KR101955018B1 - method for recovering nitrous oxide using pressure swing adsorption Process AND pressure swing adsorption APPARATUS for recovering Nitrous oxide - Google Patents

Abstract

The present invention relates to a method for recovering nitrous oxide from a nitrous oxide-containing gas mixture through pressure swing adsorption, and a pressure swing adsorption apparatus. It is possible to provide the method for recovering nitrous oxide which is separating nitrous oxide through pressure swing adsorption with an adsorbent for recovering nitrous oxide satisfying the working capacity represented by formula 1, 0.90 <= W_0-W_1/W_0. By the method for recovering nitrous oxide and the pressure swing adsorption apparatus for the same according to the present invention, it is possible to obtain a reduction effect of greenhouse gases.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering nitrous oxide using pressure circulation adsorption and a method for recovering nitrous oxide using a pressure swing adsorption process,

More particularly, the present invention relates to a method for recovering nitrous oxide using pressure swing adsorption (PSA) from a nitrous oxide-containing gas mixture and a method for recovering nitrous oxide from a pressure circulation adsorber .

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.

The prior art for adsorption technology for nitrous oxide separation is as follows.

Centi et al. (Ind. Eng. Chem. Res., Vol. 39, pp 131-137, 2000) investigated ZSM5 zeolite to remove low concentrations of nitrous oxide (500-2,000 ppm) ZSM5, which is a metal substitute such as strontium, is effective for the adsorption and removal of nitrous oxide. US 5,919,286A proposes a technique using zeolite as an adsorbent for a pressure swing adsorption process (PSA process) for the removal of nitrous oxide. US 6,273,939 B1 proposed using CaX or LSX adsorbent to remove nitrous oxide in the air prior to cryogenic distillation separation of air. US 8,246,721 B2 discloses a technique for using zeolite as an adsorbent in which at least 50% of the metal cations are substituted with one or more metal cations to purify a gas mixture containing at least 5% nitrous oxide. EP 1 092 465 A2 proposes a technique using zeolite X to remove nitrous oxide and hydrocarbon impurities in the air prior to cryogenic distillation of air.

However, the above prior arts have not been utilized in practical industry because the purity and recovery rate of nitrous oxide purified due to the lack of selective adsorption performance of the adsorbent is low.

The present inventors have intensively studied a new pressure cyclic adsorption method for selectively separating nitrous oxide from a nitrous oxide-containing gas mixture. As a result, the present inventors have developed an adsorbent excellent in selectivity to nitrous oxide compared to nitrogen and oxygen, and a pressure circulation adsorption method utilizing the same.

One aspect of the present invention is a method for recovering nitrous oxide from a nitrous oxide-containing gas mixture containing nitrous oxide, oxygen, and nitrogen at a high purity and a high recovery rate using a nitrous oxide recovery method using pressure swing adsorption (PSA) .

One aspect of the present invention is to provide a pressure circulation adsorption apparatus capable of implementing the nitrous oxide recovery method of the present invention.

One aspect of the present invention provides a method for recovering nitrous oxide by separating nitrous oxide through pressure cyclic adsorption with a nitrous oxide recovery adsorbent that satisfies the working capacity represented by the following formula 1.

[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 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 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).)

The nitrous oxide recovery method of one embodiment of the present invention may be to remove at least one selected from oxygen and nitrogen in the nitrous oxide-containing gas mixture.

The nitrous oxide-containing gas mixture may comprise 5 to 98% by volume of nitrous oxide, 0.1 to 15% by volume of oxygen, and 1 to 90% by volume of nitrogen.

Wherein the pressure circulation adsorption is performed by using at least two adsorption towers charged with the adsorbent and at least one pressurization step, an adsorption step, a pressure equalization step and a desorption step, and a desorption step in each adsorption tower, 20 bar, and the pressure of the desorption step may be vacuum to 2.1 bar.

The method for recovering nitrous oxide according to an embodiment of the present invention may be performed at a temperature of 0 to 50 ° C.

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

Another aspect of the present invention provides a pressure circulation adsorbing apparatus for separating nitrous oxide, the adsorbent containing a nitrous oxide recovery adsorbent satisfying the working capacity represented by the following formula 1 in an adsorption tower.

[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 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 nitrous oxide recovery method and the pressure circulation adsorption apparatus for the same according to the present invention effectively recover nitrous oxide having a global warming index of 310 times higher than carbon dioxide from the nitrous oxide-containing gas mixture, thereby achieving a reduction effect of greenhouse gases.

