite were dispersed into 55.0 g of acetone solvent. After uniform stirring, 4.3 g of potassium permanganate was continuously added into the solution, and at the same time, ozone (O3) gas with a flow rate of 4 mL / min was continuously introduced into the system through a flow meter (MCR-500 SLPMM, Erika Corporation, USA). After ultrasonic reaction for 2 h, the gas was stopped, and the polythiophene / MnO2 / palygorskite composite filter cake was obtained by filtration and deionized water washing.

[0025] 2. The polythiophene / MnO2 / palygorskite composite filter cake obtained in step 1 was re-dispersed in deionized water to prepare a dispersion slurry with a mass percentage concentration of 13%. Then, 5.78 g of copper chloride dihydrate was added, and the obtained dispersion liquid was immersed and adsorbed for 4 h at room temperature. After suction filtration, washing, drying, and crushing, the powder was pyrolyzed at a temperature of 300°C for 1 h under a nitrogen atmosphere to obtain a Cu 2-x S / carbon / MnO2 / palygorskite composite catalyst.

[0026] Example 3

[0027] 1. While stirring, 1.96 g of thiophene and 2.0 g of palygorskite were dispersed into 48.0 g of acetone solvent, after uniform stirring, 3.62 g of potassium permanganate was continuously added into the solution, at the same time, ozone (O3) gas with a flow rate of 6 mL / min was continuously introduced into the system through a flow meter (MCR-500 SLPMM, Erika Corporation, USA), after ultrasonic reaction for 3 h, the gas was stopped, and the polythiophene / MnO2 / palygorskite composite filter cake was prepared by filtration and deionized water washing;

[0028] 2. The polythiophene / MnO2 / palygorskite composite filter cake obtained in step 1 was re-dispersed in deionized water to prepare a dispersion slurry with a mass percentage concentration of 11%, 6.4 g of copper nitrate trihydrate was added, the obtained dispersion liquid was immersed and adsorbed at room temperature for 3 h, and then suction filtration, washing, drying, and crushing were performed, under a nitrogen atmosphere, the obtained powder was pyrolyzed at a temperature of 400°C for 2 h, and a Cu 2-x S / carbon / MnO2 / palygorskite composite catalyst was obtained.

[0029] Example 4

[0030] 1. While stirring, 1.96 g of thiophene and 2.0 g of palygorskite were dispersed into 48.0 g of acetone solvent, after uniform stirring, 3.62 g of potassium permanganate was continuously added into the solution, at the same time, ozone (O3) gas with a flow rate of 6 mL / min was continuously introduced into the system through a flow meter (MCR-500 SLPMM, Erika Corporation, USA), after ultrasonic reaction for 3 h, the gas was stopped, and the polythiophene / MnO2 / palygorskite composite filter cake was prepared by filtration and deionized water washing;

[0031] 2. The polythiophene / MnO2 / palygorskite composite filter cake obtained in step 1 was re-dispersed in deionized water to prepare a dispersion slurry with a mass percentage concentration of 11%, 6.4 g of copper nitrate trihydrate was added, the obtained dispersion liquid was immersed and adsorbed at room temperature for 3 h, and then suction filtration, washing, drying, and crushing were performed, under a nitrogen atmosphere, the obtained powder was pyrolyzed at a temperature of 400°C for 2 h, and a Cu 2-x S / carbon / MnO2 / palygorskite composite catalyst was obtained.

[0032] Figure 1 The XRD pattern of Example 4; wherein the MnO2 and Cu 2-x S in Example 4 were known by referring to the PDF cards of MnO2 and Cu 1.8S specific diffraction peak (JCPDS PDF#56-1256). Cu2S specific diffraction peaks (JCPDS PDF#33-0490) appeared at 2θ of 32.6°, 45.4°, 53.6°, and attapulgite characteristic peaks appeared at 2θ of 8°. No characteristic peaks of carbon were detected in XRD, indicating that carbon existed in amorphous form.

[0033] Figure 2 TEM photograph of Example 4; it can be seen that Cu 2-x S nanoparticles were uniformly loaded on the surface of the sheet-like MnO2, and carbon was free on the surface of the catalyst.

[0034] Comparative Example 1

[0035] In Comparative Example 1, the Cu 2-x S component was deleted, and the other processes were unchanged, and the specific steps were as follows:

[0036] 1. While stirring, 1.7 g of thiophene and 2.0 g of attapulgite were dispersed into 42.3 g of acetone solvent, after uniform stirring, 3.2 g of potassium permanganate was continuously added into the solution, at the same time, ozone (O3) gas with a flow rate of 5 mL / min was continuously introduced into the system through a flow meter (MCR-500 SLPMM, Erika Corporation, USA), after ultrasonic reaction for 2 h, the gas was stopped, and the filter cake was obtained by filtration, deionized water washing, drying, and crushing, thereby obtaining a polythiophene / MnO2 / attapulgite composite catalyst;

[0037] 2. The polythiophene / MnO2 / attapulgite composite catalyst obtained in step 1 was pyrolyzed at a temperature of 400°C for 3 h under a nitrogen atmosphere, thereby obtaining a carbon / MnO2 / attapulgite composite catalyst.

