A vanadium-based catalyst for plasma-assisted catalytic denitrification, its preparation method and application

Abstract

The present invention provides a vanadium-based catalyst for plasma-assisted catalytic denitrification, its preparation method and application, belonging to the technical field of catalytic materials. In the present invention, the formation of the TiO2 support and the loading of the active components V2O5 and MnO are completed in one step by a hydrothermal method. x Among them, the main body of the TiO2 support is amorphous, and a small amount is anatase crystal form. The catalyst as a whole presents a nano-spherical structure, and there are wrinkles on the surface layer, which promotes the increase of the specific surface area and further improves the catalytic activity. The active components V2O5 and MnO are loaded on the microporous TiO2 support by a hydrothermal method in one step. x By enhancing the internal discharge of the microporous structure of the catalyst, promoting the occurrence of the rapid SCR reaction, and the co-catalytic inhibition of ozone by γ-MnO2, the catalytic activity of the catalyst is improved and the active window is broadened.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic materials, and in particular to a vanadium-based catalyst for plasma-synergistic catalytic denitration, and a preparation method and application thereof. Background Art

[0002] Nitrogen oxides are one of the main air pollutants, which mainly come from combustion processes and industrial production processes.

[0003] NO x The most widely used technology is selective catalytic reduction (SCR), but the traditional SCR denitrification technology has harsh application conditions, with a reaction temperature of 300-350°C and a narrow reaction temperature window, which is not suitable for the treatment of non-steady-state and low-temperature flue gases in industrial boilers and industrial processes.

[0004] Plasma synergistic catalytic denitrification technology combines low-temperature plasma technology with selective catalytic reduction of NO x The combination of technologies may solve the problem of low-temperature and room-temperature NO x The problem of polluted gas purification provides technical support for the in-depth treatment of nitrogen oxide pollution in industrial boilers and industrial processes. However, this technology has not been widely used. Problems such as the activity and stability of the catalyst are technical difficulties that need to be overcome. The vanadium-titanium-based catalyst used in traditional SCR has good resistance to sulfur and water poisoning. Some scholars have introduced it into plasma synergistic catalytic denitrification, but its high activity energy density range is too narrow to be applied. Therefore, it is of great significance to broaden the activity window of vanadium-titanium-based SCR catalysts.

[0005] Therefore, how to broaden the activity window of vanadium-titanium-based SCR catalysts and improve the denitrification efficiency of vanadium-based catalysts has become a technical problem that needs to be urgently solved in this field. Summary of the invention

[0006] The object of the present invention is to provide a vanadium-based catalyst for plasma-synergistic catalytic denitrification, and a preparation method and application thereof. The vanadium-based catalyst provided by the present invention has a high denitrification efficiency under the synergistic effect of low-temperature plasma. At the same time, the vanadium-based catalyst has good sulfur and water resistance, overcoming the problems of narrow activity window and poor stability of SCR catalysts in the prior art.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a vanadium-based catalyst for plasma-synergistic catalytic denitration, comprising the following steps:

[0009] (1) mixing dodecylamine, butyl titanate and anhydrous ethanol to obtain a dodecylamine-butyl titanate-ethanol solution;

[0010] (2) Mix ammonium metavanadate, oxalic acid, manganese acetate tetrahydrate and water to obtain an active component precursor solution;

[0011] (3) Mix the active component precursor solution obtained in step (2) and the dodecylamine-titanium butoxide-ethanol solution obtained in step (1), carry out a hydrothermal reaction, and then successively carry out centrifugation, washing, drying and calcination to obtain a vanadium-based catalyst for plasma-assisted catalytic denitrification;

[0012] The preparations in step (1) and step (2) are not in a specific order.

[0013] Preferably, the way of mixing dodecylamine, titanium butoxide and absolute ethanol in step (1) is as follows:

[0014] 1) Mix dodecylamine and absolute ethanol to obtain a dodecylamine-ethanol solution;

[0015] 2) Mix titanium butoxide and absolute ethanol to obtain a titanium butoxide-ethanol solution;

[0016] 3) Mix the dodecylamine-ethanol solution obtained in step 1) and the titanium butoxide-ethanol solution obtained in step 2) to obtain a dodecylamine-titanium butoxide-ethanol solution;

[0017] The preparations in step 1) and step 2) are not in a specific order.

[0018] Preferably, the molar ratio of ammonium metavanadate to manganese acetate tetrahydrate in step (2) is (1-4):1, and the ratio of the amount of oxalic acid to the total amount of ammonium metavanadate and manganese acetate tetrahydrate is (0.5-2):1.

[0019] Preferably, the temperature of mixing in step (2) is 50-70 °C, and the mixing method is water bath heating.

[0020] Preferably, the temperature of the hydrothermal reaction in step (3) is 80-120 °C, and the time of the hydrothermal reaction is 15-24 h.

[0021] Preferably, the rotation speed of centrifugation in step (3) is 5000-7000 r / min, and the time of centrifugation is 5-10 min.

[0022] Preferably, the washing method in step (3) is: first wash with an ethanol-hydrochloric acid solution 2-3 times, and then wash with deionized water until neutral.

[0023] Preferably, the calcination temperature in step (3) is 400-550 °C, and the holding time of calcination is 3-5 h.

