Monolithic de-nox catalyst

Abstract

The application provides a monolithic denitration catalyst, wherein a porous (Mn-V-Al-Ti)Ox oxide channel intermediate layer is obtained by anodic oxidation on a substrate surface in an ionic liquid, and then a (Ta-W)Ox oxide layer is arranged in the channel of the intermediate layer through a hydrothermal method, so that a Ti-(Mn-V-Al-Ti)Ox-(Ta-W)Ox catalyst is obtained, and the catalyst has obvious SO2 oxidation inhibition effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of denitration catalysts, in particular to a denitration catalyst with high stability, low SO2 oxidation rate and high nitrogen oxide removal rate and a preparation method thereof. BACKGROUND

[0002] With the rapid development of economy and the continuous improvement of industrial level, the consumption of energy is also rising. Although emerging energy is rapidly developing and rising, energy consumption is still dominated by traditional energy such as coal. The consumption of these energies produces a large amount of pollutants such as NO x , SO2, SO3, mercury, dust, etc., which brings great pressure to the environment. In recent years, the removal of NO x has also increased research efforts, and the widely used denitration technology is selective catalytic reduction (SCR) technology. In the traditional SCR denitration process, NH3 is the reducing agent and reacts with NO x to generate N2, and this process has the characteristics of high reaction efficiency and good selectivity. Since the content of SO3 in flue gas is relatively low, it has not been paid much attention at the beginning, but as the NO x emission standard becomes more and more stringent, the selective catalytic reduction denitration technology is increasingly widely used, and the denitration catalyst in the denitration process will oxidize part of SO2 in the flue gas to SO3, thereby further increasing the content of SO3 in the flue gas, and the series of problems caused by SO3 are increasingly prominent.

[0003] Some catalysts used for SCR denitration not only can effectively remove nitrogen oxides, but also have a certain promoting effect on the oxidation of SO2. When the flue gas passes through the SCR denitration reaction zone, part of SO2 reacts with oxygen to generate SO3 under the action of the active components of the SCR catalyst, in addition, the fly ash produced by fuel combustion contains Fe2O3, Al2O3, CuO and other components, which can also catalyze the oxidation of SO2, so that the content of SO3 is further increased.

[0004] Although the content of SO3 in flue gas is relatively low compared with SO2, its harm is not inferior to that of SO2. The toxicity of SO3 is several times that of SO2, which not only seriously harms the natural environment, but also cannot be underestimated. The harm of SO3 includes blue plume and acid rain phenomenon, equipment corrosion, influence on equipment operation efficiency and induction of human diseases, etc.

[0005] In the prior art, CN201310192488 discloses a denitration catalyst with low sulfur dioxide oxidation rate and a preparation method thereof; main components of the denitration catalyst and mass fractions thereof are as follows: titanium dioxide 70-92 parts, vanadium pentoxide 0.3-1.5 parts, tungsten trioxide 2-10 parts, niobium oxide 1-5 parts, rare earth oxide 2-5 parts, and silicon-aluminum composite oxide 2-14 parts; the preparation method comprises the following steps: 1) preparation of silicon-aluminum composite oxide; 2) mixing and stirring the formula amount of silicon-aluminum composite oxide, titanium dioxide, ammonium metavanadate, ammonium paratungstate, niobium nitrate and rare earth oxide with molding auxiliary materials, deionized water and oxalic acid; 3) extruding the plastic colloid obtained in step 2) through a thin-wall mold, and then drying and calcining. The denitration catalyst reduces the sulfur dioxide oxidation rate while ensuring the denitration rate under high-temperature and high-sulfur conditions. In the simulation experiment of high temperature and high sulfur, when the SO2 concentration is 3000-5000 ppm and the reaction temperature is in the range of 380-427℃, the activity of the denitration catalyst is equivalent to that of the ordinary SCR denitration catalyst, but the sulfur dioxide oxidation rate is only 60%-80% of that of the ordinary SCR denitration catalyst.

[0006] CN201811276209 discloses a denitration catalyst and a preparation method thereof. The catalyst comprises a catalyst substrate and an active component loaded on the catalyst substrate; the loading thickness of the active component is in the range of 0-0.2 mm along the thickness direction of the surface of the catalyst substrate; the specific preparation steps include: deactivation of the traditional catalyst: cleaning, leaching, active loading; other monolithic catalysts: leaching, active loading; catalyst substrate: cleaning, active loading. By reasonably adjusting the composition and configuration ratio of the leaching solution, the leaching time and the active loading time, and the leaching method; and by combining the adjustment of the formula of the active liquid and the loading method of the active liquid, the loading of the active component in the range of 0-0.2 mm in thickness of the catalyst is successfully realized; the use of the catalyst reduces the SO2 oxidation rate, reduces the use amount and loading amount of the active component, reduces the requirements for the catalyst substrate, and effectively reduces the production cost of the catalyst. SUMMARY

[0007] Based on the above, the present application provides a denitration catalyst with high stability, low SO2 oxidation rate and high nitrogen oxide removal rate, and a preparation method thereof, in particular:

[0008] A preparation method of a high-stability denitration catalyst, comprising the following steps:

[0009] (1) surface pretreatment of a three-dimensional network structure of a foam titanium alloy metal material, the foam titanium alloy being composed of 12-14 wt.% Mn, 7-9 wt.% V, 4-5 wt.% Al, 1-2 wt.% C and Ti balance;

[0010] (2) Electrochemical oxidation treatment of the foam titanium alloy metal with the foam titanium alloy metal as an anode, inert carbon material as a cathode, and ionic liquid as an electrolyte, to form (Mn-V-Al-Ti)O x oxide on the surface of the foam titanium alloy metal under electrochemical oxidation conditions of constant voltage 50-70 V, temperature 8-12 ℃, and anodic oxidation in 1-alkyl-3-methylimidazolium hexafluorophosphate [C n mim] [PF6] ionic liquid for 10-12 h, followed by ultrasonic cleaning in anhydrous ethanol for 3-5 min and cold air drying;

