Hydrophobic manganese-based low-temperature denitration catalyst as well as preparation method and application thereof

Abstract

The invention relates to a preparation method of a hydrophobic manganese-based low-temperature denitration catalyst. According to the catalyst, a composite oxide of CeO2 and MnO2 is used as an active component, and polyacrylonitrile submicron fibers are used as a carrier; a mixed solution of carbon tetrachloride and gamma-aminopropyltriethoxysilane is used as a hydrothermal solution substrate, a mixed solution of ethyl acetate and gamma-aminopropyltriethoxysilane is used as a hydrothermal solution supernatant, and a hydrothermal-electrostatic spinning method is adopted for preparation; on the basis of the mass of the polyacrylonitrile submicron fiber carrier, the mass percentage of the active component is 10-20%, and the mass ratio of CeO2 to MnO2 in the active component is 1: (1-2). The catalyst not only can be used for catalytically reducing NO into N2 at low temperature, but also can be used for filtering particles in flue gas, has excellent water and sulfur poisoning resistance, and has relatively high economic value and wide market application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection catalytic materials, and particularly relates to a hydrophobic manganese-based low-temperature denitration catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of industrialization and urbanization, a large amount of flue gas pollutants emitted by industries such as steel and cement have become one of the main sources of atmospheric environmental pollution. The main pollutants in flue gas include particulate matter (PM), sulfur dioxide (SO2), and nitrogen oxides (NO x ). Among them, PM can cause respiratory diseases and cardiovascular diseases, SO2 can cause acid rain and smog, and NO x is an important precursor for the formation of photochemical smog and acid rain. Traditional flue gas purification technologies usually adopt a hierarchical treatment method, that is, a dust collector, a desulfurization device, and a denitration device are respectively used to remove PM, SO2, and NO x . This hierarchical treatment method has the following disadvantages: large floor area, high operating cost, limited efficiency, etc. In order to overcome the deficiencies of the traditional hierarchical treatment method, in recent years, the flue gas dust removal and denitration co-purification technology has received extensive attention and research. The flue gas dust removal and denitration co-purification technology has the advantages of high efficiency, energy saving, small floor area, etc., and is an important direction for the future development of flue gas purification technology. Therefore, developing a low-temperature catalyst that can simultaneously denitrate and remove dust is an important direction with practical significance and theoretical requirements.

[0003] A large number of patents at home and abroad have disclosed various types of denitration catalysts and their preparation processes. Patent CN105080586A discloses a SCR denitration catalyst for cement kiln flue gas, which uses titanium tungsten molybdenum powder as a carrier, vanadium oxide as an active component, and zinc oxide as an assistant. This catalyst is used at a relatively high flue gas temperature (200 - 280°C); Patent CN103861628A discloses a flue gas denitration catalyst resistant to poisoning by alkaline metal oxides, its preparation method and application, in which vanadium oxide and heteropolyacid are loaded on the carrier nano-titanium dioxide step by step, thereby preparing a denitration catalyst with better resistance to alkali metal poisoning; However, both of the above two patents use highly toxic vanadium oxide as the active component, which is prone to cause secondary pollution. Patent CN103230813A discloses a preparation method of a denitration catalyst resistant to alkali poisoning for cement kilns and Patent CN103263913A discloses a preparation method of a denitration catalyst with high specific surface area and resistant to alkali poisoning for cement kilns, both of which use manganese cerium as the active component, and the denitration activity of the catalyst is high and the ability to resist alkali metal poisoning is strong; Patent CN103537279A discloses a low-temperature denitration catalyst with added assistant and its preparation method, which uses titanium-silicon composite oxide as the carrier, manganese oxide as the active component, and metal oxides such as cerium and nickel as assistants. This catalyst has high denitration activity and strong ability to resist alkali metal poisoning; However, the ability of the manganese active component in the above patents to resist the influence of water is not strong, and the catalyst is prone to hydrolysis, corrosion or collapse in a complex atmosphere containing water vapor and SO2, which is not conducive to the practical application of the catalyst. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a hydrophobic manganese-based low-temperature denitration catalyst, its preparation method and application, which are used to improve the performance of the manganese-based denitration catalyst in resisting water and sulfur poisoning during the process of flue gas dust removal and denitration.

