JP2002326810A - Separation method and apparatus of ammonia using a metallic halide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separation method of ammonia and its apparatus which effectively separates ammonia which is on-site synthesized by the adsorption separation method such as PSA, TSA and PTSA, and capable of storage. SOLUTION: As absorbing ammonia by making contact with halide of II a or VIII group in the temperature or pressure capable of absorbing ammonia from the gas containing ammonia, the withdrawal of this is characterized by increasing a temperature or reducing a pressure. This problem is solved by the separation method of ammonia using a metallic halide and its apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technique for separating and storing ammonia.

[0002]

2. Description of the Related Art In general, ammonia is synthesized by reacting hydrogen and nitrogen in the presence of an iron-based catalyst, and this is separated by a cryogenic separation method. A variety of gases including ammonia also exist as coke oven by-product gases and the like. Zeolite and the like are known as adsorbents for adsorbing this ammonia.

Recently, waste incineration plants, thermal power plants,
Air pollution due to nitrogen oxides generated from diesel vehicles, ships, and the like has become a major problem, and as a countermeasure, denitration using ammonia as a reducing agent has been performed. In this case, since the toxicity of ammonia is strong, technology for synthesizing and supplying ammonia on the spot is being developed. It is known to use a membrane to separate the on-site synthesized ammonia (Japanese Patent Laid-Open Publication No.
-114235 gazette). The present inventors have also studied a method of adsorbing ammonia using ion-exchanged zeolite or acid-treated activated carbon for this separation (Liu, Akika, Daini
9th Petroleum and Petrochemical Symposium Kyushu Conference Abstracts, E12
(1999), Liu, Akika, 86th Catalyst Symposium, Symposium A, 3F23 (2000).

On the other hand, it is known to use calcium chloride or the like as a heat storage material for a chemical heat pump.
JP-264117 discloses a chemical heat pump utilizing the fact that calcium chloride absorbs ammonia at high pressure and releases it at low pressure. JP-A-5-2641
No. 87 discloses a heat storage device utilizing ferrous chloride releasing ammonia by heating and absorbing it by cooling, and calcium chloride absorbing ammonia by cooling and releasing it by heating. In addition, Japanese Patent Laid-Open No. 6-1
No. 36357 discloses a chemical heat storage material composed of a mixture of CaCl ₂ and CaBr ₂ . These recycle pure ammonia in a closed system. In addition, although the amount of heat absorbed and the amount of heat generated by adsorption and desorption are known, the adsorption characteristics under the separation and storage temperature and pressure conditions required for the present invention were not known.

[0005]

In order to purify ammonia by the cryogenic separation method, a large-scale apparatus is required, and it has been desired to develop a method of separating ammonia which is cheaper and easy to carry out.

In particular, when ammonia is synthesized on-site, it is required that the separation be simple and highly mobile. Since ammonia cannot be stored by the conventional separation using a membrane, strict production control is required, and there is a problem in practicality.

Further, the performance of zeolite and activated carbon is insufficient for use in adsorption and separation of ammonia. That is, in the adsorption separation method of PSA, TSA, PTSA, etc., zeolite or activated carbon has been generally used as an adsorbent. However, zeolite and activated carbon have a small amount of adsorbed ammonia, and a high vacuum must be applied to desorb the adsorbed ammonia. Until now, adsorbents had to be searched for from existing types of activated carbon or zeolite. In particular, in the case of an apparatus for synthesizing ammonia on-site, it is desired to operate under low pressure conditions from atmospheric pressure to about 3 MPa, particularly from atmospheric pressure to 1.1 MPa. In such a case, the product ammonia partial pressure in the circulating gas may vary depending on the operating conditions.
In particular, when the total pressure is about 1.1 MPa, the ammonia partial pressure is about 1 to 100 kPa. However, there is no efficient adsorbent as described above, for example, in order to separate ammonia using an adsorption separation method such as PSA under these conditions, the ammonia adsorption amount is small and a large amount of adsorbent is required. Further, when storing ammonia, liquid or gaseous ammonia is stored in an empty tower pressure vessel, but this storage vessel has to withstand high pressure.