[0011] (3) sequentially placing tantalum oxalate, ammonium metatungstate and oxalic acid into an ethylene glycol and deionized water solution, stirring at 30-35 ℃ for 3-5 min, then pouring into a hydrothermal reaction kettle, then adding the foam titanium alloy into the reaction kettle so that the solution in the hydrothermal reaction kettle completely immerses the foam titanium alloy, repeatedly performing vacuum-pumping and pressure-releasing treatment to make the solution completely enter the pore channels on the surface of the foam titanium alloy, then increasing the temperature to 95-100 ℃ at a rate of 5-7 ℃ / min, and hydrothermally reacting for 2-3 h, then taking out the foam titanium alloy and washing with deionized water and acetone, and cold air drying;

[0012] (4) calcining at 1-2 ℃ / min to 300-400 ℃ under air atmosphere for 1-2 h.

[0013] Further, the hydrothermal solution comprises 0.02-0.05 mol tantalum oxalate, 0.04-0.08 mol ammonium metatungstate, and 5-7 g / L oxalic acid.

[0014] Further, the volume ratio of the ethylene glycol and deionized water is 1: (2-3).

[0015] Further, the equipment for repeatedly performing vacuum-pumping and pressure-releasing treatment is a SHB-Ⅲ circulating water vacuum pump, and the number of times of repeatedly performing vacuum-pumping and pressure-releasing treatment is 10-15 times.

[0016] Further, the 1-alkyl-3-methylimidazolium hexafluorophosphate [C n mim] [PF6] ionic liquid is purified before being used as an anodic oxidation solution, the [C n mim] [PF6] ionic liquid is dissolved in dichloromethane, a small amount of water is added, the mixture is shaken and mixed, then the water layer is removed after being separated by standing, and the [C - mim] [PF6] ionic liquid is repeatedly washed with water for 3-5 times until Br - is completely washed out, AgNO3 is used to verify whether Br - is completely washed out in the water layer to determine whether Br n is completely washed out in the ionic liquid, then the [C mim] [PF6] ionic liquid is dried with magnesium sulfate, filtered, distilled under reduced pressure, and vacuum dried at 65-70 ℃ for 5-6 h to obtain purified 1-alkyl-3-methylimidazolium hexafluorophosphate [C mim] [PF6] ionic liquid.

[0017] Further, the surface pretreatment is alkaline degreasing and acid etching, the alkaline degreasing solution is a mixture of 29wt.% sodium silicate, 15wt.% sodium hydroxide, 8wt.% sodium carbonate and 17wt.% sodium phosphate, the alkaline degreasing time is 65℃, and the time is 8min; the acid etching is 25wt.% nitric acid and 1.7wt.% hydrofluoric acid, the temperature is room temperature, and the time is 1.5min.

[0018] A monolithic denitration catalyst, the catalyst uses a three-dimensional network structure of foam manganese vanadium aluminum titanium alloy with a pore size of 50-100μm as a substrate, a porous (Mn-V-Al-Ti)O x oxide channel intermediate layer is obtained on the surface of the substrate by anodic oxidation in an ionic liquid, and then a (Ta-W)O x oxide layer is arranged in the channel of the intermediate layer by a hydrothermal method, to obtain a Ti-(Mn-V-Al-Ti)O x -(Ta-W)O x catalyst, under laboratory simulated flue gas conditions, the initial concentration of NO is 1000ppm, NH3 is 1000ppm, SO2 is 500ppm, O2 is 7vol.%, the remaining components are nitrogen, the total flow rate is 800mL / min, the space velocity is 200000h -1 -1, the oxidation rate of SO2 is 0.01-0.03%, and the NO removal rate is 99-100%.

[0019] Further, the foam manganese vanadium aluminum titanium alloy is composed of 12-14wt.% Mn, 7-9wt.% V, 4-5wt.% Al, and 1-2wt.% C and Ti balance.

[0020] Further, the ionic liquid is 1-alkyl-3-methyl imidazole hexafluorophosphate [C n mim][PF6] ionic liquid, the anodic oxidation conditions are: constant voltage 50-70V, temperature 8-12℃, and time 10-12h.

[0021] Further, the 1-alkyl-3-methyl imidazole hexafluorophosphate [C n mim][PF6] ionic liquid is purified before being used as an anodic oxidation solution, the [C n mim][PF6] ionic liquid is dissolved in dichloromethane, a small amount of water is added, after oscillation and mixing, the water layer is removed after standing, and the water washing is repeated 3-5 times until Br - is completely washed out, and AgNO3 is used to verify whether there is Br - in the water layer to determine the Br -Whether complete washing, then magnesium sulfate dry organic layer, filtration, distillation under reduced pressure, 65-70 °C vacuum drying 5-6 h to obtain after purification 1-alkyl-3-methyl imidazole hexafluorophosphate [C n mim][PF6] ionic liquid.

[0022] Further, the hydrothermal solution used in the hydrothermal method includes 0.02-0.05 mol of tantalum oxalate, 0.04-0.08 mol of ammonium metatungstate, and 5-7 g / L of oxalic acid, and the hydrothermal parameters are 95-100 ℃ for 2-3 h.

