KR20190040584A - Method and apparatus for producing high purity nitric oxide for semiconductor using the nitric acid production process - Google Patents

Abstract

The present invention relates to a method and an apparatus for manufacturing high purity nitrogen monoxide for a semiconductor, wherein the method for manufacturing high purity nitrogen monoxide according to the present invention comprises steps of: (a) supplying a mixed gas produced in a nitric acid manufacturing process for manufacturing a nitric acid by oxidizing ammonia and containing low purity nitrogen monoxide; (B) separating and purifying the mixed gas using the boiling point difference; and (c) adsorbing and purifying the separated and purified mixed gas by using an adsorbent.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high purity nitric oxide (NO.sub.3)

The present invention relates to a method and an apparatus for producing high purity nitrogen monoxide for semiconductor, and more particularly, to a method for producing high purity nitrogen monoxide from a mixed gas containing low purity nitrogen monoxide, which is a mass- ≪ / RTI >

The thickness of an insulating film such as an oxide film which is formed as a film on a semiconductor element in accordance with the highly integrated semiconductor device tends to be gradually thinned. When impurities penetrate into such a thin insulating film, the electrical characteristics of the semiconductor device are deteriorated.

In order to overcome such a problem, a method of forming a nitride film by depositing nitrogen (N) ions in an insulating film such as an oxide film has been developed and used. Such a nitride film can prevent a hot carrier effect caused by driving the device and impurity penetration such as boron by a subsequent heat treatment.

As a method of forming such a nitride film, there is an oxidation method using a gas such as ammonia (NH ₃ ), nitrogen monoxide (NO), or nitrous oxide (N ₂ O).

Among these gases, nitrous oxide (N ₂ O), which is easy to handle in the process and has excellent oxidative properties, is widely used, but when nitrous oxide is photo-decomposed by a lamp in a separate chamber before being introduced into a semiconductor manufacturing process chamber, Nitrogen (NO) and nitrogen (N) are recombined with each other and the amount of energy loss is increased as shown in the formula (1), so nitrogen (N) generated by photolysis of the nitrogen monoxide gradually is directly used.

[Chemical Formula 1]

N ₂ O + hv? NO + 1 / 2N ₂ ? N ₂ O + NO + N ₂

(Where h is Planck's constant and v is the frequency of the photons)

In addition, the nitrogen monoxide generates oxygen (O ₂ ) reaction radicals having a large amount of oxidation reactivity in the chamber of a high-temperature semiconductor manufacturing process for forming an oxide film, And can greatly contribute to the yield and productivity of the oxide film-forming semiconductor process.

(2)

_{4NO → N 2 O 3 + N} 2 O

N ₂ O ₃ → N ₂ + 3 / 2O ₂

N ₂ O → N ₂ + 1 / 2O ₂

Nitrogen monoxide is required to have high purity in order to prevent recombination after decomposition and to prevent defects of semiconductor wafers due to impurities in the semiconductor manufacturing process application.

Such a method for producing high purity nitrogen monoxide for semiconductors is disclosed in the following prior art documents. According to this process, sodium nitrite (NaNO ₂ ) and sulfuric acid (H ₂ SO ₄ ) are added to the reactor and mixed with stirring by a stirrer to produce nitrogen monoxide. The reaction is as follows.

(3)

3NaNO ₂ + H ₂ SO ₄ ? Na ₂ SO ₄ + NaNO ₃ + 2NO + H ₂ O

However, such a conventional method for producing nitrogen monoxide is an excess investment method for application as a small amount of manufacturing method, and it takes a lot of cost investment and production cost in mass production, and the supply price is high. Semiconductor manufacturers have a limited problem in expanding production applications of the semiconductor oxide film process due to expensive high purity nitrogen monoxide using such conventional manufacturing methods.

Accordingly, there is a desperate need for a solution to the problems of the conventional method of producing nitrogen monoxide.

KR 10-1257794 B1

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the prior art described above. One aspect of the present invention is to continuously produce high purity nitrogen monoxide using a large amount of industrial low purity nitrogen monoxide produced as a reactant for nitric acid production in the nitric acid production process And a device for applying the same.

Another aspect of the present invention is a method for purifying nitric acid, comprising the steps of separating and purifying a mixed gas containing low purity nitrogen monoxide produced in a nitric acid production process using a boiling point difference, and performing an adsorption process using the adsorbent again, To provide a method and an apparatus for producing high purity nitrogen monoxide having a purity of 99.999% or more, which is applicable to semiconductor manufacturing.

The method for producing high purity nitrogen monoxide according to the present invention comprises the steps of: (a) supplying a mixed gas produced in a nitric acid production process for producing nitric acid by oxidizing ammonia and containing low purity nitrogen monoxide; (b) separating and purifying the mixed gas using a boiling point difference; And (c) adsorbing and purifying the separated and purified mixed gas using an adsorbent; .

Further, in the method for producing high purity nitrogen monoxide according to the present invention, cooling, condensing and purifying the mixed gas by cooling, gas-liquid separation, and cooling are performed between the step (a) and the step (b).

