An integral bifunctional catalyst, preparation method and application thereof
By using LDH/GO composite catalyst in a closed environment, the problems of low purification efficiency and secondary pollution are solved, and efficient and low-energy consumption of gas purification and resource utilization are achieved.
Patent Information
- Application Number
- CN202411370134.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-29
- Publication Date
- 2024-12-24
- Estimated Expiration
- 2044-09-29
AI Technical Summary
The prior art has low purification efficiency, long reaction time and secondary pollution in a closed environment, making it difficult to effectively deal with complex polluted gases.
The preparation method of the integrated dual-function catalyst is adopted to prepare Layered Double Hydroxides (LDH) and graphene oxide (GO) composite materials through hydrothermal reaction and ultrasound, which are used to catalyze the reaction of formaldehyde oxidation and carbon dioxide reduction to methanol.
It has achieved efficient purification of harmful gases in closed environments, reduced energy consumption, avoided the generation of by-products, and had the ability to continuously and resource utilization.
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Figure CN118874472B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of environmental catalysis, and in particular to an integral bifunctional catalyst, a preparation method and application thereof. Background Art
[0002] Special closed environments (submarine, space station, etc.) have narrow spaces and a wide variety of equipment. Based on such an environment, the gases produced by normal human metabolism, equipment operation, and volatilization of non-metallic materials make the atmosphere in the environment complex. A large amount of toxic substances fills the narrow environment, endangering the life safety of people in the environment.
[0003] Human beings need to constantly inhale oxygen and expel carbon dioxide to maintain life activities. However, oxygen in such a closed environment cannot be easily taken in as in the natural environment. Instead, it needs to be prepared by the operation of various equipment. However, with the operation of various equipment, the atmosphere in the closed environment is filled with a large amount of toxic gases such as carbon monoxide (CO), volatile organic compounds (VOC) and other odorous gases in addition to oxygen. When the content of these gases exceeds the standard, it may cause explosions, poisoning and other dangerous situations, seriously endangering the life safety and health of personnel. Therefore, building a safe atmosphere in a closed environment is of great significance to the workers in this environment.
[0004] Existing purification technologies, such as catalytic combustion technology, low-temperature plasma technology, photocatalytic technology, new adsorption materials, and biological purification technology, all have certain defects, resulting in unsatisfactory application conditions. The high temperature required for catalytic combustion technology leads to the production of acidic gases, which will also endanger the safety of personnel. Low-temperature plasma technology has high efficiency and low energy consumption, but the reaction is complex and the purification conditions of various pollutants are different. It is difficult to apply it to complex closed environments at this stage. Photocatalytic technology also has low energy consumption and high efficiency, but it is difficult to handle large amounts of high-concentration polluted gases due to light source limitations. At the same time, its reaction is also unknown, and its oxidation products are not the only ones that may cause increased toxicity. In comparison, it is simpler and more convenient to use adsorption materials, but adsorption materials also have adsorption saturation and cannot be recycled, and there is a problem of secondary pollution. Biological purification technology has good development prospects, but the space occupied by the current biological purification box is too large for such a closed environment and is not applicable. For various reasons, the current optimal purification solution is catalytic oxidation technology.
[0005] The most prominent problems in the above purification technologies are low purification efficiency, long reaction time, secondary pollution, etc. The above problems can be solved by using catalytic oxidation technology. By using suitable catalytic materials and carriers, the atmospheric environment can be purified efficiently and quickly under complex conditions.
[0006] Layered double hydroxide (LDH) is a typical layered material, which is composed of a sandwich structure of HO-M-OH in the plane. The large interlayer spacing of LDH allows atoms, ions or molecules to be intercalated. These intercalation structures affect the electronic distribution of LDH, and then affect the surface electronic structure. At the same time, LDH materials also have good carbon dioxide adsorption capacity at high temperatures, and the hydroxyl groups on their surface can promote the oxidation of pollutants. The structure and composition of LDH are easy to adjust. The active metal cations of LDH materials are evenly distributed at the atomic level, which improves the catalytic activity and is also conducive to the generation of highly stable and dispersed metal substances during calcination and reduction. The strong metal-metal oxide support interaction in the calcination stage prevents the sintering of metal particles during the reaction. Graphene oxide (GO), as an important derivative of graphene, contains sufficient oxygen-containing functional groups and is considered to be a potential adsorption site and active center for constructing multifunctional nanocomposites. Therefore, by constructing LDH / GO, toxic gases can be efficiently purified. Summary of the invention
[0007] In view of the above-mentioned deficiencies in the prior art, the present invention provides an integral bifunctional catalyst, a preparation method and applications thereof. The integral bifunctional catalyst prepared by the method can be used in special systems, and can be applied to formaldehyde catalytic oxidation reactions as well as to carbon dioxide reduction to produce methanol, effectively solving the problems of low purification efficiency, long reaction time and secondary pollution existing in the prior purification technology.
