JP4634283B2 - Oxygen selective adsorbent - Google Patents

Description

  The present invention relates to an oxygen selective adsorbent. More specifically, the present invention relates to an oxygen-selective adsorbent that can adsorb a large amount of oxygen with high selectivity from an oxygen-containing atmosphere and that is easy to desorb and regenerate and is inexpensive.

  The oxygen-selective adsorbent is, for example, a deoxidizer for the purpose of preventing oxidation of foods, for example, a thermal desorption-type oxygen concentrator that performs oxygen desorption using exhaust heat from combustion exhaust gas, and a thermal desorption-type combustion oxidant Conventionally, it has been widely used as an adsorbent and the like used in an adsorption separation apparatus for separating and concentrating nitrogen and oxygen from air, such as an apparatus (see, for example, Patent Documents 1 and 2).

  As the oxygen selective adsorbent, for example, an adsorbent that utilizes an oxidation reaction of a metal such as iron powder, or a molecular sieve charcoal that utilizes an adsorption rate difference between nitrogen and oxygen is generally used. However, although the adsorbent using such metal oxidation reaction has good oxygen selectivity, a very high temperature field of about 300 ° C. or higher is required in a reducing gas atmosphere during regeneration after oxygen adsorption. There is a problem that it is difficult to reproduce easily. In addition, molecular sieve charcoal has problems such as small adsorption capacity and low oxygen selectivity at equilibrium.

  In addition to the above, oxygen-selective adsorption comprising organometallic complexes such as porphyrins and Schiff base complexes utilizing oxygen affinity, such as oxygen adsorption / separation agents in which a salcomine-based cobalt compound is supported on a porous carrier, for example. An agent has been proposed (see, for example, Patent Document 3). However, the oxygen-selective adsorbent composed of such an organometallic complex has a high oxygen selectivity, but is very expensive and has a problem that a complicated process and a large amount of chemicals are required for production. is there.

  In addition, an oxygen absorbent made of activated carbon carrying a copper halide and having a high oxygen adsorption capacity has been proposed (see, for example, Patent Document 4), but approximately 200 to 300 is required for regeneration after oxygen adsorption. There is a problem that a very high temperature field such as ° C. is necessary and it is difficult to regenerate easily.

  Furthermore, as an adsorbent composed of activated carbon, in addition to the above, for example, activated carbon small particles derived from an ion exchange resin obtained by activating a carbide obtained by heating a used granular organic ion exchanger at a specific temperature under specific conditions. (For example, refer to Patent Document 5), or an adsorbent composed of activated carbon obtained by subjecting a granular ion exchange resin to heat treatment at a specific temperature and further activated under specific conditions (for example, refer to Patent Document 6). ) Etc. are also proposed. However, all of these adsorbents are obtained by subjecting the carbide to chemical activation treatment or water vapor / carbon dioxide activation treatment to increase its specific surface area and pore volume, and thus can be easily obtained at low cost. It is not a thing, and does not have sufficient oxygen adsorption capacity and high oxygen selectivity with respect to the complexity at the time of manufacture.

As described above, various oxygen-selective adsorbents have been proposed so far, but there are currently no high-performance adsorbents such as oxygen adsorption capacity, oxygen selectivity, cost, and regeneration conditions. It is.
JP 2005-103335 A JP 2005-104740 A JP-A-5-7771 Japanese Patent Laid-Open No. 11-70330 JP-A-6-92615 JP-A-8-208212

  The present invention has been made in view of the above-mentioned background art, and provides an oxygen-selective adsorbent that can adsorb a large amount of oxygen with high selectivity from an oxygen-containing atmosphere, and that is easy to desorb and regenerate and is inexpensive. This is the issue.

  That is, the present invention relates to an oxygen-selective adsorbent obtained by carbonizing a strongly acidic cation exchange resin having an ion exchange group containing an alkali metal ion at 500 to 900 ° C. in a non-oxygen atmosphere.

  The oxygen-selective adsorbent of the present invention can adsorb oxygen in a large amount and selectively by a very simple method, and can be desorbed and regenerated by a simple operation. Also, waste ion exchange resin can be used as a raw material, which is inexpensive and has a great effect on effective use of resources.

(First embodiment)
As described above, the oxygen-selective adsorbent according to the first embodiment of the present invention is obtained by applying a strongly acidic cation exchange resin having an ion exchange group containing an alkali metal ion at 500 to 900 ° C. in a non-oxygen atmosphere. Carbonized.