It is an object of the present invention to easily carry out the method and to efficiently synthesize ammonia synthesized on-site with PSA, TSA, P
An object of the present invention is to provide an ammonia separation method and apparatus which can be separated by an adsorption separation method such as TSA and can be stored.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and have considered the use of chemical heat pumps instead of high surface area substances such as zeolite and activated carbon which have been used up to now. We focused on the ability to absorb ammonia such as calcium chloride. The pressure and temperature and the ability to absorb and desorb ammonia were investigated to determine whether these materials could be used in this process. As a result, the following findings were obtained.

[0010] By using an adsorbent of a halide of group IIa or VIII such as calcium chloride, magnesium chloride, strontium chloride, and nickel chloride, and an adsorbent in combination of different kinds of metal halides, ammonia can be efficiently adsorbed. It can be performed. This was found by experiments that the amount of ammonia adsorbed by this adsorbent was larger than that of activated carbon and zeolite up to now, and that this adsorbent exhibited a higher pressure in the pressure range around 100 kPa or lower. This is because they have a stepwise characteristic in which the amount of adsorption and desorption changes abruptly at a certain pressure point in the range.

Ammonia is adsorbed on the high pressure side of the pressure point,
Ammonia can be efficiently separated by the operation of desorption on the low pressure side. Since the amount of adsorption and desorption is very large compared to the adsorption and desorption amounts of conventional activated carbon and zeolite,
The amount of adsorbent in the ammonia adsorption separation device can be reduced. Also, the amount of desorption can be increased without using a vacuum pump to apply a high vacuum as in the past.

The adsorption characteristics of the adsorbent can be freely changed so as to meet desired operating conditions by a method of changing a pretreatment temperature and a method of changing a mixing ratio of two or more metal halides. Can be

An apparatus that continuously and efficiently separates ammonia from a gas containing ammonia by utilizing the change in the amount of adsorption and desorption due to the change in pressure of the adsorbent is a PSA. Using the change in the amount of adsorption and desorption due to the temperature change of this adsorbent
An apparatus that continuously and efficiently separates ammonia from a gas containing ammonia is TSA. A device combining this principle is PTSA.

[0014] PSA, TSA, PT using this adsorbent
If the adsorption separation principle or apparatus such as SA is applied to the separation system of the ammonia production apparatus, ammonia production can be performed efficiently.

Since this adsorbent has a very large amount of adsorption and desorption, it can be filled in a container, adsorb ammonia, and stored. When the stored ammonia is consumed, it is sucked and used by a vacuum pump.

The uptake of ammonia by the above-mentioned metal halide includes not only mere adsorption but also absorption and sorption. However, here, it is referred to as adsorption for convenience.

The present invention has been made on the basis of the above-mentioned findings, and is intended to cause ammonia to be adsorbed from a gas containing ammonia by bringing the gas into contact with a halide of Group IIa or Group VIII at a temperature or pressure at which ammonia can be adsorbed. The present invention further relates to a method for separating ammonia using a metal halide, a device therefor, and an adsorbent, characterized in that the temperature is increased or the pressure is decreased to release the same.

[0018]

DETAILED DESCRIPTION OF THE INVENTION The ammonia adsorbent used in the present invention is a halide of Group IIa or Group VIII, for example, calcium chloride, magnesium chloride, strontium chloride, nickel chloride, calcium bromide and the like. When these metal halides or hydrates thereof are used as they are, no particular treatment is required.

For each metal halide of calcium chloride, strontium chloride and calcium bromide, the change in the amount of adsorption was examined by changing the partial pressure of ammonia. Each adsorbent was prepared as a pre-treatment of 1.0 × 10 ⁻⁵ Torr, 52 in order to compare tablet-formed products under the same conditions.
Heat at 3K for 2 hours. This sample was filled in a container, and ammonia gas was flowed into the container at 298 K and 1 to 80 kPa. After repeating the adsorption operation and the desorption operation several times, the adsorption of each ammonia partial pressure during the adsorption operation and the desorption operation was performed. The amount was measured. FIG. 6 shows the resulting adsorption characteristics. It can be seen that the adsorption characteristics during the adsorption operation and the desorption operation have hysteresis, and the adsorption curves do not match.

