Preparation method of denitration catalyst

Abstract

The application provides a preparation method of a denitration catalyst. The manganese-vanadium-titanium alloy is oxidized in situ, and (Mn-V-Al-Ti)Ox oxides are formed on the surface of the foamed titanium alloy. The oxide layer is combined with the base material in situ, has strong combination force, and provides a roughness pore surface. The combination of the pores is beneficial to the adhesion of other active components.

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 foam titanium alloy metal material, the foam titanium alloy is 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, electrochemical oxidation conditions: constant voltage 50-70 V, temperature 8-12 ℃, anodic oxidation for 10-12 h in 1-alkyl-3-methylimidazolium hexafluorophosphate [C n mim] [PF6] ionic liquid, then ultrasonic cleaning with 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 enters 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 hydrothermal reaction 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 300-400 ℃ under air atmosphere at a rate of 1-2 ℃ / min for 1-2 h.

[0013] Further, the hydrothermal solution includes 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 the repeated vacuum-pumping and pressure-releasing treatment is a SHB-III circulating water vacuum pump, and the number of times of the repeated vacuum-pumping and pressure-releasing treatment is 10-15.

[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 there is Br - in the water layer to determine whether the Br n in the ionic liquid is completely washed out, then the [C mim] [PF6] ionic liquid is obtained by drying the organic layer with magnesium sulfate, filtering, distilling under reduced pressure, and vacuum drying at 65-70 ℃ for 5-6 h.

[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 whether 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.% Mn, 7-9 wt.% V, 4-5 wt.% Al, 1-2 wt.% C, and Ti as the balance;

[0025] (2) performing electrochemical oxidation treatment on 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)O x 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 an electrochemical oxidation electrolyte of 150-170 g / L sulfuric acid and 8-10 g / L 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 treatment 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] Further, the equipment for repeatedly vacuumizing and depressurizing is SHB-III circulating water vacuum pump, and the number of times of repeatedly vacuumizing and depressurizing is 10-15 times.

[0031] Further, 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.

[0032] The present application first adopts a foamed metal substrate as a carrier of the catalyst, referring to the attached Figure 4 The foamed substrate has extremely high mechanical properties, compared with the powder catalyst, the foamed metal catalyst has extremely small gas pressure drop, facilitating the passing and purification of flue gas, the present application limits the specific titanium material component, the foamed titanium alloy is composed of 12-14wt.% Mn, 7-9wt.% V, 4-5wt.% Al and 1-2wt.% C and Ti balance, the components can be purchased or self-made, if self-made, traditional foamed metal smelting method can be adopted after smelting of the metal, the smelting self-made method does not make any limitation on the present application, as long as the foamed titanium alloy is composed of 12-14wt.% Mn, 7-9wt.% V, 4-5wt.% Al and 1-2wt.% C and Ti balance, and a three-dimensional structure (large pore size 50-100μm) can be obtained.

[0033] In addition, Mn and V in the titanium alloy in the present application are key components, forming manganese oxide and vanadium oxide, which are traditional denitration catalyst components, the coating method in the prior art is usually to prepare vanadium-manganese oxide on the surface of the carrier by sol-gel, but if the carrier is a metal foam, since the surface of the metal carrier is smooth, this leads to peeling or falling off of the vanadium-manganese oxide prepared by sol-gel from the metal substrate, in order to improve and avoid the peeling problem, in the prior art, such as 2021101948302 a preparation method of a denitration catalyst, a three-dimensional large-pore structure foamed titanium is used as a substrate, a mixed solution of hydrofluoric acid and malic acid is used to corrode the titanium under hydrothermal conditions, that is, under high temperature and high pressure conditions, the metal substrate is immersed and etched, corrosion wrinkles and corrosion large pores are formed on the surface of the three-dimensional foamed titanium, then nano-pores are formed by anodic oxidation, and finally, active components are loaded on the surface of the foamed material by a one-step complexation method of citric acid, simply speaking, the document obtains a rough surface by hydrothermal and anodic oxidation, and then loads active components, although the rough surface can improve the loading amount and bonding strength of the active components to some extent, but the bonding effect is still not ideal in the actual use of the catalyst, therefore, the present application adopts a specific titanium alloy containing manganese and vanadium, in-situ electrochemical oxidation corrosion is adopted to form (Mn-V-Al-Ti)O 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 in the preparation process, the above impurities directly affect the effect of anodic oxidation, such as trace water, Na + and Br – poisoning denitration catalyst, which is usually removed in advance during the preparation of denitration, specifically: first dissolve the ionic liquid crude product into 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 pure product.

[0035] After anodic oxidation, (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 (Mn-V-Al-Ti)O x oxide layer is 30-200μm, because it is in-situ electrochemical oxidation synthesis, therefore has extremely high bonding force, which significantly improves the life of catalyst.

