JPH02207838A - Oxygen and nitrogen separation adsorbent, adsorption method and application equipment - Google Patents

Abstract

PURPOSE:To efficiently produce an adsorbent for separating oxygen and nitrogen by subjecting zeolite based on silica and alumina to ion exchange with cations contg. Ca and Sr. CONSTITUTION:Zeolite based on silica and alumina and having a crystal structure of A type, X type, Y type, L type, etc., is subjected to ion exchange with cations contg. Ca and Sr to obtain an adsorbent for separating oxygen and nitrogen. An adsorption tower is packed with this adsorbent and a gaseous mixture contg. nitrogen and oxygen is passed through the tower to produce oxygen-rich gas. When the adsorbent is satd. with nitrogen, the feed of the gaseous mixture is stopped and nitrogen-rich gas is removed from the adsorbent. The pref. content of Sr is 0-65wt.% of the content of Ca at the time of producing the adsorbent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a method for reducing O2 and N2 from a gas containing O2 and N2.
The present invention relates to a method of separating 02 and N2 in a gas, and particularly to a method of separating and concentrating 02 and N2 in a gas using an adsorbent.

[Prior Art] Conventionally, as a method for separating 02 and N2 from a mixed gas containing Ox and N2, for example, taking air as the mixed gas, there is a cryogenic separation method (air liquefaction distillation method). , and adsorption methods have been put into practical use.

Among these, in the adsorption method using an adsorbent, a zeolite-based adsorbent or a carbonaceous-based adsorbent that acts as a molecular sieve is used. Using this zeolite adsorbent, O2 and N2
In order to separate nitrogen components, an adsorption tower filled with activated adsorbent is pressurized with the target product gas until it reaches a predetermined adsorption pressure, and the gas to be adsorbed is passed through this at a predetermined flow rate to separate nitrogen components. selectively adsorbed on an adsorption bed.

It is customary to take out a portion of the oxygen-enriched gas discharged from the tower that has a predetermined oxygen purity as a product gas. By the way, in order to improve the purity and yield of the target product gas obtained by this adsorption method and further increase the economic efficiency of the apparatus, it is necessary to increase the NZ adsorption capacity of the adsorbent.

Among inventions related to adsorbents, those that improve adsorption performance by ion exchange, especially those that ion exchange a single component with zeolite, are disclosed in JP-A-61-35850 and JP-A-61-35850.
No. 0-179134, No. 62-27037, No. 60-
139337 and 60-68052.

However, there is no product in which multiple components are ion-exchanged.

Among these inventions, one related to an agent for efficiently recovering 02 from which N2 has been adsorbed and separated is disclosed in Japanese Patent Application Laid-Open No. 17913/1986.
No. 4 and No. 60-68052.

In JP-A-60-179134, zeolite 13X
In JP-A No. 60-68052, N is replaced with Ba.
This method involves ion-exchanging alkaline earth metals with a-type zeolite. In these inventions, only a single component is ion-exchanged.

In the present invention, the N2 adsorption capacity was increased by ion-exchanging calcium and strontium into a zeolite containing Si, LiCa, and alumina as main components.

[Problem to be solved by the invention]

Equipment costs for conventional oxygen production processes are expensive, and in particular, adsorbent costs account for more than 20% of the total equipment costs.

The present invention aims to increase the N2 adsorption capacity of the adsorbent, reduce the amount of adsorbent used, and significantly reduce equipment costs.

[Means to solve the problem]

The effectiveness of zeolites in adsorption methods can be based on two completely different principles.

Firstly, in the cross-sectional projection, different molecules can be separated by passing only relatively small molecules through the pores of a homogeneous zeolite, so that the actual adsorption cavities of these molecules can be accessed. Yes (sieve effect).

Second, due to the polar nature of the internal surface of zeolite crystals, more polar molecules are adsorbed preferentially to less polar molecules, and the more the shape of the molecule can be accessed through the zeolite pores, the more polarized it becomes. Molecules are adsorbed preferentially to molecules that are more weakly polarized (polarization effect).

The adsorption technology that has been put to practical use with zeolites uses either of these principles, and in some cases both principles work simultaneously. Zeolite pore size is influenced by cations. When synthesized, zeolites are generally obtained in the Na form. This material has a pore size (direct diameter) of about 4 people, and the pore size can be narrowed by introducing ions into a larger volume instead of Na ions using the ion exchange method. On the other hand.

