A cosolvent for ammonium metavanadate dissolution and a preparation method thereof

Abstract

The present application relates to a kind of for ammonium metavanadate dissolution cosolvent and its preparation method, each component is according to mass percentage 15~25% single ethanol amine, 10~20% urea, 20~35% ethylenediamine, 15~25% propylene glycol, 5~10% oxalic acid, 0.05~1% defoaming agent, 1~5% emulsifier and 10~30% deionized water, preparation process includes first taking different proportion single ethanol amine, urea, ethylenediamine and propylene glycol are input into reaction kettle, after reaction, the cosolvent precursor is prepared;Second, defoaming agent, emulsifier, deionized water and oxalic acid are added to precursor, after mixing uniformly, it is cooled to room temperature, and product is obtained.The cosolvent prepared by the present application has the advantages of low melting point, high dissolution efficiency and good stability, the addition of oxalic acid and single ethanol amine in the cosolvent makes the prepared SCR catalyst have good denitration performance, and improves the product competitiveness.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of preparation of denitration catalysts, and particularly relates to a dissolving solvent for ammonium metavanadate and a preparation method thereof. BACKGROUND

[0002] The active components of the vanadium-based catalyst commonly used in industry include oxides, chlorides and collaborative materials of vanadium, but the most common active component is V2O5 containing one or several additives. The catalyst with V2O5 as the main component is almost effective for all oxidation reactions. The main active component of the vanadium-based SCR catalyst is V2O5, and the content thereof is 0-3%. In the preparation process of the catalyst, vanadate is commonly used as the precursor solution of V2O5, so that V2O5 has better dispersibility in the catalyst and the active centers are uniformly distributed.

[0003] Ammonium metavanadate is a white or slightly yellowish crystalline powder, slightly soluble in cold water, hot ethanol and diethyl ether, soluble in hot water and dilute ammonia. Since ammonium metavanadate is difficult to dissolve in water under normal conditions, a certain amount of dissolving solvent is needed to dissolve it in water. The patent with the application number CN113578303A discloses a dissolving solvent for ammonium metavanadate, which dissolves ammonium metavanadate by adding oxalic acid. 7.5 or more parts of oxalic acid are needed to completely dissolve 1 part of ammonium metavanadate. The patent with the application number CN113578303A uses monoethanolamine as a dissolving solvent to dissolve ammonium metavanadate. 2 parts of monoethanolamine are needed to completely dissolve 1 part of ammonium metavanadate. The above two dissolving solvents can be used to dissolve ammonium metavanadate, but the two dissolving solvents have large dosage and low dissolution efficiency. Excessive addition will affect the activity of the catalyst, and monoethanolamine has low melting point, easily condenses into solid at low temperature, has large volatility, is harmful to human body, and is inconvenient for industrial production. Therefore, in view of the above problems, it is urgent to develop a new dissolving solvent for ammonium metavanadate with high dissolution efficiency, small dosage, and without affecting the structure and denitration performance of V2O5 / TiO2 SCR catalyst. SUMMARY

[0004] In order to solve the above problems, a dissolving solvent for ammonium metavanadate and a preparation method thereof are provided, and an excellent ammonium metavanadate dissolving solvent is screened out through ammonium metavanadate dissolution and catalyst denitration performance test. The dissolving solvent has the characteristics of high dissolution efficiency, small dosage, low melting point, small volatility, low surface tension, and can improve the activity of the SCR catalyst, and has good stability. The preparation method of the dissolving solvent is simple in process and convenient to operate.

[0005] The application adopts the technical scheme that a dissolving aid for ammonium metavanadate comprises the following components in percentage by mass: monoethanolamine 15-25%, urea 10-20%, ethylenediamine 20-35%, propylene glycol 15-25%, oxalic acid 5-10%, defoaming agent 0.05-1%, emulsifier 1-5%, and deionized water 10-30%.

[0006] Further, the defoaming agent is glycerol monostearate.

[0007] Further, the glycerol monostearate has a molar ratio of glycerol to stearic acid of 1.3:1, a solid content of 29.0-31.0%, and a viscosity of 0.1-0.9 Pa·s.

[0008] Further, the emulsifier is obtained by compounding one or more of Span-80, Span-85, Tween-80, and Tween-85 in any ratio.