[0036] Then through the hydrothermal and calcination process, (Mn-V-Al-Ti)Ox (Ta-W)O is formed on the surface of the oxide layer. x The oxide layer, ultimately yielding Ti-(Mn-V-Al-Ti)O x -(Ta-W)O x In the hydrothermal process, it is crucial to ensure that the solution completely penetrates the nanopores; otherwise, the active component cannot be coated onto the carrier surface with high binding strength. This invention employs an SHB-Ⅲ type circulating water vacuum pump, repeatedly evacuating and depressurizing 10-15 times. Under vacuum, fine bubbles appear on the surface of the foamed titanium immersed in the hydrothermal solution, demonstrating a positional exchange between the solution and the gas within the pores, thus achieving complete solution penetration into the pores. The oxide is then obtained through hydrothermal treatment and calcination. See the appendix for the oxide morphology. Figure 7 .

[0037] The flue gas composition used in this invention has the following initial concentrations: NO 1000 ppm, NH3 1000 ppm, SO2 500 ppm, O2 7 vol.%, with the remainder being nitrogen. The total flow rate is 800 mL / min, and the space velocity is 200,000 h⁻¹. -1 .

[0038] The formula for calculating the SO2 oxidation rate is: SO3 amount after reaction / SO2 amount before reaction.

[0039] The formula for calculating NOx removal rate is: (NOx removal rate at reactor inlet) / (NOx removal rate at reactor inlet) = (NOx removal rate at reactor inlet) / ... x NO content at reactor outlet x (NOx content) / NOx content at reactor inlet.

[0040] Beneficial technical effects

[0041] (1) This invention forms (Mn-V-Al-Ti)O on the surface of foamed titanium alloy by in-situ oxidation of manganese vanadium titanium alloy. x The oxide layer is bonded to the substrate in situ with strong adhesion and provides a rough porous surface, which facilitates the adhesion of other active components.

[0042] (2) By means of (Mn-V-Al-Ti)O x Surface hydrothermal-calcination preparation of (Ta-W)O x In the layer, Ta directly affects the chlorine oxidation of SO2, while Mn-V and W directly affect NO. x The removal rate, that is, the catalyst of the present invention reduces the sulfur dioxide oxidation rate while ensuring the denitrification rate 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 graphs of different embodiments and comparative examples. x NO conversion rate graphs of different embodiments and comparative examples.

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

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

[0047] BRIEF DESCRIPTION OF DRAWINGS Figure 4 SEM graphs of foamed titanium alloys.

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

[0049] BRIEF DESCRIPTION OF DRAWINGS Figure 6 SEM graphs of (Mn-V-Al-Ti)O x Oxidized surfaces.

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

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

[0052] (1) The surface of a foamed titanium alloy metal material with a three-dimensional network structure is pretreated, 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 electrochemically oxidized by taking the foamed titanium alloy metal as an anode and inert carbon material as a cathode, so that (Mn-V-Al-Ti)O x oxide is formed 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 a 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) Put 0.035 mol of tantalum oxalate, 0.06 mol of ammonium metatungstate and 6 g / L of oxalic acid into a solution containing ethylene glycol and deionized water in sequence, the volume ratio of ethylene glycol to deionized water is 1:2.5, pour into a hydrothermal reaction kettle after stirring at 32.5℃ for 4 min, then add the titanium foam alloy into the reaction kettle, so that the solution in the hydrothermal reaction kettle completely immerses the titanium foam alloy, repeatedly perform vacuumizing-depressurizing treatment to make the solution completely enter the pores on the surface of the titanium foam alloy, then increase to 97.5℃ at a rate of 6℃ / min, hydrothermal reaction for 2.5 h, take out the titanium foam alloy and wash with deionized water and acetone, and dry by cold air.

[0055] (4) increase to 350℃ at a rate of 1.5℃ / min under air atmosphere and calcine for 1.5 h.

[0056] The equipment for repeatedly performing vacuumizing-depressurizing treatment is a SHB-III circulating water vacuum pump, and the number of times of repeatedly performing vacuumizing-depressurizing treatment is 13.