[0038] Comparative Example 2

[0039] In Comparative Example 2, the MnO2 component in the sample prepared in Example 4 was deleted, and the other processes were unchanged, and the specific steps were as follows:

[0040] 1. While stirring, 1.7 g of thiophene and 2.0 g of attapulgite were dispersed into 42.3 g of acetone solvent, after uniform stirring, 9.8 g of anhydrous ferric chloride was continuously added into the solution, after ultrasonic reaction for 2 h, the gas was stopped, and the filter cake was obtained by filtration and deionized water washing, thereby obtaining a polythiophene / attapulgite composite filter cake.

[0041] 2. The polythiophene / attapulgite composite filter cake obtained in step 1 was dispersed in deionized water to form a slurry with a mass percentage of 11%, and 6.1 g of copper sulfate pentahydrate was added. The obtained dispersion was immersed and adsorbed at room temperature for 3 h, and then filtered, washed, dried, and crushed. The obtained powder was pyrolyzed at 400°C for 3 h under a nitrogen atmosphere to obtain a Cu 2-x S / attapulgite / carbon composite catalyst.

[0042] Comparative Example 3

[0043] In Comparative Example 3, the carbon component in the sample prepared in Example 4 was removed, and the other processes were unchanged. The specific steps were as follows:

[0044] 1. While stirring, 2.0 g of attapulgite was dispersed in 42.3 g of acetone solvent. After uniform stirring, 3.2 g of potassium permanganate was added to the solution, and ozone (O3) gas with a flow rate of 5 mL / min was continuously introduced into the system through a flow meter (MCR-500 SLPMM, Erika Corporation, USA). After ultrasonic reaction for 2 h, the gas was stopped, and the mixture was filtered and washed with deionized water to obtain a MnO2 / attapulgite composite filter cake.

[0045] 2. The MnO2 / attapulgite composite filter cake obtained in step 1 was dispersed in deionized water to form a slurry with a mass percentage of 11%, and 6.1 g of copper sulfate pentahydrate and 3.1 g of sodium thiosulfate were added to the dispersion. After ultrasonic reaction for 30 min, the obtained dispersion was hydrothermally reacted at 180°C for 3 h, cooled to room temperature, uniformly stirred, filtered, washed, dried, and crushed. The obtained powder was pyrolyzed at 400°C for 3 h under a nitrogen atmosphere to obtain a Cu 2-x S / MnO2 / attapulgite composite catalyst.

[0046] Comparative Example 4

[0047] In Comparative Example 4, the Cu 2-x S component in the sample prepared in Example 4 was replaced with a Cu component, and the other processes were unchanged. The specific steps were as follows:

[0048] 1. While stirring, 2.0 g of attapulgite was dispersed in 42.3 g of acetone solvent. After uniform stirring, 3.2 g of potassium permanganate was added to the solution, and ozone (O3) gas with a flow rate of 5 mL / min was continuously introduced into the system through a flow meter (MCR-500 SLPMM, Erika Corporation, USA). After ultrasonic reaction for 2 h, the gas was stopped, and the mixture was filtered and washed with deionized water to obtain a MnO2 / attapulgite composite filter cake.

[0049] 2. The MnO2 / attapulgite composite filter cake obtained in step 1 is re-dispersed in deionized water to prepare a dispersion slurry with a mass percentage of 11%, 6.1 g of copper sulfate pentahydrate and 2.0 g of glucose (equivalent to the amount of carbon in thiophene) are added to the dispersion, and after ultrasonic reaction for 30 min, the obtained dispersion is subjected to hydrothermal reaction at a temperature of 180 ℃ for 3 h, cooled to room temperature, stirred uniformly, and then subjected to filtration, washing, drying, and crushing. Under a nitrogen atmosphere, the obtained powder is subjected to pyrolysis reaction at a temperature of 400 ℃ for 3 h to obtain a Cu / carbon / MnO2 / attapulgite composite catalyst.

[0050] Performance evaluation

[0051] Catalytic oxidation activity evaluation: the catalyst in the present application is subjected to catalytic oxidation experiment with toluene as a simulation gas. The activity evaluation of the catalyst is performed on a light-heat synergistic catalytic reaction VOC adsorption and desorption device (VDRT-3000 type, Quzhou Wade Instrument Co., Ltd.). The light source used in the reaction is a PLS SXE300 full-spectrum xenon lamp light source from Beijing Po Fei Le Science and Technology Co., Ltd., and the reaction light rate density is 300 mW / m 2 . 0.1 g of the catalyst is placed in a quartz tube (inner diameter of 28 mm), toluene is generated by nitrogen bubbling at room temperature, high-purity air is used as the carrier gas, and the toluene concentration is controlled by adjusting the flow rates of the bubbling gas and the carrier gas, i.e., the toluene concentration is 400 ppm, the catalyst dosage is 200 mg, the reaction gas flow rate is 167 mL / min, the mass space velocity is 50,000 mL / g·h, and nitrogen is used as the balancing gas. The toluene concentration is analyzed online by a GC-2014 gas chromatograph (Shimadzu Corporation, Japan). As can be seen from the test results in Table 1, the Cu 2-x S / carbon / MnO2 / attapulgite composite catalyst prepared in the present application exhibits good light-heat catalytic activity, and the conversion rate of toluene can reach 93%.