[0009] The preparation method of the dissolving aid for ammonium metavanadate comprises the following steps:

[0010] (1) monoethanolamine, urea, ethylenediamine, and propylene glycol are taken in different percentages by weight into a reaction kettle, stirred, heated to 120-150 DEG C, and kept at the temperature for 0.5-2 h, and then cooled to room temperature to obtain a dissolving aid precursor;

[0011] (2) a certain amount of the precursor, defoaming agent, emulsifier, and deionized water are added into a beaker, heated to 50-75 DEG C, and stirred for 0.5-1.5 h, and then oxalic acid is added, the mixture is uniformly mixed, heating is stopped, and slow stirring is performed until room temperature is reached, to obtain an ammonium metavanadate dissolving aid.

[0012] Further, the reaction kettle in step (1) has a working pressure of 0.2-0.5 MPa, and a stirring speed of 100 r / min.

[0013] Further, the dissolving aid has a pH value of 10-12 and a viscosity of 18-24 mPa·s.

[0014] The application has the following advantages:

[0015] 1. High dissolution efficiency, which can improve the activity of a catalyst. In industrial production, oxalic acid is often used to dissolve ammonium metavanadate. The solubility of ammonium metavanadate and oxalic acid in water is very small. In an oxalic acid solution, because ammonium metavanadate has oxidizing property and oxalic acid has reducing property, oxidation-reduction reaction occurs between the two to cause dissolution, and the reaction principle is as follows:

[0016] 2NH4VO3+4C2H2O4®(NH4)2[(VO)2(C2O4)3]+2CO2+4H2O+HOOC-COOH+[O]®2CO2+H2O

[0017] The valence of vanadium in the reaction changes from five to four, and a complex (NH4)2(VO)2(C2O4)3 is generated. In this process, the amount of oxalic acid is large, and the dissolution rate is slow. The auxiliary solvent provided by the present application can quickly and completely dissolve the same amount of ammonium metavanadate with a small amount, thereby improving the dissolution efficiency; V 4+ / V 5+ The ratio of V is one of the important factors affecting the de-NOx activity of the catalyst, and the existence of non-stoichiometric vanadium species (V n+ ,n≤4) is beneficial to electron transfer, and within a certain range, the value of V 4+ / V 5+ under the same conditions, the value of V is positively correlated with the de-NOx activity of the catalyst. The addition of oxalic acid and monoethanolamine in the auxiliary solvent can adjust the valence of the active component V and improve the activity of the catalyst.

[0018] 2. Improve the stability of the auxiliary solvent. Monoethanolamine, urea and ethylenediamine react to form a cyclic urea organic amine under high-pressure reaction kettle, and the organic amine has good stability, which provides convenience for industrial transportation and use.

[0019] 3. Low melting point, not easy to condense in low temperature environment. The commonly used auxiliary solvents of ammonium metavanadate also include monoethanolamine, diethanolamine and triethanolamine, and the melting points are 10.5℃, 28℃ and 21.2℃ respectively. In a low temperature environment, it is easy to condense into a solid, which brings many inconveniences to the users. The auxiliary solvent provided by the present application has a low melting point, and can be normally stored and used in a low temperature environment, which greatly reduces the storage and use cost.

[0020] 4. Small volatility. Among the alcohol amine auxiliary solvents, the effect of monoethanolamine is the best, but the boiling point of monoethanolamine is low, and it is easy to volatilize when dissolving ammonium metavanadate, and has a strong irritating smell, which is very harmful to the human body after inhalation. The auxiliary solvent of the present application has small volatilization when dissolving ammonium metavanadate, has no obvious smell, greatly reduces the harm to the human body, and is more suitable for industrial production.

[0021] 5. The auxiliary solvent provided by the present application also has the characteristics of low surface tension, can be dissolved at a lower temperature, does not affect the structure and de-NOx performance of the V2O5 / TiO2 SCR catalyst, and the dissolution performance is better than that of the above-mentioned commonly used ammonium metavanadate auxiliary solvent, and has good stability. The preparation method of the auxiliary solvent is simple in process and convenient to operate. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are further described below. Example 1

[0023] A kind of for ammonium metavanadate dissolution cosolvent, the defoaming agent used in the cosolvent is glycerol monostearate, emulsifier is Span-80, preparation process is:

[0024] (1) first, 15g of monoethanolamine, 15g of urea, 20g of ethylenediamine and 20g of propylene glycol are weighed into the reaction kettle, stirred to 140 DEG C, and kept for 1h, and then cooled to room temperature to prepare the cosolvent precursor;

[0025] (2) the prepared precursor is added to a beaker with 0.2g of glycerol monostearate, 3g of Span-80 and 21.8g of deionized water, heated to 65 DEG C and stirred for 1h, then 5g of oxalic acid is added, mixed uniformly, heated to stop, slowly stirred to room temperature, to obtain ammonium metavanadate cosolvent.