[0024] The present invention provides a vanadium-based catalyst for plasma-assisted catalytic denitrification prepared by the preparation method described in the above technical solution.

[0025] The present invention provides the application of the vanadium-based catalyst for plasma-assisted catalytic denitrification described in the above technical solution in plasma-assisted catalytic denitrification.

[0026] The present invention provides a preparation method of a vanadium-based catalyst for plasma-assisted catalytic denitrification, comprising the following steps: (1) mixing dodecylamine, tetrabutyl titanate and absolute ethanol to obtain a dodecylamine-tetrabutyl titanate-ethanol solution; (2) mixing ammonium metavanadate, oxalic acid, manganese acetate tetrahydrate and water to obtain an active component precursor solution; (3) mixing the active component precursor solution obtained in step (2) and the dodecylamine-tetrabutyl titanate-ethanol solution obtained in step (1), carrying out a hydrothermal reaction, and then successively carrying out centrifugation, washing, drying and calcination to obtain a vanadium-based catalyst for plasma-assisted catalytic denitrification; the preparations of step (1) and step (2) are not in a sequential order. The present invention prepares the catalyst by a hydrothermal method. By controlling the raw materials and preparation process parameters, the generation of the TiO 2 support and the loading of the active components V 2 O 5 and MnO x can be completed in one step. Among them, the TiO 2 support is mainly amorphous and a small amount is anatase crystal form. The vanadium-based catalyst (V 2 O 5 -MnO x / microporous TiO 2 catalyst) as a whole presents a nanospherical structure, and there are wrinkles on the surface layer, which promotes the improvement of the specific surface area and further improves the catalytic activity; by using a one-step hydrothermal method, the active components V 2 O 5 and MnO x are loaded on the microporous TiO 2 support. By enhancing the internal discharge of the microporous structure of the catalyst, promoting the occurrence of the fast SCR reaction, and the co-catalytic inhibition of ozone by γ-MnO 2 , the catalytic activity of the catalyst is improved and the active window is broadened. The results of the examples show that the vanadium-based catalyst provided by the present invention, under the synergistic action of low-temperature plasma, can promote the denitrification reaction based on the fast SCR mechanism, enabling the polluted gas containing NO x at normal temperature and pressure to maintain a denitrification efficiency of more than 90% in the range of an airspeed of 70000-80000 h -1 and an energy density of 262-504 J·L -1 . At the same time, the vanadium-based catalyst also has good sulfur and water resistance, overcoming the problems of narrow active window and poor stability of SCR catalysts in the prior art. Description of the Drawings

[0027] Figure 1 It is a schematic structural diagram of a coaxial cylindrical dielectric barrier discharge reactor provided by the present invention;

[0028] Figure 2 It is the catalytic activity curve of the vanadium-based catalyst for plasma-assisted catalytic denitrification obtained in Examples 1-4 of the present invention;

[0029] Figure 3 It is 4V prepared in Comparative Example 1 2 O 5 / TiO 2 The catalytic activity curve of the catalyst;

[0030] Figure 4 It is 4V prepared in Comparative Example 2 2 O 5 -4MnO x / TiO 2 The catalytic activity curve of the catalyst;

[0031] Figure 5 It is the sulfur and water resistance performance curve of the vanadium-based catalyst for plasma-assisted catalytic denitrification provided in Example 4 of the present invention;

[0032] Figure 6 It is the XRD patterns of the vanadium-based catalyst provided in Example 4 of the present invention, anatase TiO provided in Comparative Example 3 2 and microporous TiO provided in Comparative Example 4 2 ;

[0033] Figure 7 It is the N 2 isothermal adsorption and desorption curves of the vanadium-based catalyst provided in Example 4 of the present invention, anatase TiO provided in Comparative Example 3 2 and microporous TiO provided in Comparative Example 4; 2 ;

[0034] Figure 8 It is the SEM image of the vanadium-based catalyst provided in Example 4 of the present invention. Detailed Description of the Invention

[0035] The present invention provides a preparation method of a vanadium-based catalyst for plasma-assisted catalytic denitrification, comprising the following steps:

[0036] (1) Mix dodecylamine, tetrabutyl titanate and absolute ethanol to obtain a dodecylamine-tetrabutyl titanate-ethanol solution;

[0037] (2) Mix ammonium metavanadate, oxalic acid, manganese acetate tetrahydrate and water to obtain an active component precursor solution;

[0038] (3) Mix the active component precursor solution obtained in step (2) and the dodecylamine-titanium butoxide-ethanol solution obtained in step (1), conduct a hydrothermal reaction, and then perform centrifugation, washing, drying, and calcination in sequence to obtain a vanadium-based catalyst for plasma-assisted catalytic denitrification;

[0039] The preparations of step (1) and step (2) are not in a specific order.

[0040] In the present invention, unless otherwise specified, the raw materials used are commercially available products well-known to those skilled in the art.

[0041] In the present invention, dodecylamine, titanium butoxide, and absolute ethanol are mixed to obtain a dodecylamine-titanium butoxide-ethanol solution.