If Na ions are replaced with divalent Ca ions, the pore size can be expanded. The reason is that instead of two Na ions,
This is because only one Ca ion with substantially similar ionic radius enters the crystal lattice. A change in pore size naturally affects the selectivity of the zeolite due to the sieving effect, although other properties of importance as far as industrial applications are concerned are also changed. The introduction of this divalent ion increases the polarity of the crystal lattice,
More rapid adsorption and desorption of molecules can be promoted.

The zeolite according to the present invention has A
Type, X type, Y type, L type, Offretite
ta), Erionite ([Er1onite-),
Using at least one selected from mordenite, ferrierite, and ZSM-5, the present inventors have developed an adsorbent N2 It was found that the adsorption capacity was significantly increased.

Regarding the N2 adsorption amount of such composite ion exchange type zeolite, in the conventional adsorption research for Nz and Oz,
Nothing was made clear.

In the present invention, calcium and strontium are used as composite ions, and the ion exchange rate of strontium is 0 to 65.
It has been revealed that the amount of N2 adsorption is large at wt%, preferably 10 to 40 wt%.

〔Example〕

An embodiment of the present invention will be described below.

Adsorption Capacity Measuring Method> FIG. 4 shows a 02 and N2 adsorption capacity measuring device for evaluating the performance of the modifier obtained by the present invention, and the measurement is performed as follows. A vessel 2 (inner diameter 30 m, height 55-) is filled with 8.0 g of adsorbent 1, and is desorbed and regenerated by vacuum pump 1 via V-1. .

The temperature of the adsorbent 5 was controlled by a temperature controller 4. On the other hand, Vessel 3 is connected to 02.02 via V-6 or V-7. Alternatively, after the vacuum regeneration is completed by pressurizing with N2 in advance, only V-3 is opened, vessels 2 and 3 are connected, and the pressure change in the vessel 2 is measured by the pressure sensor 6. The pressure was left until it converged to a constant value, and the converged value was taken as the equilibrium pressure. The amount of N2 gas transferred from the vessel 3 to the vessel 2, that is, the N2 adsorption capacity, was determined from the pressure change of the pressure gauge 8 of the vessel 3. Also,
The temperature change inside the vessel 2 was measured with a thermocouple 7.

After the measurement is completed, vessels 2 and 3 are purged with He gas via V-5. Vacuum regeneration, connection of vessel 2゜3, H
Measurements were made by repeating each cycle of e-purge.

First, type A is used as the crystal structure of zeolite, and magnesium and calcium are used as cations.

Strontium, barium, lithium, manganese.

Ion exchange was performed using nickel and chromium nitrates.

Comparative Example 1> Diameter 1fi1. Using 150 g of cylindrical Na-A type zeolite with a length of 5 ml as a raw material, 87 g of magnesium nitrate was added to I
It was added to the water of Q and impregnated at 25° C. for at least 24 hours with stirring, then washed with water and baked in a constant temperature bath at 250° C. for a working time to prepare a test sample, and the adsorption capacity was measured by the adsorption capacity measurement method.

Comparative Example 2> Cylindrical Na-A type zeolite 15 with a diameter of 1 m and a length of 5 cm
Using 0g of calcium nitrate as a raw material, 97g of calcium nitrate was added to IQ water and impregnated with stirring at at least 25°C for 24 hours, washed with water, and baked at 250°C in a constant temperature bath for a working time.

Comparative Example 3> Strontium nitrate was used for ion exchange, and the other operations were the same as in Example 1.

<Comparative Example 4> Barium nitrate was used for ion exchange, and other operations were the same as in Example 1.

<Comparative Example 5> Lithium nitrate was used for ion exchange, and other operations were the same as in Example 1.

<Comparative Example 6> Manganese nitrate was used for ion exchange, and other operations were the same as in Example 1.

Comparative Example 7> Nickel nitrate was used for ion exchange, and the other operations were the same as in Example 1.

Comparative Example 8> Chromium nitrate was used for ion exchange, and the other operations were as in Example 1.
It is similar to

Comparative Example 9 The N2 adsorption capacity of Na-A zeolite was measured by an adsorption capacity measuring method.

Table 1 shows the results of Comparative Examples 1 to 9 organized as N2 adsorption capacity at a temperature of 25°C, an adsorption pressure of 0.25, and a Q of 95ata.

Table 1 From Table 1, in the case of Comparative Example 2, the N2 adsorption capacity is 4 and 8.
It showed the maximum value of N cc / g, which was about 1.92 times higher than that of Comparative Example 9, which is the raw material zeolite.

