Method for removing hydrazine hydrate impurities by hydrogen peroxide

Abstract

The present application relates to the process of impurity decomposition and recycling of hydrazine hydrate, in particular to a method for removing impurities of hydrazine hydrate by hydrogen peroxide method. The dilute hydrazine hydrate produced by the hydrogen peroxide method is concentrated, and the feed is added from the feed position of the catalytic reaction rectifying tower with hydrolysis catalyst, and the impurities are hydrolyzed to remove the impurities in the preparation of hydrazine hydrate by the hydrogen peroxide method. The present application is simple to operate, and has good process stability. The removal rate of 2,3-butanedione dihydrazone reaches more than 98%, and the hydrazine hydrate is generated by hydrolysis of 2,3-butanedione dihydrazone. The yield of hydrazine hydrate is 100.5%, and good economic benefits are obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to a process for decomposing and recovering hydrazine hydrate from impurities, in particular to a method for removing hydrazine hydrate impurities by hydrogen peroxide method. BACKGROUND

[0002] Hydrazine hydrate is an important inorganic fine chemical intermediate, which is widely used in the synthesis of pesticides, medicines, blowing agents, initiators, curing agents, polymerization catalysts, etc.

[0003] There are many industrial synthesis routes for hydrazine hydrate, the main routes include Lassaigne method, urea method, ketone hydrazine method, and hydrogen peroxide oxidation method. At present, the urea method and the ketone hydrazine method are mainly used in domestic production, and the more economical and environmentally friendly hydrogen peroxide method is used by Arkema in France and Mitsubishi Chemical in Japan.

[0004] The hydrogen peroxide method was first proposed by UGINE KUHLMANN company in France and was first industrialized. In the patent US3972878A, it is introduced that under the action of a catalyst, hydrogen peroxide is used as an oxidizing agent to oxidize a mixture of ammonia water and butanone to synthesize the corresponding butanone hydrazine (methyl ethyl ketone hydrazine).

[0005]

[0006] The patent CN1248546A of Arkema in France details the scheme of obtaining hydrazine hydrate and butanone by pressurized hydrolysis of butanone hydrazine. A pressurized reaction rectification tower with 40 plates is used, the reaction pressure is controlled at 8-10 bar, and the reaction temperature is controlled at 175-190℃. Butanone hydrazine and water are continuously fed into the tower to react, the generated butanone is taken out from the top of the tower, and the generated dilute hydrazine hydrate is obtained from the tower bottom and then subjected to subsequent dehydration, concentration, rectification, and filtration processes to obtain 80% hydrazine hydrate. The reaction equation is as follows:

[0007]

[0008] The patent JP3882859B2 of Japan reports that 2,3-butanedione dioxime is generated in the production process of hydrazine hydrate by hydrogen peroxide method, and the relative proportion of the impurity to hydrazine hydrate is about 0.4%. The structure of the impurity is as follows:

[0009]

[0010] The generation mechanism is speculated to be as follows: in the synthesis process of butanone hydrazine, hydrogen peroxide, butanone, and ammonia can generate butanone oxime, butanone oxime, hydrazine, and butanone hydrazone (an intermediate in the pressurized hydrolysis of butanone hydrazine) to generate 2,3-butanedione dioxime, and the reaction equation is as follows:

[0011]

[0012] Currently, foreign reports utilize the higher boiling point of 2,3-butanedione dihydrazone compared to hydrazine hydrate to separate and remove impurities from hydrazine hydrate via column distillation. Indian patent WO2018065997A1 uses 60-70% hydrazine hydrate for distillation. During distillation, the aqueous phase escapes more easily from the top of the column than hydrazine, leading to the formation of anhydrous hydrazine in the reboiler. Anhydrous hydrazine poses a risk of explosion at high temperatures, indicating a significant safety hazard. Furthermore, the distillation process consumes a large amount of energy, increasing the cost of hydrazine hydrate. Japanese patent JP3882859B2 discloses a method for recycling this impurity. The process involves dehydrating and concentrating 40% hydrazine hydrate in a distillation column until the impurity content in the bottoms exceeds 2.4%, then cooling and crystallizing. The bottoms liquid is filtered to obtain crude 2,3-butanedione dihydrazone with a purity of 55%, which is then purified with ethanol to obtain 99% pure 2,3-butanedione dihydrazone. Approximately 0.4g of 2,3-butanedione dihydrazone is produced as a byproduct per 100g of 80% hydrazine hydrate. However, this method has virtually no marketable channels for the separated 2,3-butanedione dihydrazone, making its recovery largely meaningless. Although this method reduces the concentration of hydrazine hydrate and limits the concentration in the bottoms, the filtration and crystallization of high-concentration hydrazine hydrate still pose certain safety hazards.