[0005] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0006] The present invention provides a preparation method of a hydrophobic manganese-based low-temperature denitration catalyst. The catalyst uses a composite oxide of CeO2 and MnO2 as the active component and polyacrylonitrile submicron fiber as the carrier; a mixed solution of carbon tetrachloride and γ-aminopropyltriethoxysilane is used as the hydrothermal liquid base, and a mixed solution of ethyl acetate and γ-aminopropyltriethoxysilane is used as the upper layer of the hydrothermal liquid, and it is prepared by a hydrothermal-electrospinning method; based on the mass of the polyacrylonitrile submicron fiber carrier, the mass percentage content of the active component is 10 - 20%, and the mass ratio of CeO2 to MnO2 in the active component is 1:(1 - 2); the preparation method of the catalyst specifically includes the following steps:

[0007] (1) Weigh carbon tetrachloride and γ-aminopropyltriethoxysilane and mix them evenly to obtain a hydrothermal liquid substrate, which is placed in a hydrothermal reaction kettle. Then, weigh cerium salt, manganese salt, morphology control agent, and deionized water and mix them evenly to obtain an active component precursor solution. The active component precursor solution is guided into the hydrothermal reaction kettle through a glass rod. Weigh ethyl acetate and γ-aminopropyltriethoxysilane and mix them evenly to obtain an upper layer solution of the hydrothermal liquid, and the upper layer solution of the hydrothermal liquid is guided into the hydrothermal reaction kettle through a glass rod. After a three-layer solution of hydrothermal liquid substrate - active component precursor solution - upper layer solution of the hydrothermal liquid is formed in the hydrothermal reaction kettle, it is placed in an oven for hydrothermal reaction to obtain active component powder;

[0008] (2) Weigh N,N-dimethylformamide and polyacrylonitrile and stir and mix them to form a spinning dope. Then, add the active component powder prepared in step (1) into the spinning dope and continue to stir to obtain a spinning solution; the spinning solution is subjected to microfluidic electrospinning to obtain a hydrophobic manganese-based low-temperature denitration catalyst loaded with the active component.

[0009] Preferably, in step (1), the cerium salt is cerium nitrate hexahydrate and / or cerium chloride hexahydrate.

[0010] Preferably, the manganese salt is manganese nitrate hexahydrate and / or manganese chloride.

[0011] Preferably, the morphology control agent is tetrabutylammonium bromide.

[0012] Preferably, the mass ratio of the cerium salt, the morphology control agent, and the deionized water is 1:(0.5 - 1.0):(40 - 60).

[0013] Preferably, in the hydrothermal reaction of step (1), the mass ratio of carbon tetrachloride to γ-aminopropyltriethoxysilane is 1:(0.1 - 0.2).

[0014] Preferably, in the hydrothermal reaction of step (1), the mass ratio of ethyl acetate to γ-aminopropyltriethoxysilane is 1:(0.1 - 0.2).

[0015] Preferably, in step (1), the mass ratio of the hydrothermal liquid substrate, the active component precursor solution, and the upper layer solution of the hydrothermal liquid is (0.2 - 0.4):1:(0.3 - 0.5).

[0016] Preferably, in step (2), the mass ratio of N,N-dimethylformamide to polyacrylonitrile is (9 - 10):1.

[0017] Preferably, in step (2), the electrospinning is carried out in a microfluidic electrospinning integrated machine.

[0018] Preferably, in the step (2), the temperature of the electrospinning is 20-35 °C.

[0019] Preferably, in the step (2), the spinning voltage of the electrospinning is 15-25 kV.

[0020] Preferably, in the step (2), the injection rate of the syringe for the electrospinning is 0.5-1.5 mL / h.

[0021] Preferably, in the step (1), the temperature of the hydrothermal reaction is 160-180 °C.

[0022] Preferably, in the step (1), the time of the hydrothermal reaction is 4-8 h.

[0023] Preferably, in the step (1), after the hydrothermal reaction, filtration and drying are further included.

[0024] Preferably, the temperature of the drying is 80-100 °C.

[0025] Preferably, the time of the drying is 6-12 h.

[0026] The present invention also provides a hydrophobic manganese-based low-temperature denitration catalyst, which is prepared by using the preparation method of the hydrophobic manganese-based low-temperature denitration catalyst described in any one of the foregoing.

[0027] The present invention also provides a flue gas denitration method, which uses the foregoing hydrophobic manganese-based low-temperature denitration catalyst to perform denitration treatment on the flue gas.