In the method of recovering nitrous oxide according to the present invention and the pressure circulation adsorption device therefor, 80 to 99% by volume or 99% by volume or more of the gas mixture generated in the process of producing nitrous oxide by pyrolysis of ammonium nitrate and the process of producing adipic acid, Can be recovered at a high recovery rate and can be reused industrially. Further, nitrous oxide having a purity of 80 to 99% by volume recycled by the present invention can be further purified through a post-process such as a low-temperature distillation process to produce ultra high purity nitrous oxide of 99.999% by volume or more, have.

That is, since the nitrous oxide recovery method of the present invention and the pressure circulation adsorption apparatus for the same can purify nitrous oxide from the nitrous oxide-containing gas mixture at a high purity and a high recovery rate, It is possible to obtain an economic benefit.

1 is an exemplary schematic diagram of an exemplary pressure cycling adsorber of the present invention.
2 is an adsorption isotherm of the adsorbent (dealumin zeolite Y) used in Examples 1 to 4 at 20 ° C.
3 is an adsorption isotherm of the adsorbent (Sylobead silica gel) used in Examples 5 to 8 at 20 ° C.
4 is an adsorption isotherm of the adsorbent (zeolite 13X) used in Comparative Examples 1 to 4 at 20 ° C.

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.

Generally, in the production gas of the nitrous oxide production process by pyrolysis of ammonium nitrate or the exhaust gas of the adipic acid production process, for example, 5 to 98% by volume of nitrous oxide, 0.1 to 15% by volume of oxygen and 1 to 90% And a small amount of carbon dioxide, carbon monoxide, nitrogen dioxide, nitrogen monoxide, water vapor, and the like.

Of these, the gas components that must be removed to purify nitrous oxide are oxygen and nitrogen. The present inventors have found that by removing nitrogen and / or oxygen from a nitrous oxide-containing gas mixture such as a product gas in the process of producing nitrous oxide by pyrolysis of ammonium nitrate or an exhaust gas of an adipic acid production process and thereby obtaining nitrocellulose with high purity (high concentration) The present inventors have invented the present invention by studying a pressure circulation adsorption method capable of purification.

One aspect of the present invention provides a method for recovering nitrous oxide by separating nitrous oxide through pressure cyclic adsorption with a nitrous oxide recovery adsorbent that satisfies the working capacity represented by the following formula 1.

[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 is reduced and the amount of nitrous oxide in the exhaust gas is increased, The recovery rate of nitrous oxide may decrease. 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.

In the method of recovering nitrous oxide according to an embodiment of the present invention, 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.

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 further satisfy the above-described expression (2) or (3).

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.

In the nitrous oxide recovery method of one embodiment of the present invention, the adsorbent may be 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.

The pressure cyclic adsorption of the nitrous oxide recovery method of one embodiment of the present invention is carried out by using two or more adsorption towers charged with the adsorbent and performing at least one pressurization step, adsorption step, pressure equalization step and desorption step in each adsorption tower , 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.

In the pressure circulation adsorption of the present invention, a desorption process by a normal pressure regeneration method or a vacuum regeneration method may be adopted. The adsorption of the pressure cycling adsorption according to the present invention can be carried out in a pressurized state and a desolvated state under atmospheric or vacuum conditions by a pressurization step, an adsorption step, a pressure equalization and a rinse step and a normal pressure decompression step And a desorption step that operates in a vacuum state. The pressure cycling adsorption of the present invention is preferably carried out by a normal pressure regeneration method 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.

The pressure cycling adsorption of the present invention compresses a nitrous oxide-containing gas mixture and introduces it into an adsorbent bed where adsorption takes place at high pressure. The nitrous oxide is adsorbed on one adsorption tower of at least two adsorption towers operating alternately. The gas mixture from which the nitrous oxide has been removed is discharged from the adsorption tower, and the portion where the nitrous oxide adsorption is performed in the adsorption tower gradually moves to the outlet of the adsorption tower. The gas mixture at the outlet of the adsorption column may contain no more than 10 vol%, no more than 5 vol%, more specifically no more than 2 vol% nitrous oxide. The supply of the nitrous oxide-containing gas mixture is stopped when the portion where the nitrous oxide adsorption occurs at the adsorption tower reaches a predetermined point between the inlet and outlet of the adsorption tower. The pressure in the adsorption tower 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 boost the pressure of the other adsorption column.

