Fe-Cu composite heteroatom molecular sieve catalyst and preparation method and application thereof

Abstract

The present invention discloses an Fe-Cu composite heteroatom molecular sieve catalyst, its preparation method and application. It is prepared by the amine complexation method, wherein the mass ratio of Fe:Cu is 0.2~1.5:0.2~2. The specific surface area of the Fe-Cu composite heteroatom molecular sieve catalyst is 389.00~552.21 cm<supgt;2< / supgt>·g<supgt;‑1< / supgt>. When catalyzing toluene combustion, the conversion rate can reach 97~99% at 320~410 °C, and when catalyzing propylene combustion, the conversion rate can reach 92~99% at 290~410 °C. The Fe-Cu composite catalyst provided by the present invention has a simple preparation method, inexpensive and easily available raw materials, and mild reaction conditions. By adjusting the different ratios of copper atoms and iron atoms, the synergistic effect between the bimetals is improved, and a catalyst suitable for low-temperature catalytic combustion is obtained. When this catalyst is applied to catalytic combustion for degrading VOCs, VOCs can be rapidly and efficiently degraded under relatively mild conditions.

Description

Technical Field

[0001] The present invention relates to a catalyst for VOCs catalytic combustion reaction and a preparation method thereof, and in particular to a catalyst with synergistic effect between bimetal and molecular sieve and a preparation method thereof and application in VOCs catalytic combustion reaction; belonging to the field of catalytic technology. Background Art

[0002] The petrochemical and organic chemical production processes are one of the main sources of volatile organic compounds (VOCs). In addition to being extremely harmful to the environment, VOCs can also irritate human skin and mucous membranes and cause cancer in humans and animals. In order to control the emission of VOCs, my country promulgated the "Law of the People's Republic of China on the Prevention and Control of Air Pollution" and accordingly issued the "Comprehensive Emission Standards for Air Pollutants" (GB16297-1996) to limit the emission of 16 organic substances. Therefore, it is of great significance to develop effective and applicable methods to reduce the emission of VOCs.

[0003] Among the technologies for treating VOCs emissions, catalytic combustion is often considered because of its unique advantages. Catalytic combustion, also known as catalytic oxidation, refers to the oxidation of high-concentration VOCs with the assistance of a catalyst to degrade them into water and carbon dioxide. It is generally considered to be an efficient and energy-saving strategy. Most organic matter in VOCs can be degraded by catalysts under certain temperature conditions.

[0004] The principle of catalytic oxidation of VOC molecules is generally that after VOC molecules contact the active sites on the catalyst, the catalyst will be reduced, and the oxygen in the air will replenish the oxygen vacancies on the catalyst, and the catalyst will be oxidized. The entire oxidation-reduction process will continue to cycle during the catalytic combustion process. By changing the reaction pathway, reducing the reaction activation energy, and significantly reducing the reaction temperature, low-temperature combustion, reduced energy consumption, improved safety, fewer by-products, high treatment efficiency, and less prone to re-pollution can be achieved.

[0005] The research on VOCs catalytic combustion reaction mainly focuses on catalysts. The most studied catalyst type is precious metal catalyst. The cost of precious metal industrial application is too high and difficult to be applied in practice. Transition metals are low in cost and have variable valence states, and often have better activity in toluene oxidation reaction.

[0006] Chinese patent CN113786835A uses Co3O4 as the active component and mixes it with alkaline earth metal components, thereby significantly improving the catalytic combustion activity of the catalyst in VOCs. However, this method requires the use of an acid solution to adjust the pH value, and the preparation process is relatively complicated.

[0007] Chinese patent CN106944092A involves the synthesis of Fe-MnO2 catalysts. The Fe salts and Mn salts used in this method are cheap and easily available. Under mild reaction conditions, no precious metals need to be loaded, and higher photothermal catalytic degradation of VOCs activity can be obtained at a lower cost. However, this catalyst is a metal oxide doped with a single metal, and the catalyst has fewer active sites.

[0008] Chinese patent CN107754809A relates to the preparation of a Cu-Mn-Zr composite catalyst. When catalyzing the degradation of ester organic volatiles, the temperature is obviously lower than most other catalysts already used in the industry. However, the preparation method is a simple metal mixing, the specific surface area of ​​the catalyst is small, and the metal dispersion and stability are poor.

[0009] Most of the current high-efficiency catalysts have the problems of complicated preparation or high cost, few active sites and low conversion rate of toluene oxidation. There is an urgent need to develop new high-efficiency catalysts. Summary of the invention

[0010] The present invention aims to provide a method for preparing a Fe-Cu composite heteroatom molecular sieve catalyst, and apply the catalyst to the catalytic combustion of VOCs. The bimetallic heteroatom molecular sieve catalyst prepared by the method has the advantages of simple operation, good activity, and relatively low price, and can degrade VOCs quickly and efficiently under relatively mild conditions.