[0026] The weight percentage composition of the ammonium metavanadate cosolvent prepared by the above steps is: monoethanolamine 15%, urea 15%, ethylenediamine 20%, propylene glycol 20%, oxalic acid 5%, defoaming agent 0.2%, emulsifier 3% and deionized water 21.8%. The final ammonium metavanadate cosolvent has a pH value of 10.8 and a viscosity of 18.9 mPa·s. Example 2

[0027] A kind of for ammonium metavanadate dissolution cosolvent, the defoaming agent used in the cosolvent is glycerol monostearate, emulsifier is Tween-80, preparation process is:

[0028] (1) first, 15g of monoethanolamine, 20g of urea, 20g of ethylenediamine and 15g of propylene glycol are weighed into the reaction kettle, stirred to 125 DEG C, and kept for 1.5h, and then cooled to room temperature to prepare the cosolvent precursor;

[0029] (2) the prepared precursor is added to a beaker with 0.2g of glycerol monostearate, 3g of Tween-80 and 19.8g of deionized water, heated to 60 DEG C and stirred for 1h, then 7g of oxalic acid is added, mixed uniformly, heated to stop, slowly stirred to room temperature, to obtain ammonium metavanadate cosolvent.

[0030] The weight percentage composition of the ammonium metavanadate cosolvent prepared by the above steps is: monoethanolamine 15%, urea 20%, ethylenediamine 20%, propylene glycol 15%, oxalic acid 7%, defoaming agent 0.2%, emulsifier 3% and deionized water 19.8%. The final ammonium metavanadate cosolvent has a pH value of 11.1 and a viscosity of 19.4 mPa·s. Example 3

[0031] A kind of cosolvent for ammonium metavanadate dissolution, the defoaming agent used in the cosolvent is glycerol monostearate, and the emulsifier is Span-80 and Tween-80.The preparation process is:

[0032] (1) First, 25g of monoethanolamine, 10g of urea, 23g of ethylenediamine and 15g of propylene glycol are weighed into a reaction kettle, stirred to 135℃, and kept for 0.5h, then cooled to room temperature to prepare a cosolvent precursor;

[0033] (2) The prepared precursor is added to a beaker with 0.2g of glycerol monostearate, 1.5g of Span-80, 1.5g of Tween-80 and 15.8g of deionized water, heated to 55℃ and stirred for 1.5h, then 8g of oxalic acid is added, mixed evenly, then heated, slowly stirred to room temperature to obtain an ammonium metavanadate cosolvent.

[0034] The weight percentage composition of the ammonium metavanadate cosolvent prepared by the above steps is: monoethanolamine 25%, urea 10%, ethylenediamine 23%, propylene glycol 15%, oxalic acid 8%, defoaming agent 0.2%, emulsifier 3% and deionized water 15.8%. The final ammonium metavanadate cosolvent has a pH value of 11.8 and a viscosity of 21.1 mPa•s. Example 4

[0035] A kind of cosolvent for ammonium metavanadate dissolution, the defoaming agent used in the cosolvent is glycerol monostearate, and the emulsifier is Span-85 and Tween-85.The preparation process is:

[0036] (1) First, 20g of monoethanolamine, 15g of urea, 30g of ethylenediamine and 15g of propylene glycol are weighed into a reaction kettle, stirred to 145℃, and kept for 1h, then cooled to room temperature to prepare a cosolvent precursor;

[0037] (2) The prepared precursor is added to a beaker with 0.2g of glycerol monostearate, 1.5g of Span-85, 1.5g of Tween-85 and 11.8g of deionized water, heated to 70℃ and stirred for 1.5h, then 5g of oxalic acid is added, mixed evenly, then heated, slowly stirred to room temperature to obtain an ammonium metavanadate cosolvent.