[0057] The surface pretreatment is 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 8 min at 65℃, and the acid etching is 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) perform surface pretreatment on a three-dimensional network structure titanium foam alloy metal material, the titanium foam alloy is composed of 12 wt.% Mn, 7-9 wt.% V, 4 wt.% Al, 1 wt.% C and Ti balance, the surface pretreatment is 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 8 min at 65℃, and the acid etching is 25 wt.% nitric acid and 1.7 wt.% hydrofluoric acid at room temperature for 1.5 min;

[0060] (2) electrochemically oxidize the titanium foam alloy metal with the titanium foam alloy metal as an anode, inert carbon material as a cathode and ionic liquid as an electrolyte, form (Mn-V-Al-Ti)O x oxide on the surface of the titanium foam alloy, and the electrochemical oxidation conditions are: constant voltage of 50 V, temperature of 8℃, anodic oxidation in 1-alkyl-3-methylimidazolium hexafluorophosphate [C 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 1:2.5, and stirred at 32.5℃ for 4min, 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 in the water layer to determine whether Br - was completely washed out in 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 [mim][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 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 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 network 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 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 min; the acid etching is 25 wt.% nitric acid and 1.7 wt.% hydrofluoric acid, the temperature is room temperature, and the time is 1.5 min;

[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 of 60 V, temperature of 10°C, and anode oxidation in 1-alkyl-3-methylimidazolium hexafluorophosphate [C n mim][PF6] ionic liquid for 11 h, and then ultrasonic cleaning in anhydrous ethanol for 4 min and cold air drying;

[0080] (3) 0.035 mol of tantalum oxalate and 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 and deionized water is 1:2.5, and after stirring at 32.5°C for 4 min, the solution is poured into a hydrothermal reaction kettle, then the foam titanium alloy is added to 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°C at a rate of 6°C / min, and hydrothermal reaction is carried out for 2.5 h, the foam titanium alloy is taken out, washed with deionized water and acetone, and dried by cold air.

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

[0082] The 1-alkyl-3-methylimidazolium hexafluorophosphate [C n mim][PF6] ionic liquid is purified before being used as an anode oxidation solution, and the [C n mim][PF6] ionic liquid is dissolved in dichloromethane, a small amount of water is added, the mixture is shaken and mixed, and then the water layer is removed after being left to stand and stratified, and the water washing is repeated until the Br - is completely washed out, and AgNO3 is used to verify whether there is Br - in the water layer to determine whether the 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, comprising 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 8min; the acid etching is 25wt.% nitric acid and 1.7wt.% hydrofluoric acid, the temperature is room temperature, and the time is 1.5min;

[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 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, anodic 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;

[0087] (3) 0.06mol ammonium metatungstate and 6g / L 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 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, and 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 2.5h, 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 the calcination treatment is carried out for 1.5h.

[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 [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 from the ionic liquid - , 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 a three-dimensional reticular foam titanium alloy 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 for 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, the electrochemical oxidation conditions are constant voltage 60V and temperature 10°C in 1-alkyl-3-methyl imidazole hexafluorophosphate [C n mim][PF6] ionic liquid, then the foam titanium alloy is ultrasonically cleaned in anhydrous ethanol for 4min and dried by cold air;

[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 to 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 by repeatedly vacuumizing and depressurizing 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, 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 method for preparing a denitrification catalyst, characterized in that... Includes the following steps: (1) Surface pretreatment is performed on the three-dimensional network structure foam titanium alloy metal material, wherein the foam titanium alloy is composed of 12-14wt.%Mn, 7-9wt.%V, 4-5wt.%Al, 1-2wt.%C and Ti balance; (2) Using foamed titanium alloy metal as the anode and inert carbon material as the cathode, 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 50-70V, temperature 8-12℃, electrochemical oxidation electrolyte is 150-170g / L sulfuric acid and 8-10g / L oxalic acid aqueous solution, after electrochemical oxidation, ultrasonic cleaning with anhydrous ethanol for 3-5min, and drying with cold air. (3) 0.02-0.05 mol tantalum oxalate, 0.04-0.08 mol ammonium metatungstate and 5-7 g / L oxalic acid are placed in a solution of ethylene glycol and deionized water with a volume ratio of 1:(2-3). After stirring at 30-35℃ for 3-5 min, the mixture is poured into a hydrothermal reactor. Then, foamed titanium alloy is added to the reactor so that the solution in the hydrothermal reactor completely submerges the foamed titanium alloy. The process of repeatedly evacuating and depressurizing is repeated so that the solution completely enters the pores on the surface of the foamed titanium alloy. Then, the temperature is increased to 95-100℃ at 5-7℃ / min and the hydrothermal reaction is carried out for 2-3 h. The foamed titanium alloy is then removed and washed with deionized water and acetone, and dried with cold air. (4) Calcination treatment in air atmosphere at 300-400℃ at a rate of 1-2℃ / min for 1-2 hours.

2. The method for preparing a denitrification catalyst as described in claim 1, characterized in that... 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.

3. The method for preparing a denitrification catalyst as described in claim 1, characterized in that... The surface pretreatment consisted of 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 temperature was 65°C and the time was 8 min. The acid etching consisted of 25 wt.% nitric acid and 1.7 wt.% hydrofluoric acid. The temperature was room temperature and the time was 1.5 min.

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