[0011] At present, heteroatom molecular sieve catalysts usually have high metal dispersion and catalytic stability, but the activity of a single transition metal is limited. In order to enhance the activity of transition metals, the present invention utilizes the synergistic effect between bimetallic compounds to solve the problem of poor activity of transition metals.

[0012] The present invention provides a Fe-Cu composite heteroatom molecular sieve catalyst, which is prepared by an amine complexation method, wherein Fe:Cu=0.2~1.5:0.2~2 (mass ratio); the ratio of iron atoms to copper atoms in the Fe-Cu composite heteroatom molecular sieve of the present invention has a significant effect on the low-temperature activity of the catalyst in the VOCs oxidation combustion reaction. The present invention determines the ratio with higher activity through experiments, preferably, Fe:Cu=0.2~0.8:0.3~1.5.

[0013] The Fe-Cu composite catalyst prepared by the present invention has a large specific surface area (389.00~552.21cm 2 ·g -1), which is beneficial to the contact between organic waste gas and active components and improves the degradation rate. The activity is low under low temperature (especially below 327°C) catalytic conditions, but the catalytic activity is significantly improved at 327~410°C, and the conversion rate reaches 97~99%. The catalytic activity of the Fe-Cu composite heteroatom molecular sieve catalyst with Fe:Cu=0.2~0.8:0.3~1.5 becomes better at 300~410°C.

[0014] The present invention provides a method for preparing the above-mentioned Fe-Cu composite heteroatom molecular sieve catalyst, comprising the following steps:

[0015] 1) Mix the amine complexing agent, copper nitrate trihydrate and ferric nitrate nonahydrate in a beaker and stir for a while until they are uniform;

[0016] The amine complexing agent is one of triethanolamine, triethylenetetramine, isopropanolamine and triethanolamine phosphate;

[0017] 2) adding a molecular sieve template to the mixture stirred evenly in step 1) and stirring evenly;

[0018] The molecular sieve template is one of tetrapropylammonium hydroxide, tetrapropylammonium bromide and tetraethylammonium hydroxide, and the mass concentration of the template is 20-40%;

[0019] 3) adding aluminum sulfate 18hydrate to the mixture of step 2) and stirring evenly;

[0020] 4) Slowly add ethyl orthosilicate to the mixture in step 3) with a dropper while stirring, and stir evenly;

[0021] The ratio of the above raw materials is: the molar ratio of tetraethyl orthosilicate: complexing agent: metal source is 50-150:1-5:1-3, the mass ratio of tetraethyl orthosilicate to template agent is 10-20:20-30, and the mass ratio of tetraethyl orthosilicate to aluminum sulfate 18hydrate is 10-25:0.1-1.2;

[0022] 5) stirring the mixture in step 4) at room temperature overnight;

[0023] 6) placing the mixture in step 5) into a polytetrafluoroethylene liner and installing a hydrothermal autoclave, and then placing it into an oven for crystallization;

[0024] 7) washing the catalyst after crystallization in step 6) to neutrality, centrifuging and drying, and then placing it in a muffle furnace for calcination;

[0025] 8) The sample calcined in step 7) is mixed and stirred with the prepared ammonium chloride solution, and heated and exchanged in a water bath. The sample after multiple exchanges is centrifuged and dried. The dried sample is placed in a muffle furnace for calcination to finally obtain a Fe-Cu composite heteroatom molecular sieve catalyst.

[0026] The copper nitrate trihydrate, the iron nitrate nonahydrate and the amine complexing agent are regulated according to the molar ratio (complexing agent: metal source = 1-5: 1-3). The mass ratio of the obtained Fe-Cu composite catalyst is Fe: Cu = 0.2-1.5: 0.2-2. Preferably, the Fe: Cu of the Fe-Cu composite catalyst is 0.2-0.8: 0.3-1.5.

[0027] The copper nitrate trihydrate, iron nitrate nonahydrate and amine complexing agent used in step 1) are preferably 99% pure. The stirring process of step 1) allows the two mixed metal ions to be stably and uniformly dispersed in the alkaline solution.

[0028] The Fe-Cu composite catalyst obtained by the present invention has low catalytic activity at low temperature (especially below 327°C), but the catalytic activity is significantly improved at 327-410°C, exceeding 96%, and the subsequent increase in temperature has little effect on the catalytic activity. The catalytic activity of VOCs oxidation is stable at 97-99%.

