Preparation method of binuclear vanadyl oxalate SCR (Selective Catalytic Reduction) catalyst regeneration liquid

Abstract

The invention relates to a preparation method of binuclear vanadyl oxalate SCR catalyst regeneration liquid, and belongs to the technical field of SCR catalyst regeneration liquid. The method comprises the following steps: adding oxalic acid dihydrate into water, and stirring for the first time until the oxalic acid dihydrate is completely dissolved to obtain an oxalic acid solution; adding ammonium metavanadate into the oxalic acid solution batch by batch, carrying out second stirring so as to carry out a chemical reaction, continuously introducing nitrogen into a chemical reaction system, and removing carbon dioxide generated by the chemical reaction so as to prepare a binuclear vanadyl oxalate complex solution; after the binuclear vanadyl oxalate complex solution is cooled to a set temperature, polyethylene glycol is added into the binuclear vanadyl oxalate complex solution for third stirring, and a primary regeneration solution is obtained; the primary regeneration liquid is filtered, and binuclear vanadyl oxalate SCR catalyst regeneration liquid is obtained; wherein the density of the binuclear vanadyl oxalate SCR catalyst regeneration liquid is 1g / cm < 3 > to 1.5 g / cm < 3 >, the molar concentration of vanadium is 1mol / L to 2.5 mol / L, and the pH value is 1.5 to 4.5.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of SCR catalyst regeneration liquid, in particular to a preparation method of a double-core vanadyl oxalate SCR catalyst regeneration liquid. BACKGROUND

[0002] SCR (Selective Catalytic Reduction) catalysts are widely used in industrial flue gas treatment systems to reduce NOx emissions in flue gas. However, the catalyst gradually deactivates during use due to various reasons, including poisoning by alkali metals (such as K + , Ca 2+ ), carbon deposition, and loss of vanadium components. Currently, there are many defects in the regeneration technology for deactivated catalysts:

[0003] Strong acid corrosion: When traditional processes use sulfuric acid to clean deactivated catalysts, strong acid reacts with TiO2 carriers to form soluble titanium oxysulfate, causing the carrier skeleton to dissolve, the specific surface area of the catalyst to decrease by more than 20%, and the porosity and mechanical strength to decrease. This structural damage directly shortens the service life of the catalyst, and the activity recovery rate after regeneration is only 70% to 80%, and it is difficult to withstand long-term operation under high temperature and high dust conditions.

[0004] Active loss: Although oxalic acid cleaning can gently remove alkali metal poisoning substances (such as K + , Ca 2+ ), it will cause partial dissolution and loss of vanadium active components (such as V2O5) on the catalyst surface. To make up for the loss of activity, the traditional process needs to increase "secondary impregnation", which not only prolongs the regeneration cycle to 3 to 5 days, but also easily introduces impurities (such as Na + , SO42-), causing the selectivity of the catalyst to decrease.

[0005] Waste liquid pollution: The waste liquid generated by the nitric acid cleaning process contains high concentrations of nitrate and heavy metal ions, which needs to be treated through multiple neutralization processes, and the Ca(NO3)2 sludge generated after treatment is a hazardous waste that needs to be landfilled at an additional environmental protection cost. More seriously, the traditional waste liquid cannot be recycled, which not only exacerbates resource waste, but also poses a risk of secondary pollution. SUMMARY

[0006] The application provides a preparation method of a double-core vanadyl oxalate SCR catalyst regeneration liquid to solve the technical problem of how to achieve efficient and low-corrosion regeneration of the SCR catalyst.

[0007] The application provides a preparation method of a double-core vanadyl oxalate SCR catalyst regeneration liquid, which comprises the following steps:

[0008] adding dihydrate oxalic acid into water to perform first stirring until the dihydrate oxalic acid is completely dissolved to obtain an oxalic acid solution;

[0009] adding ammonium metavanadate into the oxalic acid solution in batches to perform second stirring to perform a chemical reaction, and continuously introducing nitrogen into the system of the chemical reaction to remove carbon dioxide generated by the chemical reaction to obtain a dimeric oxovanadium oxalate complex solution;

[0010] after the dimeric oxovanadium oxalate complex solution is cooled to a set temperature, adding polyethylene glycol into the dimeric oxovanadium oxalate complex solution to perform third stirring to obtain a primary regeneration solution;

[0011] filtering the primary regeneration solution to obtain a dimeric oxovanadium oxalate SCR catalyst regeneration solution;

[0012] The dimeric oxovanadium oxalate SCR catalyst regeneration solution has a density of 1 g / cm 3 ~ 1.5 g / cm 3 , a molar concentration of vanadium of 1 mol / L ~ 2.5 mol / L, and a pH value of 1.5 ~ 4.5.