The results of the comparative example are organized by ionic radius and shown in Figure 5. As a result, the maximum value of the Nz adsorption amount is between the ionic radius of 1.7 and 1.9 (between Ca ions and Sr ions). considered to be a thing. Therefore, an attempt was made to increase the amount of N2 adsorption by changing the composite ion of Ca and Sr, that is, the mixing ratio of both ions.

The optimum mixing ratio of Ca and Sr was determined in the following example.

<Example 1> Cylindrical Na-A type zeolite 15 with a diameter of 1 mm and a length of 5 mm
Using 0g of calcium nitrate as a raw material, add 97g of calcium nitrate to IQ and impregnate it at 25℃ for 24 hours with stirring, then wash with water and bake in a constant temperature bath at 250℃ for a working time.The sample was added to IQ water with 21g of strontium nitrate. After adding and impregnating at 25℃ for 24 hours with stirring, washing with water and soaking in a constant temperature bath for 25 hours.
A sample fired at 0° C. for a working time was used as a test sample, and the adsorption capacity of Nz was measured by an adsorption performance measuring method.

<Example 2> Cylindrical Na-A type zeolite 15 with a diameter of 1 cm and a length of 5 cm
Using 0g of calcium nitrate as a raw material, add 97g of calcium nitrate to IQ and impregnate it at 25℃ for 24 hours with stirring, wash with water, and bake in a constant temperature bath at 250℃ for a working time.The sample was added to IQ water with 42g of strontium nitrate. After adding and impregnating at 25℃ for 24 hours with stirring, washing with water and soaking in a constant temperature bath for 25 hours.
A sample fired at 0° C. for a working time was used as a test sample, and the N 2 adsorption capacity was measured using the measurement method described above.

<Example 3> Cylindrical Na-A type zeolite 15 with a diameter of 1 cm and a length of 5 cm
0g'S- raw material, 97g of calcium nitrate was added to IQ's water and impregnated with stirring at 25℃ for 24 hours, washed with water, and baked in a constant temperature bath at 250℃ for a processing time. The sample was impregnated with water and stirred at 25°C for 24 hours, washed with water, and baked in a constant temperature bath at 250°C for a working time, and the Nz adsorption capacity was measured using the above-mentioned measurement method. .

Examples 1 to 3 and Comparative Examples 2 and 3 are shown in Table 2 and FIG. 6.

Table 2 As a result, the Sr content is 0 to 65 wt%, preferably 1
It was found that the N2 adsorption capacity at 0 to 40 wt% was large. Especially in Example 1, ie.

Maximum N2 adsorption capacity at 25wt% Sr content is 6.5
It was found that Ncc/g.

Ions other than Sr, namely Ba, Li, and Mn.

A composite ion adsorbent in which Ca was exchanged with metal ions of Ni and Cr was manufactured, and the N2 adsorption capacity was clarified in Comparative Examples 10 to 16.

Comparative Example 10> Diameter 11. Cylindrical Na-A type zeolite 15 with a length of 5 cm
0g as raw material, 48g of calcium nitrate.

Then, 20 g of barium nitrate was added to 1a of water and impregnated with stirring at 25°C for 24 hours, then washed with water and baked at 250°C in a constant temperature bath for a working time. The N2 adsorption capacity was measured.

Comparative Example 11> 48 g of calcium nitrate in 150 g of Na-A zeolite
A test sample was prepared in the same manner as in Example 10 by adding 13 g of lithium nitrate, and the N2 adsorption capacity was measured.

Comparative Example 12> Calcium nitrate 4 was added to 150 g of Na-A type zeolite.
A test sample was prepared in the same manner as in Example 10 by adding 8 g of manganese nitrate and 18 g of manganese nitrate, and the adsorption capacity of Nz was also measured.

<Comparative Example 13> 48 g of calcium nitrate in 150 g of Na-A zeolite
A test sample was prepared in the same manner as in Example 10 by adding 13 g of nickel nitrate, and the N2 adsorption capacity was measured.

<Comparative Example 14> 48 g of calcium nitrate in 150 g of Na-A zeolite
A test sample was prepared in the same manner as in Example 10 by adding 17 g of chromium nitrate, and the N2 adsorption capacity was measured.

<Comparative Example 15> 48 g of calcium nitrate in 150 g of Na-A zeolite
A test sample was prepared in the same manner as in Example 10 by adding 18 g of magnesium nitrate, and the adsorption capacity of NZ was further measured.

The results of Comparative Examples 10 to 15 are shown in Table 3.

Table 3 In the case of composite ions of calcium and strontium, the nitrogen adsorption capacity was 6.5 Ncc/g, which was a 35% improvement in nitrogen adsorption capacity compared to the calcium exchanger that had the best performance in single ion exchange.

