KR101955015B1 - method and APPARATUS for recovering nitrous oxide - Google Patents

Abstract

The present invention relates to a method and apparatus for recovering nitrous oxide. The method for recovering nitrous oxide can recover nitrous oxide with a high purity of 99.999 vol% or more that can be used for industries of semiconductors, LCDs, OLEDs and others from a nitrous oxide-containing gas mixture such as a production gas of a nitrous oxide production process, an exhaust gas generated from an adipic acid production process or the like at a high recovery rate of about 90% or more. The method of the present invention comprises: a pressure swing adsorption process of removing one or more of nitrogen and oxygen from the nitrous oxide-containing gas mixture to concentrate nitrous oxide, and using an adsorbent for recovering nitrous oxide satisfying work capacity represented by equation 1, 0.90 <= w_0-w_1/w_0; an impurity removal adsorption process of removing one or more of impurities of carbon dioxide, nitrous oxide, water vapor and organic hydrocarbon from a gas mixture passing through the pressure swing adsorption process; and a distillation process of recovering nitrous oxide by distilling a gas mixture passing through the impurity removal adsorption process.

Description

METHOD AND APPARATUS FOR RECOVERING NITROUS OXIDE BACKGROUND OF THE INVENTION &lt; RTI ID = 0.0 &gt;

The present invention relates to a nitrous oxide purification technique, and more particularly, to a hybrid nitrous oxide recovery method and apparatus for recovering nitrous oxide from a nitrous oxide-containing gas mixture.

In recent years, demand for nitrous oxide (N ₂ O) has increased significantly in microelectronic processes such as semiconductor, LCD, and OLED manufacturing. Specifically, nitrous oxide is used in a process of forming a silicon oxide layer by reacting with silane by a chemical method or a plasma deposition method. Nitrous oxide is also used for nitriding thin film silicon films.

Industrial processes for producing nitrous oxide by pyrolyzing ammonium nitrate (Nitrate) and producing adipic acid produce exhaust gas containing high concentration of nitrous oxide. The main components of these exhaust gases are nitrous oxide, nitrogen and oxygen. It is required to recover the nitrous oxide from the nitrous oxide-containing exhaust gas and reuse it industrially. Nitrous oxide is one of the representative greenhouse gases, and its global warming potential (GWP) is 310 times higher than that of carbon dioxide. By recycling and recycling nitrous oxide, it is possible not only to reduce greenhouse gas emissions, but also to obtain economic benefits by industrial use. Therefore, a separation process for recovering nitrous oxide from a nitrous oxide-containing gas mixture produced by pyrolysis of ammonium nitrate and nitrous oxide-containing exhaust gas discharged from an adipic acid production process is required.

However, a process for recovering and purifying nitrous oxide having a high purity from nitrous oxide-containing exhaust gas has not yet been widely applied in the industry.

US Patent No. 6,348,083 discloses a method and apparatus for recovering nitrous oxide contained in exhaust gas generated in an industrial process for producing adipic acid, nitric acid, glycoxic acid, nitrous oxide or phenol. The exhaust gas used in this patent contains 5 vol% to 99.9 vol% of nitrous oxide and contains at least one gas impurity selected from the group consisting of nitrogen, oxygen and carbon monoxide. The exhaust gas is passed through at least one permeation module (membrane separation module) to recover gas containing 85% by volume to 90% by volume of nitrous oxide. However, nitrous oxide-containing exhaust gas generated in the adipic acid production process contains carbon dioxide, nitrogen dioxide, nitrogen monoxide, organic hydrocarbons, water vapor, and the like in addition to the impurities presented in this patent. Therefore, it is impossible to efficiently remove high-purity nitrous oxide for semiconductors and to recover high yields of these semiconductors by using only the permeation module separation (membrane separation) technology proposed by this patent. Further, the separation membrane material and the membrane separation process of the permeation membrane separation module used in this patent are not specifically shown.

One aspect of the present invention is to provide a high purity (99.999% by volume) gas which can be used for a semiconductor, an LCD, and an industrial use such as an OLED from a gas mixture containing a nitrous oxide such as a production gas in a nitrous oxide production process or an exhaust gas generated in an adipic acid production process, (About 90% or more) of nitrous oxide can be recovered at a high recovery rate (about 90% or more).

Another aspect of the present invention is to provide a nitrous oxide recovery apparatus capable of implementing the nitrous oxide recovery method.

One aspect of the present invention is a method for removing nitrogen oxides from a gas mixture containing nitrous oxide by removing at least one of nitrogen and oxygen to concentrate the nitrous oxide and pressurizing the nitrous oxide recovery adsorbent Cyclic adsorption process; An impurity removing adsorption step of removing impurities of at least one of carbon dioxide, nitrogen dioxide, water vapor and organic hydrocarbons from the gas mixture after the pressure circulation adsorption step; And a distillation step of distilling the gas mixture after the impurity removal adsorption step to recover the nitrous oxide.

[Formula 1]

W ₀ is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar in the adsorption isotherm at 20 ° C of the adsorbent, W ₁ is the adsorption amount of nitrous oxide in the adsorption isotherm at 20 ° C Amount of nitrogen adsorption (mol / kg).)

The method of recovering nitrous oxide further comprises a pretreatment step for removing at least one of moisture in a fine droplet state, oil fractions in a fine droplet state, and fine particle impurities from a gas mixture containing nitrous oxide before the pressure circulation adsorption step Lt; / RTI &gt;

Another aspect of the present invention is a method for producing Removing impurities from the gas mixture containing nitrous oxide to remove at least one of carbon dioxide, nitrogen dioxide, water vapor and organic hydrocarbons; A pressure circulation adsorption step of using the adsorbent for recovering nitrous oxide which satisfies the working capacity represented by the following formula (1), by concentrating the nitrous oxide by removing at least one of nitrogen and oxygen from the gas mixture after the impurity removal adsorption step; And a distillation step of distilling the gas mixture through the pressure circulation adsorption step to recover the nitrous oxide.

[Formula 1]

W ₀ is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar in the adsorption isotherm at 20 ° C of the adsorbent, W ₁ is the adsorption amount of nitrous oxide in the adsorption isotherm at 20 ° C Amount of nitrogen adsorption (mol / kg).)

The method for recovering nitrous oxide further includes a pretreatment step for removing at least one of moisture in a fine droplet state, oil in a fine droplet state, and fine particle impurities from a gas mixture containing nitrous oxide before the impurity removal adsorption step Lt; / RTI &gt;

The nitrous oxide recovery method may further include a step of compressing and cooling the gas mixture before the pressure cycling adsorption process or the distillation process.

The adsorbent may further satisfy the nitrous oxide / nitrogen selectivity represented by the following formula (2).

[Formula 2]

(A _N2O is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar at the adsorption isotherm of the adsorbent at 20 ° C and A _N2 is the adsorption amount of nitrogen of the adsorbent under the pressure of 10 bar at the adsorption isotherm at 20 ° C Adsorption (mol / kg).)

The adsorbent may further satisfy the nitrous oxide / oxygen selectivity expressed by the following formula (3).

[Formula 3]

(In the formula 3, A _N2O is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar in the adsorption isotherm at 20 ° C of the adsorbent and A _O2 is the adsorption amount of oxygen in the adsorption isotherm at 20 ° C Adsorption (mol / kg).)

Wherein the pressure circulation adsorption step uses two or more adsorption towers charged with the adsorbent and the pressurization step, the adsorption step, the equilibrium pressure and the washing step, and the desorption step are performed at least once in each adsorption tower, and the pressure in the adsorption step is 1.7 To 20 bar, and the pressure of the desorption step may be vacuum to 2.1 bar.

The pressure cycling adsorption process may be performed at a temperature of 0 to 50 캜.

The adsorbent may be De-Aluminated Zeolite Y or Sylobead Silica Gel.

The content of Si and Al in the dealuminated zeolite Y may satisfy the following formula (4).

[Equation _{4] 5≤SiO 2 / Al 2 O} 3 ≤30

The impurity removal adsorption process may be carried out by using at least one adsorbent selected from the group consisting of sodium hydroxide, calcium hydroxide and potassium hydroxide at a temperature of 10 to 50 DEG C and a pressure of 1 to 10 bar or an adsorbent coated with silica or zeolite, Removing at least one of water vapor and organic hydrocarbons using at least one adsorbent of silica, zeolite, alumina silicate and activated carbon at a temperature of 10 to 50 DEG C and a pressure of 1 to 10 bar; . &Lt; / RTI &gt;

Wherein the distillation step comprises: a packed tower filled with a filler made of a metal or ceramic material at a temperature of -160 to -10 DEG C and a pressure of 3 to 30 bar; Or a multi-stage tray tower comprising a plurality of stages.