[0013] There are currently literature reports on the hydrolysis of methyl ethyl ketone (MEK) using weakly acidic resins. For example, patent CN109437133A describes the hydrolysis of MEK using a weakly acidic cation exchange resin D113 as a catalyst. The process involves mixing MEK, water, and the catalyst, then adding them to the bottom of a distillation column. Reactive distillation is carried out at a temperature of 90-120°C, continuously distilling off the byproducts of MEK and water azeotropes. After reactive distillation, the residue in the bottom of the column is further distilled to obtain a 40-80% (w / w) hydrazine hydrate aqueous solution, with a hydrazine hydrate yield of over 90%. However, the catalyst mentioned in that patent is ineffective for the 2,3-butanedione dihydrazone mentioned in this patent, and the final hydrolysis product still requires further purification through distillation. Furthermore, the maximum operating temperature of the ion exchange resin is 90-100°C, and the reliability of this resin under prolonged high-temperature, MEK-containing, and aqueous conditions in a reactive distillation column needs further confirmation.

[0014] Against the background described above, this invention proposes a hydrogen peroxide method for removing hydrazine hydrate impurities that is simple to operate and can improve the yield of hydrazine hydrate. Summary of the Invention

[0015] In view of the shortcomings of the prior art, the present invention provides a method for removing hydrazine hydrate impurities using hydrogen peroxide.

[0016] To achieve the above objectives, the present invention adopts the following technical solution:

[0017] A method for removing impurities in the preparation of hydrazine hydrate by hydrogen peroxide method involves concentrating the dilute hydrazine hydrate produced by the hydrogen peroxide method, feeding it into the feed position of a catalytic reactive distillation column with added hydrolysis catalyst, and hydrolyzing the impurities to remove them from the preparation of hydrazine hydrate by hydrogen peroxide method.

[0018] The catalyst-filled reactive distillation column is a packed column with 10-50 theoretical plates, preferably 15-30 theoretical plates.

[0019] The hydrolysis catalyst has 5-25 theoretical plates above the position of the catalytic reaction distillation column, preferably 5-15 theoretical plates, and 5-25 theoretical plates below the position of the hydrolysis catalyst, preferably 5-15 plates.

[0020] The feed location is in the middle or above the location of the hydrolysis catalyst; preferably, the feed location is in the middle or above the location of the hydrolysis catalyst, no more than 4 theoretical plates away.

[0021] The amount of catalyst used is 0.01-0.2 times the hourly feed mass of concentrated hydrazine hydrate, preferably 0.03-0.05 times.

[0022] The hydrolysis catalyst is one or a combination of several of the following: aluminum oxide, titanium dioxide, zinc oxide, ferric oxide, and copper oxide.

[0023] The hydrolysis catalyst is in the form of spheres or long cylinders, with a specific surface area of ​​80-120 m². 2 / g.

[0024] The concentration of the concentrated hydrazine hydrate is 40%-80%, preferably 60%-67%.

[0025] The temperature of the bottom of the catalytic reactive distillation column is 90-150℃, and the reaction pressure is 0.1-0.5 MPa. Preferably, the bottom temperature is 100-110℃, and the reaction pressure is 0.1-0.15 MPa.

[0026] The reflux ratio at the top of the catalytic reactive distillation column is 0.5-5, preferably 1-2.