[0023] A preparation method of a denitration catalyst, comprising the following steps:

[0024] (1) performing surface pretreatment on a three-dimensional network structure of a foam titanium alloy metal material, wherein the foam titanium alloy is composed of 12-14 wt.% of Mn, 7-9 wt.% of V, 4-5 wt.% of Al, 1-2 wt.% of C, and Ti as the balance;

[0025] (2) electrochemically oxidizing the foam titanium alloy metal with the foam titanium alloy metal as an anode and inert carbon material as a cathode to form (Mn-V-Al-Ti)Ox oxide on the surface of the foam titanium alloy, and the electrochemical oxidation conditions are as follows: constant voltage of 50-70 V, temperature of 8-12 ℃, and electrochemical oxidation electrolyte of 150-170 g / L of sulfuric acid and 8-10 g / L of oxalic acid aqueous solution; after the electrochemical oxidation, the foam titanium alloy is ultrasonically cleaned with anhydrous ethanol for 3-5 min and dried by cold air;

[0026] (3) sequentially placing tantalum oxalate, ammonium metatungstate, and oxalic acid into an ethylene glycol and deionized water solution, stirring at 30-35 ℃ for 3-5 min, then pouring into a hydrothermal reaction kettle, adding the foam titanium alloy into the reaction kettle, so that the solution in the hydrothermal reaction kettle completely immerses the foam titanium alloy, repeatedly performing vacuumizing and pressure releasing to make the solution completely enter the pores on the surface of the foam titanium alloy, then increasing the temperature to 95-100 ℃ at a rate of 5-7 ℃ / min, and performing hydrothermal reaction for 2-3 h; taking out the foam titanium alloy and washing with deionized water and acetone, and drying by cold air;

[0027] (4) increasing the temperature to 300-400 ℃ at a rate of 1-2 ℃ / min under air atmosphere and performing calcination for 1-2 h.

[0028] Further, the hydrothermal solution includes 0.02-0.05 mol of tantalum oxalate, 0.04-0.08 mol of ammonium metatungstate, and 5-7 g / L of oxalic acid.

[0029] Further, the volume ratio of ethylene glycol to deionized water is 1: (2-3).

[0030] Furthermore, the equipment used for repeated vacuuming and depressurization is the SHB-Ⅲ type circulating water vacuum pump, and the number of times for vacuuming and depressurization is repeated is 10-15 times.

[0031] Furthermore, the surface pretreatment consists of alkaline degreasing and acid etching. The alkaline degreasing solution is a mixture of 29 wt.% sodium silicate, 15 wt.% sodium hydroxide, 8 wt.% sodium carbonate, and 17 wt.% sodium phosphate. The alkaline degreasing time is 65°C for 8 minutes. The acid etching solution consists of 25 wt.% nitric acid and 1.7 wt.% hydrofluoric acid. The temperature is room temperature for 1.5 minutes.

[0032] This invention first uses a foamed metal substrate as a catalyst support, see Appendix Figure 4 The foam substrate has extremely high mechanical properties. Compared with powdered catalysts, foamed metal catalysts have extremely low gas pressure drop, which facilitates the passage and purification of flue gas. This invention specifies that the specific titanium material composition of the foamed titanium alloy is composed of 12-14 wt.% Mn, 7-9 wt.% V, 4-5 wt.% Al, and 1-2 wt.% C and Ti as the balance. This composition can be purchased or made in-house. If made in-house, it can be smelted using the traditional foamed metal smelting method after metal smelting. The in-house smelting method does not limit this invention in any way, as long as the foamed titanium alloy is composed of 12-14 wt.% Mn, 7-9 wt.% V, 4-5 wt.% Al, and 1-2 wt.% C and Ti as the balance, and has a three-dimensional structure (large pore size 50-100 μm).

[0033] Furthermore, Mn and V are key components in the titanium alloy of this invention, forming manganese oxide and vanadium oxide, which are traditional denitrification catalyst components. Existing coating methods typically involve preparing vanadium-manganese oxides via sol-gel on a support surface. However, if the support is a metal foam, the smooth surface of the metal support leads to the sol-gel preparation of vanadium-manganese oxides peeling or falling off from the metal substrate. To improve and avoid this peeling problem, existing technologies, such as a denitrification catalyst preparation method (e.g., 2021101948302), use three-dimensional macroporous structured titanium foam as the substrate and etch the titanium using a mixture of hydrofluoric acid and malic acid under hydrothermal conditions, i.e., at high temperatures... Under high temperature and pressure, etching is performed into the metal substrate, forming corrosion wrinkles and large corrosion channels on the surface of three-dimensional foamed titanium. Then, nanopores are formed through anodic oxidation. Finally, active components are loaded onto the foam surface using a one-step citric acid complexation method. In short, this literature obtains a rough surface through hydrothermal and anodic oxidation, and then loads active components. Although the rough surface improves the loading and bonding strength of the active components to some extent, the bonding effect is still not ideal in actual catalyst use. Therefore, this invention uses a specific titanium alloy containing manganese and vanadium, and performs in-situ electrochemical oxidation corrosion to obtain (Mn-V-Al-Ti)O on the surface of the foamed titanium alloy. xoxide, electrochemical oxidation condition: constant voltage 50-70V, temperature 8-12℃, in 1-alkyl-3-methylimidazolium hexafluorophosphate [C n mim][PF6] ionic liquid for 10-12h, then ultrasonic cleaning in anhydrous ethanol for 3-5min, cold air drying, in addition, the electrolyte used in anodic oxidation is not necessarily ionic liquid, but also can be 150-170g / L sulfuric acid and 8-10g / L oxalic acid aqueous solution, in terms of pore formation, the uniformity and size stability of the pores formed by ionic liquid are better than those of conventional sulfuric acid and oxalic acid mixed solution, especially the (Mn-V-Al-Ti)O x oxide prepared by using ionic liquid has obvious advantages in the stability or life of catalyst, see attached Figure 6 .