The pretreatment may be carried out at a temperature of 10 to 40 DEG C and a pressure of 1 to 2 bar.

In another aspect of the present invention, there is provided a process for purifying nitrous oxide, comprising the steps of: removing at least one of nitrogen and oxygen from a gas mixture containing nitrous oxide to concentrate nitrous oxide, and adsorbing a nitrous oxide recovering adsorbent satisfying the working capacity represented by the following formula A pressure circulation adsorbent comprising; An impurity removing adsorption unit connected to the pressure circulation adsorption unit and removing at least one impurity of carbon dioxide, nitrogen dioxide, water vapor and organic hydrocarbons from the gas mixture passed through the pressure circulation adsorption unit; And a distillation unit connected to the impurity removing adsorbing unit and distilling the gas mixture passing through the impurity removing adsorbing unit to recover nitrous oxide.

[Formula 1]

W ₀ is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar in the adsorption isotherm at 20 ° C of the adsorbent, W ₁ is the adsorption amount of nitrous oxide in the adsorption isotherm at 20 ° C Amount of nitrogen adsorption (mol / kg).)

The nitrous oxide recovery device is connected to the pressure circulation adsorbing part and removes at least one of moisture in the fine droplet state, oil in the fine droplet state, and fine particle impurities from the gas mixture containing nitrous oxide, And a pre-treatment unit for supplying the gas mixture to the pressure circulation adsorption unit.

Another aspect of the present invention relates to an adsorbing apparatus comprising: an impurity removing adsorbent for removing at least one impurity of carbon dioxide, nitrogen dioxide, water vapor and organic hydrocarbons from a gas mixture containing nitrous oxide; Removing at least one of nitrogen and oxygen from the gas mixture passing through the impurity removing adsorbing section to concentrate the nitrous oxide and adsorbing a nitrous oxide recovering adsorbent satisfying the working capacity represented by the following formula 1 A pressure circulation adsorption unit included in the adsorption column; And a distillation unit connected to the pressure circulation adsorption unit and distilling the gas mixture passed through the pressure circulation adsorption unit to recover nitrous oxide.

The nitrous oxide recovery apparatus is connected to the impurity removing adsorption unit and removes at least one of moisture in a fine droplet state, oil fractions in a fine droplet state, and fine particle impurities from a gas mixture containing nitrous oxide, And a pretreatment unit for supplying the adsorbed gas mixture to the impurity removing and adsorbing unit.

The adsorbent may further satisfy the nitrous oxide / nitrogen selectivity represented by the following formula (2).

[Formula 2]

(A _N2O is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar at the adsorption isotherm of the adsorbent at 20 ° C and A _N2 is the adsorption amount of nitrogen of the adsorbent under the pressure of 10 bar at the adsorption isotherm at 20 ° C Adsorption (mol / kg).)

The adsorbent may further satisfy the nitrous oxide / oxygen selectivity expressed by the following formula (3).

[Formula 3]

(In the formula 3, A _N2O is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar in the adsorption isotherm at 20 ° C of the adsorbent and A _O2 is the adsorption amount of oxygen in the adsorption isotherm at 20 ° C Adsorption (mol / kg).)

The pressure circulation adsorption unit may include at least two adsorption towers charged with the adsorbent, and the pressurization step, the adsorption step, the pressure equalization step and the desorption step may be performed at least once in each adsorption tower.

Wherein the impurity removing adsorption unit comprises a first adsorption tower containing at least one adsorbent selected from the group consisting of sodium hydroxide, calcium hydroxide and potassium hydroxide, or an adsorbent thereof coated with silica or zeolite; And a second adsorption tower containing at least one adsorbent of silica, zeolite, alumina silicate and activated carbon.

The distillation unit may include a packed tower filled with a filler made of a metal or a ceramic material, or a tray tower composed of a plurality of stages.

According to an embodiment of the present invention, nitrous oxide having a global warming index (GWP) of 310 can be recovered from a nitrous oxide-containing gas mixture by the method and apparatus for recovering nitrous oxide to obtain a reduction effect of greenhouse gases. Also, it is possible to recover high purity (99.999% by volume or more) nitrous oxide from a nitrous oxide-containing gas mixture at a high recovery rate (about 90% or more) and to use it for industrial applications such as semiconductors, LCDs and OLEDs.

1 is a schematic diagram of an exemplary nitrous oxide recovery process of the present invention.
2 is a schematic diagram of an exemplary nitrous oxide recovery process of the present invention.
3 is a schematic diagram of an exemplary nitrous oxide recovery process of the present invention.
4 is an adsorption isotherm at 20 캜 of the adsorbent (dealumin zeolite Y) used in the pressure swing adsorption process of Example 1. Fig.
5 is an adsorption isotherm at 20 DEG C of the adsorbent (Sylobead silica gel) used in the pressure swing adsorption process of Example 2. Fig.
6 is an adsorption isotherm at 20 DEG C of the adsorbent (zeolite 13X) used in the pressure swing adsorption process of Comparative Example 1. Fig.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Whenever a component is referred to as " including " an element throughout the specification, it is to be understood that the element may include other elements, not the exclusion of any other element, unless the context clearly dictates otherwise. Also, singular forms include plural forms unless the context clearly dictates otherwise.

Throughout this specification, " A to B " means " A to B " unless otherwise defined.

The present invention relates to a process for producing high-purity nitrous oxide of 99.999% by volume or more, which can be used for a semiconductor, an LCD, an OLED, or the like, from a nitrous oxide-containing gas mixture such as a production gas in a nitrous oxide production process or an exhaust gas from an adipic acid production process, (About 90% or more).

More specifically, one aspect of the present invention relates to a process for adsorbing nitrogen oxides, comprising: a pressure cycling adsorption step of removing at least one of nitrogen and oxygen from a gas mixture containing nitrous oxide to concentrate nitrous oxide; An impurity removing adsorption step of removing impurities of at least one of carbon dioxide, nitrogen dioxide, water vapor and organic hydrocarbons from the gas mixture after the pressure circulation adsorption step; And a distillation step of distilling the gas mixture after the impurity removal adsorption step to recover the nitrous oxide.

Further, in the nitrous oxide recovery method of the present invention, the pressure cycle adsorption process may be performed prior to the impurity removal adsorption process, but may be performed after the impurity removal adsorption process.

Accordingly, another aspect of the present invention provides a process for removing impurities from a gas mixture containing nitrous oxide, which comprises removing impurities from at least one of carbon dioxide, nitrogen dioxide, water vapor, and organic hydrocarbons; A pressure circulation adsorption step of removing at least one of nitrogen and oxygen from the gas mixture after the impurity removal adsorption step to concentrate the nitrous oxide; And a distillation step of distilling the gas mixture through the pressure circulation adsorption step to recover the nitrous oxide.

According to another aspect of the present invention, there is provided a gas-liquid separator comprising: a pressure-circulating adsorbent for removing at least one of nitrogen and oxygen from a gas mixture containing nitrous oxide to concentrate nitrous oxide; An impurity removing adsorption unit connected to the pressure circulation adsorption unit and removing at least one impurity of carbon dioxide, nitrogen dioxide, water vapor and organic hydrocarbons from the gas mixture passed through the pressure circulation adsorption unit; And a distillation unit connected to the impurity removing adsorption unit and distilling the gas mixture passing through the impurity removing adsorption unit to recover nitrous oxide,

Another aspect of the present invention relates to an adsorbing apparatus comprising: an impurity removing adsorbent for removing at least one impurity of carbon dioxide, nitrogen dioxide, water vapor and organic hydrocarbons from a gas mixture containing nitrous oxide; A pressure circulation adsorption unit connected to the impurity removal adsorption unit to remove at least one of nitrogen and oxygen from the gas mixture passed through the impurity removal adsorption unit to concentrate nitrous oxide; And a distillation unit connected to the pressure circulation adsorption unit and distilling the gas mixture passed through the pressure circulation adsorption unit to recover nitrous oxide.

Such a nitrous oxide recovery method of the present invention is characterized in that a pressure circulation adsorption process using an adsorbent that selectively separates nitrous oxide from nitrogen and / or oxygen is used as a process to concentrate the nitrous oxide concentration to about 80 to 99% , And 99.999% by volume or more of nitrous oxide can be purified by the distillation process and recovered at a high recovery rate (about 90% or more). In addition, the method for recovering nitrous oxide according to an embodiment of the present invention includes an impurity removing adsorption process using an adsorbent having excellent adsorption performance against water and impurities such as organic hydrocarbons, thereby recovering nitrous oxide with higher purity . Such a nitrous oxide recovery method may be implemented through a nitrous oxide recovery apparatus according to an embodiment of the present invention.