Further, in the method for producing high purity nitrogen monoxide according to the present invention, the step (b) may include the steps of removing high boiling point impurities relatively higher in boiling point than the nitrogen monoxide gas from the mixed gas using the first distillation column; And removing the low boiling point impurities relatively low in boiling point from the mixed gas from which the high boiling point impurities have been removed by using the second distillation column.

Also, in the method for producing high purity nitrogen monoxide according to the present invention, a step of compressing, cooling, condensing and purifying the mixed gas from which the low boiling point impurities have been removed is performed between the step (b) and the step (c). .

In addition, in the method for producing high purity nitrogen monoxide according to the present invention, the step (c) may be carried out by using a pair of adsorption towers each having the adsorbent disposed therein, alternately adsorbing the impurities in any one of the first adsorption towers And the adsorbent is heated and regenerated in the other second adsorption column.

Further, in the method for producing high-purity nitrogen monoxide according to the present invention, the step (c) further includes cooling and storing the adsorbed and purified mixed gas.

Meanwhile, the apparatus for producing high purity nitrogen monoxide according to the present invention comprises: a supply unit for supplying a mixed gas produced in a nitric acid production process for producing nitric acid by oxidizing ammonia, the gas mixture containing low purity nitrogen monoxide; A distillation section comprising at least one distillation column including a reboiler, a column, and a cooler, the distillation section purifying the mixed gas using a boiling point difference; And at least one adsorption column in which an adsorbent is disposed, wherein the adsorption unit adsorbs and purifies the purified gas mixed in the distillation unit.

Further, in the apparatus for producing high purity nitrogen monoxide according to the present invention, the distillation section may be arranged such that the distillation columns are separated and arranged in pairs, and one of the first distillation columns receives the mixed gas from the supply section, The second distillation tower, which is the other one, receives the purified mixed gas from the first distillation column and removes low boiling point impurities relatively low in boiling point than the nitrogen monoxide.

Further, in the apparatus for producing high purity nitrogen monoxide according to the present invention, the adsorption section may further include a heating section in which a pair of adsorption towers are separately arranged and each of the adsorption towers is heated, The first adsorption tower, which is one of the adsorption towers, adsorbs and purifies the mixed gas, and the second adsorption tower regenerates the adsorbent.

Further, in the apparatus for producing high purity nitrogen monoxide according to the present invention, a first cooling chiller for cooling the mixed gas supplied from the supply unit and condensing the impurities; And a gas-liquid separator for separating the mixed gas in the gaseous phase from the impurities in the condensed liquid phase and supplying the gaseous mixture gas to the first distillation column.

Further, in the apparatus for producing high purity nitrogen monoxide according to the present invention, a compressor for supplying and compressing the mixed gas from the distillation section; And a second cooling chiller that receives and compresses the mixed gas compressed from the compressor to condense and remove impurities and supply the mixed gas to the adsorption unit.

Further, in the apparatus for producing high purity nitrogen monoxide according to the present invention, a cooling tank for receiving the mixed gas from the adsorption unit and cooling and storing the mixed gas at a predetermined temperature is further included.

Further, in the apparatus for producing high purity nitrogen monoxide according to the present invention, the cooling tank may include: a tank unit having a storage space therein so as to store the mixed gas; An injection tube for injecting the mixed gas into the accommodation space; A cooling jacket having a hollow through which the first refrigerant flows, the cooling jacket surrounding the outer surface of the tank; And a cooling tube which is formed in a spiral tube shape and in which the second refrigerant flows and which is disposed in the accommodation space.

The features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings.

Prior to that, terms and words used in the present specification and claims should not be construed in a conventional and dictionary sense, and the inventor may properly define the concept of the term in order to best explain its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

According to the present invention, a large amount of low-purity nitrogen monoxide produced in a commercial production process of industrial nitric acid can be purified to continuously mass-produce high purity nitrogen monoxide for semiconductors, thereby reducing the investment cost of the reaction process equipment required in the prior art can do.

In addition, the mixed gas produced after the ammonia oxidation reaction in the nitric acid production process is separated and purified to produce nitrogen monoxide having a purity of 99.98% or more, and again, 99.999% or more of high purity nitrogen monoxide is produced through the adsorption process. Thereby reducing production costs.

Further, the production cost reduction of the high purity nitrogen monoxide according to the present invention can lead to an increase in production efficiency and an increase in application in the semiconductor oxide film production process.

1 and 2 are flowcharts of a method for producing high purity nitrogen monoxide according to an embodiment of the present invention.
3 is a flow chart of a method for producing high purity nitrogen monoxide according to another embodiment of the present invention.
FIG. 4 is a schematic view showing a high purity nitrogen monoxide nitrogen producing apparatus according to the present invention.
5 is a cross-sectional view schematically showing a cross section of the cooling tank shown in Fig.

BRIEF DESCRIPTION OF THE DRAWINGS The objectives, specific advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. It should be noted that, in the present specification, the reference numerals are added to the constituent elements of the drawings, and the same constituent elements are assigned the same number as much as possible even if they are displayed on different drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the present invention, detailed description of related arts which may unnecessarily obscure the gist of the present invention will be omitted.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 are flowcharts of a method for producing high purity nitrogen monoxide according to an embodiment of the present invention.