[0029] The Fe-Cu composite catalyst obtained when the Fe:Cu mass ratio is 0.2-0.8:0.3-1.5 has better activity than catalysts with other ratios at a temperature above 220°C.

[0030] Preferably, the mixed salt solution in step 1) is stirred for 5 to 10 minutes until all metal salt particles change color, thereby ensuring that the salt solution is evenly mixed.

[0031] Preferably, the stirring time of the mixed salt solution in step 2) is 10 to 20 minutes to ensure uniform mixing.

[0032] Preferably, the stirring speed of the mixed salt solution in step 3) is 300-700 rpm, which can ensure that the metal salt particles are mixed and dissolved more evenly in the solution.

[0033] Preferably, the mixed salt solution in step 4) is added with tetraethyl orthosilicate at a rate lower than 2 mL / min, so as to ensure that tetraethyl orthosilicate can be completely hydrolyzed in the solution.

[0034] Preferably, the temperature of the mixed salt solution in step 5) is maintained at 20-30° C. overnight for 12-24 hours, so that all metal ions can be completely mixed and uniformly mixed in the mixed solution.

[0035] Preferably, the polytetrafluoroethylene liner in step 6) is selected to have a specification of 50-100 mL, the oven temperature is selected to be 120-180° C., and the crystallization time is selected to be 24-72 h.

[0036] Preferably, deionized water or distilled water is used for the washing process in step 7), the drying temperature is 60-90°C, and the roasting conditions are: the heating rate is 2-4°C / min, from room temperature to 400-550°C, and the constant temperature time is 4h-6h.

[0037] Preferably, in step 8), the mass ratio of the calcined sample to the ammonium chloride solution is 1:10-1:20, and the concentration of the ammonium chloride solution is 0.5-1 mol / L.

[0038] The present invention provides an application of the Fe-Cu composite heteroatom molecular sieve catalyst in the degradation of VOCs waste gas. In this application, the Fe-Cu composite heteroatom molecular sieve catalyst is placed in a fixed bed quartz tube reactor to catalyze the degradation reaction of organic waste gas, and the reaction temperature of the degradation reaction is 150-450°C and the space velocity is 14000-36000h -1 .

[0039] In order to improve the catalytic effect, preferably, when the Fe:Cu=0.2~1.5:0.2~2, the degradation reaction temperature is 160~430°C and the space velocity is 14000~36000h -1 .

[0040] In order to improve the catalytic effect, preferably, when the Fe:Cu=0.2~0.8:0.3~1.5, the degradation reaction temperature is 180~410°C and the space velocity is 14000~36000h -1 .

[0041] Beneficial effects of the present invention:

[0042] The Fe-Cu composite catalyst provided by the present invention has a simpler preparation method than most of the reported catalysts, and the raw materials in the present invention are cheap and easily available, the reaction conditions are mild, and the synergistic effect between the two metals is improved by adjusting different ratios of copper atoms and iron atoms to obtain a catalyst most suitable for low-temperature catalytic combustion; when the catalyst is applied to catalytic combustion to degrade VOCs, VOCs can be degraded quickly and efficiently under relatively mild conditions, and will have great application value and broad application prospects when put into actual production. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a curve diagram of the degradation of toluene at different temperatures by the Fe-Cu composite catalyst obtained in Examples 1-3 and the comparative example.

[0044] Figure 2This is a curve chart of the degradation of toluene by the Fe-Cu composite catalyst obtained in Example 4-7 at different temperatures.

[0045] Figure 3 It is a curve diagram of the degradation of propylene at different temperatures for the Fe-Cu composite catalyst obtained in Examples 1-3 and the comparative example.

[0046] Figure 4 The H2-TPR spectra of the Fe-Cu composite catalysts obtained in Examples 1-3 and the comparative example under the same temperature range. DETAILED DESCRIPTION

[0047] The present invention is further described below by way of examples, but is not limited to the following examples. All reagents used in the following examples are analytically pure. Example 1

[0048] The preparation method of the Fe-Cu composite catalyst for degrading VOCs waste gas in this embodiment comprises the following steps:

[0049] 1) Weigh 0.34 g of ferric nitrate nonahydrate, 0.1 g of copper nitrate trihydrate, and 0.6 g of triethanolamine. First add triethanolamine into a beaker, then add iron salt and copper salt respectively, and stir for 5 minutes.

[0050] 2) Add 25.95 g of TAPOH (25%) to the beaker in step 1), stir for 10 min, then add 0.556 g of aluminum sulfate 18hydrate and stir evenly.