1 to 3 are schematic views of an exemplary nitrous oxide recovery process of the present invention. Hereinafter, the nitrous oxide recovery method and the nitrous oxide recovery apparatus of the present invention will be described with reference to FIGS. 1 to 3. FIG. However, the present invention is not necessarily limited to Fig. 1 to Fig. 3, and a person skilled in the art can freely modify it within the scope of the technical idea of the present invention.

The nitrous oxide concentration and pressure circulation adsorption process 20 is a process of selectively separating nitrous oxide from at least one of nitrogen and oxygen from a nitrous oxide-containing gas mixture and concentrating it at a high concentration. The nitrous oxide-containing gas mixture to be concentrated includes, by way of example, 10 to 98% by volume of nitrous oxide, 0.5 to 60% by volume of nitrogen, 0 to 40% by volume of oxygen, 0 to 5% 0 to 1% by volume of carbon dioxide, 0 to 2% by volume of nitrogen dioxide, 0 to 2% by volume of nitrogen monoxide, 0 to 1% by volume of water vapor, 0 to 1% . From the nitrous oxide-containing gas mixture, the nitrous oxide may be selectively separated from at least one of nitrogen and oxygen through the nitrous oxide concentration-pressure cyclic adsorption step (20) and concentrated to a concentration of 80 to 99% by volume.

As described above, the present invention includes a distillation process for recovering nitrous oxide at a high purity and a nitrous oxide condensation pressure circulation adsorption process, whereby the nitrous oxide can be recovered at a high recovery rate of about 90% or more. Also, by passing through the concentration process through the pressure cycling adsorption process, it is possible to recover nitrous oxide at a high recovery rate of about 90% or more without recycling the undigested gas mixture generated in the distillation process. Thus, energy unnecessarily wasted in the distillation step can be saved, and the process cost can be reduced.

At this time, the higher the nitrous oxide recovery rate based on the nitrous oxide contained in the gas mixture supplied to the nitrous oxide concentration pressure cycling adsorption step 20, the smaller the loss of nitrous oxide is preferable.

In order to concentrate the nitrous oxide at a high efficiency and a high concentration, the adsorbent used for the nitrous oxide concentration adsorption process should have an excellent selective adsorption performance for nitrous oxide and nitrogen.

To this end, in the nitrous oxide concentration pressure cyclization adsorption step 20, a nitrous oxide recovery adsorbent satisfying the working capacity expressed by the following formula 1 may be used.

[Formula 1]

W ₀ is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar in the adsorption isotherm at 20 ° C of the adsorbent, W ₁ is the adsorption amount of nitrous oxide in the adsorption isotherm at 20 ° C Amount of nitrogen adsorption (mol / kg).)

The working capacity of the adsorbent may be related to the purity and recovery of the nitrous oxide to be purified. Specifically, when the working capacity is too small, the amount of nitrous oxide separated by the adsorbent between the operating pressure (adsorption pressure and desorption pressure) of the pressure circulation adsorption process 20 is reduced and the amount of nitrous oxide in the exhaust gas And the recovery rate of nitrous oxide to be purified may be lowered.

Therefore, even if the distillation process is performed in the subsequent process, the amount of nitrous oxide in the finally recovered gas mixture becomes small, and the nitrous oxide recovery rate in the entire process may be lowered. As in the case of the above formula 1, % Or more can not be realized.

Further, the ratio of the separated nitrous oxide to the oxygen and nitrogen adsorbed and separated may be reduced, and the purity of nitrous oxide in the product may be lowered.

Therefore, in order to industrially reuse the nitrous oxide containing 70 to 99% by volume, specifically 80 to 99% by volume, or 99% by volume or more of nitrous oxide from the gas mixture containing nitrous oxide by a high recovery rate, It may be preferable to satisfy the expression (1).

Accordingly, the working capacity of the adsorbent expressed by the above formula (1) is preferably 0.90 or more, more specifically 0.92 or more. The upper limit of the working capacity is not particularly limited but may be 1.00 or less, 0.98 or less, or 0.96 or less.

In the formula 1, W ₀ may be 3.50 to 6.00 mol / kg, 3.50 to 5.00 mol / kg, or 3.50 to 4.00 mol / kg, but is not limited thereto.

In the formula 1, W ₁ may be 0.10 to 3.00 mol / kg, 0.10 to 2.00 mol / kg, 0.10 to 1.00 mol / kg, or 0.10 to 0.50 mol / kg, but is not limited thereto.

Further, the adsorbent may further satisfy the nitrous oxide / nitrogen selectivity represented by the following formula (2).

[Formula 2]

(A _N2O is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar at the adsorption isotherm of the adsorbent at 20 ° C and A _N2 is the adsorption amount of nitrogen of the adsorbent under the pressure of 10 bar at the adsorption isotherm at 20 ° C Adsorption (mol / kg).)

Further, the adsorbent may further satisfy the nitrous oxide / oxygen selectivity represented by the following formula (3).

[Formula 3]

(In the formula 3, A _N2O is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar in the adsorption isotherm at 20 ° C of the adsorbent and A _O2 is the adsorption amount of oxygen in the adsorption isotherm at 20 ° C Adsorption (mol / kg).)

Equation 2 and Equation 3 relate to the nitrous oxide / nitrogen or nitrous oxide / oxygen adsorption selectivity of the adsorbent.

The nitrous oxide / nitrogen or nitrous oxide / oxygen adsorption selectivity of the adsorbent can affect the purity of the recovered nitrous oxide. When the adsorbent's nitrous oxide / nitrogen or nitrous oxide / oxygen adsorption selectivity is low, the adsorbent's nitrous oxide separation performance is not good. If the adsorbed nitrogen or oxygen is not sufficiently removed, the purity of recovered nitrous oxide Can be degraded.

Accordingly, when recycling 99.999% by volume or more of high purity nitrous oxide through a subsequent distillation process, the process conditions may become severe, or the process time may be prolonged and the overall process cost may increase.

Therefore, in order to recover industrially the high recovery rate of 70 to 99% by volume, specifically 80 to 99% by volume, or 99% by volume or more of nitrous oxide from the gas mixture containing nitrous oxide, Or Equation 3 may be further satisfied.

In the formulas 2 and 3, A _N2O may be 3.50 to 6.00 mol / kg, 3.50 to 5.00 mol / kg, or 3.50 to 4.00 mol / kg, but is not limited thereto.

In the formula 2, A _N2 may be 0.10 to 2.00 mol / kg, 0.10 to 1.00 mol / kg, or 0.10 to 0.60 mol / kg, but is not limited thereto.

In the formula 3, A _O2 may be 0.10 to 2.00 mol / kg, 0.10 to 1.00 mol / kg, or 0.10 to 0.60 mol / kg, but is not limited thereto.

Specific examples of the adsorbent may include De-Aluminated Zeolite Y or Sylobead Silica Gel. However, the present invention is not limited thereto.

In one example, when the adsorbent is dealuminized zeolite Y, the content of Si and Al in the adsorbent may satisfy the following formula (4).

[Equation _{4] 5≤SiO 2 / Al 2 O} 3 ≤30

More specifically, the formula (4) may be _{10≤SiO 2 / Al 2 O 3 ≤30} , or _{15≤SiO 2 / Al 2 O 3 ≤25} . The reason why the content of Si and Al in the dealuminated zeolite Y satisfies the above formula 4 is not clear, but the working capacity of nitrous oxide / nitrogen or nitrous oxide / oxygen selectivity and nitrous oxide is increased, Purity and recovery can be improved.

The specific surface area of the adsorbent may be 300 to 1000 m ² / g, 300 to 800 m ² / g, or 400 to 800 m ² / g, but is not limited thereto.

In the pressure circulation adsorption step (20) of the method for recovering nitrous oxide according to an embodiment of the present invention, at least two adsorption towers charged with the adsorbent are used, and the pressurization step, the adsorption step, the equilibrium pressure and the desorption step, The pressure of the adsorption step is 1.7 to 20 bar, and the pressure of the desorption step may be vacuum (0 bar) to 2.1 bar. The adsorption pressure may be more specifically from 5 to 15 bar, and the desorption pressure may be more specifically from vacuum to 1 bar, or from 0.3 to 1 bar.