Next, for each metal halide of magnesium chloride and nickel chloride, the change in the amount of adsorption was examined by changing the partial pressure of ammonia. Each adsorbent was heated at 1.0 × 10 ⁻⁵ Torr, 523 K for 2 hours as a pretreatment in order to compare tablet-formed ones under the same conditions. This sample was filled in a container, and 298K, 1
Ammonia gas was allowed to flow at ~ 80 kPa, and the amount of adsorption at each ammonia partial pressure during the adsorption operation was measured. FIG. 7 shows the resulting adsorption characteristics.

The ammonia adsorption characteristics of the metal halide can be controlled by adjusting the hydration water of the metal halide. This adjustment can be made by changing the heating temperature of the pretreatment.

Changing the pretreatment temperature of calcium chloride,
The adsorption characteristics were changed. Calcium chloride was tableted and pretreated as 298K, 448K, 523, respectively.
K, 723 K, and heated at 1.0 × 10 ⁻⁵ Torr for 2 hours. This sample is filled in a container, and 298K,
After ammonia gas was introduced at 1 to 80 kPa and the adsorption operation and the desorption operation were repeated several times, the adsorption amount at each ammonia partial pressure during the adsorption operation and the desorption operation was measured. FIG. 8 shows the change in the amount of adsorption due to the partial pressure of ammonia when the pretreatment temperature of calcium chloride was changed.

The ammonia adsorption characteristics can be controlled by combining different types of metal halides.

The adsorption characteristics were changed by combining calcium chloride and calcium bromide. Calcium chloride and calcium bromide were prepared in respective aqueous solutions, and the molar ratios of calcium chloride and calcium bromide were 1: 0 and 2:
1,1: 1,1: 2,0: 1 were mixed. After evaporating and drying the water, the mixture was tablet-formed and heated at 523 K and 1.0 × 10 ⁻⁵ Torr for 2 hours as a pretreatment. This sample was filled in a container, and 298K, 1
Ammonia gas was allowed to flow at 〜80 kPa, and the adsorption operation and the desorption operation were repeated several times. Then, the adsorption amount at each ammonia partial pressure during the adsorption operation and the desorption operation was measured. FIG. 9 shows the change in the amount of adsorption due to the partial pressure of ammonia during adsorption and the change in the amount of adsorption due to the partial pressure of ammonia during desorption when the mixing ratio of calcium chloride and calcium bromide is changed.

To compare the characteristics of the present adsorbent, FIG.
Figure 2 shows the case of activated carbon and zeolite. The activated carbon used was granular activated carbon derived from coconut shell, and the zeolite used was Na-type Y zeolite. For zeolite, after tableting, each was pre-treated at 523 K at 1.0 × 10 ⁻⁵ To
Heated at rr for 2 hours. This sample was filled in a container, and ammonia gas was flowed into the container at 298 K and 1 to 80 kPa, and the amount of adsorption at each ammonia partial pressure during the adsorption operation was measured. FIG. 7 shows the resulting adsorption characteristics.

It can be seen that the amount of metal halide adsorbed is larger than that of activated carbon or zeolite. It can also be seen that the adsorption amount changes stepwise at a certain pressure point.

As the ammonia adsorbent used in the present invention, a commercially available product can be used as it is. The particle size is not particularly limited, but is usually about 5 μm to 100 mm, preferably 10 μm to 100 mm.
It is about μm to 30 mm. Not only granules but also sheets and honeycombs may be formed. Further, it can be used by being supported on a porous material such as silica, alumina, granular carbon, activated carbon, zeolite or the like or a high surface area substance.

When the number of hydrates is adjusted to change the ammonia adsorption characteristics, it is 100 kPa or less, preferably 90 kPa or less.
While evacuation is performed at a pressure of kPa or less, or by flowing a dry gas, 273K to 1000K, preferably 3K
Place under a predetermined temperature of 73K to 873K. The predetermined temperature condition processing time is determined according to the purpose of use of the adsorbent.

