KR101777605B1 - Recrystallization method of hydrazinium nitroformate - Google Patents

Abstract

The present invention relates to a recrystallization method of hydrazinium hydrate (HNF), and more particularly, to a recrystallization method for controlling the shape and particle size of nitroform hydrazine crystals. In order to accomplish the above object, the present invention provides a method for preparing a nitroform hydrazine solution, comprising the steps of: preparing a nitroform hydrazine solution having a concentration of 16 to 20 mass% using acetonitrile as a solvent; introducing a predetermined volume of non-solvent into the nitroform hydrazine solution at a predetermined rate; And a step of recrystallizing the nitroform hydrazine by cooling the mixed solution of the nitroform hydrazine solution and the non-solvent, thereby providing a method for recrystallization of nitroform hydrazine.

Description

RECRECIALLIZATION METHOD OF HYDRAZINIUM NITROFORMATE OF NITROFORM HYDRAZINE [0002]

The present invention relates to a recrystallization method of hydrazinium hydrate (HNF), and more particularly, to a recrystallization method for controlling the shape and particle size of nitroform hydrazine crystals.

Perchloroammonium (AP) is the most commercially available rocket propellant because of its economical, good performance and many other explosive advantages. However, when decomposed, a large amount of hydrochloric acid (HCl) gas is generated, It has disadvantages. Accordingly, nitroform hydrazine (HNF) is attracting attention as a substitute for perchlorammonium (AP).

Nitroform hydrazine (HNF) is environmentally friendly and has a high density of 1.86 g · cm ^-1 or higher. It was first synthesized by Hanzsch, a German chemist more than 110 years ago. However, due to the following problems, Respectively.

The nitrile hydrazine (HNF) crystal obtained in the synthesis process is irregular in shape of a plate or a needle. Such a nitroform hydrazine (HNF) crystal has poor filling density and instability, and workability is very bad due to its sensitivity to stability.

In order to solve the above problem, many researches related to recrystallization of nitroform hydrazine (HNF) are under way.

It is an object of the present invention to provide a recrystallization method of nitroform hydrazine capable of producing nitroform hydrazine (HNF) having a particle size of not more than a predetermined size and an aspect ratio of particles of not more than a predetermined value.

In order to accomplish the above object, the present invention provides a method for preparing a nitroform hydrazine solution, comprising the steps of: preparing a nitroform hydrazine solution having a concentration of 16 to 20 mass% using acetonitrile as a solvent; introducing a predetermined volume of non-solvent into the nitroform hydrazine solution at a predetermined rate; And a step of recrystallizing the nitroform hydrazine by cooling the mixed solution of the nitroform hydrazine solution and the non-solvent, thereby providing a method for recrystallization of nitroform hydrazine.

In one embodiment, the predetermined volume is 0.4 to 0.6 times the volume of the solvent.

In one embodiment, the non-solvent is 1,2-dichloroethane.

In one embodiment, the predetermined rate is 8 to 12 ml / min.

In one embodiment, the step of recrystallizing the nitroform hydrazine is characterized in that the mixed liquid is cooled at a cooling rate of 1 ^° C / min.

In one embodiment, the step of recrystallizing the nitroform hydrazine is characterized in that the mixed liquid is stirred by an ultrasonic stirrer.

According to the present invention, it is possible to produce nitroform hydrazine (HNF) having a particle size of not more than a predetermined size and an aspect ratio of particles of not more than a predetermined value, and to manufacture a rocket propellant having a high packing density.

1 is an electron micrograph (SEM) photograph of nitroform hydrazine (HNF) by conventional recrystallization.
2 is a scanning electron micrograph (SEM) photograph of a nitroform hydrazine (HNF) particle prepared by a recrystallization method according to the present invention.
3 is a scanning electron micrograph (SEM) photograph of a nitroform hydrazine (HNF) particle produced by an ultrasonic stirrer according to a recrystallization method according to the present invention.

Hereinafter, an embodiment of the present invention will be described in detail. In the present specification, different embodiments are given the same or similar reference numerals, and the description thereof is replaced with the first explanation. As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

There is a process developed by TNO (hereinafter referred to as TNO process) for the synthesis of nitroform hydrazine (HNF). The TNO process involves the transfer of nitroform to 1,2-dichloroethane by the addition of sodium chloride to an aqueous solution of nitroform and subsequent reaction with hydrazine (N2H4) in 1,2-dichloroethane to form nitroform hydrazine (HNF ). Nitroform hydrazine (HNF) is then dried and washed, with a purity of 99-100%.