[0008] To achieve the above object, the technical solution adopted by the present invention to solve the technical problem is: to provide a method for preparing an integral bifunctional catalyst, comprising the following steps:
[0009] S1. dissolving a transition metal salt in an alkaline solution, then performing a hydrothermal reaction, and then cooling to room temperature to obtain a solution with a precipitate;
[0010] S2, adding hexadecyltrimethylammonium bromide, anionic ligand and chloroform to the solution with precipitate obtained in step S1 and stirring;
[0011] S3, separating the suspension containing solid matter in the aqueous phase and the organic phase, washing them, and then centrifuging to obtain a precipitate, and drying to obtain a composite material;
[0012] S4, adding the composite material obtained in step S3 to the graphene oxide solution, stirring and ultrasonicating, and then freeze-drying to obtain a catalyst powder;
[0013] S5. Add the catalyst powder obtained in step S4 into deionized water, spray it onto the film after stirring and ultrasonicating, and then dry it naturally to obtain an integral bifunctional catalyst.
[0014] Furthermore, in step S1, the transition metal salt is two or three of nickel salt, manganese salt, cerium salt, iron salt, zinc salt, cobalt salt and copper salt.
[0015] Further, in step S1, the alkaline solution is at least one of a urea solution, a sodium hydroxide solution and a potassium hydroxide solution.
[0016] Furthermore, in step S1, the molar ratio of transition metal atoms in the transition metal salt is 1-9:1-2 or 1-8:1-2:1-2.
[0017] Furthermore, in step S1, the molar ratio of transition metal atoms in the transition metal salt is 1-9:1 or 1-8:1:1.
[0018] Furthermore, in step S1, the mass volume ratio of the transition metal salt and the alkaline solution is 0.5-0.9 g:25-35 mL.
[0019] Furthermore, in step S1, the concentration of the alkaline solution is 0.2-0.4 mol / L.
[0020] Further, in step S1, stirring is performed at a rate of 450-550 r / min.
[0021] Further, in step S1, stirring is performed at a rate of 500 r / min.
[0022] Further, in step S1, the dissolved solution is placed in a 50 mL polytetrafluoroethylene-lined autoclave.
[0023] Furthermore, in step S1, the temperature of the hydrothermal reaction is 80-200°C and the time is 2-12 h.
[0024] Further, in step S2, the anionic ligand is one of nitrate, sulfate, chloride and acetate.
[0025] Furthermore, in step S2, the molar volume ratio of hexadecyltrimethylammonium bromide, the anionic ligand, the solution with precipitate obtained in step S1 and chloroform is 2 mol:6 mol:30 mL:30 mL.
[0026] Further, in step S2, stirring is performed for 1-2 h.
[0027] Further, in step S2, stirring is performed for 1 h.
[0028] Furthermore, in step S3, the washing sequence is washing with chloroform for 3-4 times, then washing with acetone for 1-2 times, and then washing with water for 3-4 times.
[0029] Furthermore, in step S3, the washing sequence is washing with chloroform for 3 times, then washing with acetone for 1 time, and then washing with water for 3 times.
[0030] Further, in step S3, centrifugation is performed at a speed of 7500-8500 r / min for 5-10 min.
[0031] Further, in step S3, centrifugation is performed at a speed of 8000 r / min for 5 min.
[0032] Further, in step S3, drying is performed at 60-100° C. for 12-48 h.
[0033] Further, in step S4, the concentration of the graphene oxide solution is 5-15 wt%.
[0034] Further, in step S4, the concentration of the graphene oxide solution is 10 wt %.
[0035] Further, in step S4, the mass volume ratio of the composite material obtained in step S3 to the graphene oxide solution is 9 g:1 mL.
[0036] Furthermore, in step S4, the ultrasonic time is 30-60 min.
[0037] Further, in step S4, freeze-drying is performed at -80°C for 48-72 h.
[0038] Further, in step S5, the mass ratio of the catalyst powder obtained in step S4 to deionized water is 1 g:100 mL.
[0039] Further, in step S5, stirring is performed at 450-550 r / min for 25-35 min and ultrasonication is performed for 25-35 min.