[0042] In the present invention, the volume ratio of dodecylamine to titanium butoxide is preferably (3 - 5):(6 - 10), more preferably (4 - 5):(7 - 9), and further preferably 4.5:7.5. By controlling the amounts of dodecylamine and titanium butoxide in the present invention, the surfactant is adsorbed on the surface of TiO 2 to prevent the agglomeration of TiO 2 and improve the morphology of the carrier, and it is easier to obtain spherical TiO 2 .

[0043] In the present invention, the preferred way to mix dodecylamine, titanium butoxide, and absolute ethanol is as follows:

[0044] 1) Mix dodecylamine and absolute ethanol to obtain a dodecylamine-ethanol solution;

[0045] 2) Mix titanium butoxide and absolute ethanol to obtain a titanium butoxide-ethanol solution;

[0046] 3) Mix the dodecylamine-ethanol solution obtained in step 1) and the titanium butoxide-ethanol solution obtained in step 2) to obtain a dodecylamine-titanium butoxide-ethanol solution;

[0047] The preparations of step 1) and step 2) are not in a specific order.

[0048] In the present invention, it is preferred to mix dodecylamine and absolute ethanol to obtain a dodecylamine-ethanol solution.

[0049] In the present invention, the volume ratio of dodecylamine to absolute ethanol is preferably (3 - 5):100, more preferably (4 - 5):100, and further preferably 4.5:100. There are no specific limitations on the specific operation of mixing dodecylamine and absolute ethanol in the present invention. Using the mixing operations well-known to those skilled in the art, it is sufficient to mix dodecylamine and absolute ethanol evenly.

[0050] The present invention preferably mixes tetrabutyl titanate and absolute ethanol to obtain a tetrabutyl titanate - ethanol solution.

[0051] In the present invention, the volume ratio of tetrabutyl titanate to absolute ethanol is preferably (6 - 10):100, more preferably (7 - 9):100, and further preferably 7.5:100. The present invention has no special limitation on the specific operation of mixing tetrabutyl titanate and absolute ethanol. Using the mixing operations well-known to those skilled in the art, it is only necessary to make tetrabutyl titanate and absolute ethanol mix evenly.

[0052] After obtaining the dodecylamine - ethanol solution and the tetrabutyl titanate - ethanol solution, the present invention preferably mixes the dodecylamine - ethanol solution and the tetrabutyl titanate - ethanol solution to obtain a dodecylamine - tetrabutyl titanate - ethanol solution.

[0053] In the present invention, the mixing method of the dodecylamine - ethanol solution and the tetrabutyl titanate - ethanol solution is preferably to add the tetrabutyl titanate - ethanol solution dropwise to the dodecylamine - ethanol solution and then stir. In the present invention, the stirring time is preferably 1 - 3 h, more preferably 2 h. The present invention has no special limitation on the stirring rate, which can be determined according to the common technical knowledge of those skilled in the art. By mixing in the above manner, the present invention can make tetrabutyl titanate and dodecylamine mix evenly in ethanol.

[0054] The present invention mixes ammonium metavanadate, oxalic acid, manganese acetate tetrahydrate and water to obtain an active component precursor solution.

[0055] In the present invention, the molar ratio of ammonium metavanadate to manganese acetate tetrahydrate is preferably (1 - 4):1, more preferably (1 - 3):1, and further preferably 1:1; the ratio of the amount of substance of oxalic acid to the sum of the amounts of substance of ammonium metavanadate and manganese acetate tetrahydrate is preferably (0.5 - 2):1, more preferably (1 - 1.5):1, and further preferably 1.5:1. By controlling the dosage relationship of ammonium metavanadate, oxalic acid and manganese acetate tetrahydrate, the purpose of the present invention is to promote the formation of the precursor solution, improve the vanadium - manganese element ratio of the catalyst, enhance the ability of the catalyst to inhibit ozone generation, and thus broaden the active window.

[0056] In the present invention, the water is preferably deionized water. In the present invention, the mass - to - volume ratio of ammonium metavanadate to water is preferably (0.05 - 0.1) g:100 mL, more preferably (0.07 - 0.09) g:100 mL. By controlling the above dosage relationship, the present invention can make the raw materials dissolve fully in water.

[0057] In the present invention, the temperature of the mixing is preferably 50 to 70 °C, more preferably 60 °C; the mixing method is preferably water bath heating. The present invention has no special limitation on the mixing time, which can be determined according to the common technical knowledge of those skilled in the art. By means of water bath heating, the present invention can promote the dissolution of raw materials in water, so that each component is uniformly mixed.

[0058] After obtaining the dodecylamine-titanium butoxide-ethanol solution and the active component precursor solution, the present invention mixes the active component precursor solution and the dodecylamine-titanium butoxide-ethanol solution and then performs a hydrothermal reaction, and then successively performs centrifugation, washing, drying and calcination to obtain a vanadium-based catalyst for plasma-assisted catalytic denitrification.

[0059] In the present invention, the mixing method of the active component precursor solution and the dodecylamine-titanium butoxide-ethanol solution is preferably to drop the active component precursor solution into the dodecylamine-titanium butoxide-ethanol solution and then stir. In the present invention, the stirring time is preferably 2 to 10 h, more preferably 4 to 8 h, and further preferably 5 to 6 h. The present invention has no special limitation on the stirring rate, which can be determined according to the common technical knowledge of those skilled in the art. By the above mixing method, the present invention can uniformly mix each component.