[0034] As a kind of green organic solvent, ionic liquid has good solubility, conductivity, wide electrochemical window, good thermal stability, and can be recycled compared with traditional solvents, the present application uses [C n mim][PF6] ionic liquid, which inevitably contains Na + , Br – and trace water during preparation, the above impurities directly affect the effect of anodic oxidation, such as trace water, Na + and Br – poison the denitration catalyst, which is usually removed in advance during the preparation of denitration, specifically: first dissolve the ionic liquid crude product in dichloromethane, then add a small amount of secondary water and mix, shake the mixed solution for several minutes to fully mix, remove the water layer after standing for a period of time, and repeat the water washing for about ten times. Add AgNO3 solution dropwise in the last washed water, if there is no white precipitate generated, it means that Br or Cl in the mixed solution has been basically washed out. Then dry the layer with magnesium sulfate, filter the mother liquor, distill most of the dichloromethane solvent under reduced pressure, and dry under vacuum to remove residual dichloromethane and trace water, finally get the pure product.

[0035] After anodic oxidation, a (Mn-V-Al-Ti)O x oxide layer is formed on the surface of titanium alloy, which has certain nanopores with a pore size of 5-50nm, see attached Figure 6 , the thickness of the (Mn-V-Al-Ti)O x oxide layer is 30-200μm, because it is in-situ electrochemical oxidation synthesis, it has extremely high bonding force, which significantly improves the life of the catalyst.

[0036] Then through the hydrothermal and calcination process, (Mn-V-Al-Ti)Ox oxide layer surface forms (Ta-W)O x oxidation layer, finally obtained Ti-(Mn-V-Al-Ti)O x -(Ta-W)O x Catalyst, hydrothermal process should be noted and ensure that the solution can completely enter the nanopore, otherwise the active component cannot be coated on the surface of the carrier with high binding force, the present application adopts SHB-III type circulating water vacuum pump, the number of repeated vacuumizing-depressurizing is 10-15 times, the water pump is in vacuum state, the foam titanium surface immersed in the hydrothermal solution appears fine bubbles, which proves that the solution exchanges position with the gas in the pore, and then realizes that the solution completely enters the inside of the pore, and then obtains the oxide through hydrothermal and calcination. Figure 7 .

[0037] The flue gas composition used in the application: the initial concentration of NO is 1000 ppm, the concentration of NH3 is 1000 ppm, the concentration of SO2 is 500 ppm, the concentration of O2 is 7 vol.%, and the rest is nitrogen, the total flow is 800 mL / min, and the space velocity is 200000 h-1. -1 .

[0038] The calculation formula of SO2 oxidation rate is = the amount of SO3 after reaction / the amount of SO2 before reaction.

[0039] The calculation formula of NOx removal rate is = (the content of NOx at the inlet of the reactor-the content of NOx at the outlet of the reactor) / the content of NOx at the inlet of the reactor. x . x The content of NOx at the outlet of the reactor.

[0040] Beneficial technical effects

[0041] (1) The present application forms (Mn-V-Al-Ti)O x oxide on the surface of the foam titanium alloy by in-situ oxidation of manganese vanadium titanium alloy, the oxide layer is combined with the substrate in-situ, the binding force is strong, and a roughness pore surface is provided, and the pore combination is beneficial to the adhesion of other active components.

[0042] (2) (Ta-W)O x layer is prepared on the surface of (Mn-V-Al-Ti)O x by hydrothermal-calcination, wherein Ta directly affects the oxidation of SO2, Mn-V and W directly affect the removal rate of NO x , that is, the catalyst of the present application ensures the denitration rate while reducing the oxidation rate of sulfur dioxide under high temperature and high sulfur conditions.

[0043] (3) The catalyst of the present application has the SO2 oxidation rate of 0.01-0.03% and the NO removal rate of 99-100% under the conditions that the initial concentration of NO is 1000 ppm, the concentration of NH3 is 1000 ppm, the concentration of SO2 is 500 ppm, the concentration of O2 is 7 vol.%, the rest is nitrogen, the total flow rate is 800 mL / min, the space velocity is 200000 h-1, and the temperature is 300-400℃. -1 , the SO2 oxidation rate is 0.01-0.03%, and the NO removal rate is 99-100%. BRIEF DESCRIPTION OF DRAWINGS

[0044] BRIEF DESCRIPTION OF DRAWINGS Figure 1 NO conversion rate graph of different embodiments and comparative examples. x NO conversion rate graph of different embodiments and comparative examples.

[0045] BRIEF DESCRIPTION OF DRAWINGS Figure 2 SO2 conversion rate graph of different embodiments and comparative examples.

[0046] BRIEF DESCRIPTION OF DRAWINGS Figure 3 Stability test graph of example 1 and example 3.

[0047] BRIEF DESCRIPTION OF DRAWINGS Figure 4 SEM graph of foamed titanium alloy.

[0048] BRIEF DESCRIPTION OF DRAWINGS Figure 5 SEM graph of foamed titanium alloy after oxidation treatment.

[0049] BRIEF DESCRIPTION OF DRAWINGS Figure 6 SEM graph of (Mn-V-Al-Ti)O x oxidized surface.

[0050] BRIEF DESCRIPTION OF DRAWINGS Figure 7 SEM graph of catalyst after calcination. DETAILED DESCRIPTION Example 1

[0051] A preparation method of a denitration catalyst comprises the following steps:

[0052] (1) The foamed titanium alloy metal material with a three-dimensional network structure is subjected to surface pretreatment, and the foamed titanium alloy is composed of 13 wt.% Mn, 8 wt.% V, 4.5 wt.% Al, 1.5 wt.% C, and Ti balance.

[0053] (2) The foamed titanium alloy metal is used as an anode, and inert carbon material is used as a cathode to electrochemically oxidize the foamed titanium alloy metal, so as to form (Mn-V-Al-Ti)O x oxide on the surface of the foamed titanium alloy, and the electrochemical oxidation conditions are as follows: constant voltage 60 V, temperature 10℃, and the electrochemical oxidation electrolyte is 160 g / L sulfuric acid and 9 g / L oxalic acid aqueous solution, and after the electrochemical oxidation, the foamed titanium alloy is ultrasonically cleaned with anhydrous ethanol for 4 min and dried by cold air.