When the adsorption and desorption pressures are in the above range, the adsorbent of the pressure-cycled adsorption method of the present invention for the nitrous oxide recovery method has a high nitrous oxide working capacity and a high selectivity for nitrous oxide / nitrogen and / or nitrous oxide / oxygen, It may be suitable to purify nitrous oxide at the recovery rate.

The nitrous oxide recovery method of one embodiment of the present invention may be performed at a temperature of 0 to 50 ° C, but is not limited thereto. More specifically from 0 to 40 占 폚, from 10 to 40 占 폚, or from 10 to 30 占 폚.

Hereinafter, an exemplary process of the nitrous oxide recovery method using the pressure cyclic adsorption of one embodiment of the present invention will be described in more detail. However, this is for the purpose of helping understanding of the present invention, and the present invention is not limited thereto.

The pressure circulation adsorption process 20 may be performed by a desorption process by a normal pressure regeneration process or a vacuum regeneration process. The adsorption of the pressure cycling adsorption process 20 can be operated under a pressurized state and the desorption can be operated under atmospheric or vacuum conditions and the pressurization step, the adsorption step, the pressure equalizing step and the rinse step, Blowdown) or a vacuum (Vacuum) operation can be repeatedly performed. It is preferable that the desorption process of the pressure circulation adsorption process 20 is performed by the atmospheric pressure regeneration process from the viewpoint of energy cost, but it is not limited to the atmospheric pressure regeneration method, and a vacuum regeneration method is also possible.

In the pressure recirculation adsorption step 20, the compressed nitrous oxide-containing gas mixture is introduced into the first adsorption tower 21 and the second adsorption tower 22 where adsorption takes place at high pressure. The nitrous oxide is adsorbed on at least one of the two adsorption towers which are alternately operated. Here, a description will be given of a process in which nitrous oxide is recovered by pressure circulation adsorption on the basis of the first adsorption column 21. The gas mixture from which the nitrous oxide has been removed is discharged from the first adsorption tower 21 and the portion where the nitrous oxide adsorption is performed in the first adsorption tower 21 gradually moves to the outlet of the first adsorption tower 21. The gas mixture at the outlet of the first adsorption column 21 may contain no more than 10 volume%, no more than 5 volume%, more specifically no more than 2 volume% nitrous oxide. The supply of the nitrous oxide-containing gas mixture is stopped when the portion where the nitrous oxide adsorption is performed in the first adsorption tower 21 reaches a predetermined point between the inlet and the outlet of the first adsorption tower 21. The pressure in the first adsorption tower 21 is lowered to the primary pressure while discharging the gas in the forward direction as the flow direction of the nitrous oxide-containing gas mixture to be supplied. The gases emitted here are mainly nitrogen and oxygen. This exhaust gas can be used to partially raise the pressure of the second adsorption column 22. [

In the pressure swing adsorption process 20, the adsorption pressure may be 1.7 to 20 bar, and more specifically 5 to 15 bar. Within the above range, the adsorbent of the present invention may be suitable for purifying nitrous oxide with high purity and high recovery as the working capacity of nitrous oxide in the adsorbent of pressure cycling adsorption is high and the nitrous oxide / nitrogen selectivity and / or nitrous oxide / oxygen selectivity is high .

The primary pressure lowered in the cocurrent depression step, such as the nitrous oxide-containing gas mixture or the flow direction of the exhaust gas, may be 1 to 4 bar. The first adsorption column 21 is further depressurized to a pressure lower than the primary pressure of at least one equalization step to a pressure equal to 2.1 bar. Generally, the gas discharged from the pressure equalization step is supplied to the second adsorption tower 22 and used for re-pressurization. The first adsorption tower 21 reduces the pressure of the first adsorption tower 21 to the desorption pressure effective for desorbing the nitrous oxide having a pressure lower than the counter-current countercurrent to the flow of the nitrous oxide-containing gas mixture to recover the nitrous oxide-containing desorption gas. The desorption pressure can be from vacuum to 2.1 bar. Within the above range, the adsorbent of the present invention may be suitable for purifying nitrous oxide with high purity and high recovery as the working capacity of nitrous oxide in the adsorbent of pressure cycling adsorption is high and the nitrous oxide / nitrogen selectivity and / or nitrous oxide / oxygen selectivity is high . More specifically, the desorption pressure may be from vacuum to 1 bar, or from 0.3 to 1 bar.

The temperature at which the pressure cycling adsorption process 20 is performed may be 0 to 50 캜, though not particularly limited thereto. More specifically from 0 to 40 占 폚, from 10 to 40 占 폚, or from 10 to 30 占 폚.

The process temperature and pressure of the nitrous oxide-rich concentrated pressure recycle adsorption process 20 can be controlled by the first compressor 51 and the first cooler 52. The gas mixture introduced into the nitrous oxide condensation pressure recirculation adsorption process 20 is compressed by the first compressor 51 and the temperature of the gas mixture is regulated constantly while the compression heat is removed through the first cooler 52 . The second flocculator (53) can remove moisture and oil generated during the compression process and the cooling process. The exhaust gas discharged from the nitrous oxide condensation pressure recirculation adsorption process 20 may contain 0.5 to 10% by volume of nitrous oxide. The nitrous oxide contained in the exhaust gas may be pyrolytically decomposed or catalytically decomposed and then released to the atmosphere. A nitrous oxide-containing gas mixture of 80 to 99% by volume can be obtained by the nitrous oxide concentration-pressure cyclic adsorption process (20). When the high concentration concentrated nitrous oxide-containing gas mixture is supplied to the impurity removing adsorption step 30 as shown in FIGS. 1 and 3, or when the pressure circulating adsorption step is carried out after the impurity removing adsorption step as shown in FIG. 2, May be fed to process (40).

The impurity removal adsorption process 30 removes at least one impurity of carbon dioxide, nitrogen dioxide, water vapor, and organic hydrocarbons contained in the concentrated gas mixture in the nitrous oxide condensation pressure recirculation adsorption process 20 as shown in FIGS. 1 and 3 Nitrogen dioxide, water vapor, and organic hydrocarbons contained in the gas mixture supplied to the nitrous oxide condensation pressure circulation adsorption process 20, which is performed in the previous stage of the nitrous oxide nitrogen concentration-pressure recirculation adsorption process 20 as shown in FIG. 2 And removing at least one impurity. That is, the impurity adsorption step 30 is a step of removing impurities such as carbon dioxide, nitrogen dioxide, water vapor, or organic hydrocarbons contained in the nitrous oxide-containing gas mixture. Since these impurities can not be removed in the nitrous oxide concentration pressure cyclization adsorption process 20 or the distillation process 40, they must be separated through a separate process. 0 to 5% by volume of carbon dioxide, 0 to 2% by volume of nitrogen dioxide, 0 to 1% by volume of water vapor, and 0 to 1% by volume or less of carbon dioxide are contained in the production gas of the nitrous oxide production process or the exhaust gas of the adipic acid production process. Organic hydrocarbons and the like. In the impurity removing adsorption step 30, the impurities are adsorbed and removed to lower the contents of nitrogen dioxide, carbon dioxide, and water vapor to 1.0 ppm or less, and the organic hydrocarbons to 0.1 ppm or less.

In the impurity removal and adsorption step 30, carbon dioxide and nitrogen dioxide may be adsorbed by adsorbents such as sodium hydroxide (NaOH), calcium hydroxide (Ca (OH) ₂ ) or potassium hydroxide (KOH) commonly used in the industry or those adsorbed on silica or zeolite The adsorbent (for example, Ascarite®, an adsorbent coated with sodium hydroxide on silica) can be removed by a gas-solid reaction in a packed bed. At this time, steam is generated by the reaction. After the gas-solid reaction adsorbent is consumed, the adsorbent can be removed and filled with fresh adsorbent. The steam and the organic hydrocarbons produced by the neutralization adsorption reaction of water vapor with carbon dioxide or nitrogen dioxide in the impurity removal adsorption step 30 may be adsorbed on silica or zeolite (X, Y, CaY, ZnX, 5A, 13X, etc.) Alumina silicate, or activated carbon, and an adsorption layer of these adsorbents. The impurity removal adsorption process 30 may be performed at a temperature of 10 to 50 DEG C and a pressure of 1 to 10 bar. One adsorption tower containing both carbon dioxide, nitrogen dioxide, moisture and an organic hydrocarbon removal adsorption layer can be used. However, the adsorption tower having carbon dioxide and nitrogen dioxide removal adsorption layer and the adsorption tower having moisture and organic hydrocarbon removal adsorption layer are separately used Lt; / RTI &gt; In order to continuously operate the adsorption step, two or more carbon dioxide, nitrogen dioxide adsorption tower, and water and organic hydrocarbon adsorption tower may be installed, respectively, to perform regeneration and operation. As a specific example, the first adsorption tower 31 may be configured to remove carbon dioxide and nitrogen dioxide in the gas mixture containing nitrous oxide in the adsorption step 30, and the water vapor in the gas mixture containing nitrous oxide, The second adsorption tower 32 may be configured to remove water vapor and organic hydrocarbons generated by the neutralization adsorption reaction of carbon dioxide or nitrogen dioxide in the first adsorption tower 31.

