V-W type active liquid auxiliary agent with high stability and preparation method of V-W type active liquid auxiliary agent

Abstract

The invention relates to a V-W type active liquid auxiliary agent with high stability and a preparation method thereof, and the V-W type active liquid auxiliary agent comprises the following components by mass: 1-10% of ammonium metavanadate; 1 to 10% of ammonium metatungstate; 1-15% of oxalic acid; 0.4-1% of an organic chelating agent, and the balance being deionized water. The organic chelating agent is one or a mixture of organic phosphate or organic carboxylate; the ratio of the organic phosphate to the organic carboxylate ranges from 1: 8 to 5: 1; according to the method, the material cost is low, and under the same active liquid concentration, if the hydrolysis rate of the active liquid is about equal to 0, only the proportion of the organic chelating agent in the method needs to be increased to 0.4% or above; in addition, the active liquid has high stability, after the organic chelating agent is added, the stable period of the active liquid can be maintained for a long time, and no hydrolysate is generated even if the active liquid is stored for a long time.

Description

Technical Field

[0001] This invention relates to the field of chemical catalyst technology, and in particular to a highly stable VW-type active liquid additive and its preparation method. Background Technology

[0002] SCR (Selective Catalytic Reduction) is the active loading stage after the denitrification catalyst is regenerated. This stage is usually based on the impregnation method. First, the regenerated support is placed in a mixed solution containing VW active component precursors. By controlling the impregnation temperature, time and solution concentration, the active components are uniformly attached by adsorption and ion exchange on the support surface. Then, the precursors are decomposed into oxide active phases such as V2O5 and WO3 through low-temperature pre-drying and medium-temperature calcination. Finally, an active coating with controllable thickness and good dispersion is formed on the support surface. At the same time, the chemical bonding (such as VO-Ti bond) during the calcination process enhances the binding strength between the active components and the support, avoiding secondary loss during operation.

[0003] In the current process of preparing active liquid, oxalic acid solution is usually used to dissolve ammonium metavanadate and ammonium metatungstate to form VW-type impregnation active liquid. The active liquid prepared by this method is widely used because of its good activity and ease of preparation.

[0004] However, during storage, the vanadium species in the solution gradually hydrolyze and polymerize, forming a thick layer of black hydrolysis products on the inner wall of the container. This causes a decrease in the concentration of active components in the solution, which can only be solved by periodically adding active precursors or adding oxalic acid. However, the stability is low, so the effect lasts for a short period of time. It is necessary to frequently add active precursors to maintain the effect. The problems of large input of active precursors and high material costs urgently need to be solved. Summary of the Invention

[0005] In view of the current state of the prior art, the technical problem to be solved by the present invention is to provide a highly stable VW-type active liquid additive and its preparation method, which has high stability so that the stable cycle of the active liquid can be maintained for a long time, while effectively reducing the frequency of additive addition and significantly reducing the amount of additive, thereby significantly reducing material costs.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a VW type active liquid additive with high stability, characterized in that, by mass percentage, it includes the following components: ammonium metavanadate 1-10%; ammonium metatungstate 1-10%; oxalic acid 1-15%; organic chelating agent 0.4-1%, and the remainder is made up to 100% with deionized water;

[0007] Preferably, the organic chelating agent is one or a mixture of both of organic phosphates and organic carboxylates.

[0008] Preferably, if the organic chelating agent is a mixture of organic phosphate and organic carboxylate, the ratio of organic phosphate to organic carboxylate is in the range of 1:8 to 5:1.

[0009] A method for preparing a highly stable VW-type active liquid additive, characterized by comprising the following steps:

[0010] S1. First, prepare a certain amount of organic phosphate or organic carboxylate or a mixture of the two in a specific ratio to obtain an organic chelating agent;

[0011] S2. Then add the organic chelating agent to a certain amount of deionized water and mix well;

[0012] S3. Finally, oxalic acid, ammonium metavanadate, and ammonium metatungstate are added to deionized water in proportion, and the mixture is stirred at room temperature for 18 hours to form a homogeneous and stable solution.

[0013] Compared with the prior art, the advantages of the present invention are as follows:

[0014] 1. The material cost of the present invention is low because, under the same active liquid concentration, if the hydrolysis rate of the active liquid is to be approximately equal to 0, the proportion of the organic chelating agent in the present invention only needs to be increased to more than 0.4%; while if similar additives on the market are used, the proportion of the additives needs to be increased to at least 4% to achieve the same effect.