[0028] Due to the adoption of the above technical solutions, the present invention has the following advantages compared with the prior art:

[0029] (1) For the catalyst of the present invention, the composite oxide nanoparticles of hydrophobic CeO2 and MnO2 are used as the active components, which not only endows the catalyst with excellent SCR denitration effect, but also can avoid excessive contact between the active components and water molecules at low temperature, reduce the competitive adsorption of reaction molecules and water molecules on the catalyst surface, and thus improve the low-temperature water resistance of the catalyst.

[0030] (2) The catalyst of the present invention adopts a hydrothermal reaction of a three-layer solution of a hydrothermal liquid substrate - an active component precursor solution - an upper layer solution of the hydrothermal liquid, which can enable the active components to be surface-modified by γ-aminopropyltriethoxysilane in two ways, namely hydrolysis reaction and surface cross-linking, during the preparation process, further improving the hydrophobicity of the active components.

[0031] (3) The present invention uses polyacrylonitrile submicron fibers as the carrier, which can cooperate with dust removal during the catalytic denitration process of the active components, enabling the catalyst to have the function of simultaneous dust removal and denitration.

[0032] (4) The catalyst of the present invention can not only catalytically reduce NO to N2 at low temperatures, but also filter particles in flue gas, and at the same time has excellent resistance to water and sulfur poisoning.

[0033] (5) The preparation raw materials of the catalyst of the present invention are easy to obtain, the process is simple, the pollutant removal efficiency is high, and it has high economic value and broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a field emission scanning electron microscope picture of the catalyst active component powder prepared in Example 1.

[0035] Figure 2 It is a field emission scanning electron microscope picture of the catalyst active component powder prepared in Comparative Example 1.

[0036] Figure 3 It is a NO removal efficiency diagram of the catalysts prepared in Examples 1-2 and Comparative Example 1.

[0037] Figure 4 It is an anti-water and sulfur poisoning activity diagram of the catalysts prepared in Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0038] For the convenience of understanding the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the understanding of the disclosure of the present invention is more thorough and comprehensive.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0040] The present invention provides a method for preparing a hydrophobic manganese-based low-temperature denitration catalyst. The catalyst uses a composite oxide of CeO2 and MnO2 as the active component and polyacrylonitrile submicron fibers as the carrier; a mixed solution of carbon tetrachloride and γ-aminopropyltriethoxysilane is used as the hydrothermal liquid base, and a mixed solution of ethyl acetate and γ-aminopropyltriethoxysilane is used as the upper layer of the hydrothermal liquid, and is prepared by a hydrothermal-electrospinning method; based on the mass of the polyacrylonitrile submicron fiber carrier, the mass percentage content of the active component is 10-20%, and the mass ratio of CeO2 to MnO2 in the active component is 1:(1-2); the preparation method of the catalyst specifically includes the following steps:

[0041] (1) Weigh carbon tetrachloride and γ-aminopropyltriethoxysilane and mix them evenly to obtain a hydrothermal liquid substrate, which is placed in a hydrothermal reaction kettle. Then, weigh cerium salt, manganese salt, morphology control agent, and deionized water and mix them evenly to obtain an active component precursor solution. The active component precursor solution is guided into the hydrothermal reaction kettle through a glass rod. Weigh ethyl acetate and γ-aminopropyltriethoxysilane and mix them evenly to obtain an upper layer solution of the hydrothermal liquid. The upper layer solution of the hydrothermal liquid is guided into the hydrothermal reaction kettle through a glass rod. After a three-layer solution of hydrothermal liquid substrate - active component precursor solution - upper layer solution of the hydrothermal liquid is formed in the hydrothermal reaction kettle, it is placed in an oven for hydrothermal reaction to obtain active component powder;

[0042] (2) Weigh N,N-dimethylformamide and polyacrylonitrile and stir to mix them to form a spinning dope. Then, add the active component powder prepared in step (1) to the spinning dope and continue to stir to obtain a spinning solution; The spinning solution is subjected to microfluidic electrospinning to obtain a hydrophobic manganese-based low-temperature denitration catalyst loaded with active components.

[0043] In some embodiments, in step (1), the cerium salt is cerium nitrate hexahydrate and / or cerium chloride hexahydrate.

[0044] In some embodiments, in step (1), the manganese salt is manganese nitrate hexahydrate and / or manganese chloride.