[0051] 3) Slowly add 17.337 g of ethyl orthosilicate into the beaker in step 2) using a dropper, and stir the mixed solution at 500 rpm at room temperature for 12 h.

[0052] 4) Place the mixed solution in step 3) into a 100 mL polytetrafluoroethylene liner and place the assembled hydrothermal autoclave in a 140°C oven for 48 h.

[0053] 5) Take out the sample in step 4), wash it with deionized water until it is neutral, and dry it in an oven at 80°C. Take out the dried sample and calcine it. The calcination conditions are: increase the temperature to 550°C at 2°C / min and keep the temperature constant for 6 hours.

[0054] 6) Stir the sample in step 5) and ammonium chloride solution (1 mol / L) in a ratio of 1:20, place in a water bath at 60°C and stir for 2 hours. After exchanging three times under this condition, place the sample in an oven at 80°C to dry.

[0055] 7) The sample in step 6) was taken out and calcined. The calcination conditions were: increasing the temperature to 500°C at 2°C / min and keeping the temperature constant for 5 hours. Finally, a Fe-Cu (mass ratio of 1:0.5) composite catalyst was obtained. Example 2

[0056] The preparation method of the Fe-Cu composite catalyst for degrading VOCs waste gas in this embodiment comprises the following steps:

[0057] 1) Weigh 0.34 g of ferric nitrate nonahydrate, 0.2 g of copper nitrate trihydrate, and 0.6 g of triethanolamine. First add triethanolamine into a beaker, then add iron salt and copper salt respectively, and stir for 5 minutes.

[0058] 2) Add 25.95 g of TAPOH (25%) to the beaker in step 1), stir for 10 min, then add 0.556 g of aluminum sulfate 18hydrate and stir evenly.

[0059] 3) Slowly add 17.337 g of ethyl orthosilicate into the beaker in step 2) using a dropper, and stir the mixed solution at 500 rpm at room temperature for 12 h.

[0060] 4) Place the mixed solution in step 3) into a 100 mL polytetrafluoroethylene liner and place the assembled hydrothermal autoclave in a 140°C oven for 48 h.

[0061] 5) Take out the sample in step 4), wash it with deionized water until it is neutral, and dry it in an oven at 80°C. Take out the dried sample and calcine it. The calcination conditions are: increase the temperature to 550°C at 2°C / min and keep the temperature constant for 6 hours.

[0062] 6) Stir the sample in step 5) and ammonium chloride solution (1 mol / L) in a ratio of 1:20, place in a water bath at 60°C and stir for 2 hours. After exchanging three times under this condition, place the sample in an oven at 80°C to dry.

[0063] 7) Take out the sample in step 6) and calcine it. The calcination conditions are: increase the temperature to 500°C at 2°C / min and keep the temperature constant for 5h. Finally, the Fe-Cu (mass ratio is 1:1) composite catalyst is obtained. Example 3

[0064] The preparation method of the Fe-Cu composite catalyst for degrading VOCs waste gas in this embodiment comprises the following steps:

[0065] 1) Weigh 0.34 g of ferric nitrate nonahydrate, 0.3 g of copper nitrate trihydrate, and 0.6 g of triethanolamine. First add triethanolamine into a beaker, then add iron salt and copper salt respectively, and stir for 5 minutes.

[0066] 2) Add 25.95 g of TAPOH (25%) to the beaker in step 1), stir for 10 min, then add 0.556 g of aluminum sulfate 18hydrate and stir evenly.

[0067] 3) Slowly add 17.337 g of ethyl orthosilicate into the beaker in step 2) using a dropper, and stir the mixed solution at 500 rpm at room temperature for 12 h.

[0068] 4) Place the mixed solution in step 3) into a 100 mL polytetrafluoroethylene liner and place the assembled hydrothermal autoclave in a 140°C oven for 48 h.

[0069] 5) Take out the sample in step 4), wash it with deionized water until it is neutral, and dry it in an oven at 80°C. Take out the dried sample and calcine it. The calcination conditions are: increase the temperature to 550°C at 2°C / min and keep the temperature constant for 6 hours.

[0070] 6) Stir the sample in step 5) and ammonium chloride solution (1 mol / L) in a ratio of 1:20, place in a water bath at 60°C and stir for 2 hours. After exchanging three times under this condition, place the sample in an oven at 80°C to dry.

[0071] 7) The sample in step 6) was taken out and calcined. The calcination conditions were: increasing the temperature to 500°C at 2°C / min and keeping the temperature constant for 5 hours. Finally, a Fe-Cu (mass ratio of 1:1.5) composite catalyst was obtained.