As shown in FIG. 1, the method for producing high purity nitrogen monoxide according to the present invention comprises the steps of: (a) supplying a mixed gas generated in a nitric acid production process for producing nitric acid by oxidation of ammonia, S100), (b) separating and purifying the mixed gas using the boiling point difference (S200), and (c) adsorbing and purifying the separated and purified mixed gas using the adsorbent (S300).

The present invention relates to a process for producing high purity nitrogen monoxide. In order to form an oxide film on a semiconductor element in a semiconductor manufacturing process, nitrogen monoxide is used, and high purity is required in order to prevent semiconductor wafer defects due to recombination after decomposition and impurities. Conventionally, sodium nitrite (NaNO ₂ ) and sulfuric acid (H ₂ SO ₄ ) were stirred to produce high purity nitrogen monoxide for semiconductors. However, this method requires a lot of cost investment and production cost in mass production as a small amount of manufacturing method, As a solution to this problem, a method for producing high purity nitrogen monoxide according to the present invention has been found.

Specifically, the method for producing high purity nitrogen monoxide according to the present invention includes a mixed gas supply step (S100), a separation purification step (S200), and an adsorption purification step (S300).

First, in the mixed gas supply step (S100), nitrogen monoxide generated in the commercial nitric acid production process is separated and supplied to a separation and purification step (S200) to be described later.

In general, the commercial production process of industrial nitric acid is based on the Ostwald process, which can be divided into three main process steps:

Ⅰ: Ammonia oxidation step

4NH ₃ (g) + 5O ₂ (g)? 4NO (g) + 6H ₂ O (g)

II: Nitric Oxide Oxidation and Nitric Oxide Dimerization Step

_{2NO (g) + O 2 (} g) → 2NO 2 (g)

_{2NO 2 (g) → N 2} O 4 (g)

III: Nitrogen absorption step

3N ₂ O ₄ (g) + 2H ₂ O (1)? 4HNO ₃ (aq) + 2NO (g)

According to this method, nitrogen monoxide is produced by high-temperature oxidation of ammonia under a noble metal catalyst, wherein the generated nitrogen monoxide is converted to a nitrogen dioxide complex such as nitrogen tetroxide through an oxidation process and nitrogen tetraoxide reacts with water to produce nitric acid do. At this time, the produced silver nitrate silver concentration is 50 to 69% by weight, and if necessary, the concentration step is further performed to produce 90 to 98% by weight of nitric acid.

In the present invention, a high purity nitrogen monoxide is produced by using a part of the flow of nitrogen monoxide generated by the high temperature oxidation of ammonia in the industrial nitric acid production process, a separation purification step (S200), an adsorption purification step (S300) The bar and mixed gas supply step (S100) may be executed in connection with the nitric acid production process. On the other hand, in the mixed gas supply step (S100), nitrogen monoxide is supplied in the form of a mixed gas mixed with other impurities with low purity. That is, the mixed gas generated after the ammonia oxidation step in the nitric acid production step or after the nitric acid production is mixed with nitrogen monoxide together with impurities, and the mixed gas is supplied. These mixed gases include nitrogen monoxide, nitrous oxide, nitrogen dioxide, moisture, unreacted ammonia and the like in addition to air. Among them, moisture and nitrous oxide are contained in a large amount, and therefore, low purity nitrogen monoxide here is not suitable for direct use for semiconductors.

Meanwhile, in order to receive and supply the mixed gas from the nitric acid production process, a part of the mixed gas produced in the nitric acid production process is separately stored and used, or a separate supply pipe is connected to the piping facility in which the mixed gas flows in the nitric acid production process, And a valve may be provided to separate a portion of the mixed gas flow at the top of the nitric acid generator and directly use it.

As described above, the present invention does not produce low purity nitrogen monoxide through a separate process but uses low purity nitrogen monoxide which is mass-produced for the purpose of producing nitric acid in an industrial nitric acid production process, To produce a continuous and high-purity nitrogen monoxide.

When the mixed gas is separately supplied in the nitric acid production process, the separation and purification step (S200) is performed. Since the constituents of the mixed gas have different boiling points, in the separation purification step (S200), impurities other than nitrogen monoxide can be removed using the boiling point difference of each component. At this time, the main impurities to be removed are moisture, nitrous oxide, nitrogen dioxide, unreacted ammonia, nitrogen, oxygen and the like. Such separation purification can be carried out using at least one or more distillation columns. The distillation column includes a reboiler, a column, and a cooler, and its structure and function correspond to the conventional knowledge of the present invention, and a description thereof will be omitted.

On the other hand, for example, the separation and purification step (S200) can perform a two-step separation and purification process using a pair of distillation columns. Specifically, high boiling point impurities are removed from the first distillation column of one of the pair of distillation columns, and low boiling point impurities are continuously removed from the other second distillation column. The boiling point of nitrogen monoxide is about -151.8 ° C. Relatively, nitrogen dioxide, unreacted ammonia, water and the like, including nitrous oxide having a boiling point of approximately -88.8 ° C, have boiling points higher than nitrogen monoxide. The components with a higher boiling point than nitrogen monoxide are called high boiling point impurities. On the other hand, among the components of the mixed gas, the components having relatively low boiling points such as nitrogen (boiling point: about -198.5 ° C.) and oxygen (boiling point: about -183 ° C.) are called low boiling point impurities.