When the adsorption characteristics are changed by mixing different kinds of metal halides, the respective solids are mixed and adjusted. Alternatively, an aqueous solution of each metal halide is mixed at a predetermined ratio, and this is evaporated and dried, and heated while evacuating at a pressure of 100 kPa or less,
Alternatively, a dry gas is allowed to flow, and
The hydrate number is adjusted by placing at a predetermined temperature of 0K.

In the present invention, ammonia is adsorbed by bringing it into contact with a halide of Group IIa or Group VIII at a temperature or pressure at which ammonia can be adsorbed. As means for this, pressure swing adsorption (PSA), temperature swing adsorption Law (TS
A), pressure-temperature swing adsorption method (PTSA) is preferred.

PSA: In the pressure swing adsorption (PSA) method, various systems such as a two-column system, a three-column system, and a parallel system have been devised according to a system of a switching system between adsorption and desorption. The method of the present invention employs any pressure swing adsorption (PS
A) Although applicable to a system, a two-column pressure swing adsorption (PSA) method is described here as a representative.

A typical example of this device is shown in FIG.
Two adsorption towers 101 filled with an ammonia adsorbent 121 made of a Group IIa or Group VIII halide are arranged in parallel. The bottom of each adsorption tower 101 is connected to an ammonia-containing gas supply line, and the top is connected to a separation gas discharge line for extracting the remaining gas that has absorbed and separated ammonia. Further, a branch pipe is connected in the middle of the ammonia-containing gas supply line, and this branch pipe is connected to an ammonia extraction line via a vacuum pump 102. A valve 103 is attached to each line.

In order to separate ammonia using this apparatus, first, an ammonia-containing gas is sent to one adsorption tower 101 at a pressure capable of adsorbing ammonia to adsorb ammonia, and the remaining gas is discharged from a separation gas discharge line. Let it.
When the ammonia is sufficiently adsorbed and leaks to the separation gas, the valve 103 is switched to send the ammonia-containing gas to the other adsorption tower 101 to continue the adsorption. The adsorption tower in which ammonia is adsorbed is connected to an ammonia extraction line and depressurized by a vacuum pump 102 to desorb and recover ammonia. By repeating this ammonia adsorption step and the desorption step alternately in each column, ammonia can be continuously separated.

The pressure at which ammonia can be adsorbed and the pressure at which ammonia can be desorbed differ depending on the type and temperature of each metal halide, and are determined in advance by experiments. Specifically, the adsorption pressure curve and the desorption pressure curve of ammonia both have a step, so the pressure to be adsorbed is the pressure in the upper part of the adsorption curve, preferably the pressure near the end. The pressure for desorption is preferably controlled at the pressure at the lower part of the desorption curve, preferably at the pressure near the end. FIG.
As an example, calcium chloride and strontium chloride are adsorbed at 80 kPa or more and desorbed at 35 kPa or less. Calcium bromide may be adsorbed at 7 kPa or more and desorbed at 2 kPa or less.

TSA: In the temperature swing adsorption (TSA) method, various systems such as a two-column system, a three-column system, and a parallel system have been devised according to a system of a switching system between adsorption and desorption. The method of the present invention can be applied to any temperature swing adsorption (TS
A) Although it can be applied to a system, a two-column temperature swing adsorption (TSA) method is described here as a representative.

A typical example of this device is shown in FIG.
Two adsorption towers 101 filled with an ammonia adsorbent 121 made of a Group IIa or Group VIII halide are arranged in parallel. A heater 111 is provided in each adsorption tower 101.
And a cooler 112 are provided. In addition, an ammonia-containing gas supply line is connected to the bottom, and a separation gas discharge line for extracting the remaining gas that has absorbed and separated ammonia is connected to the top. Further, a branch pipe is connected in the middle of the ammonia-containing gas supply line, and this branch pipe is connected to an ammonia extraction line via a vacuum pump 102. Valve 103 on each line
Is attached.