[0072] Comparative Example

[0073] This example provides a method for preparing a Cu catalyst, comprising the following steps:

[0074] 1) Weigh 0.3 g of copper nitrate trihydrate and 0.6 g of triethanolamine. First add triethanolamine into a beaker, then add copper salt, and stir for 5 minutes.

[0075] 2) Add 25.95 g of TAPOH (25%) to the beaker in step 1), stir for 10 min, then add 0.556 g of aluminum sulfate 18hydrate and stir evenly.

[0076] 3) Slowly add 17.337 g of ethyl orthosilicate into the beaker in step 2) using a dropper, and stir the mixed solution at 500 rpm at room temperature for 12 h.

[0077] 4) Place the mixed solution in step 3) into a 100 mL polytetrafluoroethylene liner and place the assembled hydrothermal autoclave in a 140°C oven for 48 h.

[0078] 5) Take out the sample in step 4), wash it with deionized water until it is neutral, and dry it in an oven at 80°C. Take out the dried sample and calcine it. The calcination conditions are: increase the temperature to 550°C at 2°C / min and keep the temperature constant for 6 hours.

[0079] 6) Stir the sample in step 5) and ammonium chloride solution (1 mol / L) in a ratio of 1:20, place in a water bath at 60°C and stir for 2 hours. After exchanging three times under this condition, place the sample in an oven at 80°C to dry.

[0080] 7) Take out the sample in step 6) and calcine it. The calcination conditions are: increase the temperature to 500°C at 2°C / min and keep the temperature constant for 5h. Finally, a Cu-based catalyst with a mass fraction of 1% is obtained. Example 4

[0081] The preparation method of the Fe-Cu composite catalyst for degrading VOCs waste gas in this embodiment comprises the following steps:

[0082] 1) Weigh 0.2 g of ferric nitrate nonahydrate, 0.25 g of copper nitrate trihydrate, and 0.3 g of triethylenetetramine. First add triethanolamine into a beaker, then add iron salt and copper salt respectively, and stir for 5 minutes.

[0083] 2) Add 25.95 g of TAPOH (25%) to the beaker in step 1), stir for 10 min, then add 0.556 g of aluminum sulfate 18hydrate and stir evenly.

[0084] 3) Slowly add 17.337 g of ethyl orthosilicate into the beaker in step 2) using a dropper, and stir the mixed solution at 500 rpm at room temperature for 12 h.

[0085] 4) Place the mixed solution in step 3) into a 100 mL polytetrafluoroethylene liner and place the assembled hydrothermal autoclave in a 140°C oven for 48 h.

[0086] 5) Take out the sample in step 4), wash it with deionized water until it is neutral, and dry it in an oven at 80°C. Take out the dried sample and calcine it. The calcination conditions are: increase the temperature to 550°C at 2°C / min and keep the temperature constant for 6 hours.

[0087] 6) Stir the sample in step 5) and ammonium chloride solution (1 mol / L) in a ratio of 1:20, place in a water bath at 60°C and stir for 2 hours. After exchanging three times under this condition, place the sample in an oven at 80°C to dry.

[0088] 7) The sample in step 6) was taken out and calcined. The calcination conditions were: increasing the temperature to 500°C at 2°C / min and keeping the temperature constant for 5 hours. Finally, a Fe-Cu (mass ratio of 0.4:2) composite catalyst was obtained. Example 5

[0089] The preparation method of the Fe-Cu composite catalyst for degrading VOCs waste gas in this embodiment comprises the following steps:

[0090] 1) Weigh 0.2 g of ferric nitrate nonahydrate, 0.2 g of copper nitrate trihydrate, and 0.2 g of isopropanolamine. First add triethanolamine into a beaker, then add iron salt and copper salt respectively, and stir for 5 minutes.

[0091] 2) Add 25.95 g of TAPOH (25%) to the beaker in step 1), stir for 10 min, then add 0.556 g of aluminum sulfate 18hydrate and stir evenly.

[0092] 3) Slowly add 17.337 g of ethyl orthosilicate into the beaker in step 2) using a dropper, and stir the mixed solution at 500 rpm at room temperature for 12 h.

[0093] 4) Place the mixed solution in step 3) into a 100 mL polytetrafluoroethylene liner and place the assembled hydrothermal autoclave in a 140°C oven for 48 h.

[0094] 5) Take out the sample in step 4), wash it with deionized water until it is neutral, and dry it in an oven at 80°C. Take out the dried sample and calcine it. The calcination conditions are: increase the temperature to 550°C at 2°C / min and keep the temperature constant for 6 hours.