[0027] Advantages of this invention:

[0028] This invention utilizes a catalyst to hydrolyze hydrazine hydrate impurities into butanedione and hydrazine hydrate under mild conditions. This process is safe, reliable, and simple to operate, and improves the yield of hydrazine hydrate. The hydrolysis catalyst used in this invention possesses good stability, high-temperature resistance, chemical resistance, and high mechanical strength, allowing for long-term operation within the column. Furthermore, the selected hydrolysis catalyst has a large specific surface area and high hydrolysis activity. Placing it at a specific location in the reactive distillation column ensures sufficient contact and reaction with 2,3-butanedione dihydrazone, thus solving the problem of removing the 2,3-butanedione dihydrazone impurity from hydrazine hydrate using the hydrogen peroxide method. Attached Figure Description

[0029] Figure 1 The graph shows the effect of impurity removal rate at different time periods during 313 hours of operation, as provided in this embodiment of the invention.

[0030] Figure 2 The graph shows the yield of hydrazine hydrate at different time periods during 313 hours of operation, as provided in this embodiment of the invention. Detailed Implementation

[0031] The present invention is illustrated below with reference to examples, but is not intended to limit the invention. Any simple substitutions or modifications made to the present invention by those skilled in the art are within the scope of the technical solutions protected by this invention.

[0032] This invention utilizes a catalyst to hydrolyze hydrazine hydrate impurities into butanedione and hydrazine hydrate under mild conditions. This process is safe, reliable, and simple to operate, and improves the yield of hydrazine hydrate. Furthermore, the method employs catalytic reactive distillation to hydrolyze 2,3-butanedione dihydrazone. The butanedione produced during catalytic hydrolysis is collected from the top of the column, while the hydrazine hydrate is collected from the bottom, further promoting the catalytic hydrolysis process and achieving highly efficient hydrolysis of 2,3-butanedione dihydrazone. The reaction equation is as follows:

[0033]

[0034] The raw materials in the following examples are prepared using the hydrogen peroxide method for hydrazine hydrate.

[0035] Example 1: Preparation of 65% hydrazine hydrate

[0036] The dilute hydrazine hydrate collected from the hydrolysis tower bottom is pumped into a 50mm diameter, 1.5m high hydrazine hydrate concentration tower, with the tower pressure controlled at -70kPa negative pressure for dehydration. Dilute hydrazine hydrate is continuously fed into the tower at a feed rate of 50g / min and a reflux ratio of 0.5. Water is continuously collected at a rate of 27g / min when the tower top temperature is 68-70℃, and hydrazine hydrate (hydrazine hydrate content 65%, containing 0.4% 2,3-butanedione hydrazone) is continuously collected at a rate of 23g / min when the tower bottom temperature is 85-87℃.

[0037] Example 2

[0038] The DN40 impurity hydrolysis tower, with a height of 0.8m, is divided into three sections: a 0.3m upper and lower section with ordinary packing (i.e., 3×3θ ring packing, theoretically 30 plates / meter); and a 0.2m middle section filled with 81g of spherical alumina catalyst (specific surface area 100m²). 2 / g) was used as the reaction section. The control system pressure was 0.15 MPa, and the temperature was raised to 110-113℃ at the bottom of the column and 100-103℃ at the top of the column for hydrolysis reaction. The feed rate of 65% hydrazine hydrate obtained in Example 1 was controlled to be about 45 g / min, and the feed position was in the middle of the reaction section; the reflux ratio was 1. The dimethylglyoxal aqueous solution (containing 1.66% dimethylglyoxal) was collected from the top of the column at a rate of 8.15 g / min, and at the same time, the colorless 80% hydrazine hydrate was collected from the bottom of the column at a rate of 36.85 g / min. The analysis showed that the content of 2,3-butanedione dihydrazone was <0.004% (impurity removal rate >99%), and the yield was 100.5%. 2,3-butanedione dihydrazone decomposed to produce hydrazine hydrate.