[0013] Optionally, the dimeric oxovanadium oxalate SCR catalyst regeneration solution has a density of 1.15 g / cm 3 ~ 1.25 g / cm 3 , a molar concentration of vanadium of 1.5 mol / L ~ 2.0 mol / L, and a pH value of 2.0 ~ 4.0.

[0014] Optionally, the molar ratio of the dihydrate oxalic acid to the ammonium metavanadate is 1.8 ~ 2.2:1.

[0015] Optionally, the mass of the polyethylene glycol is 0.1% ~ 0.5% of the mass of the dimeric oxovanadium oxalate SCR catalyst regeneration solution.

[0016] Optionally, the purity of the dihydrate oxalic acid is ≥ 99.6%.

[0017] Optionally, the purity of the ammonium metavanadate is ≥ 99.5%, and the mass fraction of total impurities of the ammonium metavanadate is ≤ 0.1%.

[0018] Optionally, the purity of the polyethylene glycol is ≥ 98%, and the molecular weight of the polyethylene glycol is 3,500 ~ 4,500.

[0019] Optionally, the mass ratio of the dihydrate oxalic acid to the water is 0.5 ~ 0.8:1, and the temperature of the water is 40°C ~ 60°C.

[0020] Optionally, the rate of the first stirring is 100 r / min ~ 150 r / min, and the time of the first stirring is 30 min ~ 60 min.

[0021] Optionally, the second stirring rate is 150 r / min to 200 r / min.

[0022] Optionally, the nitrogen flow rate is 0.5 L / min to 1.0 L / min.

[0023] Optionally, the chemical reaction temperature is 75℃ to 85℃, and the chemical reaction time is 120 min to 150 min.

[0024] Optionally, the set temperature is 40℃ to 50℃.

[0025] Optionally, the third stirring rate is 100 r / min to 150 r / min, and the third stirring time is 30 min to 60 min.

[0026] The above technical solution provided by the embodiments of the present application has the following advantages compared with the prior art:

[0027] The embodiments of the present application provide a preparation method of a dual-core vanadyl oxalate selective catalytic reduction (SCR) catalyst regeneration solution. The method comprises the following steps: first, dissolving dihydrate oxalic acid in water, ensuring complete dissolution of the dihydrate oxalic acid through first-stage stirring, to form an oxalic acid solution; then, adding ammonium metavanadate to the oxalic acid solution in batches and performing second-stage stirring, while introducing nitrogen to remove generated carbon dioxide, thereby facilitating smooth reaction, to finally obtain a dual-core vanadyl oxalate complex solution; next, cooling the obtained dual-core vanadyl oxalate complex solution to a predetermined temperature, and adding polyethylene glycol for third-stage stirring, to prepare a primary regeneration solution; and then, performing a filtration operation on the primary regeneration solution, to obtain a dual-core vanadyl oxalate SCR catalyst regeneration solution. The characteristic parameters of the dual-core vanadyl oxalate SCR catalyst regeneration solution are as follows: the density is 1 g / cm 3 ~ 1.5 g / cm 3 , the molar concentration of vanadium is 1 mol / L~2.5 mol / L, and the pH value is 1.5~4.5. By accurately controlling the molar ratio of dihydrate oxalic acid to ammonium metavanadate and performing the reaction in a nitrogen atmosphere, carbon deposition and alkali metal impurities can be efficiently removed. In addition, polyethylene glycol is used as a carrier protection technology, which effectively inhibits the corrosion of oxalic acid on the titanium dioxide (TiO2) carrier, thereby maintaining the structural stability of the catalyst. The method effectively solves the physical and chemical poisoning problems that the SCR catalyst may encounter during the regeneration process by comprehensively using various regeneration technologies such as physical cleaning, chemical cleaning, and thermal regeneration, and realizes efficient, low-corrosion, and low-cost regeneration effect. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate preferred embodiments of the present application and, together with the description, serve to explain the principles of the application.

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings required to be used in the embodiments or prior art description will be briefly introduced. Obviously, those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0030] Figure 1 A flowchart of a preparation method of a double-core vanadyl oxalate SCR catalyst regeneration solution provided by the embodiments of the present application is shown in the figure. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of protection of the present application.