[0040] Further, in step S5, stirring is performed at 500 r / min for 30 min and ultrasonication is performed for 30 min.
[0041] Furthermore, in step S5, the film is one of a basalt fiber film, a nano-carbon film, a nano-alumina film and a nano-titanium dioxide film.
[0042] The integral bifunctional catalyst is prepared by the preparation method of the integral bifunctional catalyst.
[0043] The above-mentioned integral bifunctional catalyst is used to purify hazardous gases in special closed environments.
[0044] The process of purifying hazardous gases by the above-mentioned integral bifunctional catalyst in a special closed environment includes:
[0045] (1) Adjust the air pump to draw gas from the environment into the system;
[0046] (2) Under the action of the pump, the ambient gas enters the catalytic reaction chamber;
[0047] (3) The gas reacts in the catalytic chamber to generate carbon dioxide and water, which then further enter the electrolytic cell for reaction;
[0048] (4) In the electrolytic cell, carbon dioxide is reacted to generate oxygen which is discharged into the environment and methanol which is collected.
[0049] A system for purifying harmful gases in a closed environment comprises the above-mentioned integral bifunctional catalyst, a catalytic reaction chamber, an electrolytic cell and a pump.
[0050] The above-mentioned system for purifying harmful gases in a closed environment includes a catalytic reaction system, an electrolysis system, a condensation chamber and an alcohol storage chamber. The catalytic reaction system and the electrolysis system are connected and opened by an air pipe. The initial end of the system for purifying harmful gases in a closed environment is provided with a fan and a pump, and the catalytic reaction system is provided with an integral bifunctional catalyst; the catalytic reaction system and the electrolysis system are connected and opened by an air pipe, and an electrolysis cell is provided in the electrolysis system. In the electrolysis cell, cathode catalysts are provided on the cathode plate and the cathode metal mesh, and anode catalysts are provided on the anode metal mesh and the anode plate. The electrolysis system is also provided with a partition, a heating sleeve, a multi-gas detector, a liquid addition / exchange tank and a cation exchange membrane; the electrolysis system is connected to the condensation chamber through a ball valve, the condensation chamber is connected to the alcohol storage chamber, and the other end of the ball valve is connected to the mixing chamber.
[0051] The present invention has the following beneficial effects:
[0052] 1. The present invention provides a catalyst for efficient air purification, which can solve the problems of high energy consumption, low efficiency and secondary pollution of traditional air purification, and can fully activate oxygen to catalytically oxidize pollutants such as formaldehyde to form carbon dioxide and water in one step (driving HCHO+O at room temperature). 2 →CO 2 +H 2 O), without producing other toxic byproducts (such as CO: HCHO + 1 / 2O 2 →CO+H 2 O).
[0053] 2. The catalyst prepared by the method provided by the present invention also has the function of electrocatalytic carbon dioxide reduction, and can convert the generated carbon dioxide and water into methanol and oxygen through electrocatalytic technology (electrocatalytic driving CO 2 +2H 2 O→CH 3 OH+3 / 2O 2), on the one hand, it solves the problem of gas emissions in special closed environments (for example, carbon dioxide emissions from submarines will be tracked by radar), and on the other hand, it realizes the resource utilization of waste and can provide oxygen environment and fuel methanol for special facilities.
[0054] 3. The monolithic bifunctional catalyst prepared by the method provided by the present invention can be used in a system for purifying harmful gases in a closed environment. It can be applied to the catalytic oxidation reaction of polluted gas, namely formaldehyde, and can also be used for the fuel utilization of carbon dioxide, namely, the reduction of carbon dioxide to produce methanol. The system for purifying harmful gases in a closed environment can continuously purify formaldehyde in the environment. BRIEF DESCRIPTION OF THE DRAWINGS
[0055] Figure 1 A schematic diagram of a system in which the catalyst of the present invention can be used;
[0056] Among them, 1. catalytic reaction system; 1-1. integral bifunctional catalyst; 1-2. fan; 1-3. pump; 2. electrolysis system; 2-1. multi-gas detector; 2-2. liquid adding / changing tank; 2-3. heating jacket; 2-4. partition; 2-5. cation exchange membrane; 2-6. cathode plate; 2-7. cathode metal mesh; 2-8. ball valve; 2-9. mixing chamber; 2-10. anode metal mesh; 2-11. anode plate; 3. condensation chamber; 4. alcohol storage chamber. DETAILED DESCRIPTION
[0057] The principles and features of the present invention are described below, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific conditions are specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.