The adsorption pressure may be from 1.7 to 20 bar, and more specifically from 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 adsorption column lowers the pressure further downward from a vacuum of at least one equalization step to a pressure equal to or lower than the primary pressure of 2.1 bar. Generally, the gas discharged from the pressure equalization step is supplied to another adsorption tower and used for repressurization. The adsorption column is depressurized to a desorption pressure effective for desorbing nitrous oxide below sub-atmospheric pressure countercurrent to the flow of the nitrous oxide-containing gas mixture to recover the nitrous oxide-containing desorbent 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 nitrous oxide recovery method using pressure cyclic adsorption of the present invention is carried out may be 0 to 50 캜, though it is 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.

 As an example of a pressure circulation adsorption apparatus in which the method of recovering nitrous oxide using the pressure circulation adsorption according to an embodiment of the present invention is performed, a pressure circulation adsorption apparatus for recovering nitrous oxide using two adsorption towers is schematically illustrated in FIG. Respectively. Hereinafter, the method for recovering nitrous oxide according to the present invention will be described in detail with reference to the schematic diagram shown in FIG.

As described above, the pressure circulation adsorption of the present invention is made by the atmospheric pressure regeneration method or the vacuum regeneration method. The pressure circulation adsorption is a system which is operated under pressure or adsorption at a pressurized state or at a normal pressure or a vacuum state and pressurization, adsorption, equilibration and rinse steps and atmospheric pressure decompression or vacuum And a desorption step operated in a vacuum mode.

In the adsorption step, compressed nitrous oxide-containing gas mixture is supplied to the adsorption tower AD1 of FIG. 1 to adsorb nitrous oxide while increasing the pressure of the adsorption tower. The valve V1 (valve V2, V3, V5 closing) shown in Fig. 1 is opened to supply a nitrous oxide-containing gas mixture to the adsorption tower AD1, while adsorbing nitrous oxide while pressurizing, passing through the valve V6 (valves V7 and V8) Nitrogen and oxygen are released.

When the adsorption step is completed, a pressure equalization and a washing step are performed. In the washing step, first, the pressure in the adsorption tower AD1 and the pressure in the adsorption tower AD2 are opened by opening the valves V5 and V8 (valves V1, V2, V3, V4, V5, Equalize. Then, the valves V3 and V8 (valves V1, V3, V4, V5, and V6. V7 are closed) are opened to send the high concentration nitrous oxide recovered in the adsorption step of the adsorption tower AD2 to the adsorption tower AD1 to clean the nitrous oxide adsorbed by the adsorption agent .

In the desorption step, after the pressure equalization and washing step is completed, the valve V3 (valves V1, V4, V5, V6, V7 and V8 are closed) is opened to decompress the adsorption tower AD1 at atmospheric pressure or vacuum to desorb and recover the adsorbed nitrous oxide. Simultaneously with this process, the valve V2 opens and the nitrous oxide-containing gas mixture is advanced to the adsorption tower AD2. When the adsorption tower AD2 is saturated with nitrous oxide, the supply valve V2 of the nitrous oxide-containing gas mixture is closed and passed to the cleaning step.

At the same time, the desorbed adsorption tower AD1 is again supplied with the pressurized nitrous oxide-containing gas mixture. This series of steps is repeated and the nitrous oxide is continuously recovered.

Another aspect of the present invention provides a pressure circulation adsorbing apparatus for separating nitrous oxide, the adsorbent containing a nitrous oxide recovery adsorbent satisfying the working capacity represented by the following formula 1 in an adsorption tower.

[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).)

This is an apparatus capable of performing a nitrous oxide recovery method using pressure circulation adsorption according to an embodiment of the present invention, wherein the adsorbent for recovering nitrous oxide satisfying the above formula 1 is contained in each adsorption tower of the pressure circulation adsorption apparatus . Thus, nitrous oxide can be purified from a mixture of nitrous oxide-containing gas such as a product gas produced by the pyrolysis of ammonium nitrate or a product gas produced by the adipic acid production process in a high purity and a high recovery rate.

The working capacity of the adsorbent may be related to the purity and recovery of the nitrous oxide recovered. 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 is reduced and the amount of nitrous oxide in the exhaust gas is increased, The recovery rate of nitrous oxide may decrease. 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).

In the pressure cycling adsorption apparatus of one embodiment of the present invention, 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 decomposition ability is poor. Since the nitrogen or oxygen to be removed is not sufficiently removed by adsorption, the purity of recovered nitrous oxide .

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 further satisfy the above-described expression (2) or (3).

Other explanations for the adsorbent are omitted since they are the same as those described in the method for recovering nitrous oxide using the pressure cyclic adsorption of one embodiment of the present invention.

Other configurations of the pressure circulation adsorbing device of one embodiment of the present invention may adopt known configurations and are not limited to specific configurations.