Separation purification in the first distillation column proceeds for the purpose of removing high boiling point impurities. As the temperature of the upper cooler is maintained at -85 to -95 ° C. by using liquid nitrogen and the temperature of the lower reboiler is maintained at -60 to- Keep the temperature at 50 ℃ and keep the operating pressure at 3 ~ 5 atm. According to the low temperature distillation method, under such operating conditions, high boiling point impurities are condensed in the lower part of the first distillation column and discharged through the pipe as a liquid phase, and a mixed gas containing nitrogen monoxide is discharged onto the first distillation tower. Here, the discharged mixed gas flows into the second distillation column.

In the second distillation tower, the upper cooler temperature is maintained at -150 to -140 ° C. using liquid nitrogen and the lower reboiler temperature is maintained at -90 to -80 ° C., and low-boiling impurities in the gas phase are removed through the piping connected to the upper portion of the second distillation tower And the mixed gas containing nitrogen monoxide is collected through the lower part of the second distillation tower.

Here, the operation conditions of the distillation column are not necessarily limited to those described above, and the scope of the present invention is not limited by the operation conditions.

While the purity of nitrogen monoxide in the mixed gas gradually increases during the separation and purification process of the two stages, it is not possible to secure a high purity nitrogen monoxide of 99.995% or more, which is required for use in the production of semiconductors. Then, the adsorption purification step (S300) is performed on the mixed gas collected through the lower part of the second distillation tower.

The adsorption purification step (S300) is a step of purifying the mixed gas separated and purified by using an adsorbent. At this time, the adsorbent to be used is determined according to the impurities to be adsorbed and purified. For example, the adsorbent is formed by at least one selected from the group consisting of molecular sieve, activated carbon, silica gel, activated alumina gel, . Preferably, a moire cure sieve having pores capable of adsorbing impurities without absorbing nitrogen monoxide is suitable. Such an adsorbent is disposed in the adsorption tower, and the adsorption purification process can be performed using at least one adsorption tower.

In the present invention, the adsorption purification step and the regeneration step may be performed at the same time. Here, the regeneration step regenerates the adsorbent reacting with the impurities, and the adsorbent may be heated to a predetermined temperature. Specifically, a pair of adsorption towers in which the adsorbent is disposed are used, and during the adsorption and purification of the impurities in the first adsorption tower, the adsorbent is regenerated in the second adsorption tower. Here, the adsorption purification step and the regeneration step alternate between the first adsorption tower and the second adsorption tower. On the other hand, in order to heat the adsorbent, a heating unit such as an electric heater is provided in the adsorption tower, and the temperature of the adsorption tower where the adsorption purification step is performed can be maintained at room temperature.

Through this purification process, it is possible to produce nitrogen monoxide for high purity semiconductor of 99.999% or more.

In general, according to the present invention, a high-purity nitrogen monoxide for semiconductor is purified in a large quantity by continuously mass-producing a large amount of low purity nitrogen monoxide produced in a commercial production process of industrial nitric acid, It is possible to simplify the production of high purity nitrogen monoxide of 99.999% or more through the adsorption process after separating and purifying the produced mixed gas after the ammonia oxidation reaction, thereby reducing investment cost and production cost required in the prior art . This can be expected to increase production efficiency and increase application in the semiconductor oxide film manufacturing process.

3 is a flow chart of a method for producing high purity nitrogen monoxide according to another embodiment of the present invention.

Referring to FIG. 3, the present invention may further include a cooling condensation purification step (S150) between a mixed gas supply step (S100) and a separation purification step (S200).

The cooling condensation purification step (S150) is a step performed before the separation purification step (S200) for the high temperature mixed gas supplied from the nitric acid production process. In the cooling condensation purification step (S150), first, the high-temperature mixed gas is cooled to condense a part of the impurities in the mixed gas. Here, the cooling of the mixed gas may be performed using a cooling chiller for the heat exchanger, and the temperature of the cooling chiller may be maintained at -20 to -10 ° C. However, the temperature of the cooling chiller is not necessarily limited thereto. The impurities condensed in this process are mainly a part of moisture and nitrogen monoxide.

When some of the impurities are condensed in the liquid phase, the liquid impurities are removed through gas-liquid separation, and the remaining mixed gas is introduced into the separation and purification step (S200). Here, the gas-liquid separator may be a commonly used gas-liquid separator.

Meanwhile, the high purity nitrogen monoxide producing method according to the present invention may further include a cooling condensation purification step (S250) between the separation purification step (S200) and the adsorption purification step (S300).

In the cooling condensation purification step (S250), the mixed gas from which the low boiling point impurities are removed is compressed and cooled to condense and remove residual impurities in the mixed gas. Here, a compressor or the like is used for compressing the mixed gas, and a cooling chiller or the like is used for cooling. At this time, the temperature of the cooling chiller is kept in the range of -20 to 10 ° C, preferably -15 to 0 ° C.