[0058] Example 1
[0059] In one embodiment of the present invention, Figure 1 As shown, a system for purifying harmful gases in a closed environment is provided, the system comprising a catalytic reaction system 1, an electrolysis system 2, a condensation chamber 3 and an alcohol storage chamber 4, the catalytic reaction system 1 and the electrolysis system 2 are connected and opened through an air pipe, and a fan 1-2 and a pump 1-3 are provided at the initial end of the system for purifying harmful gases in a closed environment, firstly, the poisonous gas is drawn into the system under the action of the pump 1-3, and under the action of the fan 1-2, the poisonous gas (formaldehyde) enters the catalytic reaction system 1 and passes through the integral bifunctional catalyst 1-1, and the poisonous gas (formaldehyde) is oxidized into carbon dioxide and water in the catalytic reaction chamber.
[0060] The catalytic reaction system 1 is connected to the electrolysis system 2 through a gas pipe. After carbon dioxide and water enter the electrolysis system 2, in the electrolysis cell, carbon dioxide is converted into methanol under the action of the cathode catalyst at the cathode plate 2-6 and the cathode metal mesh 2-7, and oxygen is generated under the action of the anode metal mesh 2-10 and the anode plate 2-11. After the reaction is completed, the electrolyte in the electrolysis system 2 can enter the liquid addition / exchange tank 2-2 for liquid replacement / addition by opening the partition 2-4.
[0061] After passing through the partition 2-4 and entering the liquid adding / exchanging tank 2-2, the gas first enters the multi-gas detector 2-1 for detection under the action of the heating sleeve 2-3. When the concentration of polluted gas and carbon dioxide is low enough and the oxygen is high enough, the ball valve 2-8 leads to the condensation chamber 3, and the condensed gas is discharged outside the system, while the liquid enters the connected alcohol storage chamber 4.
[0062] When the concentration of polluted gas and carbon dioxide is still high and the concentration of oxygen is low, the ball valve 2-8 leads to the mixing chamber 2-9, and the added electrolyte / circulated electrolyte and the mixed gas that does not meet the conditions are mixed in the mixing chamber 2-9 and then enter the electrolysis system 2 again to repeat the reaction cycle until the concentration of polluted gas and carbon dioxide is low enough and the oxygen is high enough. The ball valve 2-8 leads to the condensation chamber 3, the gas is discharged from the system, and the liquid enters the alcohol storage chamber 4.
[0063] The preparation method of the above-mentioned integral bifunctional catalyst comprises the following steps:
[0064] S1. Add 0.4495 g urea to 30 mL deionized water, then add 0.2718 g nickel nitrate hexahydrate and 0.3777 g ferric nitrate nonahydrate and stir at 500 r / min until dissolved. Transfer the dissolved solution to a 50 mL polytetrafluoroethylene-lined autoclave, then place it in an oven and heat it at 120 °C for 4 h. Take out the autoclave and cool it to room temperature to obtain a solution with a precipitate.
[0065] S2, adding 0.7289 g of hexadecyltrimethylammonium bromide, 0.51 g of sodium nitrate and 30 mL of chloroform to the solution with precipitate obtained in step S1 and stirring for 1 h;
[0066] S3, separating the suspension containing solid matter in the aqueous phase and the organic phase and washing them with chloroform three times, then with acetone once, and then with water three times, and then centrifuging at a speed of 8000 r / min for 5 min to obtain a precipitate, and then drying at 80 ° C for 24 h to obtain a composite material;
[0067] S4, adding the composite material obtained in step S3 to 5 mL of a 10 wt% graphene oxide solution, stirring and ultrasonicating for 30 min, and then freeze-drying at -80 °C for 60 h to obtain a catalyst powder (NiFe LDH / GO);
[0068] S5. Add the catalyst powder obtained in step S4 into 30 mL of deionized water, stir at 500 r / min for 30 min and ultrasonicate for 30 min, spray it evenly onto the basalt fiber film, and then dry it naturally to obtain an integral bifunctional catalyst.
[0069] Example 2
[0070] A monolithic bifunctional catalyst, the preparation method of which comprises the following steps:
[0071] S1. Add 0.6742 g of urea to 30 mL of deionized water, then add 0.2718 g of nickel nitrate hexahydrate, 0.3777 g of ferric nitrate nonahydrate and 0.2258 g of copper nitrate and stir at 500 r / min until dissolved. Transfer the dissolved solution to a 50 mL polytetrafluoroethylene-lined autoclave, then place it in an oven and heat it at 120 °C for 4 h. Take out the autoclave and cool it to room temperature to obtain a solution with a precipitate.