[0039] Example 3

[0040] The DN40 impurity hydrolysis tower, with a height of 0.8m, is divided into three sections: a 0.3m upper and lower section with ordinary packing (i.e., 3×3θ ring packing, approximately 9 theoretical plates), and a 0.2m middle section filled with 81g of long cylindrical ferric oxide catalyst (specific surface area 90m²). 2 The reaction section ( / g) was controlled by a system pressure of 0.15 MPa, with the temperature raised to 110-113℃ at the bottom and 100-103℃ at the top for hydrolysis. The feed rate of the 65% hydrazine hydrate obtained in Example 1 was controlled to be approximately 45 g / min, with the feed position in the middle of the reaction section; the reflux ratio was 1. A dimethylglyoxal aqueous solution (containing 1.66% dimethylglyoxal) was collected from the top of the column at a rate of 8.15 g / min, while a colorless 80% hydrazine hydrate was collected from the bottom of the column at a rate of 36.85 g / min. Analysis showed that it contained <0.004% 2,3-butanedione dihydrazone (impurity removal rate >99%), with a yield of 100.5%. 2,3-butanedione dihydrazone was decomposed to produce hydrazine hydrate.

[0041] Example 4

[0042] The DN40 impurity hydrolysis tower, with a height of 0.8m, is divided into three sections: a 0.3m upper and lower section with ordinary packing (i.e., 3×3θ ring packing, approximately 9 theoretical plates), and a 0.2m middle section filled with 95g of spherical alumina catalyst (specific surface area 100m²). 2 / g) was used as the reaction section. The control system pressure was 0.1 MPa, and the temperature was raised to 102-105℃ at the bottom of the column and 95-100℃ at the top of the column for hydrolysis reaction. The feed rate of 65% hydrazine hydrate obtained in Example 1 was controlled to be about 45 g / min, and the feed position was in the middle of the reaction section; the reflux ratio was 1. The dimethylglyoxal aqueous solution (containing 1.66% dimethylglyoxal) was collected from the top of the column at a rate of 8.15 g / min, and at the same time, the colorless 80% hydrazine hydrate was collected from the bottom of the column at a rate of 36.85 g / min. The analysis showed that it contained 2,3-butanedione dihydrazone <0.006% (impurity removal rate >98.77%), and the yield was 100.5%. 2,3-butanedione dihydrazone decomposed to produce hydrazine hydrate.

[0043] Example 5

[0044] The DN40 impurity hydrolysis tower, with a height of 0.9m, is divided into three sections: the upper section is a 0.4m section of ordinary packing (i.e., 3×3θ ring packing, approximately 12 theoretical plates); the lower section is a 0.3m section of ordinary packing (i.e., 3×3θ ring packing, approximately 9 theoretical plates); and the middle 0.2m section is filled with 100g of long cylindrical alumina catalyst (specific surface area 90m²). 2 / g) was used as the reaction section. The control system pressure was 0.15 MPa, and the temperature was raised to 110-113℃ at the bottom and 100-103℃ at the top of the column for hydrolysis reaction. The 65% hydrazine hydrate obtained in Example 1 was fed into the column at a position 0.1m above the reaction section (about 3 theoretical plates), with a feed rate of about 45 g / min and a reflux ratio of 1. A dimethylglyoxal aqueous solution (containing 1.66% dimethylglyoxal) was collected from the top of the column at a rate of 8.25 g / min, while a colorless 80% hydrazine hydrate was collected from the bottom of the column at a rate of 36.75 g / min. Analysis showed that it contained <0.005% 2,3-butanedione dihydrazone (impurity removal rate >98.98%), with a yield of 100.5%. 2,3-butanedione dihydrazone was decomposed to produce hydrazine hydrate.

[0045] Example 6

[0046] Using the same feed scheme as in Example 2, the reaction was carried out continuously for 300 hours. The rate and mass of product collected from the top and bottom of the column were recorded every 24 hours. The recorded data are shown in the table below. Figure 1 and 2 The record:

[0047]

[0048]

[0049]

[0050] The reaction tower operated for 313 hours, maintaining a stable impurity removal rate of over 99% and a hydrazine hydrate yield of over 100.5%. The hydrolysis catalyst used exhibited good stability and high reliability.