[0032] The range descriptions described herein, such as numerical range, ratio range, etc., include all possible sub-ranges and single values within the range, for example, the range description of "1 to 6" or "1-6" covers all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "include", "contain" and the like used herein mean "include but not limited to"; the relationship terms "first", "second" and the like are only used to distinguish different entities or operations, and do not imply actual sequence or relationship; "and / or" means that multiple cases can exist independently or simultaneously; "at least one", "multiple", "at least one" and the like refer to any combination of the corresponding objects, including single or multiple combinations of objects. The ratio relationship described herein, such as mass ratio, molar ratio, etc., should be understood as the corresponding relationship between the front and the rear in the ratio form according to the sequence of description. The raw materials, reagents, instruments and equipment used herein can be purchased or prepared by existing methods.

[0033] Figure 1 A flowchart of a preparation method of a double-core vanadyl oxalate SCR catalyst regeneration solution provided by the embodiments of the present application is shown in the figure.

[0034] Please refer to Figure 1 The embodiments of the present application provide a preparation method of a double-core vanadyl oxalate SCR catalyst regeneration solution, which comprises:

[0035] S1, adding dihydrate oxalic acid into water for first stirring until the dihydrate oxalic acid is completely dissolved to obtain an oxalic acid solution;

[0036] In some embodiments, the purity of the dihydrate oxalic acid is ≥99.6%.

[0037] The dihydrate oxalic acid with purity ≥99.6% can be more completely and quickly dissolved in water during the dissolving process, reducing the uneven dissolution or reaction obstacles caused by impurities. In addition, the dihydrate oxalic acid with purity ≥99.6% means that it contains very few other chemical substances or impurities, which helps to avoid unnecessary by-products in the subsequent reduction coordination reaction, thereby ensuring the smooth progress of the reaction.

[0038] In some embodiments, the mass ratio of the dihydrate oxalic acid to the water is 0.5-0.8:1, and the temperature of the water is 40-60°C.

[0039] The mass ratio of the dihydrate oxalic acid to the water is 0.5-0.8:1, which can ensure that the concentration of oxalic acid in the reaction system is moderate, which is conducive to the smooth progress of the reduction coordination reaction between oxalic acid and ammonium metavanadate. Too high oxalic acid concentration can cause the reaction to be too violent and difficult to control; too low oxalic acid concentration can slow down the reaction rate, or even not completely react, therefore, the mass ratio of 0.5-0.8:1 can provide an optimal reaction concentration range. For example, the mass ratio of dihydrate oxalic acid to water can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, etc.

[0040] When the water temperature is in the range of 40-60°C, the dissolving process of dihydrate oxalic acid can be accelerated, ensuring that oxalic acid can be uniformly and quickly dissolved in water to form a stable oxalic acid solution. This is helpful for subsequent mixing and reaction with ammonium metavanadate. In the examples of the present application, the water can be one of industrial tap water, distilled water, and deionized water. For example, the temperature of the water can be 40°C, 44°C, 48°C, 52°C, 56°C, 60°C, etc.

[0041] In some embodiments, the first stirring rate is 100-150 r / min, and the first stirring time is 30-60 min.

[0042] The stirring rate of 100 r / min to 150 r / min and the stirring time of 30 min to 60 min can ensure that the dihydrate oxalic acid is uniformly and fully dissolved in water to form a stable oxalic acid solution, which helps to avoid local over-concentration or under-concentration of oxalic acid in the solution, providing uniform reactants for subsequent mixing and reaction with ammonium metavanadate. Too fast stirring rate (more than 150 r / min) can cause the solution to splash or generate too much foam, while too slow stirring rate (less than 100 r / min) can cause uneven mixing of reactants. Similarly, too short stirring time (less than 30 min) can cause incomplete dissolution of oxalic acid, while too long stirring time (more than 60 min) can waste time and energy. The stirring is an industrial commonly used stirring form, and the slurry stirring is preferred. For example, the first stirring rate can be 100 r / min, 110 r / min, 120 r / min, 130 r / min, 140 r / min, 150 r / min, etc.; the first stirring time can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, etc.

[0043] S2, ammonium metavanadate is added into the oxalic acid solution in batches for second stirring to carry out chemical reaction, and nitrogen gas is continuously introduced into the system of the chemical reaction to remove carbon dioxide generated by the chemical reaction, to obtain a binuclear oxalato vanadate complex solution;

[0044] In some embodiments, the purity of the ammonium metavanadate is ≥ 99.5%, and the mass fraction of total impurities of the ammonium metavanadate is ≤ 0.1%.

[0045] The ammonium metavanadate with purity ≥ 99.5% means that it contains very few impurities, which can more accurately carry out coordination reaction with oxalic acid in the reaction to generate binuclear oxalato vanadate complex with optimized structure, which helps to reduce the generation of by-products caused by impurities introduced in the reduction coordination reaction, thereby ensuring the purity of the reaction product.