[0072] S2, adding 0.7289 g of hexadecyltrimethylammonium bromide, 0.51 g of sodium nitrate and 30 mL of chloroform to the solution with precipitate obtained in step S1 and stirring for 1 h;
[0073] S3, separating the suspension containing solid matter in the aqueous phase and the organic phase and washing them with chloroform three times, then with acetone once, and then with water three times, and then centrifuging at a speed of 8000 r / min for 5 min to obtain a precipitate, and drying at 60 ° C for 12 h after washing to obtain a composite material;
[0074] S4, adding the composite material obtained in step S3 to 5 mL of a 10 wt% graphene oxide solution, stirring and ultrasonicating for 30 min, and then freeze-drying at -80 °C for 48 h to obtain a catalyst powder (NiFeCu LDH / GO);
[0075] S5. Add the catalyst powder obtained in step S4 into 30 mL of deionized water, stir at 500 r / min for 30 min and ultrasonicate for 30 min, spray it evenly onto the basalt fiber film, and then dry it naturally to obtain an integral bifunctional catalyst.
[0076] Example 3
[0077] A monolithic bifunctional catalyst, the preparation method of which comprises the following steps:
[0078] S1. Add 0.6742 g urea to 30 mL deionized water, then add 0.2781 g zinc nitrate hexahydrate and 0.2258 g copper nitrate trihydrate and stir at 500 r / min until dissolved. Transfer the dissolved solution to a 50 mL polytetrafluoroethylene-lined autoclave, then place it in an oven and heat it at 120 °C for 4 h. Take out the autoclave and cool it to room temperature to obtain a solution with a precipitate.
[0079] S2, adding 0.7289 g of hexadecyltrimethylammonium bromide, 0.51 g of sodium nitrate and 30 mL of chloroform to the solution with precipitate obtained in step S1 and stirring for 1 h;
[0080] S3, separating the suspension containing solid matter in the aqueous phase and the organic phase and washing them with chloroform three times, then with acetone once, and then with water three times, and then centrifuging at a speed of 8000 r / min for 5 min to obtain a precipitate, and drying at 60 ° C for 12 h after washing to obtain a composite material;
[0081] S4, adding the composite material obtained in step S3 to 5 mL of a 10 wt% graphene oxide solution, stirring and ultrasonicating for 30 min, and then freeze-drying at -80 °C for 48 h to obtain a catalyst powder (ZnCu LDH / GO);
[0082] S5. Add the catalyst powder obtained in step S4 into 30 mL of deionized water, stir at 500 r / min for 30 min and ultrasonicate for 30 min, spray it evenly onto the basalt fiber film, and then dry it naturally to obtain an integral bifunctional catalyst.
[0083] Example 4
[0084] A monolithic bifunctional catalyst, the preparation method of which comprises the following steps:
[0085] S1. Add 0.36 g of sodium hydroxide to 30 mL of deionized water, then add 0.2718 g of nickel nitrate hexahydrate and 0.3777 g of ferric nitrate nonahydrate and stir at 500 r / min until dissolved. Transfer the dissolved solution to a 50 mL polytetrafluoroethylene-lined autoclave, then place it in an oven and heat it at 120 °C for 4 h. Take out the autoclave and cool it to room temperature to obtain a solution with a precipitate.
[0086] S2, adding 0.7289 g of hexadecyltrimethylammonium bromide, 0.51 g of sodium nitrate and 30 mL of chloroform to the solution with precipitate obtained in step S1 and stirring for 1 h;
[0087] S3, separating the suspension containing solid matter in the aqueous phase and the organic phase and washing them with chloroform three times, then with acetone once, and then with water three times, and then centrifuging at a speed of 8000 r / min for 5 min to obtain a precipitate, and then drying at 80 ° C for 24 h to obtain a composite material;
[0088] S4, adding the composite material obtained in step S3 to 5 mL of a 10 wt% graphene oxide solution, stirring and ultrasonicating for 30 min, and then freeze-drying at -80 °C for 60 h to obtain a catalyst powder (NiFe LDH / GO-NaOH);
[0089] S5. Add the catalyst powder obtained in step S4 into 30 mL of deionized water, stir at 500 r / min for 30 min and ultrasonicate for 30 min, spray it evenly onto the basalt fiber film, and then dry it naturally to obtain an integral bifunctional catalyst.