[0054] (3) 0.035 mol tantalum oxalate, 0.06 mol ammonium metatungstate, 6 g / L oxalic acid were sequentially put into a solution containing ethylene glycol and deionized water, the volume ratio of ethylene glycol and deionized water was 1:2.5, and then the solution was poured into a hydrothermal reaction kettle after stirring at 32.5°C for 4 min, then the foamed titanium alloy was added into the reaction kettle, so that the solution in the hydrothermal reaction kettle completely immersed the foamed titanium alloy, and the solution was completely introduced into the pores on the surface of the foamed titanium alloy through repeated vacuumizing and pressure releasing, then the temperature was increased to 97.5°C at a rate of 6°C / min, and the hydrothermal reaction was carried out for 2.5 h, then the foamed titanium alloy was taken out and washed with deionized water and acetone, and then dried by cold air.

[0055] (4) calcination treatment was carried out at 350°C under air atmosphere at a rate of 1.5°C / min for 1.5 h.

[0056] The equipment for repeated vacuumizing and pressure releasing was SHB-III circulating water vacuum pump, and the number of times of repeated vacuumizing and pressure releasing was 13.

[0057] The surface pretreatment was alkaline degreasing and acid etching, the alkaline degreasing solution was a mixture of 29 wt.% sodium silicate, 15 wt.% sodium hydroxide, 8 wt.% sodium carbonate and 17 wt.% sodium phosphate, the alkaline degreasing time was 8 min at 65°C, and the acid etching was 25 wt.% nitric acid and 1.7 wt.% hydrofluoric acid at room temperature for 1.5 min. Example 2

[0058] A preparation method of a high-stability denitration catalyst comprises the following steps:

[0059] (1) the foamed titanium alloy metal material with a three-dimensional network structure was subjected to surface pretreatment, the foamed titanium alloy was composed of 12 wt.% Mn, 7-9 wt.% V, 4 wt.% Al, 1 wt.% C and Ti balance, the surface pretreatment was alkaline degreasing and acid etching, the alkaline degreasing solution was a mixture of 29 wt.% sodium silicate, 15 wt.% sodium hydroxide, 8 wt.% sodium carbonate and 17 wt.% sodium phosphate, the alkaline degreasing time was 8 min at 65°C, and the acid etching was 25 wt.% nitric acid and 1.7 wt.% hydrofluoric acid at room temperature for 1.5 min;

[0060] (2) the foamed titanium alloy metal was subjected to electrochemical oxidation treatment with the foamed titanium alloy metal as an anode, inert carbon material as a cathode and ionic liquid as an electrolyte, and (Mn-V-Al-Ti)Ox oxide was formed on the surface of the foamed titanium alloy. x The electrochemical oxidation conditions were: constant voltage of 50 V, temperature of 8°C, anode oxidation in 1-alkyl-3-methylimidazolium hexafluorophosphate [Cmim][PF6] ionic liquid for 10 h, then ultrasonic cleaning with anhydrous ethanol for 3 min, and drying by cold air. n mim][PF6] ionic liquid for 10 h, then ultrasonic cleaning with anhydrous ethanol for 3 min, and drying by cold air.

[0061] (3) 0.02 mol tantalum oxalate, 0.04 mol ammonium metatungstate and 5 g / L oxalic acid were placed in a solution containing ethylene glycol and deionized water in sequence. The volume ratio of ethylene glycol to deionized water was 1: (2). After stirring at 30°C for 3-5 min, the solution was poured into a hydrothermal reactor. Then foamed titanium alloy was added to the reactor so that the solution in the hydrothermal reactor completely submerged the foamed titanium alloy. The vacuum-depressurization process was repeated 10 times so that the solution completely entered the pores on the surface of the foamed titanium alloy. Then the temperature was increased to 95°C at 5°C / min and the hydrothermal reaction was carried out for 2 h. The foamed titanium alloy was taken out and washed with deionized water and acetone and dried with cold air.

[0062] (4) Calcination treatment at 300℃ in air atmosphere at a rate of 1℃ / min for 1h.

[0063] The 1-alkyl-3-methylimidazolium hexafluorophosphate [C n The [m][PF6] ionic liquid is purified before being used as an anodic oxidation solution, and [C] n The [mm][PF6] ionic liquid was dissolved in dichloromethane, and a small amount of water was added. After shaking and mixing, the mixture was allowed to stand to separate into layers, and the water layer was removed. The mixture was repeatedly washed with water until the Br content reached 1%. - After thorough rinsing, use AgNO3 to verify the presence of Br in the water layer. - To determine the presence of Br in ionic liquids - After thoroughly washing, the organic layer was dried with magnesium sulfate, filtered, distilled under reduced pressure, and dried under vacuum at 65˚C for 5 h to obtain purified 1-alkyl-3-methylimidazolium hexafluorophosphate [C]. n [mim][PF6] ionic liquid. Example 3

[0064] A method for preparing a highly stable denitration catalyst includes the following steps:

[0065] (1) The surface of the three-dimensional network structure foam titanium alloy metal material is pretreated. The foam titanium alloy is composed of 13wt.%Mn, 8wt.%V, 4.5wt.%Al and 1.5wt.%C and Ti balance. The surface pretreatment is alkaline degreasing and acid etching. The alkaline degreasing solution is a mixture of 29wt.% sodium silicate, 15wt.% sodium hydroxide, 8wt.% sodium carbonate and 17wt.% sodium phosphate. The alkaline degreasing time is 65℃ and the time is 8min. The acid etching is 25wt.% nitric acid and 1.7wt.% hydrofluoric acid. The temperature is room temperature and the time is 1.5min.