[0060] In the present invention, the temperature of the hydrothermal reaction is preferably 80 to 120 °C, more preferably 90 to 100 °C, and further preferably 90 °C; the time of the hydrothermal reaction is preferably 15 to 24 h, more preferably 18 to 20 h, and further preferably 20 h. In the present invention, the hydrothermal reaction is preferably carried out in a polytetrafluoroethylene inner liner reactor. Through the hydrothermal reaction, the present invention can obtain uniformly dispersed nano-scale TiO 2 , increasing the specific surface area and dispersibility of the catalyst.

[0061] In the present invention, the rotation speed of the centrifugation is preferably 5000 to 7000 r / min, more preferably 6000 r / min; the time of the centrifugation is preferably 5 to 10 min. The present invention can remove liquid impurities by centrifugation and leave the solid product after the reaction.

[0062] In the present invention, the washing method is preferably as follows: pickling with an ethanol-hydrochloric acid solution 2 to 3 times first, and then washing with deionized water until neutral. In the present invention, the pH value of the ethanol-hydrochloric acid solution is preferably 2 to 3; the amount of the ethanol-hydrochloric acid solution used for pickling is preferably 50 to 150 mL / g, more preferably 80 to 120 mL / g, and further preferably 100 mL / g; the time for each pickling is preferably 60 min. In the present invention, the amount of deionized water used for washing with deionized water is preferably 50 to 150 mL / g, more preferably 80 to 120 mL / g, and further preferably 100 mL / g; the time for washing with deionized water is preferably 30 min. By washing in the above manner, the present invention can remove residual absolute ethanol and impurities dissolved therein.

[0063] In the present invention, the drying temperature is preferably 60 to 105 °C, more preferably 70 to 90 °C, and further preferably 80 °C; the drying time is preferably 6 to 12 h, more preferably 8 to 10 h, and further preferably 8 h. By drying, the present invention can remove moisture, facilitating subsequent calcination.

[0064] In the present invention, the calcination temperature is preferably 400 to 550 °C, preferably 450 to 500 °C, and further preferably 500 °C; the holding time for calcination is 3 to 5 h, more preferably 3 to 4 h, and further preferably 3 h. By calcination, the present invention can convert ammonium metavanadate and manganese acetate in the precursor solution into V 2 O 5 and MnO x respectively, and at the same time burn out the surface impurities of TiO 2 , improving the purity of the catalyst.

[0065] The present invention uses a hydrothermal method to prepare the catalyst. By controlling the raw materials and preparation process parameters, the generation of the TiO 2 support and the loading of the active components V 2 O 5 and MnO x can be completed in one step. The main body of the TiO 2 support is amorphous, and a small amount is anatase crystal form. The V 2 O 5 -MnO x / microporous TiO 2 catalyst as a whole presents a nano-spherical structure, and there are wrinkles on the surface layer, which promotes the increase of the specific surface area and further improves the catalytic activity; using the one-step hydrothermal method to load the active components V 2 O 5 and MnO x on the microporous TiO 2On the carrier, by enhancing the internal discharge of the catalyst microporous structure, promoting the occurrence of the rapid SCR reaction, and γ-MnO 2 The co-catalysis inhibits the ozone effect, improves the catalytic activity of the catalyst, and broadens the activity window.

[0066] The present invention provides a vanadium-based catalyst for plasma-assisted catalytic denitration prepared by the preparation method described in the above technical solution.

[0067] The carrier of the vanadium-based catalyst for plasma-assisted catalytic denitration provided by the present invention is microporous TiO 2 , where TiO 2 The carrier main body is amorphous, and a small amount is anatase crystal form. The catalyst has a nano-microsphere structure, a loose structure, a rich pore structure, and wrinkles on the surface, which promotes the increase of the specific surface area. The pore volume is significantly higher than that of anatase or rutile TiO 2 , thereby enhancing the microdischarge in the catalyst pores, expanding the catalyst activation energy density range, reducing the denitration energy consumption, and TiO 2 provides good stability for the catalyst.

[0068] The active component of the vanadium-based catalyst for plasma-assisted catalytic denitration provided by the present invention is: α-V 2 O 5 , which makes the vanadium-based catalyst have good catalytic activity and stability; using MnO 2 with γ-MnO x as the main component as a co-catalyst to inhibit the generation of ozone, enhance the activity of low-temperature plasma-assisted catalytic denitration, and broaden the activity window.

[0069] The present invention also provides the application of the vanadium-based catalyst for plasma-assisted catalytic denitration described in the above technical solution in plasma-assisted catalytic denitration.

[0070] The present invention has no special limitation on the specific manner of the application, and the application manner well-known to those skilled in the art can be adopted.

[0071] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts belong to the scope of protection of the present invention.