The nitrous oxide-containing gas mixture purified in the impurity removal adsorption step 30 contains no more than 1.0 ppm (volume) of nitrogen dioxide and no more than 0.1 ppm (volume) of organic hydrocarbons.

The size of the adsorbent to be filled in the adsorption towers 21 and 22 of the nitrous oxide concentration and adsorption process 20 and the adsorption towers 31 and 32 of the impurity removal adsorption process 30 is preferably in the range of 3 mm to 30 mm, The optimal size should be selected in consideration of the adsorption force and the pressure loss in the adsorption layer.

The composition of the gas mixture enriched and purified by the nitrous oxide-rich concentrated pressure recycle adsorption process 20 and the impurity adsorption process 30 may contain not less than 80% by volume, more preferably not less than 90% by volume of nitrous oxide , Nitrogen dioxide, carbon dioxide, and water vapor of 1.0 ppm or less, organic hydrocarbons of 0.1 ppm or less, and trace amounts of carbon monoxide and nitrogen monoxide.

The distillation step 40 is a step of compressing and cooling the gas mixture passed through the nitrous oxide-rich concentrated pressure recycle adsorption process 20 and the impurity removal adsorption process 30, separating the distillation and recovering the nitrous oxide with high purity. The distillation step 40 is a step in which the nitrous oxide-containing gas mixture purified and concentrated through the nitrous oxide-rich concentrated pressure recycle adsorption process 20 and the impurity removal adsorption process 30 contains nitrogen, oxygen, Nitrogen monoxide and the like are removed by distillation at a high pressure and a low temperature using vapor pressure (boiling point) difference to recover 99.999% by volume or more of high purity nitrous oxide. The distillation step 40 may be performed at a temperature of -160 to -10 ° C and a pressure of 3 to 30 bar and the temperature and pressure may be controlled by the second compressor 61 and the second cooler 62 Can be performed. The cooling water is removed from the second cooler 62 to cool it to the liquefaction temperature of the nitrous oxide, and the water or the residue is removed from the third coagulant 63 and then supplied to the distillation tower 41. The process conditions for performing the distillation step (40) may be determined according to the vapor-liquid equilibrium vapor pressure of nitrous oxide.

During the process of cooling in the second cooler 62, fine droplets of oil may be produced, which can be removed from the third coagulant 63. The third flocculator 63 may be equipped with a stainless steel net of 200 to 300 mesh, and may be a device commonly used in industry, but is not particularly limited.

The distillation tower 41 of the distillation step 40 may be a packed tower filled with a non-corrosive metal such as aluminum having a size of 5 mm to 30 mm or a ceramic filler such as alumina, For example, a multi-stage tower composed of a sieve tray or a valve tray may be used. The number of theoretical stages of the distillation tower (41) is preferably in the range of 5 to 50. A more preferable theoretical number of stages may be 10 to 30 singlets.

The nitrous oxide can be condensed and refluxed to the distillation column 41 by operating the condenser 43 installed on the distillation column 41 in the temperature range of -160 to -20 ° C. At this time, the reflux ratio is preferably in the range of 1 to 5. At the bottom of the distillation column 41, there is provided a steam generator 42 for vaporizing nitrous oxide to supply steam to the distillation column 41. At the bottom of the distillation column 41, the nitrous oxide liquid purified at high purity from the steam generator 42 is recovered.

The method of recovering the nitrous oxide according to an embodiment of the present invention is not essential but it is not necessary to recycle the gas mixture that has not been liquefied in the condenser 43 of the distillation step 40 to the nitrous oxide concentrated pressure recycle adsorption process 20 The method comprising the steps of: The uncarbonated gas mixture in the condenser 43 contains about 10% by volume or more of nitrous oxide and is recycled to the pressure circulation adsorption process 20 to perform the nitrous oxide recovery process. As a result, the finally recovered nitrous oxide The recovery rate can be further improved.

The method for recovering nitrous oxide according to an embodiment of the present invention further includes a pretreatment step (10) for removing at least one of moisture in a fine droplet state, oil fractions in a fine droplet state, and fine particle impurities from a gas mixture containing nitrous oxide .

This pretreatment process may be performed at the forefront of the nitrous oxide recovery process according to an embodiment of the present invention. Specifically, when the process is performed in the order of the pressure cycling adsorption process and the impurity removal adsorption process according to one exemplary aspect of the present invention, the adsorption can be performed before the pressure cycling adsorption process. Further, if the process is carried out in the order of the impurity removal adsorption process and pressure circulation adsorption process, it can be carried out before the impurity removal adsorption process.

The pretreatment step (10) removes water or oil particles and particle impurities in a very small amount of droplets contained in a nitrous oxide-containing gas mixture such as a production gas in a nitrous oxide production process or an exhaust gas generated in an adipic acid production process Process. The nitrous oxide-containing gas mixture, such as the product gas in the nitrous oxide production process or the exhaust gas generated in the adipic acid production process, may contain a small amount of water, oil or fine particles in a droplet state. A first flocculator (12) may be used to remove the water droplets or oil droplets. The first flocculator 12 is a device for collecting fine droplets to form a large liquid droplet. The first flocculator 12 may be equipped with a stainless steel net of 200 to 300 mesh or a device commonly used in industry, , And is not particularly limited. In order to remove particulate impurities, a filtration device 13 equipped with a filter cloth may be used. The filter cloth may be in the form of a bag filter or a cartridge. The filter cloth or the filtration apparatus is not particularly limited, and a commonly used filter cloth or a filtration apparatus can be used.

The pretreatment step 10 is preferably performed at a temperature of 10 to 40 ° C and a pressure of 1 to 2 bar, but the operation conditions of the pretreatment step are not limited thereto.

Through the nitrous oxide recovery and purification process of the present invention, the purity of the finally recovered nitrous oxide is 99.999% by volume or more and the nitrous oxide recovery rate is about 90% or more. According to the present invention, nitrous oxide recovered at a high purity of 99.999% by volume or more can be used for industries such as semiconductor, LCD, and OLED.

Hereinafter, preferred embodiments and comparative examples of the present invention will be described. However, the following examples are only a preferred embodiment of the present invention, and the present invention is not limited to the following examples.

&Lt; Analysis method of nitrous oxide concentration >

A GC (gas chromatography) method was used to measure the concentration of the nitrous oxide-containing gas mixture before and after pyrolysis. PDD (Pulsed Discharge Detector) was used as the detector of GC. Carboxene 1010 PLOT and Molecular sieve 5A were used for the analysis column. In addition, TCD (Thermal Conductivity Detector) was used for high-concentration nitrous oxide analysis.

GC analysis conditions are summarized in Table 1.

Analyzer YL Instrument 6500 GC system Detector PDD, TCD Transfer gas He (10.0 mL / min) column Carboxen-1010 PLOT, 30 mx 0.53 mm ID
Molecular sieve 5A, 30 mx 0.53 mm ID Inlet temperature 200 ℃ Detector temperature 200 ℃ Column temperature 150 ℃ Sample volume 50 μL

The process for recovering nitrous oxide according to the present invention is a pilot scale process as shown in Fig. A specific method of performing the nitrous oxide recovery process for the exhaust gas from the adipic acid production process is described with reference to FIG.

[ Example  One]

(1) Pretreatment Step: The pretreatment step (10) is a step of supplying the exhaust gas generated in the adipic acid production step from the supply device (11) and supplying the exhaust gas from the first condenser (12) The fine droplets and dusts of water and oil were removed. The first agglomerator was equipped with a 200 mesh stainless steel net having a thickness of 20 cm, and the stainless steel net had a diameter of 30 cm and a length of 60 cm. The filtration apparatus is equipped with a bag filter made of a polyester material. The bag filter has a diameter of 30 cm and a length of 80 cm. The supply flow rate of the gas mixture supplied to the nitrous oxide recovery process in FIG. 1 is 60 Nm ³ / hr and the composition is as follows.