[0090] Comparative Example 1
[0091] A method for preparing a catalyst comprises the following steps:
[0092] S1. Add 0.3777 g of ferric nitrate nonahydrate and 0.2718 g of nickel nitrate hexahydrate into 30 mL of ammonia water and stir at 500 r / min until dissolved. Then transfer the dissolved solution into a 50 mL polytetrafluoroethylene-lined autoclave, and heat it in an oven at 120 °C for 4 h. Take out the autoclave and cool it to room temperature to obtain a solution with a precipitate.
[0093] S2, adding 0.7289 g of hexadecyltrimethylammonium bromide, 0.51 g of sodium nitrate and 30 mL of chloroform to the solution with precipitate obtained in step S1 and stirring for 1 h;
[0094] S3, separating the suspension containing solid matter in the aqueous phase and the organic phase and washing them with chloroform three times, then with acetone once, and then with water three times, and then centrifuging at a speed of 8000 r / min for 5 min to obtain a precipitate, and drying at 80 ° C for 24 h after washing to obtain a composite material;
[0095] S4, adding the composite material obtained in step S3 to 5 mL of a 10 wt% graphene oxide solution, stirring and ultrasonicating for 30 min, and then freeze-drying at -80 °C for 60 h to obtain a catalyst powder;
[0096] S5. Add the catalyst powder obtained in step S4 into 30 mL of deionized water, stir at 500 r / min for 30 min and ultrasonicate for 30 min, spray it evenly onto the basalt fiber film, and then dry it naturally to obtain a catalyst.
[0097] Comparative Example 2
[0098] A method for preparing a catalyst comprises the following steps:
[0099] S1. Add 0.3777 g of ferric nitrate nonahydrate, 0.2258 g of copper nitrate and 0.2718 g of nickel nitrate hexahydrate into 30 mL of ammonia water and stir at 500 r / min until dissolved. Then transfer the dissolved solution into a 50 mL polytetrafluoroethylene-lined autoclave, put it into an oven and heat it at 120 °C for 4 h. Take out the autoclave and cool it to room temperature to obtain a solution with a precipitate.
[0100] S2, adding 0.7289 g of hexadecyltrimethylammonium bromide, 0.51 g of sodium nitrate and 30 mL of chloroform to the solution with precipitate obtained in step S1 and stirring for 1 h;
[0101] S3, separating the suspension containing solid matter in the aqueous phase and the organic phase and washing them with chloroform three times, then with acetone once, and then with water three times, and then centrifuging at a speed of 8000 r / min for 5 min to obtain a precipitate, and drying at 80 ° C for 24 h after washing to obtain a composite material;
[0102] S4, adding the composite material obtained in step S3 to 5 mL of a 10 wt% graphene oxide solution, stirring and ultrasonicating for 30 min, and then freeze-drying at -80 °C for 60 h to obtain a catalyst powder;
[0103] S5. Add the catalyst powder obtained in step S4 into 30 mL of deionized water, stir at 500 r / min for 30 min and ultrasonicate for 30 min, spray it evenly onto the basalt fiber film, and then dry it naturally to obtain a catalyst.
[0104] Comparative Example 3
[0105] A method for preparing a catalyst comprises the following steps:
[0106] S1. Add 0.2781 g zinc nitrate hexahydrate and 0.2258 g copper nitrate trihydrate into 30 mL ammonia water and stir at 500 r / min until dissolved. Then transfer the dissolved solution into a 50 mL polytetrafluoroethylene-lined autoclave, and heat it in an oven at 120 °C for 4 h. Take out the autoclave and cool it to room temperature to obtain a solution with a precipitate.
[0107] S2, adding 0.7289 g of hexadecyltrimethylammonium bromide, 0.51 g of sodium nitrate and 30 mL of chloroform to the solution with precipitate obtained in step S1 and stirring for 1 h;
[0108] S3, separating the suspension containing solid matter in the aqueous phase and the organic phase and washing them with chloroform three times, then with acetone once, and then with water three times, and then centrifuging at a speed of 8000 r / min for 5 min to obtain a precipitate, and drying at 80 ° C for 24 h after washing to obtain a composite material;
[0109] S4, adding the composite material obtained in step S3 to 5 mL of a 10 wt% graphene oxide solution, stirring and ultrasonicating for 30 min, and then freeze-drying at -80 °C for 60 h to obtain a catalyst powder;
[0110] S5. Add the catalyst powder obtained in step S4 into 30 mL of deionized water, stir at 500 r / min for 30 min and ultrasonicate for 30 min, spray it evenly onto the basalt fiber film, and then dry it naturally to obtain a catalyst.