Combinations of complex ions other than those listed above have a smaller N2 adsorption capacity than calcium exchangers.

A suitable raw material zeolite was selected according to the following example.

<Example 16) Cylindrical Na-A type zeolite 1 with a diameter lam and a length of 5 m
Using 50g of raw material, 97g of calcium nitrate and 21g of strontium were added to IQ water and impregnated at 25℃ for 24 hours with stirring, then washed with water and baked at 250℃ in a constant temperature bath for a working time.The sample was used as a test sample. By the measurement method described above, N
The adsorption capacity of 2 was measured.

<Example 17> The other operations were the same as in Example 1, using Na-X type zeolite as the raw material.

<Example 18> The other operations were the same as in Example 16, using Na-Y type zeolite as the raw material.

<Example 19> Na-L type zeolite was used as the raw material, and the other operations were the same as in Example 16.

<Example 20> Offretite was used as the raw material, and the other operations were the same as in Example 16.

<Example 21> Erionite was used as the raw material, and the other operations were the same as in Example 16.

<Example 22> Mordenite was used as the raw material, and the other operations were the same as in Example 16.

<Example 23> Ferrite was used as the raw material, and the other operations were the same as in Example 16.

<Example 24> ZSM-5 was used as the raw material, and the other operations were the same as in Example 16.

The results of Examples 16 to 24 are shown in Table 4.

Table 4 Among these, Examples 16, 17 and 22 have high N2 adsorption capacities, so the raw material zeolite is type A.

Type X and Mordenite are suitable.

In particular, type A is most suitable.

<Example 25> Strontium ion exchange rate 25w obtained in Example 1
Pressure swing adsorption was performed using t% adsorbent. The contents will be explained below using FIG.

Two adsorption towers 13A filled with adsorbent 2Q.

13B each has a valve 11A for switching raw material gas supply.
, IIB, valve 12A for switching desorption gas extraction during depressurization
, 12B, product gas delivery switching valve 15A, 1
5B, and valves 16A and 16B for switching gas supply from the buffer tank 32. After the raw material gas 21 is pressurized to adsorption pressure by the compressor 30, it is supplied to the adsorption tower 13 selected by the valve 11. The gas separated and concentrated in the adsorption process is taken out from the adsorption tower 13 selected by the valve 15 and temporarily stored in the product tank 32, and most of it is taken out of the system as the product gas 22. The remainder of the gas stored in the product tank 32 is sent to the adsorption tower 13 selected by the valve 16 and used for normal pressure purge and preliminary pressurization. Regarding the desorption gas, when the atmospheric pressure is released, the adsorption tower 1 selected by the valve 12
Desorption gas 23 is released to the atmosphere from 3, and when the pressure is reduced, the valve 12
The desorption gas 23 sucked by the vacuum pump 31 from the selected adsorption tower 13 is released to the atmosphere.

Adsorption and regeneration are repeated over time in the two adsorption towers 11A and 11B, and the contents thereof will be explained in more detail by taking as an example the case where oxygen is separated and removed from the raw material gas.

The step of supplying the raw material gas to the adsorption tower 13A is referred to as step I,
The successive steps will be explained in order below.

In process I, the raw material gas pressurized to 1.5 atmospheres by the compressor 30 is passed through the valve 11.
A, the gas is supplied to the adsorption tower 13A, and is stored as an oxygen-free gas in the product tank 32 through the valve 15A. During this time, the adsorption tower 13B is evacuated under reduced pressure by the vacuum pump 31 while the valve 12B is kept open. In step (2), the vacuum pump 31 of the adsorption tower 13A remains open with the valve 12A open.
It is decompressed and exhausted.

During this time, the raw material gas pressurized to 1.5 ata by the compressor 30 is supplied to the adsorption tower 13B through the valve 11B, and is stored in the product tank 32 through the valve 15B as purified gas.

After completing process ■, return to process ■ again.

The opening/closing sequence of the valves is as shown in Table 4.

Table 4 0...Valve open X...Valve closed The pressure swing adsorption apparatus shown in FIG. 4 was operated according to the operating procedure shown in Table 5.

The operating conditions in Table 5 are two adsorption towers with a capacity of 2Ω and an adsorption pressure of 1.5a.
ta, regeneration pressure 0.34ata, cycle time 120s
And so.

Comparative Example 16> Pressure swing adsorption was carried out using the calcium ion exchange adsorbent obtained in Example 1. The operating method is the same as in Example 25.