- nitrous oxide (N ₂ O): 35% by volume,

- Nitrogen (N ₂ ): 60.0 vol%

- Oxygen (O ₂ ): 2.7 vol%

- Carbon dioxide (CO ₂ ): 2 vol%

- water (H ₂ O): 0.3% by volume

- Nitrogen dioxide (NO ₂ ): 200 ppm

- nitrogen monoxide (NO): 800 ppm

- Organic hydrocarbons: 100 ppm

). 10bar 압력 하의 아산화질소/질소 선택도(A_N2O/A_N2)는 7.6이고, 10bar 압력 하의 아산화질소/산소 선택도(A_N2O/A_O2)는 7.7이다. (2) Nitrous Oxide Condensation Pressure Circulation Adsorption Process: Two adsorption columns filled with de-aluminum zeolite Y (DEGUSSA, WESSALITH DAY F-20, SiO ₂ / Al ₂ O ₃ = 20), adsorbent excellent in adsorption to nitrous oxide (21, 22) was carried out for the pressure cycling adsorption process. The two adsorption towers (21, 22) in the pressure cycling adsorption process used in the experiments were 18 cm in diameter and 600 cm in length. 4, the adsorption amount (W ₀ ) at a pressure of 10 bar was 3.91 mol / kg, the adsorption amount (W ₁ ) at a pressure of 0.3 bar was 0.25 mol / kg (

). The nitrous oxide / nitrogen selectivity (A _N2O / A _N2 ) at 10 bar pressure is 7.6 and the nitrous oxide / oxygen selectivity (A _N2O / A _O2 ) at 10 bar pressure is 7.7.

The gas mixture from the pretreatment step (10) is pressurized by the first compressor (51), cooled to room temperature in the first cooler (52), and then water and oil are removed from the second agglomerator (53) And supplied to the adsorption towers (21, 22). The composition of the nitrous oxide-containing gas mixture to be supplied to the adsorption towers (21, 22) was the same as the composition of the gas mixture fed to the pretreatment step (10), and the flow rate was 60 Nm ³ / hr. The adsorption temperature was room temperature, the adsorption pressure was 10 bar, and the desorption pressure was 0.3 bar. The adsorption time and the washing time were set to 100 sec and 140 sec, respectively. The composition of the gas mixture used in the cleaning step in the cleaning gas is nitrous oxide was 90% by volume and nitrogen 10% by volume flow rate was 1/10 of the nitrous oxide-containing gas mixture flow to be supplied to 6 Nm ³ / hr. The composition of the nitrous oxide-containing gas mixture was analyzed using the gas chromatography method shown in Table 1 above. The flow rate of the desorption product obtained in the washing step and the depressurization step of the pressure circulation adsorption step was 26.5 Nm ³ / hr. The composition was 90.3% by volume of nitrous oxide, 0.2% by volume of oxygen and 8.8% by volume of nitrogen, and 0.7% by volume of carbon dioxide, 500 ppm, 34 ppm of nitrogen dioxide, 138 ppm of nitrogen monoxide and 17 ppm of organic hydrocarbons.

The nitrous oxide concentration of the exhaust gas in the pressure cycle adsorption process was 6.3 vol% and the flow rate was 39.5 Nm ³ / hr. The recovery of nitrous oxide from the product is calculated by dividing the recovery of nitrous oxide in the washing and decompression stages by the sum of the supply of nitrous oxide in the pressurization and adsorption stages and the supply of nitrous oxide in the cleaning stage. The recovery rate of nitrous oxide calculated by this method was 90.5%. The gas mixture containing 6.3 vol% of nitrous oxide discharged from the nitrous oxide condensation pressure cyclic adsorption process was subjected to high frequency induction pyrolysis treatment to lower the concentration of nitrous oxide released into the air to 100 ppm or less.

(3) Impurity removal adsorption process: The impurity removal adsorption process 30 is a process in which the concentrated gas mixture (90.3% by volume of nitrous oxide, 0.2% by volume of oxygen and 8.8% by volume of nitrogen, 0.7 volume%, water 500 ppm, nitrogen dioxide 34 ppm, nitrogen monoxide 138 ppm and organic hydrocarbon 17 ppm) were supplied to the adsorption towers 31 and 32 to remove impurities such as carbon dioxide, nitrogen dioxide, water vapor and organic hydrocarbons. In the impurity removal adsorption step 30, the adsorption layers filled with the adsorbents of the first adsorption tower 31 and the second adsorption tower 32 are respectively 20 cm in diameter and 200 cm in length. In the first adsorption tower 31, Ascarite (R), which is an adsorbent coated with sodium hydroxide, was filled in silica having a size of 5 to 10 mm, and zeolite 5A was loaded in the second adsorption tower 32 in a size of 5 to 10 mm. The first filling tower 31 is equipped with a jacket for supplying cooling water to remove heat generated by the adsorption reaction. The first adsorption column and the second adsorption column were operated at a normal temperature and a pressure of 1.5 bar, respectively. In the first adsorption column 31, carbon dioxide and nitrogen dioxide react with sodium hydroxide to be removed, and water vapor is generated. The water vapor and the organic hydrocarbons contained in this gas and the supplied gas mixture are adsorbed and removed in the second adsorption tower 32. The flow rate of the nitrous oxide-containing gas mixture purified in the impurity removal adsorption step (30) was 26.3 Nm ³ / hr, and the composition was as follows.

- 90.9% by volume of nitrous oxide,

Nitrogen (N ₂ ): 8.9 vol%

- Oxygen (O ₂ ): 0.2 vol%

- Carbon dioxide (CO ₂ ): 0.2 ppm

- Water vapor: 0.6 ppm

- nitrogen dioxide (NO ₂ ): 0.2 ppm

- nitrogen monoxide (NO): 15 ppm

- Organic hydrocarbons: 0.1 ppm

(4) Distillation: by feeding to the distillation step 40, the impurity removal and the adsorption process (30) the gas mixture (nitrous oxide and 90.9% by volume) flow rate to the distillation step (40) of the 26.3 Nm ³ / hr purified from by Nitrogen and oxygen were removed to obtain high purity nitrous oxide. The gas mixture discharged from the second adsorption tower 32 of the impurity removal adsorption step 30 is pressurized to a pressure of 20 bar by the second compressor 61 of the distillation step 40, After removing the heat, the gas mixture was cooled to a temperature of -60 DEG C, and the resulting water and oil droplets were removed from the third coagulant 63 and then fed to the distillation column 41. [ The distillation column 41 is filled with a 5/8 inch stainless steel pall ring, the filling layer is 15 cm in diameter and 6 m in height. The nitrous oxide was condensed in the condenser 43 provided on the top of the distillation column 41 and recycled to the distillation column 41. The temperature of the condenser 43 was kept at -70 캜. The reflux ratio of the distillation column 41 was maintained at 2. The non-liquefied gas mixture (7.7% by volume of nitrous oxide, flow rate 2.6 Nm ³ / hr) was recycled in the condenser 43 to the nitrous oxide concentrated pressure cyclic adsorption process 20. The liquid nitrous oxide was vaporized in the steam generator 42 provided at the lower portion of the distillation tower 41 and supplied to the distillation tower 41. The temperature of the steam generator 42 was maintained at -23 캜. The nitrous oxide purified at high purity was recovered from the lower steam generator of the distillation column (41). The flow rate of the liquid nitrous oxide recovered in the distillation step (40) was about 23.7 Nm ^{3 /} hr (42.6 kg / hr). The composition was as follows and the purity of carbon dioxide was 99.9999% by volume. The amount of nitrous oxide recovered from the nitrous oxide-containing gas introduced into the distillation process by the distillation process was 97.1%. The recovery rate of nitrous oxide in the recovering step of the present invention is 89.8% when it is not considered to recycle the gas mixture discharged from the upper condenser 43 of the distillation step 40 to the nitrous oxide concentrated pressure cyclic adsorption process.