[0038] The weight percentage composition of the ammonium metavanadate cosolvent prepared by the above steps is: monoethanolamine 20%, urea 15%, ethylenediamine 30%, propylene glycol 15%, oxalic acid 5%, defoaming agent 0.2%, emulsifier 3% and deionized water 11.8%. The final ammonium metavanadate cosolvent has a pH value of 12 and a viscosity of 23.7 mPa•s. Example 5

[0039] A kind of cosolvent for ammonium metavanadate dissolution, the defoaming agent used in the cosolvent is glycerol monostearate, and the emulsifier is Span-80 and Tween-85.The preparation process is:

[0040] (1) First, 20 g of monoethanolamine, 10 g of urea, 20 g of ethylenediamine and 20 g of propylene glycol are weighed into a reaction kettle, stirred to 130 DEG C, and kept at 130 DEG C for 1.5 h, and then cooled to room temperature to obtain a cosolvent precursor;

[0041] (2) The prepared precursor is added to a beaker with 0.2 g of glycerol monostearate, 1.5 g of Span-80, 1.5 g of Tween-85 and 19.8 g of deionized water, heated to 65 DEG C and stirred for 1 h, then 7 g of oxalic acid is added, mixed uniformly, and then heated to stop, slowly stirred to room temperature, to obtain an ammonium metavanadate cosolvent.

[0042] The weight percentage composition of the ammonium metavanadate cosolvent prepared by the above steps is: monoethanolamine 20%, urea 10%, ethylenediamine 20%, propylene glycol 20%, oxalic acid 7%, defoaming agent 0.2%, emulsifier 3% and deionized water 19.8%. The final ammonium metavanadate cosolvent has a pH value of 11.1 and a viscosity of 21.6 mPa•s.

[0043] The solubilizing effect of the cosolvents of Examples 1-5 is detected, and oxalic acid, monoethanolamine and diethanolamine are selected as comparative examples. 50 g of ammonium metavanadate is added to 500 ml of water, and oscillated at 99 DEG C for 5-10 minutes using a constant temperature oscillator at a vibration frequency of about 60 rpm. The solubilizing effect of the cosolvent and the residue of ammonium metavanadate are shown in Table 1.

[0044] Table 1 Solubility comparison table

[0045]

[0046] As shown in Table 1, the cosolvent prepared by the method of the present application has good effect on the dissolution of ammonium metavanadate. As can be seen from Comparative Examples 1, 2, 3 and Example 1, under the same conditions of other components and operation conditions, the dissolution amount of the present application is the highest, reaching 100%. Using the cosolvent of the present application, only 24-25 g is needed to obtain a dissolution amount of 100%, which has higher dissolution efficiency and good application prospect in the fields of environmental protection and denitration catalysis technology.

Claims

1. A process for the preparation of a co-solvent for ammonium metavanadate dissolution, characterized by: It comprises the following steps: (1) Each component is as follows in terms of mass percentage: monoethanolamine 15-25%, urea 10-20%, ethylenediamine 20-35%, propylene glycol 15-25%, oxalic acid 5-10%, defoaming agent 0.05-1%, emulsifier 1-5% and deionized water 10-30%. The defoaming agent is glycerol monostearate, the molar ratio of glycerol to stearic acid in the glycerol monostearate is 1.3:1, the solid content is 29.0-31.0%, the viscosity is 0.1-0.9 Pa•s, the emulsifier is compounded by one or more of Span-80, Span-85, Tween-80 and Tween-85 in any ratio, monoethanolamine, urea, ethylenediamine and propylene glycol are put into a reaction kettle in different weight percentages, the temperature is raised to 120-150°C under stirring, and then the reaction is kept for 0.5-2 h, and finally the temperature is cooled to room temperature to obtain a cosolvent precursor; (2) A certain amount of the precursor, defoaming agent, emulsifier and deionized water are added into a beaker, heated to 50-75°C and stirred for 0.5-1.5 h, and then oxalic acid is added, the mixture is uniformly mixed, heating is stopped, and slow stirring is carried out until the temperature is cooled to room temperature to obtain an ammonium metavanadate cosolvent, the pH value of the cosolvent is 10-12, and the viscosity is 18-24 mPa•s.

2. The process for the preparation of a co-solvent for ammonium metavanadate dissolution as claimed in claim 1, wherein: The working pressure of the reaction kettle in step (1) is 0.2-0.5 MPa, and the stirring speed is 100 r / min.

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