Further, the present invention may further include a cooling storage step (S400) after the adsorption purification step (S300).

In the cooling storage step (S400), the mixed gas subjected to the adsorption purification process is cooled to a predetermined temperature and stored. For this purpose, a cooling tank is used, the temperature of which is maintained at -20 to 0 ° C and the internal pressure can be maintained at 300 to 700 psi. Under these conditions, impurities such as moisture in the mixed gas stored in the cooling tank are condensed and separated in the lower portion of the cooling tank. Therefore, nitrogen monoxide having a higher purity can be obtained through the upper part of the cooling tank.

Hereinafter, an apparatus capable of performing the above-described method for producing high purity nitrogen monoxide will be described. The description of the overlapping contents is omitted or simply described. However, since the apparatus described below is an example of a device to which the method for producing high purity nitrogen monoxide according to the present invention can be applied, the method for producing high purity nitrogen monoxide according to the present invention is necessarily performed only by the present apparatus, But is not limited to.

FIG. 4 is a schematic view showing a high purity nitrogen monoxide nitrogen producing apparatus according to the present invention.

4, the apparatus for producing high purity nitrogen monoxide according to the present invention comprises a supply portion (not shown) for supplying a mixed gas 1 produced in a nitric acid production process for producing nitric acid by oxidizing ammonia and containing low purity nitrogen monoxide A distillation section 20 including at least one or more distillation columns 21 and 23 including a reboiler 21a and 23a, a column and coolers 21c and 23c and purifying the mixed gas using a boiling point difference, And at least one adsorption tower (31, 33) in which an adsorbent is disposed. The adsorption section (30) adsorbs and purifies the purified mixed gas in the distillation section (20).

Specifically, the apparatus for producing high purity nitrogen monoxide according to the present invention includes a supply unit 10, a distillation unit 20, and an adsorption unit 30.

The supply section 10 supplies the distillation section 20 with the mixed gas 1 containing low purity nitrogen monoxide. At this time, the mixed gas (1) is generated in a nitric acid production process for producing nitric acid by oxidizing ammonia. Therefore, the supply unit 10 is configured to separately store a part of the mixed gas 1 produced from the nitric acid production process, or to continuously separate part of the flow of the mixed gas 1 and supply it in real time. For example, the supply unit 10 may be formed of a supply pipe, a valve, or the like, which is separately installed in a piping facility through which the mixed gas 1 flows in the nitric acid production process. Further, in order to control the pressure of the mixed gas (1) introduced into the supply pipe, a pressure gauge is additionally provided, or in order to prevent the pressure of the mixed gas (1) in the nitric acid manufacturing process from being drastically lowered, .

The distillation section 20 includes at least one or more distillation columns 21 and 23 to purify the mixed gas supplied from the supply section 10. The distillation columns 21 and 23 are provided with reboilers 21a and 23a disposed at the lower portion thereof, coolers 21c and 23c disposed at the upper portion thereof, and columns 21b and 23c formed between the reboilers 21a and 23a and the coolers 21c and 23c. Since the distillation towers 21 and 23 are conventional techniques, a description thereof will be omitted.

In one embodiment, the first distillation tower 21, which is one of the pair of distillation towers, receives the mixed gas from the supply unit 10 to remove the high boiling point impurity 3, and the second distillation tower 23 can be supplied with the purified mixed gas in the first distillation tower 21 to remove the low boiling point impurities 4. The high boiling point impurity 3 is an impurity such as nitrous oxide, nitrogen dioxide, unreacted ammonia, and water having a relatively high boiling point as compared with nitrogen monoxide. The low boiling point impurity 4 is an impurity such as nitrogen or oxygen having a relatively low boiling point .

Here, in the first distillation tower 21, the temperature of the cooler 21c may be maintained at -85 to -95 DEG C, the temperature of the reboiler 21a may be maintained at -60 to -50 DEG C, and the operation pressure may be maintained at 3 to 5 atmospheres , And the high boiling point impurity 3 is condensed and discharged in a liquid phase through a pipe connected to the lower portion of the first distillation tower 21. The purified mixed gas flows through the second distillation tower 23 ).

The second distillation column 23 is maintained at a temperature of -150 to -140 ° C. in the upper cooler 23c and a temperature of -90 to -80 ° C. in the lower reboiler 23a, 2 distillation tower 23, and the purified mixed gas is delivered to the adsorption unit 30 through the piping under the second distillation tower 23.

The adsorption section 30 includes the adsorption towers 31 and 33 to purify the purified gas mixture in the distillation section 20. Here, at least one adsorption tower (31, 33) is disposed, and an adsorbent is disposed inside each of the adsorption towers (31, 33). The adsorbent may be formed of at least one selected from the group consisting of Molecular Sieve, activated carbon, silica gel, activated alumina gel, and low-temperature regenerated gel, and preferably moireclecib. Since such an adsorbent reacts with impurities to adsorb impurities, high purity nitrogen monoxide can be obtained through the adsorption section 30. [

As one embodiment of the adsorption section 30, a pair of adsorption towers 31 and 33 may be separately disposed and heating sections 35 and 37 may be formed in the adsorption towers 31 and 33. The heating units 35 and 37 may be, for example, electric heaters or the like as means for heating the adsorbent. Therefore, while adsorbing and purifying the impurities in the first adsorption tower 31, which is one of the pair of adsorption towers 31 and 33, the adsorption agent can be regenerated by heating the adsorption agent in the second adsorption tower 33, The adsorption purification step and the regeneration step alternate between the first adsorption tower 31 and the second adsorption tower 33, so that the adsorption purification step and the regeneration step can be performed at the same time.