[0045] In some embodiments, in step (1), the morphology control agent is tetrabutylammonium bromide.

[0046] In some embodiments, in step (1), the mass ratio of the cerium salt, the morphology control agent, and the deionized water is 1:(0.5 - 1.0):(40 - 60).

[0047] In some embodiments, in the hydrothermal reaction of step (1), the mass ratio of carbon tetrachloride to γ-aminopropyltriethoxysilane is 1:(0.1 - 0.2), such as 1:0.10, 1:0.11, 1:0.12, 1:0.13, 1:0.14, 1:0.15, 1:0.16, 1:0.17, 1:0.18, 1:0.19, or 1:0.20, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0048] In some embodiments, in the hydrothermal reaction of step (1), the mass ratio of ethyl acetate to γ-aminopropyltriethoxysilane is 1:(0.1 - 0.2), such as 1:0.10, 1:0.11, 1:0.12, 1:0.13, 1:0.14, 1:0.15, 1:0.16, 1:0.17, 1:0.18, 1:0.19 or 1:0.20, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0049] In some embodiments, in step (1), the mass ratio of the hydrothermal liquid substrate, the active component precursor solution and the upper layer of the hydrothermal liquid is (0.2 - 0.4):1:(0.3 - 0.5).

[0050] In some embodiments, in step (2), the mass ratio of N,N-dimethylformamide to polyacrylonitrile is (9 - 10):1, such as 9:1, 9.1:1, 9.2:1, 9.3:1, 9.4:1, 9.5:1, 9.6:1, 9.7:1, 9.8:1, 9.9:1 or 10:1, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0051] In some embodiments, in step (2), the electrospinning is carried out in a microfluidic electrospinning integrated machine.

[0052] In some embodiments, in step (2), the temperature of the electrospinning is 20 - 35°C, such as 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C or 35°C, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0053] In some embodiments, in step (2), the spinning voltage of the electrospinning is 15 - 25 kV, such as 15 kV, 16 kV, 17 kV, 18 kV, 19 kV, 20 kV, 21 kV, 22 kV, 23 kV, 24 kV or 25 kV, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0054] In some embodiments, in step (2), the injection rate of the electrospinning is 0.5 to 1.5 mL / h, such as 0.5 mL / h, 0.6 mL / h, 0.7 mL / h, 0.8 mL / h, 0.9 mL / h, 1.0 mL / h, 1.1 mL / h, 1.2 mL / h, 1.3 mL / h, 1.4 mL / h, or 1.5 mL / h, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0055] In some embodiments, in step (1), the temperature of the hydrothermal reaction is 160 to 180 °C, such as 160 °C, 165 °C, 170 °C, 175 °C, or 180 °C, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0056] In some embodiments, in step (1), the time of the hydrothermal reaction is 4 to 8 h, such as 4 h, 5 h, 6 h, 7 h, or 8 h, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0057] In some embodiments, after the hydrothermal reaction in step (1), filtration and drying are further included.

[0058] In some embodiments, the temperature of the drying is 80 to 100 °C, such as 80 °C, 85 °C, 90 °C, 95 °C, or 100 °C, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0059] In some embodiments, the time of the drying is 6 to 12 h, such as 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, or 12 h, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0060] The present invention specifically adopts a hydrothermal reaction of a three-layer solution of a hydrothermal liquid substrate - an active component precursor solution - an upper hydrothermal liquid layer. During the formation of the composite oxide of CeO2 and MnO2, γ-aminopropyltriethoxysilane in the hydrothermal liquid substrate and the upper hydrothermal liquid layer can be used to modify the surface of the composite oxide. γ-aminopropyltriethoxysilane is connected to the composite oxide through hydrogen bonds, so that a hydrophobic structure is formed on the surface of the active component of the composite oxide. At the same time, the hydrolysis reaction of γ-aminopropyltriethoxysilane can be utilized, where the ethoxy group is hydrolyzed to silanol groups and the silanol groups undergo dehydration reactions to form Si-O-Si structures, thereby protecting the active sites of the composite oxide. Tetrabutylammonium bromide can promote the formation of sub-micron particles aggregated by nano-spherical particles of the active component of the composite oxide during the hydrothermal reaction, and a large number of micron-sized papillary structures are formed by the aggregation of nano-spherical particles. As a result, water molecules can only contact the top of the papillae and cannot enter the depressions between the papillae, ultimately improving the hydrophobic performance of the active component. Polyacrylonitrile sub-micron fibers themselves have a relatively high electronegativity and are prone to generating static electricity, while dust particles usually carry positive or negative charges, so they can be adsorbed by the electrostatic field generated by the polyacrylonitrile sub-micron fibers. In addition, during the actual application process, polyacrylonitrile sub-micron fibers can be made into fiber fabrics with a network structure. The relatively high porosity and specific surface area of the fiber fabrics can further intercept and filter dust; the active component is loaded on the polyacrylonitrile sub-micron fibers by electrospinning, so that the catalyst has a synergistic function of dust removal and denitrification.