[0095] 6) Stir the sample in step 5) and ammonium chloride solution (1 mol / L) in a ratio of 1:20, place in a water bath at 60°C and stir for 2 hours. After exchanging three times under this condition, place the sample in an oven at 80°C to dry.

[0096] 7) The sample in step 6) was taken out and calcined. The calcination conditions were: increasing the temperature to 500°C at 2°C / min and keeping the temperature constant for 5 hours. Finally, a Fe-Cu (mass ratio of 0.6:1.5) composite catalyst was obtained. Example 6

[0097] The preparation method of the Fe-Cu composite catalyst for degrading VOCs waste gas in this embodiment comprises the following steps:

[0098] 1) Weigh 0.1 g of ferric nitrate nonahydrate, 0.3 g of copper nitrate trihydrate, and 0.4 g of triethanolamine phosphate. First add triethanolamine into a beaker, then add iron salt and copper salt respectively, and stir for 5 minutes.

[0099] 2) Add 25.95 g of TAPOH (25%) to the beaker in step 1), stir for 10 min, then add 0.556 g of aluminum sulfate 18hydrate and stir evenly.

[0100] 3) Slowly add 17.337 g of ethyl orthosilicate into the beaker in step 2) using a dropper, and stir the mixed solution at 500 rpm at room temperature for 12 h.

[0101] 4) Place the mixed solution in step 3) into a 100 mL polytetrafluoroethylene liner and place the assembled hydrothermal autoclave in a 140°C oven for 48 h.

[0102] 5) Take out the sample in step 4), wash it with deionized water until it is neutral, and dry it in an oven at 80°C. Take out the dried sample and calcine it. The calcination conditions are: increase the temperature to 550°C at 2°C / min and keep the temperature constant for 6 hours.

[0103] 6) Stir the sample in step 5) and ammonium chloride solution (1 mol / L) in a ratio of 1:20, place in a water bath at 60°C and stir for 2 hours. After exchanging three times under this condition, place the sample in an oven at 80°C to dry.

[0104] 7) The sample in step 6) was taken out and calcined. The calcination conditions were: increasing the temperature to 500°C at 2°C / min and maintaining the temperature for 5 hours. Finally, a Fe-Cu (mass ratio of 0.3:1.9) composite catalyst was obtained. Example 7

[0105] The preparation method of the Fe-Cu composite catalyst for degrading VOCs waste gas in this embodiment comprises the following steps:

[0106] 1) Weigh 0.4 g of ferric nitrate nonahydrate, 0.15 g of copper nitrate trihydrate, and 0.4 g of triethylenetetramine. First add triethanolamine into a beaker, then add iron salt and copper salt respectively, and stir for 5 minutes.

[0107] 2) Add 25.95 g of TAPOH (25%) to the beaker in step 1), stir for 10 min, then add 0.556 g of aluminum sulfate 18hydrate and stir evenly.

[0108] 3) Slowly add 17.337 g of ethyl orthosilicate into the beaker in step 2) using a dropper, and stir the mixed solution at 500 rpm at room temperature for 12 h.

[0109] 4) Place the mixed solution in step 3) into a 100 mL polytetrafluoroethylene liner and place the assembled hydrothermal autoclave in a 140°C oven for 48 h.

[0110] 5) Take out the sample in step 4), wash it with deionized water until it is neutral, and dry it in an oven at 80°C. Take out the dried sample and calcine it. The calcination conditions are: increase the temperature to 550°C at 2°C / min and keep the temperature constant for 6 hours.

[0111] 6) Stir the sample in step 5) and ammonium chloride solution (1 mol / L) in a ratio of 1:20, place in a water bath at 60°C and stir for 2 hours. After exchanging three times under this condition, place the sample in an oven at 80°C to dry.

[0112] 7) The sample in step 6) was taken out and calcined. The calcination conditions were: increasing the temperature to 500°C at 2°C / min and keeping the temperature constant for 5 hours. Finally, a Fe-Cu (mass ratio of 1.5:0.78) composite catalyst was obtained.

[0113] Performance Test:

[0114] In this example, toluene and propylene are used as examples to simulate the degradation effect of the Fe-Cu composite catalyst prepared by the present invention on VOCs.