  The strongly acidic cation exchange resin used in the present embodiment has an ion exchange group containing an alkali metal ion. As described above, one of the major characteristics is that the alkali acid ion is contained in the strongly acidic cation exchange resin, and this gives the oxygen selective adsorbent excellent in oxygen selectivity and oxygen adsorption. .

  Examples of the alkali metal ions include lithium ions, sodium ions, potassium ions, and the like, and these alkali metal ions may be contained in one kind in the strong acid cation exchange resin. May be included at the same time.

  Examples of the strong acid cation exchange resin having an ion exchange group containing an alkali metal ion include a strong acid cation exchange resin having an alkali metal sulfonate group, and oxygen selectivity imparted to an oxygen selective adsorbent and This is preferable from the viewpoint of high oxygen adsorption and excellent handleability.

（式中、Ｍ¹及びＭ²はそれぞれ独立してアルカリ金属を示す）で表される繰り返し単位を有するスチレン系樹脂や、アルカリ金属スルホン酸塩基を含む繰り返し単位を有するフェノール系樹脂などがあげられるが、酸素選択性吸着剤に付与される酸素選択性及び酸素吸着性、さらには脱着再生能力がより高いという点から、かかる式（１）で表される繰り返し単位を有するスチレン系樹脂が特に好ましい。 As a representative example of the strongly acidic cation exchange resin used in the present embodiment, for example, the formula (1):

(Wherein, M ¹ and M ² each independently represents an alkali metal), a styrene resin having a repeating unit represented by the above, a phenol resin having a repeating unit containing an alkali metal sulfonate group, and the like. However, a styrene resin having a repeating unit represented by the formula (1) is particularly preferable from the viewpoint that the oxygen selectivity and oxygen adsorption property imparted to the oxygen selective adsorbent and the desorption / regeneration capacity are higher. .

  Strongly acidic cation exchange resins include MR-type strongly acidic cation exchange resins having a giant network structure and gel-type strongly acidic cation exchange resins having a gel structure, and any of them is used in this embodiment. However, MR type strongly acidic cation exchange resin is particularly preferred from the viewpoint that high oxygen adsorptivity can be imparted by the oxygen selective adsorbent.

  The shape of the strongly acidic cation exchange resin is not particularly limited, and may be, for example, spherical or powdery, or may be processed into other shapes. Further, the average molecular weight and ion exchange capacity of the strongly acidic cation exchange resin are not particularly limited, and may be the same as those of ordinary ion exchange resins.

  Furthermore, as a strong acid cation exchange resin, an unused thing can be used of course, but the used thing used for another uses, such as a water treatment, can also be used, for example. In addition, when such a used strongly acidic cation exchange resin contains a cation having a valence of 2 or more, it can be used even in a state in which such a cation having a valence of 2 or more is included. In order to further improve the oxygen selectivity and the oxygen adsorption property of the selective adsorbent, it is necessary to use after performing an ion exchange treatment with an aqueous solution of an alkali metal salt such as an alkali metal hydroxide such as sodium hydroxide. preferable. As the aqueous solution of the alkali metal salt, not only the aqueous solution of the hydroxide, but also an aqueous solution of an alkali metal nitrate, sulfate, carbonate, oxalate, chloride, acetate or the like can be used. However, an aqueous solution of hydroxide is preferable from the viewpoint of ion exchange capacity, ion exchange speed, and handleability. Further, the ion exchange treatment method is not particularly limited, and a normal column method, stirring method, or the like can be employed.

  The oxygen selective adsorbent according to the present embodiment can be obtained by carbonizing the strongly acidic cation exchange resin as described above.

  The carbonization treatment of the strongly acidic cation exchange resin is performed in an inert gas atmosphere such as nitrogen gas or argon gas or in a non-oxygen atmosphere such as vacuum. The temperature of the carbonization treatment is a range in which the thermal decomposition phenomenon occurs remarkably. However, if the temperature of the carbonization treatment is too low, the carbonization of the strong acid cation exchange resin becomes insufficient, which is the target. Since it becomes impossible to obtain an oxygen-selective adsorbent having high oxygen selectivity, oxygen adsorptivity and desorption / regeneration capability, the temperature is 500 ° C. or higher, preferably 550 ° C. or higher, more preferably 650 ° C. or higher. On the other hand, if the carbonization temperature is too high, carbonization proceeds too much, and it becomes impossible to obtain the desired high-performance oxygen-selective adsorbent. Therefore, it is 900 ° C. or less, preferably 800 ° C. or less. More preferably, it is 750 degrees C or less.