[0046] In some embodiments, the molar ratio of the dihydrate oxalic acid to the ammonium metavanadate is 1.8 to 2.2: 1.

[0047] In the synthesis of the binuclear oxovanadate complex, the molar ratio of dihydrate oxalic acid to ammonium metavanadate of 1.8-2.2:1 can ensure that the coordination reaction between oxalic acid and ammonium metavanadate occurs fully, generating the binuclear oxovanadate complex with the expected structure and catalytic performance. Secondly, the molar ratio of dihydrate oxalic acid to ammonium metavanadate of 1.8-2.2:1 can reduce the generation of by-products caused by excess or insufficient reactants, which helps to ensure the purity of the regeneration solution and avoid the adverse effects of by-products on the catalyst regeneration process. Finally, by precisely controlling the molar ratio of dihydrate oxalic acid to ammonium metavanadate, the waste of raw materials and unnecessary cost increase can be avoided. If the molar ratio is too high or too low, it may lead to excessive use of raw materials or a decrease in the quality of the regeneration solution, thereby increasing the production cost. A large amount of ammonium metavanadate added at one time may cause the reaction rate to be too fast to control, and even may trigger side reactions. In the examples of the present application, ammonium metavanadate is added to the oxalic acid solution in batches, with the batch control being 3-6 batches, preferably 4-5 batches. The batch addition helps to better control the reaction rate, making the reaction proceed smoothly and ensuring the quality and stability of the product. In addition, the batch addition of ammonium metavanadate can ensure its full contact with the oxalic acid solution, making the reaction more uniform, which helps to avoid local over-concentration or under-concentration of the reaction, making the generation of the binuclear oxovanadate complex more consistent, thereby improving the overall performance of the regeneration solution. For example, the molar ratio of dihydrate oxalic acid to ammonium metavanadate can be 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1, etc.

[0048] In some embodiments, the second stirring rate is 150-200 r / min.

[0049] In the reduction coordination reaction process, increasing the stirring rate to 150-200 r / min can ensure that the reactants are fully mixed in the solution, promoting uniform reaction between oxalic acid and ammonium metavanadate, which helps to avoid local over-concentration or under-concentration of the reaction, ensuring consistent reaction progress throughout the reaction system, and improving reaction efficiency. Secondly, the increase of the stirring rate (150-200 r / min) can enhance the mass transfer in the solution, i.e. promote the transfer of reactants to the reaction interface and the diffusion of products from the reaction interface to the solution, which helps to speed up the reaction rate, shorten the reaction time, and improve the production efficiency. Finally, in the reduction coordination reaction under heating conditions, a stirring rate of 150-200 r / min can help maintain the uniformity of the temperature of the reaction system, avoiding side reactions caused by local overheating or a decrease in reaction rate caused by local overcooling, thereby ensuring that the reaction proceeds within the optimal temperature range. For example, the second stirring rate can be 150 r / min, 160 r / min, 170 r / min, 180 r / min, 190 r / min, 200 r / min, etc.

[0050] In some embodiments, the flow rate of the nitrogen gas is 0.5 L / min to 1.0 L / min.

[0051] Nitrogen gas, as an inert gas, can provide a protective atmosphere when introduced during the reaction process, preventing the reaction of oxalic acid and ammonium metavanadate and other reactants with oxygen in the air from unnecessary oxidation, thereby ensuring the smooth progress of the reaction. The nitrogen gas used in the examples of the present application is industrial nitrogen gas with a purity of ≥99.9%. The flow rate of the nitrogen gas is 0.5 L / min to 1.0 L / min, preferably 0.7 L / min to 0.8 L / min, and the direction of the nitrogen gas is from bottom to top. During the reaction of oxalic acid and ammonium metavanadate, oxalic acid will decompose to produce carbon dioxide, which will be discharged from the reaction system to avoid its accumulation in the solution and affect the progress of the reaction. For example, the flow rate of the nitrogen gas can be 0.5 L / min, 0.6 L / min, 0.7 L / min, 0.8 L / min, 0.9 L / min, 1.0 L / min, etc.

[0052] In some embodiments, the temperature of the chemical reaction is 75°C to 85°C, and the time of the chemical reaction is 120 min to 150 min.