[0066] (2) Using foamed titanium alloy metal as the anode, inert carbon material as the cathode, and ionic liquid as the electrolyte, the foamed titanium alloy metal is electrochemically oxidized to form (Mn-V-Al-Ti)O on the surface of the foamed titanium alloy.x Oxide, electrochemical oxidation condition: constant voltage 60V, temperature 10℃, anodization in 1-alkyl-3-methylimidazolium hexafluorophosphate [C n mim][PF6] ionic liquid for 11h, then ultrasonic cleaning in anhydrous ethanol for 4min, and cold air drying;

[0067] (3) 0.035 mol of tantalum oxalate, 0.06 mol of ammonium metatungstate, and 6 g / L of oxalic acid were sequentially added to an ethylene glycol and deionized water solution with a volume ratio of ethylene glycol to deionized water of 1:2.5, stirred at 32.5℃ for 4 min, then poured into a hydrothermal reaction kettle, then the solution in the hydrothermal reaction kettle was completely immersed into the foam titanium alloy, and the solution was completely introduced into the pores on the surface of the foam titanium alloy by repeatedly vacuumizing and depressurizing 14 times, then increased to 97.5℃ at a rate of 6℃ / min, and hydrothermal reaction was carried out for 2.5h, then the foam titanium alloy was taken out and washed with deionized water and acetone, and dried by cold air.

[0068] (4) calcined at 350℃ under air atmosphere at a rate of 1.5℃ / min for 1.5h.

[0069] The 1-alkyl-3-methylimidazolium hexafluorophosphate [C n mim][PF6] ionic liquid was purified before being used as an anodizing solution, and the [C n mim][PF6] ionic liquid was dissolved in dichloromethane, a small amount of water was added, and after oscillation and mixing, the water layer was removed after standing and layering, and the water washing was repeated until Br - was completely washed out, and AgNO3 was used to verify whether Br - was completely washed out from the ionic liquid. - Then, the organic layer was dried with magnesium sulfate, filtered, distilled under reduced pressure, and vacuum dried at 67.5℃ for 5.5h to obtain the purified 1-alkyl-3-methylimidazolium hexafluorophosphate [C n mim][PF6] ionic liquid. Example 4

[0070] A method for preparing a high-stability denitration catalyst, comprising the following steps:

[0071] (1) The surface of the three-dimensional network structure foam titanium alloy metal material is pretreated. The foam titanium alloy is composed of 14wt.%Mn, 9wt.%V, 5wt.%Al and 2wt.%C and Ti balance. The surface pretreatment is alkaline degreasing and acid etching. The alkaline degreasing solution is a mixture of 29wt.% sodium silicate, 15wt.% sodium hydroxide, 8wt.% sodium carbonate and 17wt.% sodium phosphate. The alkaline degreasing time is 65℃ and the time is 8min. The acid etching is 25wt.% nitric acid and 1.7wt.% hydrofluoric acid. The temperature is room temperature and the time is 1.5min.

[0072] (2) Using foamed titanium alloy metal as the anode, inert carbon material as the cathode, and ionic liquid as the electrolyte, the foamed titanium alloy metal is electrochemically oxidized to form (Mn-V-Al-Ti)O on the surface of the foamed titanium alloy. x Oxides, electrochemical oxidation conditions: constant voltage 70V, temperature 12℃, in 1-alkyl-3-methylimidazolium hexafluorophosphate [C n Anodize in [mm][PF6] ionic liquid for 12 h, then ultrasonically clean with anhydrous ethanol for 5 min, and dry with cold air;

[0073] (3) 0.05 mol tantalum oxalate, 0.08 mol ammonium metatungstate and 7 g / L oxalic acid were placed in a solution containing ethylene glycol and deionized water in sequence. The volume ratio of ethylene glycol to deionized water was 1: (3). After stirring at 35°C for 5 min, the solution was poured into a hydrothermal reactor. Then foamed titanium alloy was added to the reactor so that the solution in the hydrothermal reactor completely submerged the foamed titanium alloy. The vacuum-depressurization process was repeated 15 times so that the solution completely entered the pores on the surface of the foamed titanium alloy. Then the temperature was increased to 100°C at 7°C / min and the hydrothermal reaction was carried out for 3 h. The foamed titanium alloy was taken out and washed with deionized water and acetone and dried with cold air.

[0074] (4) Calcination treatment at 400℃ in air atmosphere at a rate of 2℃ / min for 2h.

[0075] The 1-alkyl-3-methylimidazolium hexafluorophosphate [C n The [m][PF6] ionic liquid is purified before being used as an anodic oxidation solution, and [C] n The [mm][PF6] ionic liquid was dissolved in dichloromethane, and a small amount of water was added. After shaking and mixing, the mixture was allowed to stand to separate into layers, and the water layer was removed. The mixture was repeatedly washed with water until the Br content reached 1%. - After thoroughly rinsing, use AgNO3 to verify the presence of Br in the water layer. - To determine the presence of Br in ionic liquids - After thoroughly washing, the organic layer was dried with magnesium sulfate, filtered, distilled under reduced pressure, and dried under vacuum at 70˚C for 6 h to obtain purified 1-alkyl-3-methylimidazolium hexafluorophosphate [C]. nmim][PF6] ionic liquid.

[0076] Comparative Example 1.