  There is no particular limitation on the rate of temperature rise until reaching the temperature of the carbonization treatment, and for example, it may be appropriately set according to the type, shape, average molecular weight, etc. of the strongly acidic cation exchange resin to be used. The time for performing the carbonization treatment is not particularly limited as long as the target oxygen-selective adsorbent can be obtained. For example, it is preferably about 10 minutes to 5 hours, more preferably about 0.5 to 4 hours.

  Also, there is no particular limitation on the treatment apparatus used when carbonizing the strongly acidic cation exchange resin as long as the target oxygen-selective adsorbent can be obtained, and the temperature of the carbonization treatment is appropriately within the above range in a non-oxygen atmosphere. Anything that can be adjusted is acceptable.

  As described above, the oxygen-selective adsorbent according to the present embodiment can be obtained by carbonizing a specific strong acid cation exchange resin in a specific temperature range in a non-oxygen atmosphere, and cooling it to about room temperature as appropriate. It can be easily obtained. Therefore, there is no need to increase the specific surface area and pore volume by performing an activation treatment with chemicals or water vapor / carbon dioxide, which is conventionally performed when carbonizing an ion exchange resin, after the carbonization.

  In addition, after carbonizing the strongly acidic cation exchange resin, if a slight odor of sulfur compounds is observed, it takes place, for example, in a vacuum or in an inert gas atmosphere at room temperature to about 100 ° C., aging, etc. Sulfur compound odor can be easily removed.

  After oxygen adsorption with the oxygen selective adsorbent thus obtained, the oxygen selective adsorbent is, for example, under an inert gas atmosphere such as nitrogen gas or argon gas, under vacuum, hydrogen gas, carbon monoxide gas, etc. In a reducing gas atmosphere, the desorption / regeneration can be performed very easily by maintaining the temperature for about 3 minutes to 3 hours at a very low temperature, for example, about 80 to 120 ° C. as compared with the prior art.

  Next, the oxygen-selective adsorbent of the present invention will be described in more detail based on the following examples, but the present invention is not limited to such examples.

Example 1
1.648 g of MR type strongly acidic cation exchange resin (Rumm and Haas, Amberlite 200CT Na type, —SO ₃ Na group-containing styrene resin, spherical shape) was put into a combustion boat in an untreated state, and then Inserted into the ceramic combustion tube. An electric tubular furnace was used as an external heating source. Under nitrogen gas flow, the temperature was raised to 700 ° C. at a rate of 5 ° C./min, and after reaching 700 ° C., carbonization was performed for 3 hours. Then, it cooled to room temperature and obtained 0.638g of oxygen selective adsorption agents 1.

(Example 2)
Gel type strongly acidic cation exchange resin (manufactured by Mitsubishi Chemical Corporation, Diaion SK-1B Na type, —SO ₃ Na group-containing styrenic resin, spherical) instead of MR type strongly acidic cation exchange resin 0.326 g of oxygen selective adsorbent 2 was obtained in the same manner as in Example 1 except that 837 g was used.

  Next, the oxygen-selective adsorbents 1 and 2 obtained in Examples 1 and 2 and the general adsorbent described in Example 1 of Patent Document 3 (Japanese Patent Laid-Open No. 5-7771), Monopyridine compound (Comparative Example 1) and molecular sieve activated carbon (Morseybon X2M4 / 6, manufactured by Takeda Pharmaceutical Co., Ltd.) before the organometallic complex cobalt di (salicylal) ethylenediimine (commonly known as sarcomin) is supported on spherical silica The following tests were conducted using (Comparative Example 2) as a sample.

(Test Example 1)
Each sample was evacuated as a pretreatment at 120 ° C. for 7 hours, then subjected to an oxygen adsorption test, and a constant volume using an automatic specific surface area measuring device (BELSORP-miniII, manufactured by Nippon Bell Co., Ltd.). The oxygen equilibrium adsorption isotherm at 25 ° C. was determined by the method. The results are shown in FIG. 1 as a graph showing the change in the oxygen equilibrium adsorption amount with respect to the oxygen partial pressure. Moreover, about the oxygen selective adsorption agent 1 obtained in Example 1, the oxygen / nitrogen equilibrium adsorption isotherm at 25 degreeC was calculated | required. The results are shown in FIG. 2 as a graph showing changes in the oxygen / nitrogen equilibrium adsorption amount with respect to the partial pressure. In FIG. 1 and FIG. 2, the types of graphs corresponding to the results of each sample are as shown in the legend.