In the recrystallization process of precipitated nitroform hydrazine (HNF), TNO is used for the crystallization (HNF-C), solvent / non-solvent crystallization (HNF-S), evaporative crystallization (HNF-E), hydrazine (N2H4) (HNF-P) by adding it to a mixture of foam and 1,2-dichloroethane. Table 1 shows the physical properties of HNF according to the recrystallization process.

division HNF-C HNF-E HNF-P HNF-S Melting point, ℃ > 116 > 115 > 115 > 115 pH 4.1-4.9 4.3 ~ 5 3.8 to 4.5 4.3 ~ 4.8 D _mean , 탆 400 to 900 500 300 50 to 150 L / D <8 3 to 15 1-4 1-5 ρ _tap , kg / m ³ 800-1000 - - 400 to 600 BAM friction [N / m] 16 to 36 - - 16 to 36 BAM Impact [N] 2 to 4 - - 2 to 4 Appearance yellow
facetted yellow
needle yellow
rod diamond-shape
rod

Nitroform hydrazine (HNF), on the other hand, consists of ionic bonds between cations and anions in salt form. X-ray analysis showed that the crystal structure was monoclinic (α, γ = 90, β ≠ 90), which grows in one direction on the molecular structure. Due to such molecular structural properties, the growth habit of nitroform hydrazine (HNF) crystals is obtained in the form of needle crystals in most of its solvents.

When nitroform hydrazine (HNF) is used as an oxidizing agent for solid rocket propellants, the proportion of nitroform hydrazine (HNF) particles in the propellant composition is about 80% or more. When the aspect ratio (L / D) of the nitroform hydrazine (HNF) particles is about 4 to 5, it has a needle-like structure, and it is very difficult to charge these needle-shaped particles at about 80% or more in the propellant composition.

This is because a high tap density or bulk density can not be obtained with the needle-shaped particles. Accordingly, when nitroform hydrazine (HNF) is used in the propellant composition, the smaller the aspect ratio (L / D) of the nitroform hydrazine (HNF) particle is, the better.

In addition, since nitroform hydrazine (HNF) is easily broken and decomposed by friction, in order to lower the friction sensitivity and improve the flowability in the process of manufacturing the propellant composition, the size of the nitroform hydrazine (HNF) And the aspect ratio (L / D) are smaller.

The recrystallization method according to the present invention provides a recrystallization method for producing nitroform hydrazine (HNF) having a predetermined aspect ratio and particle size using a solvent / non-solvent crystallization method.

Hereinafter, the recrystallization method according to the present invention will be described in more detail.

First, in the recrystallization method according to the present invention, a step of preparing a nitroform hydrazine solution having a concentration of 16 to 20 mass% using acetonitrile as a solvent is performed.

In the solvent / non-solvent crystallization method, the shape of the crystal is mainly influenced by the molecular structure of the crystalline material, the nature of the solvent, the nature of the non-solvent and the crystallization operating conditions (crystallization temperature, supersaturation degree, cooling rate).

In particular, the molecular structure of the nitropo-hydrazine (HNF) crystal has inherent growth mechanism after nucleation, so that the intramolecular attraction of the nitropo-hydrazine (HNF) crystal and the intermolecular attraction are controlled by solubility and supersaturation of the nitropo-hydrazine (HNF) Crystal shape adjustment can be realized.

The size and size distribution of the crystals are highly dependent on the initial supersaturation during the crystallization process. In addition, the initial supersaturation can be controlled by the ratio of solvent / non-solvent, as well as depending on the non-solvent feed rate, injection amount, crystallization temperature and solution concentration. At this time, the concentration of the nitroform hydrazine solution may be 16 to 20 mass%.

Meanwhile, the recrystallization method of nitroform hydrazine (HNF) according to the present invention is based on using acetonitrile (ACN) as a solvent. The solubility of nitroform hydrazine (HNF) to acetonitrile (ACN) is 28.56 g at 26 ^° C and 55.71 g at 60 ^° C and is relatively temperature dependent. In addition, since the polarity of acetonitrile (ACN) has a high value of 6.2, it can be effectively applied in the case where the non-solvent having a polarity of 0 is injected at a rate of water.

Next, a step of introducing a predetermined volume of non-solvent into the nitroform hydrazine solution at a predetermined rate, cooling the mixed solution of the nitroform hydrazine solution and the non-solvent, and recrystallizing the nitroform hydrazine is performed.

The non-solvent may be any one of 1,2-dichloroethane, hexane, and dichloromethane. Preferably, the non-solvent may be 1,2-dichloroethane.

The higher the injection rate of the non-solvent, the smaller the size and the aspect ratio of the nitroform hydrazine particles. However, when the rate is higher than the constant injection rate, the size of the nitroform hydrazine particle becomes larger. Thus, the preferred rate is 8-12 ml / min.

Meanwhile, the mixed solution can be cooled at a cooling rate of 1 ^o C / min.

On the other hand, the mixed liquid of mixing the non-solvent with the nitroform hydrazine solution may be stirred with a stirrer. Particularly, when the mixed solution is stirred by an ultrasonic stirrer, a relatively small particle size of nitroform hydrazine can be obtained as compared with other kinds of stirrers.