The operation results of Example 25 and Comparative Example 16 are shown in Table 5. As a result, the oxygen yields in Example 25 and Comparative Example 16 when the product oxygen concentration was 90 VoQ% were 58% and 48%,
The amount of adsorbent used is 80 and 100 kg/Nrd O
x/h. Therefore, it was found that by adding strontium to calcium, the oxygen yield could be increased by 21% and the amount of adsorbent used could be reduced by 25%.

FIG. 2 shows a configuration diagram when the oxygen concentrator using the adsorbent according to the present invention is applied to an automobile engine. Gas supplied from a supplied device 51, such as an engine mixer, is directed to a PSA oxygen concentrator 52 to produce an oxygen-enriched gas, and the gas is directed to an automotive engine to improve engine combustion efficiency. can be increased. As a PSA oxygen concentrator 52, the adsorbent of the present invention is used in the apparatus shown in FIG.
By performing the sequence shown in Table 5, it is possible to reduce the amount of adsorbent and downsize the PSA device.
Application to automobiles becomes possible.

Furthermore, the present invention can be favorably applied to medical applications.

Conventional PSA devices are large and have difficulty in portability, but the present invention enables a small and lightweight oxygen concentrator device.

Furthermore, the present invention can also be applied to culturing microorganisms.

In other words, microorganisms consume oxygen as they grow, but if oxygen can be supplied according to the growth rate, the growth efficiency will be increased.According to the present invention, since the oxygen concentrator can be made smaller, Application becomes possible.

Further, FIG. 3 shows a configuration diagram when the oxygen concentrator using the adsorption method of the present invention is applied to coal gasification combined cycle power generation (commonly known as IGCC). Oxygen concentrator 81 using this adsorption method
The oxygen-rich gas produced by
This is a system that supplies electricity to generate electricity. By this adsorption method, the combustion efficiency of the gasifier is improved, so the combined power generation efficiency of the entire IGCC is also improved.

In order to put oxygen-blown IGCC into practical use, it is essential to produce large amounts of low-cost oxygen. According to this adsorption method, the oxygen concentrator can be downsized.

Since the device cost can be reduced, it can be applied to IGCC.

〔Effect of the invention〕

According to the present invention, the Nz adsorption capacity of zeolite can be reduced by about 25%.
Since the amount of adsorbent used can be reduced by 25%, the cost of equipment for using the adsorbent can be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of an oxygen concentrator according to an embodiment of the present invention, Fig. 2 is a block diagram of an applied example of the present invention, Fig. 3 is a block diagram of another applied example of the present invention, and Fig. 4 is a system diagram of an oxygen concentrator according to an embodiment of the present invention. Evaluation system diagram of the modifier of the present invention, Figure 5 is a diagram showing the relationship between the bond radius and Nz @ absorption capacity, and Figure 6 is a diagram showing the relationship between the ionic radius and N2 adsorption capacity91...・Vacuum pump, 2... Vessel A, 3... Vessel B, 4... Temperature controller, 5...
・Adsorbent, 6...Pressure sensor Figure 6

Claims (1)

[Claims] 1. An oxygen and nitrogen separation adsorbent characterized by ion-exchanging zeolite containing silica and alumina with cations containing calcium and strontium. 2. In claim 1, the content of strontium is 0 to 65 with respect to calcium.
An adsorbent for separating oxygen and nitrogen, characterized in that the content thereof is 10 to 40 wt%. 3. The crystal structure of the zeolite in claim 1 is type A,
X type, Y type, L type, Offretite, Erionite
TE), Mordenite, Ferrierite and ZSM-5. 4. Produce an oxygen-rich gas by passing a gas mixture containing nitrogen and oxygen through an adsorption column containing an adsorbent that selectively adsorbs nitrogen, and when the adsorbent is saturated with nitrogen, In the method of stopping the flow of the gas mixture and removing nitrogen-rich gas from the adsorbent, an adsorbent in which zeolite mainly composed of silica and alumina is ion-exchanged with cations containing calcium and strontium is used as the adsorbent. An adsorption method for separating nitrogen and oxygen from a gas mixture, characterized by: 5. According to claim 4, the oxygen-rich gas produced by the oxygen concentrator using the adsorption method using air discharged from a gas supply device such as a mixer as a raw material is supplied to the automobile engine. Application equipment as described. 6. The method according to claim 4, characterized in that the oxygen-rich gas produced by the oxygen concentrator using the adsorption method is introduced into a gasification furnace and combusted to supply steam generated by the turbine. Applied equipment.