[0053] A reaction temperature of 75°C to 85°C can provide sufficient energy for oxalic acid and ammonium metavanadate to accelerate the coordination reaction process between them. Within the temperature range of 75°C to 85°C, the movement speed of the reactant molecules increases, and the collision frequency increases, thereby promoting the formation of coordination bonds and helping to generate binuclear oxalic acid vanadyl complexes. Controlling the reaction time within 120 min to 150 min can ensure that the coordination reaction between oxalic acid and ammonium metavanadate proceeds sufficiently and achieves a high degree of reaction completion, which helps to generate binuclear oxalic acid vanadyl complexes with stable structures and excellent catalytic properties, and improves the quality of the regeneration solution. Finally, a reaction temperature of 75°C to 85°C and a reaction time of 120 min to 150 min can reduce the occurrence of side reactions. Excessive temperature or excessive reaction time can lead to the generation of by-products, affecting the performance of the regeneration solution. By precisely controlling the reaction temperature and time, side reactions can be minimized to ensure the purity and activity of the regeneration solution. For example, the reaction temperature can be 75°C, 77°C, 79°C, 81°C, 83°C, 85°C, etc. The reaction time can be 120 min, 125 min, 130 min, 135 min, 140 min, 145 min, 150 min, etc. The pressure of the chemical reaction is atmospheric pressure, which in the present application refers to 100 kpa to 102 kpa.

[0054] In the examples of the present application, the color of the solution gradually changes from initial yellow-green to deep blue, indicating the generation of binuclear oxalic acid vanadyl complexes.

[0055] S3、in the solution of the double-core vanadyl oxalate complex is cooled to a set temperature, polyethylene glycol is added to the solution of the double-core vanadyl oxalate complex for third stirring, and a primary regeneration solution is obtained;

[0056] In some embodiments, the purity of the polyethylene glycol is ≥98%, and the molecular weight of the polyethylene glycol is 3500-4500.

[0057] As a high molecular compound, polyethylene glycol has good film-forming and adhesive properties. By adding high-purity (purity ≥98%) polyethylene glycol to the regeneration solution, a protective film can be formed on the surface of the catalyst carrier, effectively isolating corrosive substances such as oxalic acid from direct contact with the carrier, thereby reducing corrosion of the carrier. High-purity (purity ≥98%) polyethylene glycol has low impurity content, which does not introduce additional harmful substances or affect the performance of the regeneration solution, which helps to maintain the stability and consistency of the regeneration solution and ensures its reliable performance in the catalyst regeneration process. In addition, the addition of polyethylene glycol can improve the rheological properties of the regeneration solution, making it easier to penetrate into the pores of the catalyst and fully contact and react with harmful substances such as carbon deposits and alkali metals, which helps to improve the regeneration efficiency and ensure that the regeneration solution can fully play its cleaning and repair functions. Polyethylene glycol with a molecular weight of 3500-4500 means that its molecular chain is longer, which can better cover and wrap the surface of the carrier, enhancing the protection effect.

[0058] In some embodiments, the mass of the polyethylene glycol is 0.1%-0.5% of the mass of the double-core vanadyl oxalate SCR catalyst regeneration solution.

[0059] As an additive, the amount of polyethylene glycol needs to be balanced between economy and effect, and controlled within the mass range of 0.1%-0.5%, which can ensure sufficient carrier protection effect and avoid unnecessary cost increase due to excessive use. This amount control helps to optimize the production cost of the regeneration solution and improve the overall process economy. Excessive polyethylene glycol may change the rheological properties of the regeneration solution, affecting its penetration and distribution in the pores of the catalyst, and even may block the pores, reducing the regeneration effect. Controlling the mass within the range of 0.1%-0.5% can avoid these side effects and ensure that the regeneration solution can fully play its various functions. For example, the mass of the polyethylene glycol can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5% of the mass of the double-core vanadyl oxalate SCR catalyst regeneration solution, etc.

[0060] In some embodiments, the set temperature is 40°C-50°C.

[0061] Setting the temperature to 40℃~50℃ ensures that polyethylene glycol fully dissolves, forming a homogeneous solution, thus better protecting the catalyst support. At high temperatures (above 50℃), some components in the regenerated solution may undergo side reactions, such as further decomposition of oxalic acid and oxidation of ammonium metavanadate. These side reactions may affect the performance and stability of the regenerated solution. Cooling the reaction solution to 40℃~50℃ effectively avoids these high-temperature side reactions, ensuring the purity and activity of the regenerated solution. For example, the set temperature can be 40℃, 42℃, 44℃, 46℃, 48℃, 50℃, etc.

[0062] In some embodiments, the third stirring rate is 100 r / min to 150 r / min, and the third stirring time is 30 min to 60 min.