[0072] Example 1

[0073] A preparation method of a vanadium-based catalyst for plasma-assisted catalytic denitration consists of the following steps:

[0074] (1) Mix dodecylamine, tetrabutyl titanate and absolute ethanol to obtain a dodecylamine-tetrabutyl titanate-ethanol solution;

[0075] (2) Mix 0.154 g of ammonium metavanadate, 0.222 g of oxalic acid, 0.081 g of manganese acetate tetrahydrate and 200 mL of deionized water to obtain an active component precursor solution; the temperature of the mixing is 60 °C, and the mixing method is water bath heating;

[0076] (3) Under stirring conditions, drop the active component precursor solution obtained in step (2) into the dodecylamine-tetrabutyl titanate-ethanol solution obtained in step (1), then stir for 2 h, then carry out a hydrothermal reaction, and then carry out centrifugation, washing, drying and calcination in sequence to obtain a vanadium-based catalyst for plasma-assisted catalytic denitrification, denoted as 4V 2 O 5 -1MnO x / microporous TiO 2 ; the temperature of the hydrothermal reaction is 90 °C, and the time of the hydrothermal reaction is 20 h; the rotation speed of the centrifugation is 6000 r / min, and the time of the centrifugation is 10 min; the washing method is: first acid wash twice with an ethanol-hydrochloric acid solution with a pH value of 2, then wash with deionized water until neutral. The amount of the ethanol-hydrochloric acid solution used for acid washing is 100 mL / g, the time for each acid washing is 60 min, the amount of deionized water used for washing with deionized water is 100 mL / g, and the time for washing with deionized water is 30 min; the drying temperature is 80 °C, and the drying time is 6 h; the calcination temperature is 500 °C, and the holding time for calcination is 5 h;

[0077] The mixing method of the dodecylamine, tetrabutyl titanate and absolute ethanol is as follows:

[0078] 1) Mix 9 mL of dodecylamine and 100 mL of absolute ethanol to obtain a dodecylamine-ethanol solution;

[0079] 2) Mix 15 mL of tetrabutyl titanate and 100 mL of absolute ethanol to obtain a tetrabutyl titanate-ethanol solution;

[0080] 3) Drop the tetrabutyl titanate-ethanol solution obtained in step 1) into the dodecylamine-ethanol solution obtained in step 2), and then stir for 1 h to obtain a dodecylamine-tetrabutyl titanate-ethanol solution.

[0081] Example 2

[0082] A preparation method of a vanadium-based catalyst for plasma-assisted catalytic denitrification consists of the following steps:

[0083] (1) Mix dodecylamine, tetrabutyl titanate and absolute ethanol to obtain a dodecylamine-tetrabutyl titanate-ethanol solution;

[0084] (2) Mix 0.154 g of ammonium metavanadate, 0.267 g of oxalic acid, 0.161 g of manganese acetate tetrahydrate and 200 mL of deionized water to obtain an active component precursor solution; the mixing temperature is 60 °C, and the mixing method is water bath heating;

[0085] (3) Dropwise add the active component precursor solution obtained in step (2) to the dodecylamine-titanium butoxide-ethanol solution obtained in step (1) under stirring, then stir for 2 h, followed by hydrothermal reaction, and then carry out centrifugation, washing, drying and calcination in sequence to obtain a vanadium-based catalyst for plasma-assisted catalytic denitrification, denoted as 4V 2 O 5 -2MnO x / microporous TiO 2 ; the temperature of the hydrothermal reaction is 90 °C, and the time of the hydrothermal reaction is 15 h; the rotation speed of the centrifugation is 6000 r / min, and the time of the centrifugation is 10 min; the washing method is: first acid wash 2 times with an ethanol-hydrochloric acid solution with a pH value of 2, then wash with deionized water until neutral. The amount of the ethanol-hydrochloric acid solution used for acid washing is 100 mL / g, the time for each acid washing is 60 min, the amount of deionized water used for washing with deionized water is 100 mL / g, and the time for washing with deionized water is 30 min; the drying temperature is 80 °C, and the drying time is 6 h; the calcination temperature is 500 °C, and the holding time of the calcination is 3 h;

[0086] The mixing method of the dodecylamine, titanium butoxide and absolute ethanol is as follows:

[0087] 1) Mix 9 mL of dodecylamine and 100 mL of absolute ethanol to obtain a dodecylamine-ethanol solution;

[0088] 2) Mix 15 mL of titanium butoxide and 100 mL of absolute ethanol to obtain a titanium butoxide-ethanol solution;

[0089] 3) Dropwise add the titanium butoxide-ethanol solution obtained in step 1) to the dodecylamine-ethanol solution obtained in step 2) under stirring, and then stir for 1 h to obtain a dodecylamine-titanium butoxide-ethanol solution.

[0090] Example 3

[0091] A preparation method of a vanadium-based catalyst for plasma-assisted catalytic denitrification, which consists of the following steps:

[0092] (1) Mix dodecylamine, titanium butoxide and absolute ethanol to obtain a dodecylamine-titanium butoxide-ethanol solution;

[0093] (2) Mix 0.154 g of ammonium metavanadate, 0.311 g of oxalic acid, 0.242 g of manganese acetate tetrahydrate and 200 mL of deionized water to obtain an active component precursor solution; the mixing temperature is 60 °C, and the mixing method is water bath heating;