  As shown in FIG. 1, the oxygen-selective adsorbents 1 and 2 obtained in Examples 1 and 2 both have an oxygen adsorption amount as compared with those of Comparative Examples 1 and 2 which are conventional adsorbents. It is clear that there are many. It is clear that these oxygen-selective adsorbents 1 and 2 show sufficiently high oxygen adsorption capacity even at a low oxygen partial pressure, unlike the conventional adsorbents of Comparative Examples 1 and 2. In particular, it can be seen that the oxygen selective adsorbent 1 of Example 1 exhibits extremely high oxygen adsorptivity not only at a high oxygen partial pressure but also at a low oxygen partial pressure.

  Further, as shown in FIG. 2, it can be seen that the oxygen-selective adsorbent 1 of Example 1 has an extremely high oxygen selectivity because the nitrogen adsorption amount is very small with respect to the oxygen adsorption amount.

(Test Example 2)
About the oxygen selective adsorption agent 1 of Example 1 which performed the oxygen adsorption test in Test Example 1, it evacuated at 120 degreeC for 3 hours, and performed the reproduction | regeneration process. About this, the oxygen adsorption test was performed on the conditions of 25 degreeC similarly to Test Example 1, and the oxygen adsorption amount was calculated | required (2nd time).

  Further, the oxygen-selective adsorbent 1 subjected to the second oxygen adsorption test was evacuated at 120 ° C. for 3 hours and regenerated again. In the same manner as above, an oxygen adsorption test was performed under the condition of 25 ° C., and the oxygen adsorption amount was determined (third time).

  The oxygen adsorption amount (first time) in Test Example 1 was set to 100, and the second and third oxygen adsorption amounts were expressed as a relative ratio to the first oxygen adsorption amount. The result is shown in the graph of FIG.

  As shown in FIG. 3, the oxygen selective adsorbent 1 of Example 1 is about 50-60% of the initial oxygen adsorption amount even when regeneration / adsorption is repeated twice or three times. It can be seen that oxygen can be adsorbed again at a high rate and can be desorbed and regenerated very easily.

  The oxygen selective adsorbent of the present invention is useful as an oxygen scavenger for foods, for example, and can be stored at low cost for a long period of time. The oxygen-selective adsorbent of the present invention is also useful as an adsorbent for adsorption type nitrogen generators and adsorption type oxygen generators, which are air separation devices, and can adsorb large amounts of oxygen with high selectivity. Therefore, it is possible to provide an air separation device that greatly contributes to the downsizing of the device, which has been a problem in the past, and has extremely high oxygen separation efficiency.

The graph which shows the change of the oxygen equilibrium adsorption amount with respect to oxygen partial pressure of the sample obtained in Examples 1, 2 and Comparative Examples 1, 2. The graph which shows the change of the oxygen / nitrogen equilibrium adsorption amount with respect to the partial pressure of the oxygen selective adsorbent obtained in Example 1 The graph which shows the relationship between the frequency | count of regeneration / adsorption repetition, and oxygen adsorption amount relative ratio of the oxygen selective adsorption agent obtained in Example 1

Claims (5)

An oxygen-selective adsorbent obtained by carbonizing a strongly acidic cation exchange resin having an ion exchange group containing an alkali metal ion at 500 to 900 ° C. in a non-oxygen atmosphere and without performing an activation treatment after the carbonization treatment .   The oxygen selective adsorbent according to claim 1, wherein the strongly acidic cation exchange resin has an alkali metal sulfonate group. A strongly acidic cation exchange resin has the formula (1):

The oxygen selective adsorbent according to claim 2, which is a styrene resin having a repeating unit represented by the formula (wherein M ¹ and M ² each independently represents an alkali metal).   The oxygen-selective adsorbent according to claim 1, wherein the strongly acidic cation exchange resin is an MR type strongly acidic cation exchange resin.   The oxygen selective adsorbent according to claim 1, wherein the strongly acidic cation exchange resin is carbonized at 550 to 800 ° C.

Images