[0051] Comparative Example 1

[0052] The DN40 impurity hydrolysis tower, with a height of 0.8m, is divided into three sections: a 0.3m upper and lower section with ordinary packing (i.e., 3×3θ ring packing, theoretically 30 plates / meter); and a 0.2m middle section filled with 81g of weakly acidic cation exchange resin D113 catalyst as the reaction section. The control system pressure is 0.15MPa, and the temperature is raised to 110-113℃ at the bottom and 100-103℃ at the top for the hydrolysis reaction. The feed rate of the 65% hydrazine hydrate obtained in Example 1 was controlled to be approximately 45 g / min, and the feed position was in the middle of the reaction section; the reflux ratio was 1, and the dimethylglyoxal aqueous solution (containing <0.1% dimethylglyoxal) was collected from the top of the column at a rate of 8.44 g / min, while the bottom of the column collected 80% hydrazine hydrate without pale yellow color at a rate of 36.56 g / min. The analysis showed that it contained 0.49% 2,3-butanedione dihydrazone (removal rate <0.5%), with a yield of 99.99%, and no decomposition of 2,3-butanedione dihydrazone to produce hydrazine hydrate was observed.

[0053] Ordinary weakly acidic cation exchange resins are not effective in hydrolyzing impurities, and the hydrazine hydrate produced in the bottom of the tower is pale yellow.

[0054] Comparative Example 2 (WO2018065997A1)

[0055] The 65% hydrazine hydrate obtained in Example 1 was continuously distilled into a DN40 distillation column. The column was maintained under vacuum of 180 mmHg, with a top temperature of 58-62°C and a bottom temperature of 65-70°C. The feed rate was controlled at 38 g / min. Refined hydrazine hydrate was continuously collected from the top at 32 g / min, and the distillate was continuously collected from the bottom at 6 g / min. The composition of the top and bottom solutions was periodically analyzed, and the data obtained are as follows:

[0056] Sampling point Hydrazine hydrate content 2,3-Butanedione hydrazone Column top 57.83％ 0％ Column bottom 103.2％ 2.53％

[0057] The analysis showed that the hydrazine hydrate content in the bottom of the distillation column was 103.2%, indicating that anhydrous hydrazine had already been produced. 51g of the bottom residue was cooled to 20℃ and filtered to obtain 2.34g of filter cake (55% dimethylglyoxaloacetate, 50.4% hydrazine hydrate (the presence of anhydrous hydrazine caused the total content to exceed 100%)). The mother liquor was reused for the next distillation. The yield of 2.34g of residue, converted to 80% hydrazine hydrate, was 0.0089t / t.

[0058] Comparative Example 3

[0059] The DN40 impurity hydrolysis tower, with a height of 0.9m, is divided into three sections: the upper section is a 0.3m section of ordinary packing (i.e., 3×3θ ring packing, approximately 9 theoretical plates); the lower section is a 0.4m section of ordinary packing (i.e., 3×3θ ring packing, approximately 12 theoretical plates); and the middle 0.2m section is filled with 81g of spherical alumina catalyst (specific surface area 100m²).2 / g) was used as the reaction section. The control system pressure was 0.15 MPa, and the temperature was raised to 110-113℃ at the bottom of the column and 100-103℃ at the top of the column for hydrolysis reaction. The feed position was 0.1m below the reaction section (about 3 theoretical plates). The feed rate of 65% hydrazine hydrate obtained in Example 1 was controlled to be about 45 g / min, with a reflux ratio of 1. The dimethylglyoxal aqueous solution (containing <0.01% dimethylglyoxal) was collected at the top of the column at a rate of 8.44 g / min, while the colorless 80% hydrazine hydrate was collected at the bottom of the column at a rate of 36.56 g / min. Analysis showed that it contained <0.47% 2,3-butanedione dihydrazone (impurity removal rate <5%), with a yield of 99.99%. No decomposition of 2,3-butanedione dihydrazone to produce hydrazine hydrate was observed.

[0060] The feed location is below the reaction section where the hydrolysis catalyst is located, so the hydrolysis catalyst cannot come into contact with 2,3-butanedione dihydrazone and has no hydrolysis effect.