On the other hand, a first cooling chiller 40 and a gas-liquid separator 50 may be further included so that impurities can be condensed and removed before the mixed gas is supplied to the distillation section 20.

The first cooling chiller 40 receives the high-temperature mixed gas from the supply unit 10 and cools it. Here, when the temperature of the first cooling chiller 40 is maintained at -20 to -10 占 폚, part of the impurities such as moisture and nitrogen monoxide in the mixed gas are condensed. The mixed gas containing the liquid condensed impurities (2) is delivered to the gas-liquid separator (50) through the piping.

The gas-liquid separator 50 separates the liquid impurities 2 in the mixed gas from the remaining mixed gas. At this time, the liquid impurities 2 are separated and discharged through piping connected to the lower part of the gas-liquid separator 50, and the mixed gas is supplied to the distillation unit 20 through the piping connected to the upper part of the gas-liquid separator 50. The mixed gas supplied to the distillation unit 20 is transferred to the buffer tank B for temporary storage via the transfer pump P and is then pressurized to 3 to 10 atm or lower so that the upper side mixed gas is supplied to the distillation unit 20 ) Into the first distillation column (21).

The apparatus for producing high purity nitrogen monoxide according to the present invention may further comprise a compressor 70 and a second cooling chiller 80.

The compressor 70 supplies the mixed gas from the distillation section 20 and compresses the mixed gas before the purified mixed gas flows into the adsorption section 30. At this time, when the distillation section 20 is formed of the first distillation tower 21 and the second distillation tower 23, the mixed gas is supplied through the lower piping of the second distillation tower 23.

The mixed gas compressed by the compressor 70 is introduced into the second cooling chiller 80. The temperature of the second cooling chiller 80 is maintained at -20 to 10 캜, preferably -15 to 0 캜, The introduced mixed gas is cooled. Thus, the mixed gas is supplied to the adsorption section 30 along the piping, with the residual impurities in the purified mixed gas being removed in the distillation section 20.

The apparatus for producing high purity nitrogen monoxide according to the present invention may further include a cooling tank (60).

The cooling tank 60 receives the purified mixed gas from the adsorption unit 30 and stores the cooled mixed gas at a predetermined temperature. At this time, the temperature in the cooling tank 60 is maintained at -20 to 0 占 폚, and the internal pressure can be maintained at 300 to 700 psi. Under these conditions, impurities such as moisture in the mixed gas stored in the cooling tank 60 are condensed and separated in the lower portion of the cooling tank 60. Therefore, nitrogen monoxide having a higher purity can be obtained through the upper portion of the cooling tank 60.

Hereinafter, a specific structure of the cooling tank 60 will be described.

5 is a cross-sectional view schematically showing a cross section of the cooling tank shown in Fig.

5, the cooling tank 60 according to the present invention may include a tank portion 61, an injection pipe 63, a cooling jacket 65, and a cooling pipe 67. [

The tank portion 61 is a container having a receiving space therein, and is formed such that a mixed gas is injected into the receiving space and is stored. Here, the internal pressure can be maintained at 300 to 700 psi. However, the internal pressure is not necessarily limited thereto.

The injection tube 63 injects the purified mixed gas transferred from the adsorption section 30 into the accommodation space of the tank section 61.

The cooling jacket 65 is formed so as to surround the outer surface of the tank portion 61 and has a hollow inside and cools the tank portion 61 while the first coolant R 1 is stored in the hollow or flows. The cooling jacket 65 is formed with a first refrigerant injection pipe into which the first refrigerant R1 is injected and a first refrigerant discharge pipe through which the first refrigerant R1 is discharged from the hollow, The mixed gas can be cooled to a predetermined temperature while circulating continuously.

The cooling pipe 67 is disposed in the receiving space of the tank portion 61 to cool the mixed gas. The cooling pipe 67 cools the mixed gas using the second refrigerant R2 flowing therein. Specifically, the cooling pipe 67 is formed in the form of a spiral tube. The contact surface with the mixed gas is expanded to efficiently cool the mixed gas have. A second refrigerant injection pipe 66 for supplying the second refrigerant R2 is connected to one end of the cooling pipe 67 and a second refrigerant pipe 66 for discharging the second refrigerant R2 is connected to the other end of the cooling pipe 67, (68) are connected to each other so that the second refrigerant (R2) circulates.

The first refrigerant R1 and the second refrigerant R2 may be freon refrigerants R22 and R407C. However, the present invention is not limited thereto. Any known refrigerant that can be used in the air conditioning refrigeration field may be used. At this time, the first refrigerant R1 and the second refrigerant R2 may be the same or different from each other. The temperature of the cooling tank 60 can be maintained at -20 to 0 占 폚 by the first and second refrigerants R1 and R2.