[0061] The present invention also provides a hydrophobic manganese-based low-temperature denitrification catalyst, which is prepared by using the preparation method of the hydrophobic manganese-based low-temperature denitrification catalyst described in any one of the foregoing.

[0062] The present invention also provides a flue gas denitrification method, which uses the hydrophobic manganese-based low-temperature denitrification catalyst described above to perform denitrification treatment on flue gas.

[0063] In some embodiments, the flue gas denitrification method is applied to the denitrification of flue gas in the fixed source industry.

[0064] In some embodiments, the fixed source industry includes the sintering industry, the cement industry, and the chemical industry.

[0065] The following further explains and illustrates the present invention with specific examples.

[0066] To better understand the present invention, the content of the present invention is further clarified below with examples, but the content of the present invention is not limited to the following examples.

[0067] Example 1:

[0068] (1) Preparation of the active component powder

[0069] Weigh 9.823 g of carbon tetrachloride and 0.982 g of γ-aminopropyltriethoxysilane, mix them evenly to obtain a hydrothermal liquid substrate, and place it in a hydrothermal reaction kettle. Then weigh 0.631 g of cerium nitrate hexahydrate, 0.825 g of manganese nitrate hexahydrate, 0.316 g of tetrabutylammonium bromide, and 25.240 g of deionized water, mix them evenly to obtain an active component precursor solution, and pour the active component precursor solution into the hydrothermal reaction kettle through a glass rod. Weigh 7.367 g of ethyl acetate and 0.737 g of γ-aminopropyltriethoxysilane, mix them evenly to obtain the upper layer liquid of the hydrothermal liquid, and pour the upper layer liquid of the hydrothermal liquid into the hydrothermal reaction kettle through a glass rod. After a three-layer solution of hydrothermal liquid substrate-active component precursor solution-upper layer liquid of hydrothermal liquid is formed in the hydrothermal reaction kettle, place it in an oven and carry out hydrothermal reaction at 160 °C for 8 h. After the hydrothermal reaction is completed, filter and place it in an oven to dry at 80 °C for 12 h to obtain the active component powder (as Figure 1 shown).

[0070] (2) Preparation of catalyst

[0071] Weigh 45 g of N,N-dimethylformamide and 5 g of polyacrylonitrile, stir and mix them to form a spinning dope. Then add the active component powder prepared in step (1) into the spinning dope, continue to stir to form a spinning solution, and use a syringe to suck the spinning solution and carry out electrospinning on the spinning solution through a microfluidic electrospinning machine. The electrospinning voltage is 15 kV, and the injection rate of the syringe is 0.5 mL / h to obtain a catalyst loaded with the active component.

[0072] (3) Catalyst effect test

[0073] Take 0.5 g of the catalyst and place it in a quartz tube with an inner diameter of 6 mm. Place the quartz tube in a tube furnace and control the heating reaction temperature through the tube furnace. Simulate flue gas by laboratory gas mixing. Inlet gas components: NO (500 ppm), NH3 (500 ppm), O2 (11 vol.%), SO2 (200 ppm, used when needed), water vapor (5 vol.%, used when needed), and the rest is N2. The total gas flow rate is 500 mL / min. Use a Laoying 3021 portable carbon emission monitor to measure the concentrations of NO and SO2. The NO removal efficiency is 100% after 3 min at 140 °C (as Figure 3 shown), and the catalyst can still maintain 100% activity for 24 h without change when water vapor and SO2 are simultaneously introduced at 140 °C (as Figure 4 shown).