- Nitrous oxide (N ₂ O): 99.9999 vol%

- nitrogen (N ₂ ): 0.8 ppm

- oxygen (O ₂ ): 0.4 ppm

- Carbon dioxide (CO ₂ ): 0.2 ppm

- water (H ₂ O): 0.4 ppm

- nitrogen dioxide (NO ₂ ): 0.1 ppm

- nitrogen monoxide (NO): 0.1 ppm

- Organic hydrocarbons: 0.1 ppm

[ Example  2]

). 10bar 압력 하의 아산화질소/질소 선택도(A_N2O/A_N2)는 8.8 이고, 10bar 압력 하의 아산화질소/산소 선택도(A_N2O/A_O2)는 8.8이다. The nitrous oxide recovery experiment was carried out in the same manner as in Example 1, except that Sylobead silica gel (GRACE GmbH & Co., SYLOBEAD SG B 127) was used as the adsorbent for the N 2 O 2 pressure cycling adsorption process. The adsorption isotherm at 20 ° C of the used Sylobead silica gel is as shown in FIG. 5, the adsorption amount (W ₀ ) at a pressure of 10 bar is 3.92 mol / kg and the adsorption amount (W ₁ ) at a pressure of 0.3 bar is 0.30 mol / kg (

). The nitrous oxide / nitrogen selectivity (A _N2O / A _N2 ) at 10 bar pressure is 8.8 and the nitrous oxide / oxygen selectivity (A _N2O / A _O2 ) at 10 bar pressure is 8.8.

The flow rate of the desorbed product obtained in the step of washing and depressurizing the pressure circulating adsorption process was 26.3 Nm ³ / hr. The composition was 90.5% by volume of nitrous oxide, 0.2% by volume of oxygen and 8.6% by volume of nitrogen and 0.7% by volume of carbon dioxide 550 ppm, 30 ppm nitrogen dioxide, 125 ppm nitrogen monoxide, and 16 ppm organic hydrocarbons. The nitrous oxide concentration of the exhaust gas in the pressure cycle adsorption process was 6.5 vol% and the flow rate was 39.7 Nm ³ / hr. The recovery rate of nitrous oxide calculated in the same manner as in Example 1 was 90.2%.

The flow rate of the purified nitrous oxide-containing gas mixture in the impurity removal adsorption process was 26.2 Nm ³ / hr, and the composition was as follows.

- 90.8% by volume of nitrous oxide,

Nitrogen (N ₂ ): 8.9 vol%

- Oxygen (O ₂ ): 0.3 vol%

- Carbon dioxide (CO ₂ ): 0.2 ppm

- Water vapor: 0.7 ppm

- nitrogen dioxide (NO ₂ ): 0.2 ppm

- nitrogen monoxide (NO): 12 ppm

- Organic hydrocarbons: 0.1 ppm

In addition, the flow rate of the liquid nitrous oxide recovered in the distillation process was about 23.5 Nm ^{3 /} hr (42.4 kg / hr). The composition was as follows and the purity of nitrous oxide was 99.9999% by volume. The flow rate of the gas mixture discharged from the top of the distillation tower was 2.8 Nm ³ / hr and the concentration of nitrous oxide was 10.7% by volume.

- Nitrous oxide (N ₂ O): 99.9999 vol%

- Nitrogen (N ₂ ): 0.9 ppm

- oxygen (O ₂ ): 0.4 ppm

- Carbon dioxide (CO ₂ ): 0.2 ppm

- water (H ₂ O): 0.3 ppm

- nitrogen dioxide (NO ₂ ): 0.1 ppm

- nitrogen monoxide (NO): 0.1 ppm

- Organic hydrocarbons: 0.1 ppm

The amount of nitrous oxide recovered from the nitrous oxide-containing gas introduced into the distillation process by the distillation process was 98.72%. In the case of not recirculating the gas mixture discharged from the upper condenser of the distillation process to the nitrous oxide concentrated pressure recycling process, the recovery rate of nitrous oxide in the recovering process of the present invention is 89.0%.

[ Comparative Example  One]

). 10bar 압력 하의 아산화질소/질소 선택도(A_N2O/A_N2)는 2.7이고, 10bar 압력 하의 아산화질소/산소 선택도(A_N2O/A_O2)는 6.1이다. The nitrous oxide recovery experiment was carried out in the same manner as in Example 1, except that zeolite 13X (UOP, 1/8 inch pellet) was used as the adsorbent in the nitrous oxide concentration pressure cycling adsorption process. The adsorption amount (W ₀ ) of the zeolite 13X at 20 ° C was as shown in FIG. 6, the adsorption amount (W ₀ ) at 5.2 bar and the adsorption amount (W ₁ ) at 3.5 bar were 3.50 mol / kg

). The nitrous oxide / nitrogen selectivity (A _N2O / A _N2 ) at 10 bar pressure is 2.7 and the nitrous oxide / oxygen selectivity (A _N2O / A _O2 ) at 10 bar pressure is 6.1.

The flow rate of the desorption product obtained in the washing and depressurization step of the pressure circulation adsorption step was 23.5 Nm ³ / hr. The composition was 59.4 vol.% Of nitrous oxide, 0.4 vol.% Of oxygen and 39.3 vol.% Of nitrogen. The other impurities were 0.9 vol. 450 ppm, 52 ppm of nitrogen dioxide, 128 ppm of nitrogen monoxide and 18 ppm of organic hydrocarbons. The nitrous oxide concentration of the exhaust gas in the pressure circulation adsorption process was 29.2 vol% and the flow rate was 42.5 Nm ³ / hr. The recovery rate of nitrous oxide calculated in the same manner as in Example 1 was 52.8%.

The flow rate of the nitrous oxide-containing gas mixture purified in the impurity removal adsorption process was 23.3 Nm ³ / hr, and the composition was as follows.

- 59.9% by volume of nitrous oxide,

- Nitrogen (N ₂ ): 39.7 vol%

Oxygen (O ₂ ): 0.4 vol%

- Carbon dioxide (CO ₂ ): 0.2 ppm

- Water vapor: 0.7 ppm

- nitrogen dioxide (NO ₂ ): 0.2 ppm

- nitrogen monoxide (NO): 18 ppm

- Organic hydrocarbons: 0.1 ppm

The distillation process was carried out so that the purity of nitrous oxide was 99.9999% by volume. The flow rate of the liquid nitrous oxide recovered in the distillation process was about 8.6 Nm ^{3 /} hr (42.4 kg / hr). The composition was as follows. The flow rate of the gas mixture discharged from the top was 14.7 Nm ³ / hr and the concentration of nitrous oxide was 36.1% by volume.

- Nitrous oxide (N ₂ O): 99.9999 vol%

Nitrogen (N ₂ ): 1.0 ppm

- Oxygen (O ₂ ): 0.5 ppm

- Carbon dioxide (CO ₂ ): 0.3 ppm

- water (H ₂ O): 0.2 ppm

- nitrogen dioxide (NO ₂ ): 0.1 ppm

- nitrogen monoxide (NO): 0.1 ppm

- Organic hydrocarbons: 0.1 ppm

The amount of nitrous oxide recovered from the nitrous oxide-containing gas introduced into the distillation process by the distillation process was 61.8%. In the case of not recirculating the gas mixture discharged from the upper condenser of the distillation process to the nitrous oxide concentrated pressure recirculation adsorption process, the recovery rate of nitrous oxide in the recovering process of the present invention is 32.6%.

From the results, it can be seen that, in the case of Comparative Example 1 using the adsorbent which does not satisfy Equations 1 to 3 of the present invention, the recovery rate of nitrous oxide in the entire process is much lower than that in Examples.

10: Pretreatment Step 11: Feeder
12: first agglomerator 13: filtration device
20: Nitrous oxide concentration pressure cyclic adsorption process
21: first pressure circulation adsorption tower 22: second pressure circulation adsorption tower
30: Impurity removal adsorption process 31: First adsorption tower
32: second adsorption tower 40: distillation step
41: Distillation column 42: Steam generator
43: condenser 51: first compressor
52: first cooler 53: second agglomerator
61: second compressor 62: second cooler
63: Third agglomerator

Claims (23)

A pressure circulation adsorption process using a nitrous oxide recovery adsorbent that satisfies a working capacity represented by the following formula 1 by concentrating nitrous oxide by removing at least one of nitrogen and oxygen from a gas mixture containing nitrous oxide;
An impurity removing adsorption step of removing impurities of at least one of carbon dioxide, nitrogen dioxide, water vapor and organic hydrocarbons from the gas mixture after the pressure circulation adsorption step; And
And a distillation step of distilling the gas mixture that has undergone the impurity removal adsorption step to recover the nitrous oxide.
[Formula 1]