[0063] Polyethylene glycol (PEG), as a carrier protectant, needs to be fully dissolved and uniformly distributed in the regenerated solution to achieve its optimal effect. Setting a stirring time of 30-60 minutes ensures that PEG is fully dissolved in the regenerated solution and uniformly dispersed throughout the liquid system. During stirring, the various components in the regenerated solution continuously mix, helping to form a homogeneous solution, which is crucial for subsequent filtration and the performance stability of the finished regenerated solution. While stirring helps mix the components, excessive stirring may generate foam, introduce impurities, or cause the regenerated solution temperature to rise, thus affecting its performance. Setting a reasonable stirring time (30-60 minutes) can ensure uniform mixing while avoiding these side effects. For example, the third stirring time can be 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, etc.

[0064] S4. Filter the primary regenerated liquid to obtain a regenerated liquid for the dual-nuclear vanadium oxalate SCR catalyst.

[0065] The regenerated solution of the dual-nuclear vanadium oxalate SCR catalyst satisfies the following condition: density of 1 g / cm³. 3 ~1.5g / cm 3 The molar concentration of vanadium is 1 mol / L to 2.5 mol / L, and the pH value is 1.5 to 4.5.

[0066] Preferably, the regenerated solution of the dual-nuclear vanadium oxalate SCR catalyst satisfies the following condition: density of 1 g / cm³. 3 ~1.5g / cm 3 The molar concentration of vanadium is 1 mol / L to 2.5 mol / L, and the pH value is 1.5 to 4.5.

[0067] In the preparation process of the regeneration liquid, some insoluble impurities such as incompletely dissolved raw material particles, reaction by-products, etc. can be generated or mixed. In the embodiments of the present application, the primary regeneration liquid of the binuclear vanadyl oxalate SCR catalyst is filtered to effectively remove these impurities, improve the purity of the regeneration liquid, and ensure that it does not introduce additional pollutants in the catalyst regeneration process. The filtration can use a precision filter with a filter core aperture of 0.1 μm to 1 μm.

[0068] The binuclear vanadyl oxalate SCR catalyst regeneration liquid provided by the embodiments of the present application can be used to regenerate the deactivated V2O5-WO3 / TiO2 catalyst in the industrial flue gas treatment system. The regeneration liquid has the functions of chemical cleaning, activity self-repairing and carrier protection, and is suitable for high-temperature and high-dust working conditions.

[0069] The present application will be further described below in combination with specific embodiments. In the following examples, the experimental methods not specified in the specific conditions are generally determined according to the national standards / industry standards; if there is no corresponding national standard / industry standard, the general international standards, conventional conditions or the conditions suggested by the manufacturers are used.

[0070] Example 1

[0071] 670 kg of industrial tap water was added to the reaction kettle, the stirring was started with a stirring rate of 120 r / min, and the temperature was heated to 45℃. Then 440 kg of dihydrate oxalic acid was slowly added, and the stirring was continued for 40 minutes until the dihydrate oxalic acid was completely dissolved. Then 200 kg of ammonium metavanadate was slowly added in four times, the stirring rate was increased to 170 r / min, and nitrogen was introduced from the bottom of the solution at a flow rate of 0.7 L / min to remove the carbon dioxide generated by the decomposition of oxalic acid. The temperature of the solution was increased to 78℃, and the reaction was continued for 150 minutes. Then the solution was cooled to 50℃, and 5 kg of polyethylene glycol (PEG-4000) was slowly added under stirring conditions, and the reaction was continued for 60 minutes. Then the product was filtered through a 0.3 μm precision filter to obtain the finished regeneration liquid. The density of the regeneration liquid was 1.18 g / cm 3 , the vanadium concentration was 1.61 mol / l, and the pH was 2.2. The obtained regeneration liquid was used for the regeneration of the deactivated SCR catalyst, and the carbon removal rate was 97.5%; the alkali metal removal rate was 93.8%, and the NOx conversion rate of the regenerated SCR catalyst was 97.6%.

[0072] Example 2

[0073] Put 685 kg of distilled water into the reactor, start stirring, stirring rate 130 r / min, heat to 48°C, slowly add 451 kg of oxalic acid dihydrate, continue stirring for 45 minutes until the oxalic acid dihydrate is completely dissolved; slowly add 207 kg of ammonium metavanadate in 5 portions to the oxalic acid solution, increase the stirring rate to 175 r / min, at the same time, pass nitrogen gas into the solution at a flow rate of 0.75 L / min from the bottom of the solution, discharge the carbon dioxide generated by the decomposition of oxalic acid, increase the temperature of the solution to 80°C, continue to react for 135 minutes; cool the solution to 45°C, slowly add 3 kg of polyethylene glycol (PEG-4000) under stirring conditions, and keep the reaction for 45 minutes; then filter through a 0.1 μm precision filter to obtain the finished product, the density of the regeneration solution is 1.21 g / cm 3 , the vanadium concentration is 1.73 mol / l, and the pH is 2.5. The obtained regeneration solution is used for the regeneration of the deactivated SCR catalyst, the carbon deposition removal rate is 98.2%; the alkali metal removal rate is 94.6%, and the NOx conversion rate of the regenerated SCR catalyst is 97.2%.