[0115] The test method is: take 50 mg of the catalysts obtained in Examples 1-3 and Comparative Examples, respectively, and place them in a quartz tube in a continuous flow fixed bed reactor, and fix them with quartz wool. Use Pano chromatography to continuously detect the concentration of toluene or propylene at the inlet and outlet of the quartz tube. The concentration of toluene or propylene at the inlet and outlet of the quartz tube is also the concentration before and after degradation of toluene or propylene. The degradation rate of toluene or propylene can be obtained by calculating the concentration before and after degradation of toluene or propylene. The composition of the reaction gas is:

[0116] The toluene feed gas is 1000ppm toluene, 21% oxygen and 79% nitrogen, and the propylene feed gas is 10000ppm propylene, 21% oxygen and 79% nitrogen, with nitrogen as the carrier gas. The flow rate of the reaction gas is 20mL / min, and the space velocity is 24000h -1 The activity evaluation temperature is 180~410℃. The conversion rate of toluene or propylene catalytic oxidation by the catalyst at different temperatures is shown in Figure 1 and Figure 2 As shown in the figure, the specific oxidation indexes (T 50 and T 90 ) and BET values ​​are shown in Table 1.

[0117] Table 1 Degradation rate of toluene by Fe-Cu composite catalyst and pore structure data of catalyst

[0118]

[0119] In the table, T 50 Represents the temperature point at which the conversion rate is 50%, T 90 Represents the temperature point at which the conversion rate is 90%, S BET represents the specific surface area, S mic represents the micropore specific surface area, S ext represents the external specific surface area, V mic represents the micropore volume, V mes represents the mesopore volume.

[0120] from Figure 1 and Figure 2It can be seen that the Fe-Cu composite catalysts obtained from Examples 1-7 and the comparative examples have low catalytic activity at low temperatures (below 250°C), but the catalytic activity of Examples 1-7 is significantly improved at 275°C, and the degradation rate of toluene is greater than 90% when the temperature reaches 307°C. The subsequent increase in temperature has no obvious effect on the catalytic activity. The conversion rate of toluene in Examples 1-6 is maintained at 97-98%, which is significantly higher than that of the comparative example. The activity of the Fe-Cu composite catalyst obtained in Example 1 is significantly higher than that of the Fe-Cu composite catalysts obtained in Examples 2-7 at 307°C.

[0121] In addition, it can be seen from Table 1 that the BET test data of the Fe-Cu composite catalyst obtained in Example 1 has the largest specific surface area and pore volume among all the examples, which is beneficial to the contact between the organic waste gas and the active components and improves the degradation rate.

[0122] from Figure 3 It can be seen that the Fe-Cu composite catalysts obtained from Examples 1-3 and the comparative examples have low catalytic activity at low temperatures (below 330°C), but the catalytic activity is significantly improved at 330°C, exceeding 95%, and the subsequent increase in temperature has no obvious effect on the catalytic activity, and the conversion rate of propylene is maintained at 95-99%. The activity of the Fe-Cu composite catalyst obtained in Example 1 is significantly higher than that of the Fe-Cu composite catalysts obtained in Examples 2-4 at 290°C.

[0123] from Figure 4 The redox performance of the catalyst can be seen in Figure 1. Among all the examples, Example 1 has the lowest temperature H2 reduction peak (248°C), indicating that this example has excellent redox ability and is conducive to the oxidation of VOC molecules in the reaction.

Claims

1. A Fe-Cu composite heteroatom molecular sieve catalyst, characterized in that: The catalyst is prepared by amine complexation, wherein the mass ratio of Fe:Cu is 0.2-1.5:0.2-2, and the specific surface area of ​​the Fe-Cu composite heteroatom molecular sieve catalyst is 389.00-552.21 m 2 ·g -1 ; The preparation method of the Fe-Cu composite heteroatom molecular sieve catalyst comprises the following steps: 1) Mix the amine complexing agent, copper nitrate trihydrate and ferric nitrate nonahydrate in a beaker and stir for a while until they are uniform; The amine complexing agent is one of triethanolamine, triethylenetetramine, isopropanolamine and triethanolamine phosphate; 2) adding a molecular sieve template to the mixture stirred evenly in step 1) and stirring evenly; The molecular sieve template is one of tetrapropylammonium hydroxide, tetrapropylammonium bromide and tetraethylammonium hydroxide, and the mass concentration of the template is 20-40%; 3) adding aluminum sulfate 18hydrate to the mixture of step 2) and stirring evenly; 4) Slowly add ethyl orthosilicate to the mixture in step 3) with a dropper while stirring, and stir evenly; 5) stirring the mixture in step 4) at room temperature overnight; 6) placing the mixture in step 5) into a polytetrafluoroethylene liner and installing a hydrothermal autoclave, and then placing it into an oven for crystallization; 7) washing the catalyst after crystallization in step 6) to neutrality, centrifuging and drying, and then placing it in a muffle furnace for calcination; 8) Mixing and stirring the sample calcined in step 7) with the prepared ammonium chloride solution, and heating and exchanging in a water bath, centrifuging and drying the sample after multiple exchanges, and placing the dried sample in a muffle furnace for calcination to finally obtain a Fe-Cu composite heteroatom molecular sieve catalyst; The proportions of the raw materials used are as follows: the molar ratio of tetraethyl orthosilicate, amine complexing agent and metal source is 50-150:1-5:1-3; the mass ratio of tetraethyl orthosilicate to template agent is 10-25:15-30; the mass ratio of tetraethyl orthosilicate to aluminum sulfate 18hydrate is 10-25:0.1-2.