In summary, the solvent / non-solvent crystallization method according to the present invention is characterized in that the solvent is directly added to a saturated solution of nitropo-hydrazine (HNF) to form nuclei, and then crystals are grown at the same temperature, A nitroform hydrazine crystal having an aspect ratio of particles of 2 or less can be obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. However, the scope and contents of the present invention are not construed to be limited or limited by the following Examples and Experimental Examples.

Example 1

The inside of the reactor was maintained at 60 ^° C and 139.25 g of nitroform hydrazine (HNF) was mixed with 250 ml of acetonitrile (ACN), and a saturated solution was prepared.

The reaction solution was stirred through a propeller type impeller to form nitroform hydrazine (HNF) crystals. When all of the solute was dissolved, it was cooled to 10 ^° C at a cooling rate of 1 ^° C per minute. The resulting crystals were filtered and washed with 50 ml of methanol. The shape of the obtained crystals was a bar size with an aspect ratio of 1: 4, and the average grain size of the crystals was 521 microns. The yield of crystallized nitroform hydrazine (HNF) was about 57% by weight.

Recrystallization was carried out by the same method as in Example 1 except that the type of stirring and the impeller were varied. The results are shown in Table 2 below.

Example Type of stirring Impeller Average particle size (microns) Average aspect ratio
(Aspect ratio) 2 Magnetic cross 528 1: 4 3 Mechanical Clover type 564 1: 4 4 Mechanical Turbine type 487 1: 4 5 Ultrasonic - 67 1: 3

Carried out by the same method as in Example 1, acetonitrile (ACN) then was raised to 60 ^o C after having added a variety of the weight of the nitro form of hydrazine (HNF) in 250ml produce a saturated solution, 10 ^o C per minute 1 ^o C. The results are shown in Table 3. The results are shown in Table 3.

Example Starting concentration
(weight %) yield
(weight%) Average particle size (microns) Average aspect ratio
(Aspect ratio) 6 36 88 748 1: 6 7 22 74 627 1: 3 8 15 69 357 1: 3

In the recrystallization by the same method as in Example 8, recrystallization experiments were carried out by changing the type of non-solvent, and the results are shown in Table 4.

Example Cost type Injection rate
(ml / min) Average particle size (microns) Average aspect ratio
(Aspect ratio) 9 Hexane 10 554 1: 4 10 Dichloromethane 10 1,000 or more 1:11 11 1,2-Dichloroethanes 10 523 1: 3.5

 In the recrystallization by the same method as in Example 11, recrystallization experiments were carried out by varying the volume ratio of the non-solvent, and the results are shown in Table 5.

Example Amount of solvent
(ml) Costs
(ml) Average particle size (microns) Average aspect ratio
(Aspect ratio) 12 125 250 1,000 or more 1: 9 13 125 125 749 1: 8 14 125 83.3 524 1: 3 15 125 62.5 468 1: 2

In the recrystallization by the same method as in Example 15, recrystallization experiments were carried out by changing the feeding rate of the non-solvent and the results are shown in Table 6.

Example Expense Injection rate
(ml / min) Average particle size (microns) Average aspect ratio
(Aspect ratio) 16 1,2-Dichloroethanes 3 1,000 or more 1: 7 17 1,2-Dichloroethanes 5 642 1: 4 18 1,2-Dichloroethanes 10 474 1: 3 19 1,2-Dichloroethanes 15 496 1: 3

In the recrystallization by the same method as in Example 18, recrystallization experiments were carried out by changing stirring speed and the results are shown in Table 7.

Example Expense Stirring speed
(rpm) Average particle size (microns) Average aspect ratio
(Aspect ratio) 20 1,2-Dichloroethanes 150 542 1: 7 21 1,2-Dichloroethanes 300 610 1: 5 22 1,2-Dichloroethanes 500 745 1: 3

After the addition of various amounts of nitroform hydrazine (HNF) by the same method as in Example 21, the temperature was raised up to the saturation concentration to produce a saturated solution, and then the non-solvent was added to recrystallize. The results are shown in Table 8.

Example Starting concentration
(weight %) Saturation temperature
( ^o C) Average particle size (microns) Average aspect ratio
(Aspect ratio) 23 31 50 412 1: 3 24 26 45 354 1: 2 25 18 25 225 1: 2

Claims (6)

Preparing a nitroform hydrazine solution at a concentration of 16 to 20 mass% using acetonitrile as a solvent; And
A predetermined volume of non-solvent is added to the nitroform hydrazine solution at a rate of 8 to 12 ml / min, the mixture is stirred with an ultrasonic stirrer while the non-solvent is added,
Cooling the mixed solution of the nitroform hydrazine solution and the non-solvent at a cooling rate of 1 占 폚 / min to recrystallize the nitroform hydrazine. The method according to claim 1,
Wherein the predetermined volume is 0.4 to 0.6 times the volume of the solvent. 3. The method of claim 2,
Lt; RTI ID = 0.0 &gt; 1, &lt; / RTI &gt; wherein the non-solvent is 1,2-dichloroethane. delete delete delete

Images