[0094] (3) Under stirring conditions, drop the active component precursor solution obtained in step (2) into the dodecylamine-titanium butoxide-ethanol solution obtained in step (1), then stir for 2 h, then carry out a hydrothermal reaction, and then carry out centrifugation, washing, drying and calcination in sequence to obtain a vanadium-based catalyst for plasma-assisted catalytic denitrification, denoted as 4V 2 O 5 -3MnO x / microporous TiO 2 ; the temperature of the hydrothermal reaction is 90 °C, and the time of the hydrothermal reaction is 15 h; the rotation speed of the centrifugation is 6000 r / min, and the time of the centrifugation is 10 min; the washing method is: first pickle with an ethanol-hydrochloric acid solution with a pH value of 2 twice, and then wash with deionized water until neutral. The amount of the ethanol-hydrochloric acid solution used for pickling is 100 mL / g, the time for each pickling is 60 min, the amount of deionized water used for washing with deionized water is 100 mL / g, and the time for washing with deionized water is 30 min; the drying temperature is 80 °C, and the drying time is 6 h; the calcination temperature is 500 °C, and the holding time of the calcination is 5 h;

[0095] The mixing method of the dodecylamine, titanium butoxide and absolute ethanol is as follows:

[0096] 1) Mix 9 mL of dodecylamine and 100 mL of absolute ethanol to obtain a dodecylamine-ethanol solution;

[0097] 2) Mix 13 mL of titanium butoxide and 100 mL of absolute ethanol to obtain a titanium butoxide-ethanol solution;

[0098] 3) Under stirring conditions, drop the titanium butoxide-ethanol solution obtained in step 1) into the dodecylamine-ethanol solution obtained in step 2), and then stir for 1 h to obtain a dodecylamine-titanium butoxide-ethanol solution.

[0099] Example 4

[0100] A preparation method of a vanadium-based catalyst for plasma-assisted catalytic denitrification, which consists of the following steps:

[0101] (1) Mix dodecylamine, titanium butoxide and absolute ethanol to obtain a dodecylamine-titanium butoxide-ethanol solution;

[0102] (2) Mix 0.154 g of ammonium metavanadate, 0.356 g of oxalic acid, 0.323 g of manganese acetate tetrahydrate and 200 mL of deionized water to obtain an active component precursor solution; the temperature of the mixing is 60 °C, and the mixing method is water bath heating;

[0103] (3) Under stirring conditions, add the active component precursor solution obtained in step (2) dropwise to the dodecylamine-titanium butoxide-ethanol solution obtained in step (1), then stir for 2 h, then carry out a hydrothermal reaction, and then carry out centrifugation, washing, drying and calcination in sequence to obtain a vanadium-based catalyst for plasma-assisted catalytic denitrification, denoted as 4V 2 O 5 -4MnO x / microporous TiO 2 ; the temperature of the hydrothermal reaction is 90 °C, and the time of the hydrothermal reaction is 15 h; the rotation speed of the centrifugation is 6000 r / min, and the time of the centrifugation is 10 min; the washing method is: first acid wash twice with an ethanol-hydrochloric acid solution with a pH value of 2, then wash with deionized water until neutral. The dosage of the ethanol-hydrochloric acid solution during acid washing is 100 mL / g, the time of each acid washing is 60 min, the dosage of deionized water during deionized water washing is 100 mL / g, and the time of deionized water washing is 30 min; the drying temperature is 80 °C, and the drying time is 6 h; the calcination temperature is 500 °C, and the holding time of the calcination is 3 h;

[0104] The mixing method of the dodecylamine, titanium butoxide and absolute ethanol is:

[0105] 1) Mix 9 mL of dodecylamine and 100 mL of absolute ethanol to obtain a dodecylamine-ethanol solution;

[0106] 2) Mix 13 mL of titanium butoxide and 100 mL of absolute ethanol to obtain a titanium butoxide-ethanol solution;

[0107] 3) Under stirring conditions, add the titanium butoxide-ethanol solution obtained in step 1) dropwise to the dodecylamine-ethanol solution obtained in step 2), and then stir for 1 h to obtain a dodecylamine-titanium butoxide-ethanol solution.

[0108] Comparative Example 1

[0109] Prepare 4V 2 O 5 / TiO 2 catalyst: Weigh 0.154 g of ammonium metavanadate and 0.237 g of oxalic acid in a small amount of deionized water, heat in a water bath at 60 °C until dissolved to obtain an active component precursor solution, and add 3 g of anatase TiO 2The powder was impregnated in the prepared solution, placed in a constant temperature water bath at 60 °C and stirred to evaporate to dryness. After the obtained product was dried at 80 °C for 6 h, it was calcined in a muffle furnace at 500 °C for 5 h to obtain the impregnation method 4V 2 O 5 / TiO 2 catalyst.

[0110] Comparative Example 2

[0111] The 4V was prepared by the impregnation method 2 O 5 -4MnO x / TiO 2 catalyst: Weigh 0.154 g of ammonium metavanadate, 0.356 g of oxalic acid, and 0.323 g of manganese acetate tetrahydrate in a small amount of deionized water, heat it in a water bath at 60 °C until dissolved to obtain the precursor solution of the active component, add 3 g of anatase TiO 2 powder and impregnate it in the prepared solution, place it in a constant temperature water bath at 60 °C and stir to evaporate to dryness. After the obtained product was dried at 80 °C for 6 h, it was calcined in a muffle furnace at 500 °C for 3 h to obtain the impregnation method 4V 2 O 5 -4MnO x / TiO 2 catalyst.