[0074] Example 2:

[0075] (1) Preparation of active component powder

[0076] Weigh 5.401 g of carbon tetrachloride and 1.080 g of γ-aminopropyltriethoxysilane, mix them evenly to obtain a hydrothermal liquid substrate, and place it in a hydrothermal reaction kettle. Then weigh 0.507 g of cerium chloride hexahydrate, 0.970 g of manganese chloride, 0.507 g of tetrabutylammonium bromide, and 30.420 g of deionized water, mix them evenly to obtain an active component precursor solution, and guide the active component precursor solution into the hydrothermal reaction kettle through a glass rod. Weigh 13.502 g of ethyl acetate and 2.700 g of γ-aminopropyltriethoxysilane, mix them evenly to obtain the upper layer liquid of the hydrothermal liquid, and guide the upper layer liquid of the hydrothermal liquid into the hydrothermal reaction kettle through a glass rod. After a three-layer solution of hydrothermal liquid substrate - active component precursor solution - upper layer liquid of hydrothermal liquid is formed in the hydrothermal reaction kettle, place it in an oven for hydrothermal reaction at 180 °C for 4 h. After the hydrothermal reaction is completed, filter and place it in an oven for drying at 100 °C for 6 h to obtain the active component powder.

[0077] (2) Preparation of the catalyst

[0078] Weigh 50 g of N,N-dimethylformamide and 5 g of polyacrylonitrile, stir and mix them to form a spinning dope. Then add the active component powder prepared in step (1) into the spinning dope and continue to stir to form a spinning solution. Use a syringe to suck the spinning solution and spin the spinning solution through a microfluidic electrospinning machine. The voltage for spinning is 25 kV, and the injection rate of the syringe is 1.5 mL / h to obtain a catalyst loaded with the active component.

[0079] (3) Catalyst effect test

[0080] Take 0.5 g of the catalyst and place it in a quartz tube with an inner diameter of 6 mm. Place the quartz tube in a tube furnace and control the heating reaction temperature through the tube furnace. Simulate flue gas by laboratory gas mixing. The inlet gas components are: NO (500 ppm), NH3 (500 ppm), O2 (11 vol.%), and the rest are N2. The total gas flow rate is 500 mL / min. Use a Laoying 3021 type portable carbon emission monitor to measure the concentrations of NO and SO2. The NO removal efficiency is 100% after 3 min at 140 °C (as Figure 3 shown).

[0081] Comparative example 1:

[0082] (1) Preparation of the active component powder

[0083] The difference from Example 1 is that the morphology control agent tetrabutylammonium bromide is replaced with 3% by mass of dilute hydrochloric acid to obtain the active component powder (as Figure 2 shown).

[0084] (2) Preparation of the catalyst

[0085] The same as Example 1.

[0086] (3) Catalyst effect test

[0087] Take 0.5 g of the catalyst and place it in a quartz tube with an inner diameter of 6 mm. Place the quartz tube in a tube furnace and control the heating reaction temperature through the tube furnace. The laboratory gas mixture is used to simulate flue gas. The inlet gas components are: NO (500 ppm), NH3 (500 ppm), O2 (11 vol.%), SO2 (200 ppm, when needed), water vapor (5 vol.%, when needed), and the rest is N2. The total gas flow rate is 500 mL / min. Use a Laoying 3021 portable carbon emission monitor to measure the concentrations of NO and SO2. The NO removal efficiency is 64% after 3 minutes at 140 °C (as Figure 3 shown), and the denitrification activity of the catalyst gradually decreases with time when water vapor and SO2 are simultaneously introduced at 140 °C (as Figure 4 shown).

[0088] Analysis:

[0089] Compared with Example 1, in Comparative Example 1, when preparing the active component powder in step (1), the morphology control agent tetrabutylammonium bromide was replaced with 3% by mass of dilute hydrochloric acid, and the catalyst would form a smooth nanosheet structure instead of a nanosphere structure with a papillary structure, resulting in a decrease in the contact probability between reaction molecules and the active sites on the catalyst surface and affecting the water and sulfur poisoning resistance performance of the catalyst. Therefore, the NO removal efficiency and water and sulfur poisoning resistance performance of the catalyst decreased significantly.

[0090] It should be understood that the above embodiments are all exemplary and do not cover all possible implementation manners included in the claims. Without departing from the scope of the present disclosure, various deformations and changes can be made on the basis of the above embodiments. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form additional embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments only represent several implementation manners of the present invention and do not limit the protection scope of the present invention patent.