For example, it is possible to include a raw gas introduction pipe into which a raw material gas to be connected to each adsorption column is introduced, an exhaust gas discharge pipe and an exhaust gas storage tank through which exhaust gas is discharged, a product gas discharge pipe through which product gas is discharged, have.

The raw gas introduction pipe, the exhaust gas discharge pipe, and the generated gas discharge pipe connected to the respective adsorption towers may be provided with fluid flow control means such as a valve for controlling the flow of the fluid.

Further, the number of adsorption towers of the pressure cycling adsorption apparatus of one embodiment of the present invention may be, for example, 2, 4, 6, or 8. However, the number of adsorption towers may be an odd number, and the total number is not particularly limited in the present invention.

The configuration of the pressure circulation adsorbing apparatus as described above is merely an example, and the present invention is not particularly limited at present, and a person skilled in the art can change to various embodiments.

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 a detector of GC, and Carboxene 1010 PLOT was used as an 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 m x 0.53 mm I.D. Inlet temperature 200 ℃ Detector temperature 200 ℃ Column temperature 150 ℃ Sample volume 50 μL

[ Example  One]

). 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.A pressure circulation adsorption process with two adsorption towers was carried out on dealluminated zeolite Y (DEGUSSA, WESSALITH DAY F-20, SiO ₂ / Al ₂ O ₃ = 20), an adsorbent with excellent working capacity for nitrous oxide Adsorption experiments were carried out for the recovery of nitrous oxide. 2, 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 two adsorption columns in the pressure cycling adsorption process used in the experiments were 2.1 cm in diameter and 100 cm in length, respectively. The composition of the nitrous oxide-containing gas mixture supplied to the adsorption column was 35 vol% of nitrous oxide, 3.0 vol% of oxygen and 62.0 vol% of nitrogen, and the flow rate was 180 Nliter / hr. The adsorption temperature was room temperature, the adsorption pressure was 10 bar and the desorption pressure was 0.3 bar. Pressure circulation adsorption was carried out with the adsorption time and the cleaning time being 100 sec and 60 sec, respectively. The composition of the gas mixture used as cleaning gas in the cleaning step was 90 vol.% Of nitrous oxide and 10 vol.% Of nitrogen, and the flow rate was 1/10 of the flow rate of the nitrous oxide-containing gas mixture supplied at 18 Nliter / hr. The concentration of nitrous oxide was analyzed using the gas chromatography method described above. The composition of the desorption products obtained in the step of washing and depressurizing the pressure cycle adsorption process was 84.6% by volume of nitrous oxide, 0.3% by volume of oxygen and 15.1% by volume of nitrogen. The composition of the exhaust gas in the adsorption process was 9.6% by volume of nitrous oxide, 4.4% by volume of oxygen and 86.0% by volume of nitrogen, and the flow rate was 117.8 Nliter / 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 85.7% by volume.

[ Example  2 to 4]

Experiments were conducted in the same manner as in Example 1 except that the adsorption time and the cleaning time were changed in Example 1, and the other conditions were the same as those in Example 1. The results are summarized in Table 2 below.

Example absorption
time
(sec) washing
time
(sec) product Exhaust gas Nitrous oxide recovery rate
(%) Nitrogen dioxide / oxygen / nitrogen concentration
(volume%) flux
(Nliter / hr) Nitrogen dioxide / oxygen / nitrogen concentration
(volume%) flux
(Nliter / hr) One 100 60 84.6 / 0.3 / 15.1 80.2 9.6 / 4.4 / 86.0 117.8 85.7 2 100 100 87.7 / 0.2 / 12.1 78.8 8.5 / 4.4 / 87.1 119.2 87.3 3 100 140 90.3 / 0.2 / 9.5 79.5 6.2 / 4.4 / 89.4 118.5 90.6 4 120 60 85.8 / 0.3 / 13.9 75.9 6.3 / 4.4 / 89.3 120.1 89.4

[Examples 5 to 8]

). 10bar 압력 하의 아산화질소/질소 선택도(A_N2O/A_N2)는 8.8이고, 10bar 압력 하의 아산화질소/산소 선택도(A_N2O/A_O2)는 8.8이다. 실험 조건과 결과는 아래 표 3에 정리하였다.Sylobead silica gel (GRACE GmbH & Co., SYLOBEAD SG B 127), an adsorbent excellent in working capacity for nitrous oxide, was used to recover nitrous oxide in the pressure cycling adsorption process in the same manner as in Examples 1 to 4 Adsorption experiments were carried out. The adsorption isotherm at 20 ° C of the used Sylobead silica gel was as shown in Fig. 3, the adsorption amount (W ₀ ) at a pressure of 10 bar was 3.92 mol / kg and the adsorption amount (W ₁ ) at a pressure of 0.3 bar was 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 experimental conditions and results are summarized in Table 3 below.