[0112] Comparative Example 3

[0113] Anatase TiO 2

[0114] Comparative Example 4

[0115] Microporous TiO 2

[0116] The catalytic activities of the vanadium-based catalysts for plasma-assisted catalytic denitrification obtained in Examples 1 to 4 were tested, and the obtained catalytic activity curves are as Figure 2 shown, where the test method is: The catalytic activity test was carried out in a coaxial cylindrical dielectric barrier discharge reactor. The structural schematic diagram of the coaxial cylindrical dielectric barrier discharge reactor is as Figure 1 shown. The reactor body is a quartz dielectric tube with an inner diameter of 8 mm, an outer diameter of 10 mm, and a length of 200 mm. The two ends of the reactor are sealed with insulating plugs. The positive electrode is a stainless steel rod with a diameter of 2 mm and a length of 200 mm placed inside the tube, and the negative electrode is a 200-mesh copper net wound outside the tube. Take 1 mL of the catalyst with a particle size of 40-60 mesh and place it in the discharge area of the reactor. The high-voltage AC power supply provides the energy required for the reaction. The flow rate of the reaction gas is 1.3 L·min -1 , where the NO concentration is 535.7 mg·m -3 , NH 3 concentration is 303.6 mg·m -3 O2 The content is 8%, N 2 is introduced as the balance gas. The reaction is carried out at normal temperature and pressure, with a discharge frequency of 9 kHz and a space velocity of 78000 h -1 . From Figure 2 it can be seen that the catalyst obtained in Example 1 has a NO -1 removal rate of 94% at an energy density of 312 J·L x . The catalyst obtained in Example 2 has a NO -1 removal rate of 91% at an energy density of 317 J·L x . The catalyst obtained in Example 3 has a NO -1 removal rate of 94% at an energy density of 305 J·L x . The catalyst provided in Example 4 has a NO -1 removal rate of 91% at an energy density of 263 J·L x . This shows that the vanadium-based catalyst provided by the present invention, under the synergistic effect of low-temperature plasma, can promote the denitrification reaction based on the fast SCR mechanism, enabling the NO x -containing polluted gas at normal temperature and pressure to maintain a denitrification efficiency of over 90% within a space velocity range of 70000 - 80000 h -1 and an energy density range of 262 - 504 J·L -1 .

[0117] The catalytic activity of the 4V 2 O 5 / TiO 2 catalyst prepared in Comparative Example 1 was tested. The test method was the same as that in Example 1, and the results obtained are as Figure 3 shown. From Figure 3 it can be seen that the 4V 2 O 5 / TiO 2 catalyst prepared in Comparative Example 1 achieved the best NO -1 removal rate at an energy density of 322 J·L x , with a removal rate of 61%, and the high-activity energy density range is narrow.

[0118] The catalytic activity of the 4V 2 O 5 -4MnO x / TiO 2 catalyst prepared in Comparative Example 2 was tested. The test method was the same as that in Example 1, and the results obtained are as Figure 4 shown. From Figure 4 it can be seen that the 4V 2 O 5 -4MnO x / TiO2 The catalyst reaches the best NO -1 removal rate at an energy density of 306 J·L x , and the removal rate is 85%.

[0119] It can be seen from Figures 2 to 4 that the vanadium-based catalyst prepared by the preparation method provided by the present invention has a significantly higher NO x removal rate than the catalyst prepared by the impregnation method, and the high-activity energy density range is wider.

[0120] The sulfur and water resistance performance of the vanadium-based catalyst for plasma-assisted catalytic denitrification provided in Example 4 was tested. The test method was as follows: The sulfur and water resistance performance was tested in a coaxial cylindrical dielectric barrier discharge reactor. The main body of the reactor was a quartz dielectric tube with an inner diameter of 8 mm, an outer diameter of 10 mm, and a length of 200 mm. Both ends of the reactor were sealed with insulating plugs. The positive electrode was a stainless steel rod with a diameter of 2 mm and a length of 200 mm placed inside the tube, and the negative electrode was a 200-mesh copper mesh wound outside the tube. 1 mL of the catalyst with a particle size of 40-60 meshes was placed in the discharge area of the reactor, and the energy required for the reaction was provided by a high-voltage AC power supply. The flow rate of the reaction gas was 1.3 L·min -1 , where the NO concentration was 535.7 mg·m -3 , NH 3 concentration was 303.6 mg·m -3 , SO 2 concentration was 572.1 mg·m -3 , O 2 content was 8%, and the water vapor content was controlled to be 2% by adjusting the temperature of the water bath. There was a heating tape from the water vapor inlet gas path interface to the reactor inlet to prevent water vapor condensation, and N 2 was introduced as a balance gas. The reaction was carried out under normal temperature and pressure, a discharge frequency of 9 kHz, and an airspeed of 78000 h -1 . When SO 2 and H 2 O coexisted, the catalyst had an NO -1 removal rate of 88% at an energy density of 297 J·L x . The sulfur and water resistance performance of the vanadium-based catalyst for plasma-assisted catalytic denitrification provided in Example 4 was as Figure 5 shown. It can be seen from Figure 5 that when only H 2 O was introduced, the activity of the catalyst decreased by about 1.5%. After introducing SO 2 , the activity of the catalyst decreased by about 5.3%. After stopping the introduction of sulfur and water, the NO x removal rate could almost recover to the initial level, indicating that the catalyst provided by the present invention has good sulfur and water resistance performance.