[0061] Comparative Example 4

[0062] The DN40 impurity hydrolysis tower, with a height of 0.9m, is divided into three sections. The upper section is a 0.5m section of ordinary packing (i.e., 3×3θ ring packing, approximately 15 theoretical plates), and the lower section is a 0.2m section of ordinary packing (i.e., 3×3θ ring packing, approximately 6 theoretical plates). The middle 0.2m section is filled with 81g of spherical alumina catalyst (specific surface area 100m²). 2 / g) was used as the reaction section. The control system pressure was 0.15 MPa, and the temperature was raised to 110-113℃ at the bottom and 100-103℃ at the top of the column for hydrolysis reaction. The feed position was 0.2m above the reaction section (about 6 theoretical plates). The feed rate of 65% hydrazine hydrate obtained in Example 1 was controlled to be about 45 g / min, with a reflux ratio of 1. The dimethylglyoxal aqueous solution (containing <0.56% dimethylglyoxal) was collected at the top of the column at a rate of 8.38 g / min, while the colorless 80% hydrazine hydrate was collected at the bottom of the column at a rate of 36.62 g / min. Analysis showed that it contained <0.32% 2,3-butanedione dihydrazone (impurity removal rate 34.98%), with a yield of 100.16%. A small amount of 2,3-butanedione dihydrazone decomposed to produce hydrazine hydrate.

[0063] The feed location is located on the upper side of the reaction section where the hydrolysis catalyst is located, and there are many trays. The hydrolysis effect of 2,3-butanedione dihydrazone is reduced. This is mainly because the butanedione released in the reaction moves to the top of the column and reacts again with hydrazine hydrate in the feed to generate 2,3-butanedione dihydrazone.

[0064] This invention hydrolyzes the impurity 2,3-butanedione dihydrazone through a catalytic reactive distillation process to obtain hydrazine hydrate and butanedione. In Example 2, the removal rate of 2,3-butanedione dihydrazone reached over 98%, and the actual yield of hydrazine hydrate was 100.5% due to the hydrolysis of the impurity, resulting in significant economic benefits. The elimination of additional distillation operations for hydrazine hydrate avoids the presence of anhydrous hydrazine, improving process safety and reducing energy consumption.

[0065] The above examples are merely illustrative of the technical concept and features of the present invention and should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the essence of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for removing impurities in the preparation of hydrazine hydrate using hydrogen peroxide, characterized in that: The dilute hydrazine produced by the hydrogen peroxide method for preparing hydrazine hydrate is concentrated and fed into the feed position of a catalytic reaction distillation column filled with hydrolysis catalyst to hydrolyze the impurities, thereby removing impurities from the hydrogen peroxide method for preparing hydrazine hydrate. The hydrolysis catalyst is one or more of aluminum oxide, titanium dioxide, zinc oxide, ferric oxide, and copper oxide; The feed location is no more than four theoretical plates above or in the middle of the location of the hydrolysis catalyst. The catalyst-filled reactive distillation column is a packed column with 15-30 theoretical plates. The hydrolysis catalyst has 5-15 theoretical plates above the position of the catalytic reaction distillation column and 5-15 theoretical plates below the position of the hydrolysis catalyst.

2. The method for removing impurities in the preparation of hydrazine hydrate using the hydrogen peroxide method according to claim 1, characterized in that: The amount of catalyst used is 0.01-0.2 times the feed mass of concentrated hydrazine hydrate per hour.

3. The method for removing impurities in the preparation of hydrazine hydrate using the hydrogen peroxide method according to claim 1, characterized in that: The hydrolysis catalyst is in the form of spheres or long cylinders, with a specific surface area of ​​80-120 m². 2 / g.

4. The method for removing impurities in the preparation of hydrazine hydrate using the hydrogen peroxide method according to claim 1, characterized in that: The concentration of hydrazine hydrate after concentration is 40%-80%.

5. The method for removing impurities in the preparation of hydrazine hydrate using the hydrogen peroxide method according to claim 1, characterized in that: The temperature of the bottom of the catalytic distillation column is 90-150℃, and the reaction pressure is 0.1-0.5 MPa.

6. The method for removing impurities in the preparation of hydrazine hydrate using the hydrogen peroxide method according to claim 1, characterized in that: The reflux ratio at the top of the catalytic reactive distillation column is 0.5-5.

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