[0074] Example 3

[0075] Put 695 kg of deionized water into the reactor, start stirring, stirring rate 145 r / min, heat to 55°C, slowly add 470 kg of oxalic acid dihydrate, continue stirring for 55 minutes until the oxalic acid dihydrate is completely dissolved; slowly add 220 kg of ammonium metavanadate in 4 portions to the oxalic acid solution, increase the stirring rate to 200 r / min, at the same time, pass nitrogen gas into the solution at a flow rate of 1.0 L / min from the bottom of the solution, discharge the carbon dioxide generated by the decomposition of oxalic acid, increase the temperature of the solution to 85°C, continue to react for 135 minutes; cool the solution to 45°C, slowly add 3 kg of polyethylene glycol (PEG-4000) under stirring conditions, and keep the reaction for 45 minutes; then filter through a 0.1 μm precision filter to obtain the finished product, the density of the regeneration solution is 1.25 g / cm 3 , the vanadium concentration is 1.85 mol / l, and the pH is 3.4. The obtained regeneration solution is used for the regeneration of the deactivated SCR catalyst, the carbon deposition removal rate is 97.9%; the alkali metal removal rate is 95.3%, and the NOx conversion rate of the regenerated SCR catalyst is 97.1%.

[0076] Comparative Example 1

[0077] Put 670 kg of industrial tap water into the reaction kettle, open the stirring, the stirring rate is 120 r / min, heat to 45℃, slowly add 440 kg of oxalic acid dihydrate, continue to stir for 40 minutes until the oxalic acid dihydrate is completely dissolved; 150 kg of ammonium metavanadate is slowly added into the oxalic acid solution in four times, the stirring rate is increased to 170 r / min, at the same time, nitrogen is introduced from the bottom of the solution at a flow rate of 0.3 L / min, the carbon dioxide generated by the decomposition of oxalic acid is discharged, the temperature of the solution is increased to 78℃, and the reaction is continued for 150 minutes; the solution is cooled to 50℃, 1 kg of polyethylene glycol (PEG-4000) is slowly added under stirring, and the reaction is kept for 60 minutes; then the product regeneration solution is obtained by filtering through a 0.3 μm precision filter, the density of the regeneration solution is 1.08 g / cm 3 , the vanadium concentration is 1.28 mol / l, and the pH is 1.5. The obtained regeneration solution is used for the regeneration of the deactivated SCR catalyst, the carbon deposition removal rate is 80.4%, the alkali metal removal rate is 82.6%, and the NOx conversion rate of the regenerated SCR catalyst is 81.9%. The vanadium concentration of the regeneration solution prepared in this example is low, which leads to insufficient reaction power when used for the regeneration of the deactivated SCR catalyst, and the regeneration effect is poor.

[0078] Comparative Example 2

[0079] Put 670 kg of industrial tap water into the reaction kettle, open the stirring, the stirring rate is 120 r / min, heat to 45℃, slowly add 440 kg of oxalic acid dihydrate, continue to stir for 40 minutes until the oxalic acid dihydrate is completely dissolved; 150 kg of ammonium metavanadate is slowly added into the oxalic acid solution in four times, the stirring rate is increased to 170 r / min, at the same time, nitrogen is introduced from the bottom of the solution at a flow rate of 0.3 L / min, the carbon dioxide generated by the decomposition of oxalic acid is discharged, the temperature of the solution is increased to 78℃, and the reaction is continued for 150 minutes; the solution is cooled to 50℃, 1 kg of polyethylene glycol (PEG-4000) is slowly added under stirring, and the reaction is kept for 60 minutes; then the product regeneration solution is obtained by filtering through a 0.3 μm precision filter, the density of the regeneration solution is 1.08 g / cm 3 , the vanadium concentration is 1.28 mol / l, and the pH is 1.5. The obtained regeneration solution is used for the regeneration of the deactivated SCR catalyst, the carbon deposition removal rate is 80.4%, the alkali metal removal rate is 82.6%, and the NOx conversion rate of the regenerated SCR catalyst is 81.9%. The vanadium concentration of the regeneration solution prepared in this example is low, which leads to insufficient reaction power when used for the regeneration of the deactivated SCR catalyst, and the regeneration effect is poor.