[0121] The vanadium-based catalyst provided by Example 4, the anatase TiO provided by Comparative Example 3 2 and the microporous TiO provided by Comparative Example 4 2 have specific surface areas and pore volumes as shown in Table 1:

[0122] Table 1 Specific surface areas and pore volumes of the catalyst provided by Example 4, the anatase TiO of Comparative Example 3 2 and the microporous TiO of Comparative Example 4 2

[0123] Sample <![CDATA[BET specific surface area / (m 2 ·g -1 )]]> <![CDATA[Pore volume / (cm 2 ·g -1 )]]> Comparative Example 3 7.208 0.047 Comparative Example 4 33.37 0.120 Example 4 47.13 0.108

[0124] As can be seen from Table 1, the specific surface area and pore volume of the microporous TiO 2 are both increased compared with those of the anatase TiO 2 , while the pore volume of the 4V 2 O 5 -4MnO x / TiO 2 catalyst is not much different from that of the microporous support, and the specific surface area is further increased, which helps to improve the activity of the catalyst.

[0125] The vanadium-based catalyst provided by Example 4, the anatase TiO provided by Comparative Example 3 2 and the microporous TiO provided by Comparative Example 4 2 have XRD images as Figure 6 shown. From Figure 6 it can be seen that the microporous TiO 2 has no obvious characteristic peaks, and the material as a whole is in an amorphous structure. After loading the active component, weak diffraction peaks of γ-MnO 2 appear, and part of the TiO 2 support transforms from amorphous to anatase type.

[0126] The vanadium-based catalyst provided by Example 4, the anatase TiO provided by Comparative Example 3 2 and the microporous TiO provided by Comparative Example 4 2 have N 2 isothermal adsorption and desorption curves as Figure 7 shown. From Figure 7 it can be seen that the adsorption amounts of the microporous TiO 2 and 4V 2 O 5 -4MnO x / TiO 2 catalyst in the low P / P 0 region are significantly higher than those of the anatase TiO 2 support, which indicates that the microporous TiO 2 and 4V 2 O 5 -4MnO​x / TiO 2 The catalyst has more microporous structures, so it has a larger specific surface area.

[0127] The SEM image of the vanadium-based catalyst provided in Example 4 is as Figure 8 shown. It can be seen from Figure 8 that the 4V 2 O 5 -4MnO x / TiO 2 catalyst as a whole presents a nano-spherical structure, and there are wrinkles on the surface layer, thus promoting the increase of the specific surface area.

[0128] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a vanadium-based catalyst for plasma-synergistic catalytic denitration, comprising the following steps: (1) mixing dodecylamine, butyl titanate and anhydrous ethanol to obtain a dodecylamine-butyl titanate-ethanol solution; (2) mixing ammonium metavanadate, oxalic acid, manganese acetate tetrahydrate and water to obtain an active component precursor solution; (3) mixing the active component precursor solution obtained in step (2) and the dodecylamine-butyl titanate-ethanol solution obtained in step (1), performing a hydrothermal reaction, and then centrifuging, washing, drying and calcining in sequence to obtain a vanadium-based catalyst for plasma-synergistic catalytic denitrification; The preparation of step (1) and step (2) is not in any particular order; The temperature of the hydrothermal reaction in step (3) is 80 to 120° C., and the time of the hydrothermal reaction is 15 to 24 hours; The volume ratio of dodecylamine to butyl titanate is (3-5):(6-10); The main body of the TiO2 carrier is amorphous, and a small amount is anatase crystal.

2. The preparation method according to claim 1, characterized in that: In the step (1), dodecylamine, butyl titanate and anhydrous ethanol are mixed in the following manner: 1) mixing dodecylamine and anhydrous ethanol to obtain a dodecylamine-ethanol solution; 2) mixing butyl titanate and anhydrous ethanol to obtain a butyl titanate-ethanol solution; 3) mixing the dodecylamine-ethanol solution obtained in step 1) and the butyl titanate-ethanol solution obtained in step 2) to obtain a dodecylamine-butyl titanate-ethanol solution; The preparation of step 1) and step 2) is not in any particular order.

3. The preparation method according to claim 1, characterized in that: In the step (2), the molar ratio of ammonium metavanadate to manganese acetate tetrahydrate is (1-4):1, and the molar ratio of oxalic acid to the total molar ratio of ammonium metavanadate and manganese acetate tetrahydrate is (0.5-2):

1.

4. The preparation method according to claim 1, characterized in that: The mixing temperature in step (2) is 50-70° C., and the mixing method is water bath heating.

5. The preparation method according to claim 1, characterized in that: The centrifugal speed in step (3) is 5000-7000 r / min, and the centrifugal time is 5-10 min.

6. The preparation method according to claim 1, characterized in that: The washing method in step (3) is: firstly washing with ethanol-hydrochloric acid solution for 2 to 3 times, and then washing with deionized water until neutral.

7. The preparation method according to claim 1, characterized in that: The calcination temperature in step (3) is 400-550° C., and the calcination holding time is 3-5 hours.

8. The vanadium-based catalyst for plasma synergistic catalytic denitrification prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the vanadium-based catalyst for plasma synergistic catalytic denitrification as claimed in claim 8 in plasma synergistic catalytic denitrification.

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