In order to separate ammonia using this apparatus, first, the inside of one adsorption tower 101 is cooled to a temperature at which ammonia can be adsorbed by a cooler 112, and an ammonia-containing gas is sent to this to adsorb ammonia. The remaining gas is discharged from the separation gas discharge line. Meanwhile, the inside of the tower is continuously cooled by the cooler 112 to a temperature at which ammonia can be adsorbed. When the ammonia is sufficiently adsorbed and leaks to the separation gas, the valve 103 is switched to send the ammonia-containing gas to the other adsorption tower 101 which has been cooled in advance by the cooler 112 to a temperature at which ammonia can be adsorbed. To continue adsorption. The adsorption tower in which ammonia is adsorbed is heated to a temperature at which ammonia can be desorbed by the heater 111, connected to an ammonia extraction line, and the desorbed ammonia is recovered by using the vacuum pump 102. By repeating this ammonia adsorption step and the desorption step alternately in each column, ammonia can be continuously separated.

Since the temperature at which ammonia can be adsorbed and the temperature at which ammonia can be desorbed differ depending on the type and pressure of each metal halide, they are determined in advance by experiments. Specifically, both the ammonia adsorption temperature curve and the ammonia desorption temperature curve have a step, so the temperature to be adsorbed is the temperature in the upper part of the adsorption curve, preferably near the end. The temperature for desorption is preferably the temperature at the lower part of the desorption curve, preferably at the temperature near its end.

PTSA: Pressure temperature swing adsorption (PTS
In the method A), various systems such as a two-column system, a three-column system, and a parallel system are devised according to a system of a switching system for adsorption and desorption. The method of the present invention can be applied to any pressure-temperature swing adsorption (PTSA) system,
The column pressure temperature swing adsorption (PTSA) method will be described as a representative.

FIG. 3 shows a representative example of this apparatus, which is basically the same as the configuration of the apparatus shown in FIG. PTSA absorbs and desorbs ammonia by a combination of pressure and temperature. Specifically, cooling is used together with adsorption with PSA, and heating is used together with desorption.

Since the pressure and temperature at which ammonia can be adsorbed and the pressure and temperature at which desorption can be performed differ depending on the type of each metal halide, they are determined in advance by experiments. Specifically, both the ammonia adsorption pressure temperature curve and the desorption pressure temperature curve have a step, so that the pressure and temperature for adsorption are the pressure and temperature of the upper part of the adsorption curve, preferably, The pressure and temperature in the vicinity of the end are set as the pressure and temperature in the lower part of the desorption curve, preferably the pressure and temperature in the vicinity of the end.

Product separation in ammonia production apparatus: FIG.
FIG. 1 shows an example of a flow of a device for producing ammonia on-site such as a denitration device and an apparatus. In this apparatus, an ammonia synthesis apparatus is connected to an ammonia-containing gas supply line of the PSA apparatus in FIG. The ammonia synthesizing apparatus is connected to a reactor 2 via a circulation compressor 202 and a heat exchanger 203 from a hydrogen / nitrogen mixer 201.
The heat exchanger 203 is connected to the ammonia-containing gas supply line of the PSA device via the cooler 205 at the outlet side of the reactor 204. Meanwhile, PSA
The separation gas discharge line of the apparatus is connected to the inlet side of the mixer 201 to form a circulation line.

The raw materials are hydrogen and nitrogen, which are
And mixed with the circulating gas and supplied to the circulating line. The circulating gas is introduced into the reactor 204 filled with the ammonia synthesis catalyst, and ammonia is synthesized. In the case of an apparatus for producing ammonia on-site, operation under mild conditions of low temperature and low pressure is desired.
500 ° C., preferably 350-420 ° C., reaction pressure 0.
It is preferable to use an ammonia synthesis catalyst using ruthenium having high activity at about 1 to 2 MPa. At this time, the reactor 204
The ammonia partial pressure of the circulating gas exiting from the reactor varies depending on the operating conditions of the reactor, but is generally about 1 to 100 kPa.

The reactor outlet gas is introduced into the adsorption separation device. As the adsorbent to be filled in the adsorption / separation device, a metal halide having an optimum characteristic in relation between the partial pressure of ammonia and the adsorption amount is selected in consideration of the operating conditions of the reactor and the operation conditions of the adsorption / separation device. At the same time, considering the characteristics of the adsorbent, the operating conditions of the reactor and the operating conditions of the adsorption / separation device, determine the optimal system for the adsorption / separation device from PSA, TSA, PTSA, etc. To determine.