[0077] A high-stability denitration catalyst preparation method comprises the following steps:

[0078] (1) Surface pretreatment of the three-dimensional reticular structure of the foam titanium alloy metal material, the foam titanium alloy is ordinary foam titanium without Mn and V components (trace not counted), the surface pretreatment is alkaline degreasing and acid etching, the alkaline degreasing solution is a mixed solution of 29wt.% sodium silicate, 15wt.% sodium hydroxide, 8wt.% sodium carbonate and 17wt.% sodium phosphate, the alkaline degreasing time is 65℃, and the time is 8min; the acid etching is 25wt.% nitric acid and 1.7wt.% hydrofluoric acid, the temperature is room temperature, and the time is 1.5min;

[0079] (2) Electrochemical oxidation treatment of the foam titanium alloy metal with the foam titanium alloy metal as an anode, inert carbon material as a cathode and ionic liquid as an electrolyte, to form oxides on the surface of the foam titanium alloy, the electrochemical oxidation conditions are: constant voltage 60V, temperature 10℃, and 1-alkyl-3-methylimidazolium hexafluorophosphate [C n mim][PF6] ionic liquid is anodized for 11h, and then ultrasonically cleaned with anhydrous ethanol for 4min and dried by cold air;

[0080] (3) 0.035mol of tantalum oxalate and 0.06mol of ammonium metatungstate, 6g / L of oxalic acid are sequentially put into a solution containing ethylene glycol and deionized water, the volume ratio of ethylene glycol and deionized water is 1:2.5, and after stirring at 32.5℃ for 4min, the solution is poured into a hydrothermal reaction kettle, then the foam titanium alloy is added into the reaction kettle, so that the solution in the hydrothermal reaction kettle completely immerses the foam titanium alloy, and the solution completely enters the pore channels on the surface of the foam titanium alloy through repeated vacuumizing and pressure releasing 14 times, then the temperature is increased to 97.5℃ at a rate of 6℃ / min, and the hydrothermal reaction is carried out for 2.5h, the foam titanium alloy is taken out, washed with deionized water and acetone, and dried by cold air.

[0081] (4) Calcination treatment at 350℃ under air atmosphere at a rate of 1.5℃ / min for 1.5h.

[0082] The 1-alkyl-3-methylimidazolium hexafluorophosphate [C n mim][PF6] ionic liquid is purified before being used as an anodizing solution, and [C n mim][PF6] ionic liquid is dissolved into dichloromethane, a small amount of water is added, after oscillation and mixing, the water layer is removed after layering, and the water washing is repeated until Br - is completely washed out, and AgNO3 is used to verify whether there is Br - in the water layer to determine whether Br- Whether complete washing, then magnesium sulfate dry organic layer, filtration, distillation under reduced pressure, 67.5 °C vacuum drying 5.5h after purification 1-alkyl-3-methyl imidazole hexafluorophosphate [C n mim][PF6] ionic liquid.

[0083] Comparative Example 2.

[0084] A high-stability denitration catalyst preparation method comprises the following steps:

[0085] (1) The surface of the three-dimensional network structure of the foam titanium alloy metal material is pretreated, the foam titanium alloy is composed of 13wt.% Mn, 8wt.% V, 4.5wt.% Al, 1.5wt.% C and Ti balance, the surface pretreatment is alkaline degreasing and acid etching, the alkaline degreasing solution is a mixture of 29wt.% sodium silicate, 15wt.% sodium hydroxide, 8wt.% sodium carbonate and 17wt.% sodium phosphate, the alkaline degreasing time is 65 °C, and the time is 8 min; the acid etching is 25wt.% nitric acid and 1.7wt.% hydrofluoric acid, the temperature is room temperature, and the time is 1.5 min;

[0086] (2) The foam titanium alloy metal is electrochemically oxidized by taking the foam titanium alloy metal as an anode, inert carbon material as a cathode and ionic liquid as an electrolyte, and (Mn-V-Al-Ti) O x oxide is formed on the surface of the foam titanium alloy, and the electrochemical oxidation conditions are as follows: constant voltage 60 V, temperature 10 °C, anodic oxidation in 1-alkyl-3-methyl imidazole hexafluorophosphate [C n mim][PF6] ionic liquid for 11 h, then ultrasonic cleaning in anhydrous ethanol for 4 min, and cold air drying;

[0087] (3) 0.06 mol of ammonium metatungstate and 6 g / L of oxalic acid are sequentially put into an ethylene glycol and deionized water solution, the volume ratio of ethylene glycol to deionized water is 1:2.5, the solution is stirred at 32.5 °C for 4 min, then poured into a hydrothermal reaction kettle, then the foam titanium alloy is added into the reaction kettle, so that the solution in the hydrothermal reaction kettle completely immerses the foam titanium alloy, the solution completely enters the pore channels on the surface of the foam titanium alloy through repeated vacuumization and pressure relief 14 times, then the temperature is increased to 97.5 °C at a rate of 6 °C / min, and the hydrothermal reaction is carried out for 2.5 h, then the foam titanium alloy is taken out, washed with deionized water and acetone, and dried by cold air.

[0088] (4) The temperature is increased to 350 °C at a rate of 1.5 °C / min under air atmosphere, and calcination treatment is carried out for 1.5 h.

[0089] The 1-alkyl-3-methyl imidazole hexafluorophosphate [C n mim][PF6] ionic liquid is purified before being used as an anodic oxidation solution, and the purified [Cn mim][PF6] ionic liquid was dissolved into dichloromethane, a small amount of water was added, after oscillation and mixing, the water layer was removed after standing, and the water washing was repeated until Br - was completely washed out, and AgNO3 was used to verify whether Br - was completely washed out in the water layer, and then the ionic liquid was used to judge whether Br - was completely washed out, then the organic layer was dried with magnesium sulfate, filtered, distilled under reduced pressure, and vacuum dried at 67.5°C for 5.5h to obtain the purified 1-alkyl-3-methyl imidazole hexafluorophosphate [C n mim][PF6] ionic liquid.

[0090] Comparative Example 3.