[0052] Table 2 shows the specific surface area of the prepared sample catalyst and the highest temperature that the sample catalyst can reach under xenon lamp irradiation. The tablet catalyst is placed at the center of the light circle, and the surface temperature of the catalyst is measured by a handheld infrared camera (DS-2TPH10-3AUF, Hangzhou Hikvision Digital Technology Co., Ltd.). The highest temperature that can be reached is recorded. As can be seen from the table, the Cu 2-x S / carbon / MnO2 / attapulgite catalyst has a high specific surface area and temperature rise, indicating that the Cu 2-x S / carbon / MnO2 / attapulgite composite catalyst prepared in the present application has excellent light-heat conversion efficiency.

[0053] Figure 3 UV-Vis absorption spectrum (UV-Vis) of Example 4 and Comparative Examples 1-2. Compared with the MnO2 / attapulgite, the Cu2-x The S / carbon / MnO2 / attapulgite composite catalyst has one more significant absorption peak at 870 nm, indicating that the catalyst has plasmon resonance effect, can form photo-thermal effect, and reduces the catalytic oxidation reaction temperature of the catalyst; on the other hand, Cu 2-x The visible light absorption band of the S / carbon / MnO2 / attapulgite composite catalyst is significantly improved in the near-infrared light absorption range, widening the absorption light range of the catalyst.

[0054] Table 1

[0055] Sample Conversion time / min Conversion of toluene Example 1 40 88％ Example 2 40 83％ Example 3 40 90％ Example 4 40 93％ Comparative Example 1 40 50％ Comparative Example 2 40 32％ Comparative Example 3 40 52％ Comparative Example 4 40 60％

[0056] Table 2

[0057] Sample Specific surface area (m 2 / g) Maximum temperature (°C) Example 4 198 228 Comparative Example 1 163 198 Comparative Example 2 97 178

Claims

1. A Cu exhibiting plasmon resonance effect 2-x The method for preparing the S / carbon / MnO2 / attapulgite composite catalyst is characterized by: (1) Disperse thiophene and attapulgite in a solvent, stir evenly, add potassium permanganate to the solution, and simultaneously introduce ozone. After sonication, stop the gas flow, filter and wash to obtain polythiophene / MnO2 / attapulgite composite filter cake. (2) The polythiophene / MnO2 / attapulgite composite filter cake from step (1) was dispersed in water to prepare a dispersion slurry. A soluble copper salt was added for adsorption, followed by filtration, washing, drying, and pulverization. The slurry was then pyrolyzed under a nitrogen atmosphere at a temperature of 300–450 °C to obtain Cu. 2-x S / carbon / MnO2 / attapulgite composite catalyst.

2. The Cu exhibiting plasmon effect according to claim 1 2-x The method for preparing the S / carbon / MnO2 / attapulgite composite catalyst is characterized by: The mass ratio of thiophene to solvent is 0.02–0.05:1, and the molar ratio of thiophene to potassium permanganate is 0.8–1.2:

1.

3. The Cu exhibiting plasmon effect according to claim 1 2-x The method for preparing the S / carbon / MnO2 / attapulgite composite catalyst is characterized by: The theoretical ratio of manganese dioxide to the mass of attapulgite is 0.5 to 1.2:

1.

4. Cu exhibiting plasmon effect according to claim 1 2-x The method for preparing the S / carbon / MnO2 / attapulgite composite catalyst is characterized by: The molar ratio of soluble copper salt to thiophene is 1.1 to 1.3:

1.

5. Cu exhibiting plasmon effect according to claim 1 2-x The method for preparing the S / carbon / MnO2 / attapulgite composite catalyst is characterized by: Soluble copper salts are one of copper sulfate, copper chloride, and copper nitrate.

6. Cu exhibiting plasmon effect according to claim 1 2-x The method for preparing the S / carbon / MnO2 / attapulgite composite catalyst is characterized by: The pyrolysis reaction time is 1 to 3 hours.

7. Cu exhibiting plasmon effect prepared by the method according to any one of claims 1-6 2-x S / carbon / MnO2 / attapulgite composite catalyst.

8. Cu exhibiting plasmon effect prepared by the method according to any one of claims 1-6 2-x The application of the S / carbon / MnO2 / attapulgite composite catalyst is characterized by: Cu 2-x S / carbon / MnO2 / attapulgite composite catalysts are used for the catalytic oxidation of VOCs.

9. The application according to claim 8, characterized in that: VOCs are catalytically oxidized under light.

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