Of the post-reaction gas introduced into the adsorption / separation apparatus, ammonia is adsorbed by the adsorbent, and hydrogen, nitrogen, a small amount of leaked ammonia, inert substances such as argon and methane are hardly adsorbed, and the mixture is mixed. Circulated to After a certain period of time, the post-reaction gas is circulated to the other ammonia adsorption tower by operating a valve, and the adsorption tower that has been performing the adsorption operation performs the desorption operation. In the desorption operation, the pressure is reduced by a vacuum pump in the case of PSA, the temperature is increased by a heater in the case of TSA, the pressure is reduced by a vacuum pump in the case of PTSA, and the temperature is reduced by a heater. Is performed in combination. By this desorption operation, ammonia is desorbed from the adsorbent, and this is separated into a product.

In order to improve the efficiency, it is preferable to provide the above device with the following mechanism. In order to prevent trace amounts of inert substances such as argon and methane contained in the raw material gas from accumulating in the circulation line, the circulation gas is partially purged from any place in the circulation line. Since a very small amount of ammonia is also contained in the barge gas, the present separation apparatus is installed in a purge line to recover this.

Ammonia storage device: FIG. 5 shows an example of a storage device using the present adsorbent. Ammonia is adsorbed and stored in a container filled with the adsorbent. When the stored ammonia is consumed, it is sucked and used by a vacuum pump. The adsorbent is determined in consideration of its operating conditions.

The type of ammonia from the gas containing ammonia to which the method of the present invention is applied is not particularly limited, but a gas obtained by synthesizing ammonia, a coke oven by-product gas,
Excess gas from a nitric acid plant or the like can be exemplified. The content of ammonia is about 0.01 to 99 mol%,
For example, in the case of an apparatus for producing ammonia on-site, the content is about 1 to 20 mol%, and examples of impurities include carbon monoxide, carbon dioxide, nitrogen, hydrogen, helium, argon, methane, and ethane depending on the origin. Such as hydrocarbons.

[0049]

EXAMPLES [Examples of PSA, TSA and PTSA] The adsorption tower of the apparatus shown in FIGS. 1, 2 and 3 is filled with various adsorbents, and the adsorption and desorption of ammonia by utilizing the stepwise adsorption characteristics. The amount was measured.

Table 1 shows the PSA of calcium chloride, strontium chloride and calcium bromide pretreated at 523K.
The amount of adsorption and desorption in the case of is shown. Ammonia-containing gas was adsorbed at various pressures at 298K, depressurized at various pressures, and desorbed. This indicated the amount of ammonia per gram of adsorbent that could be separated by one adsorption / desorption operation. In order to compare the adsorption and desorption amounts of the present adsorbent, the adsorption and desorption amounts of activated carbon and zeolite are shown. The activated carbon used was granular activated carbon derived from coconut shell, and the zeolite used was Na-type Y zeolite. After zeolite was formed into tablets, each of the zeolites was processed at 523K for 1.
Pretreatment was performed by exhausting gas at 0 × 10 ⁻⁵ Torr for 2 hours.

[0051]

[Table 1]

Table 2 shows that calcium chloride was 1.0% at 298K, 448K, 523K and 723K, respectively.
It shows the amount of adsorption and desorption when the PSA adsorption tower was filled with the pretreated gas exhausted for 2 hours at × 10 ⁻⁵ Torr and subjected to pressure swing at different pressures.

[0053]

[Table 2]

Table 3 shows that calcium chloride and calcium bromide were mixed at 1: 0, 2: 1, 1: 1, 1: 2, 0: 1,
The adsorption / desorption amount when the adsorbent at the pretreatment temperature of 523K is packed in the PSA adsorption tower and the pressure is swung at different pressures is shown.

[0055]

[Table 3]

FIG. 11 shows the amount of adsorption and desorption in the case of TSA.
Ammonia gas is adsorbed at 298 K and 40 kPa,
Heated at 73K for desorption.