Example absorption
time
(sec) washing
time
(sec) product Exhaust gas Nitrous oxide recovery rate
(%) Nitrogen dioxide / oxygen / nitrogen concentration
(volume%) flux
(Nliter / hr) Nitrogen dioxide / oxygen / nitrogen concentration
(volume%) flux
(Nliter / hr) 5 100 60 85.6 / 0.2 / 14.2 74.3 7.5 / 4.4 / 88.1 123.7 87.2 6 100 100 87.9 / 0.3 / 11.8 74.1 6.3 / 4.4 / 89.3 123.9 89.3 7 100 140 90.1 / 0.3 / 9.6 73.8 5.1 / 4.4 / 90.5 124.2 91.2 8 120 60 86.0 / 0.3 / 13.7 71.2 9.2 / 4.4 / 86.4 126.8 84.0

Through these examples, it can be confirmed that the gas mixture having a nitrous oxide concentration of 35 vol% by the adsorbent and the adsorption process according to the present invention can concentrate the nitrous oxide concentration to a high purity of 80 vol% or more and a high recovery rate of 80% or more .

[Comparative Examples 1 to 4]

). 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. 실험 조건과 결과는 아래 표 4에 정리하였다.Adsorption experiments were carried out for the recovery of nitrous oxide in the pressure cycling adsorption process in the same manner as in Examples 1 to 4 using zeolite 13X (UOP, 1/8 inch pellets) as the adsorbent. The adsorption isotherm at 20 ° C of the used zeolite 13X is shown in Fig. 4, the adsorption amount (W ₀ ) at 5.2 bar / kg under 10 bar pressure and the adsorption amount (W ₁ ) at 3.5 bar pressure 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 experimental conditions and results are summarized in Table 4 below.

Comparative Example absorption
time
(sec) washing
time
(sec) product Exhaust gas Nitrous oxide recovery rate
(%) Nitrogen dioxide / oxygen / nitrogen concentration
(volume%) flux
(Nliter / hr) Nitrogen dioxide / oxygen / nitrogen concentration
(volume%) flux
(Nliter / hr) One 100 60 58.8 / 0.4 / 40.4 66.8 25.6 / 3.5 / 70.9 131.2 53.9 2 100 100 59.4 / 0.4 / 39.8 67.9 25.0 / 3.5 / 71.5 130.1 55.3 3 100 140 62.3 / 0.4 / 35.0 66.1 24.0 / 3.5 / 72.5 131.9 56.5 4 120 60 56.5 / 0.4 / 38.0 68.9 26.2 / 3.5 / 70.3 129.1 53.4

In the comparative example outside the scope of the present invention, the nitrous oxide can be recovered from the gas mixture having a nitrous oxide concentration of 35% by volume to about 60% by volume. And the recovery rate of nitrous oxide is also as low as 60% or less.

Claims (12)

Wherein nitrous oxide is separated through pressure cyclic adsorption with a nitrous oxide recovery adsorbent satisfying the working capacity represented by the following formula (1).
[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,
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).) The method of claim 1,
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).) The method of claim 1,
And removing at least one selected from oxygen and nitrogen in the nitrous oxide-containing gas mixture. 5. The method of claim 4,
Wherein the nitrous oxide containing gas mixture comprises 5 to 98 vol% of nitrous oxide, 0.1 to 15 vol% of oxygen, and 1 to 90 vol% of nitrogen. The method of claim 1,
Wherein the pressure circulation adsorption is performed by using at least two adsorption towers charged with the adsorbent and at least one pressurization step, an adsorption step, a pressure equalization step and a desorption step, and a desorption step in each adsorption tower, 20 bar, and the pressure of the desorption step is from vacuum to 2.1 bar. The method of claim 1,
Wherein the method for recovering nitrous oxide is performed at a temperature of 0 to 50 占 폚. The method of claim 1,
Wherein the adsorbent is De-Aluminated Zeolite Y or Sylobead (R) Silica Gel. 9. The method of claim 8,
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 A pressure circulation adsorption apparatus for separating nitrous oxide from nitrogen oxides containing an adsorbent for recovering nitrous oxide which satisfies a working capacity represented by the following formula (1).
[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. 11. The method of claim 10,
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).) 11. The method of claim 10,
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).)

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