When the mixed gas is cooled and stored in the cooling tank 60 thus formed, the impurities 5 such as moisture in the mixed gas are condensed to the lower part of the space for accommodating the tank part 61, and the high purity nitrogen monoxide reaches the upper part The impurities 5 can be discharged through the impurity discharge pipe 64 connected to the lower part of the accommodation space and the high purity nitrogen monoxide can be obtained through the nitrogen monoxide discharge pipe 62 connected to the upper part of the accommodation space.

Hereinafter, the present invention will be described in more detail by way of specific examples and evaluation examples.

Example 1: Cold condensation purification and separation purification

First, in a commercial nitric acid production process, high temperature mixed gas discharged through an ammonia oxidizer was supplied at a flow rate of 1 to 10 L / min and cooled using a cooling chiller for a heat exchanger. Here, the temperature of the cooling chiller was kept at -20 to -10 ° C. At this time, some of the substances such as moisture, nitrogen dioxide, and the like in the mixed gas are condensed and separated into a liquid phase and a gas phase using a gas-liquid separator. In the lower part of the gas-liquid separator, the liquid condensate was mostly moisture and nitrogen dioxide.

Next, the mixed gas was transferred to the buffer tank for temporary storage through the piping connected to the upper part of the gas-liquid separator and the transfer pump, and pressurized to 3 to 10 atm or lower, and the mixed gas was introduced into the primary distillation tower. The upper cooler temperature of the first distillation column was maintained at -85 to -95 ° C using liquid nitrogen and the reboiler temperature was operated at -60 to -50 ° C. The operating pressure in the distillation column was 3 to 5 atm Respectively. Therefore, easily liquefied moisture, nitrogen dioxide, ammonia, nitrous oxide and the like were blown off at the lower portion of the first distillation tower, and nitrogen monoxide and the like were separated from the first distillation tower by the low temperature distillation method.

The liquid substances condensed in the lower part were removed through the liquid pipe, and the mixed gas, from which the first impurities were removed through the piping installed on the first distillation tower, was introduced into the second distillation tower. In the second distillation tower, the upper cooler temperature was maintained at -150 to -140 ° C. using liquid nitrogen and the reboiler temperature at the lower side was -90 to -80 ° C. Only high purity nitrogen monoxide was collected through the bottom of the distillation tower, Gaseous impurities (such as nitrogen and unreacted oxygen) were discharged through the top of the distillation column.

Example 2: Cold condensation purification, adsorption purification, and cold storage

The mixed gas separated and purified in Example 1 was supplied to the compressor through the lower pipe of the second distillation column, compressed and introduced into the cooling chiller. Here, the temperature of the cooling chiller was kept at -15 to 0 占 폚.

Next, the mixed gas passing through the cooling chiller was introduced into the first adsorption column and the second adsorption column. At this time, the adsorption purification step was carried out in one adsorption tower and the regeneration step was carried out alternately in the other adsorption tower. Here, the adsorbent disposed on each adsorption column used Morecurecib 3A, and the adsorption purification process was performed so that the temperature of the adsorption tower was maintained at room temperature.

Finally, the mixed gas after the adsorptive purification process was injected into a cooling tank maintained at a temperature of -20 to 0 ° C and an internal pressure of 300 to 700 psi and stored.

Evaluation Example 1: Analysis of mixed gas components introduced in the nitric acid production process

The mixed gas supplied from the nitric acid production process in Example 1 was analyzed by FT-IR and GC. The mixed gas to be analyzed is the mixed gas discharged from the ammonia oxidation unit of the nitric acid production process. As a result, nitric oxide was 9.3 vol%, nitrous oxide was 15.3 vol%, nitrogen dioxide was 7.2 vol%, and moisture was 68.2 vol%. As a result, it can be seen that the mixed gas contains a large amount of moisture and nitrous oxide, and the nitrogen monoxide is low in purity to be unsuitable for semiconductor use.

Evaluation Example 2: Analysis of the composition ratio of the substance discharged from the distillation column of Example 1

The composition ratio (%) of the substance discharged from the first distillation column and the second distillation column of Example 1 was analyzed. The results are shown in Table 1 below.

Ingredient substance The first distillation tower Second distillation tower Top bottom Top bottom NO 38.7 0.6 0.03 99.98 N ₂ O <0.001 59.2 <0.001 0.02 NO ₂ <0.001 22.1 <0.001 <0.001 H ₂ O <0.001 19.9 - <0.001 NH ₃ - 1.2 - - N ₂ 39.6 <0.001 76.2 - O ₂ 21.7 <0.001 23.5 -

As shown in [Table 1], after passing through the second distillation column, nitrogen monoxide could have a purity of 99.98% or more at the bottom of the distillation column. However, since it is required to have a purity of 99.995% or more in order to be used for semiconductor manufacturing, it is necessary to further carry out the purification step of Example 2. [

Evaluation Example 3: Impurity analysis in the cooling tank of Example 2

After executing the second embodiment, the components of the impurities located in the upper and lower parts of the cooling tank were analyzed. The results are shown in Table 2 below.