[Example of Ammonia Production] The present adsorption system was applied to an ammonia production apparatus for producing 1 Nl / h of ammonia. Table 4 shows the operating conditions at this time. Raw material hydrogen was supplied at 1.5 Nl / h, and nitrogen was supplied at 0.5 Nl / h. The reactor is filled with a ruthenium catalyst and 350
It operated at 1.1 degreeC and 1.1 MPa absolute pressure. The separation system used was a two-column PSA, and the adsorbent used was calcium chloride: calcium bromide = 1: 1. Each adsorption tower was filled with 1.4 kg of the adsorbent, and the adsorption step and the desorption step were switched every 30 minutes. In the desorption process, 20 kP with a vacuum pump
The pressure was reduced to a, and ammonia was separated. 0.5Nl of ammonia could be separated by one desorption operation.

[0058]

[Table 4]

[Embodiment of Ammonia Storage Tank] An apparatus was constructed as shown in FIG. 5, and 1 kg of nickel chloride was filled in the storage tank as an adsorbent. Add ammonia to this
0 g was introduced, and ammonia could be stored at about 1 atm. At the time of consumption, the stored ammonia could be taken out by operating the vacuum pump.

[0060]

According to the present invention, ammonia can be easily separated and purified with a compact apparatus. The apparatus of the present invention is particularly applicable to the separation and purification of on-site synthesized ammonia,
Suitable for storage.

[Brief description of the drawings]

FIG. 1 is a flow chart of PSA.

FIG. 2 is a flowchart of TSA.

FIG. 3 is a flow chart of PTSA.

FIG. 4 is a flowchart of an ammonia production apparatus using PSA for ammonia separation.

FIG. 5 is a flowchart of a storage device using the present adsorbent.

FIG. 6 is a graph showing the adsorption characteristics of each metal halide.

FIG. 7 is a graph showing the adsorption characteristics of each metal halide.

FIG. 8 is a graph showing adsorption characteristics when the pretreatment temperature of calcium chloride is changed.

FIG. 9 is a graph showing adsorption characteristics when calcium chloride and calcium bromide are combined.

FIG. 10 is a graph showing the adsorption characteristics of activated carbon and zeolite.

FIG. 11 is a graph showing the amount of adsorption and desorption when TSA is filled.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 ... Adsorption tower (adsorber) 102 ... Vacuum pump 103 ... Valve 111 ... Heater 112 ... Cooler 121 ... Ammonia adsorbent 201 ... Mixer 202 ... Circulating compressor 203 ... Heat exchanger 204 ... Reactor 205 ... Cooler

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B01J 20/04 B01J 20/04 B (72) Inventor Junichi Liu 458-2 Tsuruma, Machida-shi, Tokyo IDEX 310 Minami-Machida F term (reference) 4D012 BA01 CA20 CB16 CD04 CD07 CG01 4G066 AA32B CA29 DA05 GA14 GA16

Claims (6)

[Claims] 1. A method of contacting a group IIa or group VIII halide at a temperature or pressure capable of adsorbing ammonia from a gas containing ammonia to adsorb the ammonia,
A method for separating ammonia using a metal halide, characterized in that the temperature is increased or the pressure is decreased to release the same. 2. Ammonia filled with a halide of Group IIa or Group VIII and having an inlet for ammonia from a gas containing ammonia, an outlet for a residue adsorbing ammonia to the halide, and an outlet for ammonia desorbed. An ammonia separator comprising an adsorber and a mechanism for reducing the pressure inside the adsorber 3. Ammonia filled with a halide of Group IIa or Group VIII and having an inlet for ammonia from a gas containing ammonia, an outlet for a residue adsorbing ammonia to the halide, and an outlet for ammonia desorbed. Ammonia separator comprising an adsorber, a heater for heating the inside of the adsorber, and a cooler for cooling 4. The ammonia separation apparatus according to claim 2, further comprising a heater for heating the inside of the adsorber and a cooler for cooling. 5. An ammonia adsorbent comprising a halide of calcium, magnesium, strontium or nickel. 6. An ammonia adsorbent obtained by mixing two or more kinds of halides of group IIa or group VIII.