[0111] Comparative Example 4
[0112] A method for preparing a catalyst comprises the following steps:
[0113] S1. Add 0.4495 g urea, 0.2299 g ferrous acetate trihydrate and 0.2326 g nickel acetate tetrahydrate into 30 mL deionized water and stir at 500 r / min until dissolved. Then transfer the dissolved solution into a 50 mL polytetrafluoroethylene-lined autoclave, place it in an oven and heat it at 120 °C for 4 h. Take out the autoclave and cool it to room temperature to obtain a solution with a precipitate.
[0114] S2, adding 0.7289 g of hexadecyltrimethylammonium bromide, 0.492 g of acetic acid and 30 mL of chloroform to the solution with precipitate obtained in step S1 and stirring for 1 h;
[0115] S3, separating the suspension containing solid matter in the aqueous phase and the organic phase and washing them with chloroform three times, then with acetone once, and then with water three times, and then centrifuging at a speed of 8000 r / min for 5 min to obtain a precipitate, and drying at 80 ° C for 24 h after washing to obtain a composite material;
[0116] S4, adding the composite material obtained in step S3 to 5 mL of a 10 wt% graphene oxide solution, stirring and ultrasonicating for 30 min, and then freeze-drying at -80 °C for 60 h to obtain a catalyst powder;
[0117] S5. Add the catalyst powder obtained in step S4 into 30 mL of deionized water, stir at 500 r / min for 30 min and ultrasonicate for 30 min, spray it evenly onto the basalt fiber film, and then dry it naturally to obtain a catalyst.
[0118] Comparative Example 5
[0119] A method for preparing a catalyst comprises the following steps:
[0120] S1. Add 0.6742 g urea, 0.2457 g nickel sulfate hexahydrate, 0.2627 g ferric sulfate heptahydrate and 0.2278 g copper sulfate pentahydrate into 30 mL deionized water and stir at 500 r / min until dissolved. Then transfer the dissolved solution into a 50 mL polytetrafluoroethylene-lined autoclave, put it into an oven and heat it at 120 °C for 4 h. Take out the autoclave and cool it to room temperature to obtain a solution with a precipitate.
[0121] S2, adding 0.7289 g of hexadecyltrimethylammonium bromide, 0.852 g of sulfuric acid and 30 mL of chloroform to the solution with precipitate obtained in step S1 and stirring for 1 h;
[0122] S3, separating the suspension containing solid matter in the aqueous phase and the organic phase and washing them with chloroform three times, then with acetone once, and then with water three times, and then centrifuging at a speed of 8000 r / min for 5 min to obtain a precipitate, and drying at 80 ° C for 24 h after washing to obtain a composite material;
[0123] S4, adding the composite material obtained in step S3 to 5 mL of a 10 wt% graphene oxide solution, stirring and ultrasonicating for 30 min, and then freeze-drying at -80 °C for 60 h to obtain a catalyst powder;
[0124] S5. Add the catalyst powder obtained in step S4 into 30 mL of deionized water, stir at 500 r / min for 30 min and ultrasonicate for 30 min, spray it evenly onto the basalt fiber film, and then dry it naturally to obtain a catalyst.
[0125] Comparative Example 6
[0126] A method for preparing a catalyst comprises the following steps:
[0127] S1. Add 0.6742 g urea, 0.2278 g copper sulfate pentahydrate, 0.2688 g zinc sulfate heptahydrate and 0.6231 g gallium sulfate 18hydrate into 30 mL deionized water and stir at 500 r / min until dissolved. Then transfer the dissolved solution into a 50 mL polytetrafluoroethylene-lined autoclave, put it into an oven and heat it at 120 °C for 4 h. Take out the autoclave and cool it to room temperature to obtain a solution with a precipitate.
[0128] S2, adding 0.7289 g of hexadecyltrimethylammonium bromide, 0.852 g of sulfuric acid and 30 mL of chloroform to the solution with precipitate obtained in step S1 and stirring for 1 h;
[0129] S3, separating the suspension containing solid matter in the aqueous phase and the organic phase and washing them with chloroform three times, then with acetone once, and then with water three times, and then centrifuging at a speed of 8000 r / min for 5 min to obtain a precipitate, and drying at 80 ° C for 24 h after washing to obtain a composite material;
[0130] S4, adding the composite material obtained in step S3 to 5 mL of a 10 wt% graphene oxide solution, stirring and ultrasonicating for 30 min, and then freeze-drying at -80 °C for 60 h to obtain a catalyst powder;
[0131] S5. Add the catalyst powder obtained in step S4 into 30 mL of deionized water, stir at 500 r / min for 30 min and ultrasonicate for 30 min, spray it evenly onto the basalt fiber film, and then dry it naturally to obtain a catalyst.