Claims

1. A method for preparing a hydrophobic manganese-based low-temperature denitration catalyst, characterized in that: The catalyst uses a composite oxide of CeO2 and MnO2 as an active component and polyacrylonitrile submicron fiber as a carrier; a mixed solution of carbon tetrachloride and γ-aminopropyltriethoxysilane is used as a hydrothermal liquid base, and a mixed solution of ethyl acetate and γ-aminopropyltriethoxysilane is used as a hydrothermal liquid upper layer liquid, and is prepared by a hydrothermal-electrospinning method; based on the mass of the polyacrylonitrile submicron fiber carrier, the mass percentage of the active component is 10-20%, and the mass ratio of CeO2 to MnO2 in the active component is 1:(1-2); the preparation method of the catalyst specifically comprises the following steps: (1) Weighing carbon tetrachloride and γ-aminopropyltriethoxysilane, mixing them evenly to obtain a hydrothermal liquid base, placing them in a hydrothermal reactor, then weighing cerium salt, manganese salt, morphology control agent, and deionized water, mixing them evenly to obtain an active component precursor solution, guiding the active component precursor solution into the hydrothermal reactor by drainage with a glass rod, weighing ethyl acetate and γ-aminopropyltriethoxysilane, mixing them evenly to obtain a hydrothermal liquid upper layer liquid, guiding the hydrothermal liquid upper layer liquid into the hydrothermal reactor by drainage with a glass rod, and after a three-layer solution of hydrothermal liquid base-active component precursor solution-hydrothermal liquid upper layer liquid is formed in the hydrothermal reactor, placing it in an oven for hydrothermal reaction to obtain an active component powder; (2) Weighing N,N-dimethylformamide and polyacrylonitrile and stirring to form a spinning solution, then adding the active component powder prepared in step (1) to the spinning solution and continuing to stir to obtain a spinning solution; the spinning solution is subjected to microfluid electrospinning to obtain a hydrophobic manganese-based low-temperature denitration catalyst loaded with the active component.

2. The preparation method according to claim 1, characterized in that: In the step (1), the cerium salt is cerium nitrate hexahydrate and / or cerium chloride hexahydrate; Preferably, the manganese salt is manganese nitrate hexahydrate and / or manganous chloride; Preferably, the morphology control agent is tetrabutylammonium bromide; Preferably, the mass ratio of the cerium salt, the morphology control agent and the deionized water is 1:(0.5-1.0):(40-60).

3. The preparation method according to claim 1, characterized in that: In the hydrothermal reaction of step (1), the mass ratio of carbon tetrachloride to γ-aminopropyltriethoxysilane is 1:(0.1-0.2); Preferably, the mass ratio of the ethyl acetate to the γ-aminopropyltriethoxysilane is 1:(0.1-0.2).

4. The preparation method according to claim 3, characterized in that: In the step (1), the mass ratio of the hydrothermal liquid base, the active component precursor solution and the hydrothermal liquid upper layer liquid is (0.2-0.4):1:(0.3-0.5).

5. The preparation method according to claim 1, characterized in that: In the step (2), the mass ratio of the N,N-dimethylformamide to the polyacrylonitrile is (9-10):

1.

6. The preparation method according to claim 1, characterized in that: In the step (2), the electrospinning is carried out in a microfluidic electrospinning machine; Preferably, the electrospinning temperature is 20-35°C; Preferably, the electrospinning voltage is 15 to 25 kV; Preferably, the injection rate of the electrospinning syringe is 0.5-1.5 mL / h.

7. The preparation method according to claim 1, characterized in that: In the step (1), the temperature of the hydrothermal reaction is 160-180°C; Preferably, the hydrothermal reaction time is 4 to 8 hours.

8. The preparation method according to claim 1, characterized in that: In the step (1), after the hydrothermal reaction, filtering and drying are also included; Preferably, the drying temperature is 80-100°C; Preferably, the drying time is 6 to 12 hours.

9. A hydrophobic manganese-based low-temperature denitration catalyst, characterized in that: The catalyst is prepared by the method for preparing the hydrophobic manganese-based low-temperature denitration catalyst according to any one of claims 1 to 8.

10. A flue gas denitrification method, characterized in that: The hydrophobic manganese-based low-temperature denitration catalyst according to claim 9 is used to denitrate the flue gas.

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