W ₀ is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar in the adsorption isotherm at 20 ° C of the adsorbent, W ₁ is the adsorption amount of nitrous oxide in the adsorption isotherm at 20 ° C Nitrogen adsorption amount (mol / kg), W ₀ is 3.50 to 5.00 mol / kg, and W ₁ is 0.10 to 1.00 mol / kg. Removing impurities from the gas mixture containing nitrous oxide to remove at least one of carbon dioxide, nitrogen dioxide, water vapor and organic hydrocarbons;
A pressure circulation adsorption step of using the adsorbent for recovering nitrous oxide which satisfies the working capacity represented by the following formula (1), by concentrating the nitrous oxide by removing at least one of nitrogen and oxygen from the gas mixture after the impurity removal adsorption step; And
And a distillation step of distilling the gas mixture after the pressure circulation adsorption step to recover the nitrous oxide.
[Formula 1]

W ₀ is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar in the adsorption isotherm at 20 ° C of the adsorbent, W ₁ is the adsorption amount of nitrous oxide in the adsorption isotherm at 20 ° C Nitrogen adsorption amount (mol / kg), W ₀ is 3.50 to 5.00 mol / kg, and W ₁ is 0.10 to 1.00 mol / kg. The method of claim 1,
Further comprising a pretreatment step for removing at least one of water in the fine droplet state, oil in the fine droplet state, and fine particle impurities from the gas mixture containing nitrous oxide prior to the pressure circulation adsorption step . 3. The method of claim 2,
Further comprising a pretreatment step for removing at least one of moisture in the fine droplet state, oil in the fine droplet state, and fine particle impurities from the gas mixture containing nitrous oxide before the impurity removal adsorption step . 3. The method according to claim 1 or 2,
Further comprising compressing and cooling the gas mixture prior to the pressure cycling adsorption process or the distillation process. 3. The method according to claim 1 or 2,
Wherein the adsorbent further satisfies the nitrous oxide / nitrogen selectivity represented by the following formula (2).
[Formula 2]

(A _N2O is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar at the adsorption isotherm of the adsorbent at 20 ° C and A _N2 is the adsorption amount of nitrogen of the adsorbent under the pressure of 10 bar at the adsorption isotherm at 20 ° C Adsorption (mol / kg).) 3. The method according to claim 1 or 2,
Wherein the adsorbent further satisfies the nitrous oxide / oxygen selectivity represented by the following formula (3).
[Formula 3]

(In the formula 3, A _N2O is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar in the adsorption isotherm at 20 ° C of the adsorbent and A _O2 is the adsorption amount of oxygen in the adsorption isotherm at 20 ° C Adsorption (mol / kg).) 3. The method according to claim 1 or 2,
Wherein the pressure circulation adsorption step uses two or more adsorption towers charged with the adsorbent and the pressurization step, the adsorption step, the equilibrium pressure and the washing step, and the desorption step are performed at least once in each adsorption tower, and the pressure in the adsorption step is 1.7 To 20 bar, and the pressure of the desorption step is from vacuum to 2.1 bar. 3. The method according to claim 1 or 2,
Wherein the pressure cycle adsorption process is performed at a temperature of 0 to 50 占 폚. 3. The method according to claim 1 or 2,
Wherein the adsorbent is De-Aluminated Zeolite Y or Sylobead (R) Silica Gel. 11. The method of claim 10,
Wherein the content of Si and Al in the dealuminated zeolite Y satisfies the following formula (4).
[Equation _{4] 5≤SiO 2 / Al 2 O} 3 ≤30 3. The method according to claim 1 or 2,
The impurity removing adsorption step is a step
A step of removing at least one of carbon dioxide and nitrogen dioxide using at least one adsorbent selected from the group consisting of sodium hydroxide, calcium hydroxide and potassium hydroxide at a temperature of 10 to 50 DEG C and a pressure of 1 to 10 bar or an adsorbent thereof coated on silica or zeolite , And
Removing at least one of water vapor and organic hydrocarbons using at least one adsorbent of silica, zeolite, alumina silicate and activated carbon at a temperature of 10 to 50 DEG C and a pressure of 1 to 10 bar. Way. 3. The method according to claim 1 or 2,
Wherein the distillation step comprises: a packed tower filled with a filler made of a metal or ceramic material at a temperature of -160 to -10 DEG C and a pressure of 3 to 30 bar; Or a multi-stage tray tower comprising a plurality of stages. 4. The method according to claim 3 or 4,
Wherein the pretreatment step is carried out at a temperature of from 10 to 40 DEG C and a pressure of from 1 to 2 bar. A pressure circulation adsorption unit for adsorbing a nitrous oxide-recovering adsorbent satisfying a working capacity represented by the following formula 1 in an adsorption tower by removing at least one of nitrogen and oxygen from a gas mixture containing nitrous oxide to concentrate nitrous oxide;
An impurity removing adsorption unit connected to the pressure circulation adsorption unit and removing at least one impurity of carbon dioxide, nitrogen dioxide, water vapor and organic hydrocarbons from the gas mixture passed through the pressure circulation adsorption unit; And
And a distillation unit connected to the impurity removing adsorption unit and distilling the gas mixture passed through the impurity removing adsorption unit to recover nitrous oxide.
[Formula 1]

W ₀ is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar in the adsorption isotherm at 20 ° C of the adsorbent, W ₁ is the adsorption amount of nitrous oxide in the adsorption isotherm at 20 ° C Nitrogen adsorption amount (mol / kg), W ₀ is 3.50 to 5.00 mol / kg, and W ₁ is 0.10 to 1.00 mol / kg. An impurity removing adsorbent for removing impurities from at least one of carbon dioxide, nitrogen dioxide, water vapor and organic hydrocarbons from a gas mixture containing nitrous oxide;
Removing at least one of nitrogen and oxygen from the gas mixture passing through the impurity removing adsorbing section to concentrate the nitrous oxide and adsorbing a nitrous oxide recovering adsorbent satisfying the working capacity represented by the following formula 1 A pressure circulation adsorption unit included in the adsorption column; And
And a distillation unit connected to the pressure circulation adsorption unit and distilling the gas mixture passed through the pressure circulation adsorption unit to recover the nitrous oxide.
[Formula 1]

W ₀ is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar in the adsorption isotherm at 20 ° C of the adsorbent, W ₁ is the adsorption amount of nitrous oxide in the adsorption isotherm at 20 ° C Nitrogen adsorption amount (mol / kg), W ₀ is 3.50 to 5.00 mol / kg, and W ₁ is 0.10 to 1.00 mol / kg. 16. The method of claim 15,
Removing at least one of moisture in a fine droplet state, oil fractions in a fine droplet state, and fine particle impurities from a gas mixture containing nitrous oxide, and removing the impurity-removed gas mixture from the gas mixture containing the nitrous oxide, And a pretreatment unit for supplying the adsorbent to the adsorption unit. 17. The method of claim 16,
Removing at least one of moisture in a fine droplet state, oil fractions in a fine droplet state, and fine particle impurities from a gas mixture containing nitrous oxide, and removing the impurity-removed gas mixture from the gas mixture containing the nitrous oxide- And a pretreatment unit for supplying the adsorbent to the adsorption unit. 17. The method according to claim 15 or 16,
Wherein the adsorbent further satisfies the nitrous oxide / nitrogen selectivity represented by the following formula (2).
[Formula 2]

(A _N2O is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar at the adsorption isotherm of the adsorbent at 20 ° C and A _N2 is the adsorption amount of nitrogen of the adsorbent under the pressure of 10 bar at the adsorption isotherm at 20 ° C Adsorption (mol / kg).) 17. The method according to claim 15 or 16,
Wherein the adsorbent further satisfies the nitrous oxide / oxygen selectivity represented by the following formula (3).
[Formula 3]

(In the formula 3, A _N2O is the adsorption amount (mol / kg) of the nitrous oxide under the pressure of 10 bar in the adsorption isotherm at 20 ° C of the adsorbent and A _O2 is the adsorption amount of oxygen in the adsorption isotherm at 20 ° C Adsorption (mol / kg).) 17. The method according to claim 15 or 16,
Wherein the pressure circulation adsorption unit includes two or more adsorption towers charged with the adsorbent and the pressurization step, adsorption step, pressure equalization step and desorption step are performed at least once in each adsorption tower. 17. The method according to claim 15 or 16,
Wherein the impurity removing /
A first adsorption tower containing at least one adsorbent selected from the group consisting of sodium hydroxide, calcium hydroxide and potassium hydroxide, or an adsorbent thereof coated on silica or zeolite; And
And a second adsorption tower containing at least one adsorbent of silica, zeolite, alumina silicate and activated carbon. 17. The method according to claim 15 or 16,
Wherein the distillation section comprises:
A packed tower filled with a filler made of a metal or ceramic material, or a tray tower comprising a plurality of stages.

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