analysis
location Impurities (ppm) H ₂ O NO ₂ N ₂ O H ₂ O ₂ N ₂ CH ₄ CO ₂ CO Top 0.258 2.426 0.188 &Lt; 0.1 &Lt; 0.1 4.125 &Lt; 0.1 &Lt; 0.1 &Lt; 0.1 bottom 0.287 2.365 0.196 &Lt; 0.1 &Lt; 0.1 4.037 &Lt; 0.1 &Lt; 0.1 &Lt; 0.1

According to the results shown in [Table 2], it can be seen that, according to the present invention, nitrogen monoxide for 99.999% or more of high purity semiconductor can be produced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the same is by way of illustration and example only and is not to be construed as limiting the present invention. It is obvious that the modification or improvement is possible.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

1: mixed gas 10:
20: distillation section 21: first distillation tower
23: second distillation column 30: adsorption section
31: first adsorption tower 33: second adsorption tower
35, 37: heating section 40: first cooling chiller
50: gas-liquid separator 60: cooling tank
61: tank portion 63: injection tube
65: cooling jacket 67: cooling pipe
70: compressor 80: second cooling chiller

Claims (13)

(a) supplying a mixed gas produced in a nitric acid production process for producing nitric acid by oxidizing ammonia and containing low-purity nitrogen monoxide;
(b) separating and purifying the mixed gas using a boiling point difference; And
(c) adsorbing and purifying the separated and purified mixed gas using an adsorbent;
&Lt; / RTI &gt;
The method according to claim 1,
Between the step (a) and the step (b)
Cooling the mixed gas, separating the mixed gas by gas-liquid separation, cooling, condensing and purifying;
Further comprising the steps of:
The method according to claim 1,
The step (b)
Removing a high boiling point impurity relatively higher in boiling point than the nitrogen monoxide from the mixed gas by using the first distillation column; And
Removing low boiling point impurities relatively low in boiling point from the mixed gas from which the high boiling point impurities have been removed using the second distillation column;
&Lt; / RTI &gt;
The method of claim 3,
Between the step (b) and the step (c)
Compressing the mixed gas from which the low-boiling point impurities have been removed, cooling, cooling, condensing and purifying;
Further comprising the steps of:
The method according to claim 1,
The step (c)
Wherein a pair of adsorption towers in which the adsorbents are respectively disposed are used to adsorb and refine impurities in any one of the first adsorption columns and to heat and regenerate the adsorbent in the other one of the second adsorption columns, Way.
The method according to claim 1,
Cooling and storing the adsorbed and purified mixed gas after the step (c);
Further comprising the steps of:
A supply part for supplying a mixed gas produced in a nitric acid production process for producing nitric acid by oxidizing ammonia and containing low-purity nitrogen monoxide;
A distillation section comprising at least one distillation column including a reboiler, a column, and a cooler, the distillation section purifying the mixed gas using a boiling point difference; And
An adsorption unit including at least one adsorption column in which an adsorbent is disposed, the adsorption unit adsorbing and purifying the purified gas in the distillation unit;
Wherein the high-purity nitrogen monoxide produced by the high-
The method of claim 7,
Wherein the distillation section comprises:
The first distillation column receives the mixed gas from the supply section to remove high boiling point impurities relatively higher in boiling point than the nitrogen monoxide, and the second distillation column, And removing the low boiling point impurities relatively low in boiling point than the nitrogen monoxide by receiving the purified mixed gas in the first distillation column.
The method of claim 7,
The adsorption unit
A pair of the adsorption towers are separated and disposed,
A heating unit for heating each of the adsorption towers;
Further comprising:
Alternately, the first adsorption tower, which is one of the pair of adsorption towers, adsorbs and refines the mixed gas, and the second adsorption tower, which is another one, heats and regenerates the adsorbent.
The method of claim 7,
A first cooling chiller that cools the mixed gas supplied from the supply unit to condense the impurities; And
A gas-liquid separator for separating the impurities from the condensed liquid phase and supplying the mixed gas to the distillation column;
Further comprising: a high-purity nitrogen monoxide producing device for producing high-purity nitrogen monoxide.
The method of claim 7,
A compressor for receiving and compressing the mixed gas from the distillation section; And
A second cooling chiller that receives and compresses the mixed gas compressed from the compressor to condense and remove impurities and supply the mixed gas to the adsorption unit;
Further comprising: a high-purity nitrogen monoxide producing device for producing high-purity nitrogen monoxide.
The method of claim 7,
A cooling tank for receiving the mixed gas from the adsorption unit and cooling and storing the mixed gas at a predetermined temperature;
Further comprising: a high-purity nitrogen monoxide producing device for producing high-purity nitrogen monoxide.
The method of claim 12,
Wherein the cooling tank includes:
A tank portion having an accommodation space therein so as to store the mixed gas;
An injection tube for injecting the mixed gas into the accommodation space;
A cooling jacket having a hollow through which the first refrigerant flows, the cooling jacket surrounding the outer surface of the tank; And
A cooling pipe formed in a spiral tube shape and having a second refrigerant flowing therein and disposed in the accommodation space;
Wherein the high-purity nitrogen monoxide produced by the high-

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