2. A method for preparing the Fe-Cu composite heteroatom molecular sieve catalyst according to claim 1, characterized in that The following steps are involved: 1) Mix the amine complexing agent, copper nitrate trihydrate and ferric nitrate nonahydrate in a beaker and stir for a while until they are uniform; The amine complexing agent is one of triethanolamine, triethylenetetramine, isopropanolamine and triethanolamine phosphate; 2) adding a molecular sieve template to the mixture stirred evenly in step 1) and stirring evenly; The molecular sieve template is one of tetrapropylammonium hydroxide, tetrapropylammonium bromide and tetraethylammonium hydroxide, and the mass concentration of the template is 20-40%; 3) adding aluminum sulfate 18hydrate to the mixture of step 2) and stirring evenly; 4) Slowly add ethyl orthosilicate to the mixture in step 3) with a dropper while stirring, and stir evenly; 5) stirring the mixture in step 4) at room temperature overnight; 6) placing the mixture in step 5) into a polytetrafluoroethylene liner and installing a hydrothermal autoclave, and then placing it into an oven for crystallization; 7) washing the catalyst after crystallization in step 6) to neutrality, centrifuging and drying, and then placing it in a muffle furnace for calcination; 8) Mixing and stirring the sample calcined in step 7) with the prepared ammonium chloride solution, and heating and exchanging in a water bath, centrifuging and drying the sample after multiple exchanges, and placing the dried sample in a muffle furnace for calcination to finally obtain a Fe-Cu composite heteroatom molecular sieve catalyst; The proportions of the raw materials used are as follows: the molar ratio of tetraethyl orthosilicate, amine complexing agent and metal source is 50-150:1-5:1-3, the mass ratio of Fe:Cu is 0.2-1.5:0.2-2; the mass ratio of tetraethyl orthosilicate and template agent is 10-25:15-30; the mass ratio of tetraethyl orthosilicate and aluminum sulfate 18hydrate is 10-25:0.1-2.

3. The method for preparing the Fe-Cu composite heteroatom molecular sieve catalyst according to claim 2, characterized in that: In step 1), the mass ratio of Fe:Cu is 0.2-0.8:0.3-1.5; the mixing and stirring time is 5-10 minutes, until all metal salt particles change color.

4. The method for preparing the Fe-Cu composite heteroatom molecular sieve catalyst according to claim 2, characterized in that: The stirring time in step 2) is 10-20 min; the stirring speed in step 3) is 300-700 rpm.

5. The method for preparing the Fe-Cu composite heteroatom molecular sieve catalyst according to claim 2, characterized in that: In step 4), when ethyl orthosilicate is added dropwise to the mixture in step 3), the speed is lower than 2 mL / min.

6. The method for preparing the Fe-Cu composite heteroatom molecular sieve catalyst according to claim 2, characterized in that: The overnight temperature in step 5) is maintained at 20-30°C for 12-24 hours.

7. The method for preparing the Fe-Cu composite heteroatom molecular sieve catalyst according to claim 2, characterized in that: In step 6), the oven temperature is 120-180° C. and the crystallization time is 24-72 hours.

8. The method for preparing the Fe-Cu composite heteroatom molecular sieve catalyst according to claim 2, characterized in that: Deionized water or distilled water is used for the washing process in step 7), the drying temperature is 60-90°C, the heating rate during the roasting process is 2-4°C / min, from room temperature to 400-550°C, and the constant temperature time is 4h-6h.

9. The method for preparing the Fe-Cu composite heteroatom molecular sieve catalyst according to claim 2, characterized in that: In step 8), the mass ratio of the calcined sample to the ammonium chloride solution is 1:10-1:20, and the concentration of the ammonium chloride solution is 0.5-1 mol / L.

10. Use of the Fe-Cu composite heteroatom molecular sieve catalyst according to claim 1 in degrading VOCs waste gas, characterized in that: The Fe-Cu composite heteroatom molecular sieve catalyst is placed in a fixed bed quartz tube reactor to catalyze the degradation reaction of organic waste gas. The reaction temperature of the degradation reaction is 150-450°C and the space velocity is 14000-36000h -1 .

Images