[0132] Test example
[0133] The performance of the integral bifunctional catalyst prepared in Examples 1-3 and the catalyst prepared in Comparative Examples 1-6 was tested. The total air velocity was controlled at 1.5 L / min by a flow meter. Formaldehyde was produced by decomposing polyformaldehyde and then blown into reactor A by argon. The initial formaldehyde concentration was controlled at 100±10 ppm by adjusting the argon flow rate. Oxygen was provided by 10% oxygen in argon. After the reaction, one end of the tail gas was passed into a detector to detect the formaldehyde concentration and the other end was passed into the electrocatalytic reaction. Ag / AgCl was used as the reference electrode, the prepared film was used as the working electrode, the graphite rod was used as the counter electrode, and the NaCl with a concentration of 0.1 M was used as the 2 SO 4 The solution is an electrolyte that forms a three-electrode system. The results are shown in Table 1.
[0134] Table 1 Test results
[0135]
[0136] As shown in Table 1, it is difficult to achieve 100% CO 2 To CH 3 The conversion of OH can be carried out independently in multiple cycles, which effectively solves the problem of low conversion rate and thus the difficulty in catalyst application.
[0137] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. A system for purifying harmful gases in a closed environment, characterized in that: It includes a catalytic reaction system, an electrolysis system, a condensation chamber and an alcohol storage chamber. The catalytic reaction system and the electrolysis system are connected and opened through an air pipe. The initial end of the system for purifying harmful gases in a closed environment is provided with a fan and a pump. The catalytic reaction system is provided with an integral bifunctional catalyst. The catalytic reaction system and the electrolysis system are connected and opened through an air pipe. The electrolysis system is provided with an electrolytic cell. In the electrolytic cell, a cathode plate and a cathode metal mesh are provided with a cathode catalyst, and an anode metal mesh and an anode plate are provided with an anode catalyst. The electrolysis system is also provided with a partition, a heating sleeve, a multi-gas detector, a liquid addition / exchange tank and a cation exchange membrane. The electrolysis system is communicated with the condensation chamber through a ball valve, the condensation chamber is connected with the alcohol storage chamber, and the other end of the ball valve is connected with the mixing chamber. The cathode catalyst and the anode catalyst are both integral bifunctional catalysts; The method for preparing the monolithic bifunctional catalyst comprises the following steps: S1, dissolving a transition metal salt in an alkaline solution, then performing a hydrothermal reaction, and then cooling to room temperature to obtain a solution with a precipitate, wherein the transition metal salt is two or three of a nickel salt, a manganese salt, a cerium salt, an iron salt, a zinc salt, a cobalt salt, and a copper salt; S2, adding hexadecyltrimethylammonium bromide, anionic ligand and chloroform to the solution with precipitate obtained in step S1 and stirring; S3, separating the suspension containing solid matter in the aqueous phase and the organic phase, washing them, and then centrifuging to obtain a precipitate, and drying to obtain a composite material; S4, adding the composite material obtained in step S3 to the graphene oxide solution, stirring and ultrasonicating, and then freeze-drying to obtain a catalyst powder; S5. Add the catalyst powder obtained in step S4 into deionized water, spray it onto the film after stirring and ultrasonicating, and then dry it naturally to obtain an integral bifunctional catalyst.
2. The system for purifying harmful gases in a closed environment according to claim 1, characterized in that: In step S1, the alkaline solution is at least one of a urea solution, a sodium hydroxide solution and a potassium hydroxide solution.
3. The system for purifying harmful gases in a closed environment according to claim 1, characterized in that: In step S1, the molar ratio of transition metal atoms in the transition metal salt is 1-9:1-2 or 1-8:1-2:1-2.
4. The system for purifying harmful gases in a closed environment according to claim 1, characterized in that: In step S2, the anionic ligand is one of nitrate, sulfate, chloride and acetate.
5. The system for purifying harmful gases in a closed environment as claimed in claim 1, characterized in that: In step S3, the washing sequence is washing with chloroform for 3-4 times, then washing with acetone for 1-2 times, and then washing with water for 3-4 times.
6. The system for purifying harmful gases in a closed environment as claimed in claim 1, characterized in that: In step S5, the film is one of a basalt fiber film, a nano-carbon film, a nano-alumina film and a nano-titanium dioxide film.