[0091] A preparation method of a high-stability denitration catalyst comprises the following steps:

[0092] (1) The surface of the three-dimensional reticular structure of the foam titanium alloy metal material is pretreated, the foam titanium alloy is composed of 13wt.% Mn, 8wt.% V, 4.5wt.% Al, 1.5wt.% C and Ti balance, the surface pretreatment is alkaline degreasing and acid etching, the alkaline degreasing solution is a mixed solution of 29wt.% sodium silicate, 15wt.% sodium hydroxide, 8wt.% sodium carbonate and 17wt.% sodium phosphate, the alkaline degreasing time is 65°C, and the time is 8min; the acid etching is 25wt.% nitric acid and 1.7wt.% hydrofluoric acid, the temperature is room temperature, and the time is 1.5min;

[0093] (2) The foam titanium alloy metal is electrochemically oxidized by taking the foam titanium alloy metal as an anode, inert carbon material as a cathode and ionic liquid as an electrolyte, and a (Mn-V-Al-Ti)O x oxide is formed on the surface of the foam titanium alloy, and the electrochemical oxidation conditions are as follows: constant voltage 60V, temperature 10°C, anode oxidation in 1-alkyl-3-methyl imidazole hexafluorophosphate [C n mim][PF6] ionic liquid for 11h, and then ultrasonic cleaning in anhydrous ethanol for 4min and cold air drying;

[0094] (3) 0.035mol of tantalum oxalate and 0.06mol of ammonium metatungstate are sequentially put into an ethylene glycol and deionized water solution, the volume ratio of ethylene glycol and deionized water is 1:2.5, the solution is stirred at 32.5°C for 4min, then poured into a hydrothermal reaction kettle, then the foam titanium alloy is added into the reaction kettle, so that the solution in the hydrothermal reaction kettle completely immerses the foam titanium alloy, the solution completely enters the pore channels on the surface of the foam titanium alloy through repeated vacuumizing and pressure releasing 14 times, then the temperature is increased to 97.5°C at a rate of 6°C / min, and the hydrothermal reaction is carried out for 2.5h, then the foam titanium alloy is taken out and washed with deionized water and acetone, and dried by cold air.

[0095] The 1-alkyl-3-methylimidazolium hexafluorophosphate [C n The [m][PF6] ionic liquid is purified before being used as an anodic oxidation solution, and [C] n The [mm][PF6] ionic liquid was dissolved in dichloromethane, and a small amount of water was added. After shaking and mixing, the mixture was allowed to stand to separate into layers, and the water layer was removed. The mixture was repeatedly washed with water until the Br content reached 100%. - After thorough rinsing, use AgNO3 to verify the presence of Br in the water layer. - To determine the presence of Br in ionic liquids - To determine if the organic layer was completely washed, the organic layer was dried with magnesium sulfate, filtered, distilled under reduced pressure, and dried under vacuum at 67.5˚C for 5.5 h to obtain purified 1-alkyl-3-methylimidazolium hexafluorophosphate [C]. n [mim][PF6] ionic liquid.

[0096] Appendix Figure 1 Appendix Figure 2 Appendix Figure 3 Appendix Figure 4 Appendix Figure 5 Appendix Figure 6 and attached Figure 7 The above examples and comparative examples were tested. In Example 1, the anodic oxidation solution was a 160 g / L sulfuric acid and 9 g / L oxalic acid aqueous solution. In Examples 2-4, the anodic oxidation solution was 1-alkyl-3-methylimidazolium hexafluorophosphate [C]. n [mim][PF6] Ionic liquid, see appendix Figure 1 and attached Figure 3 It can be seen that the anodic oxidation solution mainly affects the stability of the denitrification catalyst, and has little impact on NO. x Conversion rate was not significantly affected, as shown in the attached figure. Figure 3 As shown, the conversion rate of the catalyst in Example 3 decreased to around 92% after 270 hours, while the conversion rate of the catalyst in Example 1 decreased to around 77% after 270 hours. This is likely mainly related to the binding force of the active components. Comparative Example 1 used ordinary foamed titanium, which did not contain Mn and V (trace amounts were negligible). Comparative Example 2 did not contain tantalum active components. Comparative Example 3 was not calcined, making it difficult to expose the active components. See Appendix. Figure 2 It can be seen that tantalum salt has a significant inhibitory effect on SO2 conversion rate; at a temperature of 300-400℃, the SO2 oxidation rate is 0.01-0.03%.

[0097] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A monolithic de-NOx catalyst characterized by The catalyst is based on a three-dimensional network structure of foam manganese vanadium aluminum titanium alloy with a pore size of 50-100 μm, and a porous (Mn-V-Al-Ti)O x oxide channel intermediate layer is obtained on the surface of the substrate by anodic oxidation in an ionic liquid, and then a (Ta-W)O x oxide layer is arranged in the channels of the intermediate layer by a hydrothermal method, to obtain Ti-(Mn-V-Al-Ti)O x -(Ta-W)O x The catalyst has an SO2 oxidation rate of 0.01-0.03% and a NO removal rate of 99-100% under laboratory simulated flue gas conditions, with an initial concentration of NO being 1000 ppm, NH3 being 1000 ppm, SO2 being 500 ppm, O2 being 7 vol.%, the remaining components being nitrogen, a total flow rate being 800 mL / min, a space velocity being 200000 h -1 -1, a temperature being 300-400 ℃. The foam manganese vanadium aluminum titanium alloy consists of 12-14 wt.% Mn, 7-9 wt.% V, 4-5 wt.% Al, 1-2 wt.% C and Ti balance; The ionic liquid is 1-alkyl-3-methylimidazolium hexafluorophosphate [C n mim][PF6] ionic liquid, anodic oxidation conditions: constant voltage 50-70 V, temperature 8-12 °C, time 10-12 h.

2. The monolithic de-NOx catalyst according to claim 1, wherein The hydrothermal solution used in the hydrothermal method comprises 0.02-0.05 mol of tantalum oxalate, 0.04-0.08 mol of ammonium metatungstate, 5-7 g / L of oxalic acid, and the hydrothermal parameters are 95-100 ℃ for 2-3 h.

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