[0015] 2. The active liquid formulation of the present invention has high stability. After the addition of organic chelating agent, the stability period of the active liquid can be maintained for a long time. Even if stored for a long time, no hydrolysis products are generated, and there is no need to frequently add organic chelating agent. Detailed Implementation

[0016] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly. The term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0017] To keep the following description of the embodiments of the present invention clear and concise, detailed descriptions of known functions and known components are omitted.

[0018] A highly stable VW-type active liquid additive, by mass percentage, comprises the following components: ammonium metavanadate 1-10%; ammonium metatungstate 1-10%; oxalic acid 1-15%; organic chelating agent 0.4-1%; the remainder is made up to 100% with deionized water.

[0019] Organic chelating agents are one or a mixture of organic phosphates or organic carboxylates;

[0020] If the organic chelating agent is a mixture of organic phosphate and organic carboxylate, the ratio of organic phosphate to organic carboxylate is in the range of 1:8 to 5:1.

[0021] A method for preparing a highly stable VW-type active liquid additive includes the following steps:

[0022] S1. First, prepare a certain amount of organic phosphate or organic carboxylate or a mixture of the two in a specific ratio to obtain an organic chelating agent;

[0023] S2. Then add the organic chelating agent to a certain amount of deionized water and mix well;

[0024] S3. Finally, oxalic acid, ammonium metavanadate, and ammonium metatungstate are added to deionized water in proportion, and the mixture is stirred at room temperature for 18 hours to form a homogeneous and stable solution.

[0025] Active liquid aging test:

[0026] Weigh a grams of the active solution and heat it in a 40°C water bath for 24 hours. Then, remove the solution, filter out the hydrolysis product, and weigh it. The mass is b grams. The ratio of the mass of the hydrolysis product to the mass of the active solution is defined as a / b, which is the hydrolysis rate of the active solution within 24 hours. The smaller the hydrolysis rate, the better the stability of the active solution.

[0027] The comparison results are as follows:

[0028] 1. Ordinary VW type active solution:

[0029] experimental group active liquid mass / g Hydrolysis product mass / g Additive Name Additives percentage 24h hydrolysis rate / % ordinary active liquid 60.378 1.234 - - 2.04

[0030] 2. Similar active liquids on the market:

[0031] experimental group active liquid mass / g Hydrolysis product mass / g Additive Name Additives percentage 24h hydrolysis rate / % Similar product 1 60.141 1.406 Alkylamines 2 2.34 Similar product 1 60.166 ≈0.014 Alkylamines 4 0.02

[0032] To achieve the same effect as this invention, similar products would need to increase the proportion of additives to at least 4%.

[0033] 3. The active liquid of this invention patent:

[0034]

[0035] If you want the hydrolysis rate of the active liquid to be approximately zero, simply increase the proportion of the organic chelating agent in this invention to more than 0.4%.

[0036] This invention enables the V and W species in the active liquid to form highly stable complexes with the organic chelating agent by adding only a small amount of organic chelating agent, thereby effectively improving the overall stability of the VW type active liquid while ensuring that the loading of active components remains unchanged after impregnation.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A highly stable VW-type active liquid additive, characterized in that, The product comprises the following components by mass percentage: 1-10% ammonium metavanadate; 1-10% ammonium metatungstate; 1-15% oxalic acid; 0.4-1% organic chelating agent, with the remainder made up to 100% with deionized water.

2. The highly stable VW-type active liquid additive according to claim 1, characterized in that, The organic chelating agent is one or a mixture of organic phosphates or organic carboxylates.

3. The highly stable VW-type active liquid additive according to claim 2, characterized in that, If the organic chelating agent is a mixture of organic phosphate and organic carboxylate, the ratio of organic phosphate to organic carboxylate is in the range of 1:8 to 5:

1.

4. A method for preparing a highly stable VW-type active liquid additive, characterized in that, Includes the following steps: S1. First, prepare a certain amount of organic phosphate or organic carboxylate or a mixture of the two in a specific ratio to obtain an organic chelating agent; S2. Then add the organic chelating agent to a certain amount of deionized water and mix well; S3. Finally, oxalic acid, ammonium metavanadate, and ammonium metatungstate are added to deionized water in proportion, and the mixture is stirred at room temperature for 18 hours to form a homogeneous and stable solution.

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