[0080] The one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0081] The double-core vanadyl oxalate SCR catalyst regeneration liquid provided by the embodiment of the present application can release active vanadyl ions (VO 2 + ) to efficiently remove carbon deposition, and C2O42- can form a soluble complex with alkali metals (K + , Ca 2+ ) to remove the alkali metals.

[0082] The double-core vanadyl oxalate SCR catalyst regeneration liquid provided by the embodiment of the present application can directly supplement the vanadium elements lost by the SCR catalyst, thereby eliminating the complex step of secondary impregnation of V2O5 in the traditional process, greatly shortening the regeneration process time, and improving the production efficiency.

[0083] In the embodiment of the present application, polyethylene glycol is introduced as a carrier protective agent to dynamically protect the hydroxyl groups on the surface of TiO2 through hydrogen bonds, effectively inhibiting the corrosion of oxalic acid on the catalyst carrier, and compared with the traditional sulfuric acid cleaning, the specific surface area loss is smaller, and the service life of the catalyst is significantly prolonged.

[0084] In the embodiment of the present application, the waste liquid generated in the regeneration process can be recycled more than 5 times after calcium hydroxide precipitation treatment, thereby significantly reducing the industrial flue gas treatment cost.

[0085] The above is only the specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown in the present application, but will conform to the widest scope consistent with the principles and novel features of the present application.

Claims

1. A method for preparing a regenerated solution of a dual-nuclear vanadium oxalate SCR catalyst, the method comprising: Oxalic acid dihydrate is added to water and stirred until it is completely dissolved to obtain an oxalic acid solution. Ammonium metavanadate was added batch by batch to oxalic acid solution and stirred a second time to carry out a chemical reaction. Nitrogen gas was continuously introduced into the chemical reaction system to remove carbon dioxide produced by the chemical reaction, thus obtaining a binuclear oxalate vanadium complex solution. After the binuclear vanadium oxalate complex solution is cooled to a set temperature, polyethylene glycol is added to the binuclear vanadium oxalate complex solution and stirred for a third time to obtain a primary regeneration solution; The primary regenerated solution was filtered to obtain a regenerated solution for the dual-nuclear vanadium oxalate SCR catalyst. The regenerated solution of the dual-nuclear vanadium oxalate SCR catalyst satisfies the following condition: density of 1 g / cm³. 3 ~1.5g / cm 3 The molar concentration of vanadium is 1 mol / L to 2.5 mol / L, and the pH value is 1.5 to 4.

5.

2. The method according to claim 1 or 2, characterized in that, The regenerated solution of the dual-nuclear vanadium oxalate SCR catalyst meets the following requirements: density of 1.15 g / cm³. 3 ~1.25g / cm 3 The molar concentration of vanadium is 1.5 mol / L to 2.0 mol / L, and the pH value is 2.0 to 4.

0.

3. The method according to claim 1 or 2, characterized in that, The molar ratio of oxalic acid dihydrate to ammonium metavanadate is 1.8 to 2.2:

1.

4. The method according to claim 1 or 2, characterized in that, The mass of the polyethylene glycol is 0.1% to 0.5% of the mass of the regenerated solution of the vanadium oxalate SCR catalyst.

5. The method according to claim 1 or 2, characterized in that, The purity of the oxalic acid dihydrate is ≥99.6%; and / or, The ammonium metavanadate has a purity ≥99.5%, and the total impurity mass fraction of the ammonium metavanadate is ≤0.1%; and / or, The polyethylene glycol has a purity of ≥98% and a molecular weight of 3500-4500.

6. The method according to claim 1 or 2, characterized in that, The mass ratio of oxalic acid dihydrate to water is 0.5–0.8:1, and the temperature of the water is 40°C–60°C; and / or, The first stirring rate is 100 r / min to 150 r / min, and the first stirring time is 30 min to 60 min.

7. The method according to claim 1 or 2, characterized in that, The second stirring rate is 150 r / min to 200 r / min; and / or, The nitrogen flow rate is 0.5 L / min to 1.0 L / min.

8. The method according to claim 1 or 2, characterized in that, The temperature of the chemical reaction is 75℃~85℃, and the time of the chemical reaction is 120min~150min.

9. The method according to claim 1 or 2, characterized in that, The set temperature is 40℃~50℃.

10. The method according to claim 1 or 2, characterized in that, The third stirring rate is 100 r / min to 150 r / min, and the third stirring time is 30 min to 60 min.

Images