Xenon adsorbent

Abstract

A xenon adsorbent capable of efficiently adsorbing xenon, even at a low concentration, from a mixture gas is Provided. A xenon adsorbent comprising a zeolite having a pore size in the range of 3.5 to 5 Å and a silica alumina molar ratio in the range of 10 to 30.

Claims

1. A xenon adsorbent comprising: a zeolite having a pore size in the range of 3.5 to 5 Å; and a silica alumina molar ratio in the range of 10 to 30, wherein the xenon adsorbent comprises silver, an ultraviolet-visible absorption spectrum of the silver measured after calcination of the xenon adsorbent at 500° C. in air has an absorbance peak in the range of 290 to 350 nm, and the absorbance peak has a maximum value in the range of 310 to 330 nm.

2. The xenon adsorbent according to claim 1, further comprising at least one selected from the group consisting of lithium, sodium, potassium, magnesium, calcium, strontium, barium, iron, and copper, as a metal component contained in the zeolite.

3. The xenon adsorbent according to according to claim 1, wherein the stoichiometric ratio of the metal component relative to the aluminum in the zeolite is 0.1 to 1.0 equivalent amount (in a case where a valence of an ion of a metal is represented by n, the equivalent amount is a value obtained by multiplying a metal/Al molar ratio by the valence n of the metal).

4. The xenon adsorbent according to claim 1, wherein the zeolite comprises at least one structure selected from the group consisting of CHA-type, FER-type, HEU-type, and MW-type.

5. The xenon adsorbent according to claim 1, wherein the xenon adsorbent is a molded body.

6. The xenon adsorbent according to claim 1, wherein the xenon adsorbent further comprises at least one selected from the group consisting of lithium, sodium, potassium, magnesium, calcium, strontium, barium, iron, and copper, as a metal component contained in the zeolite, and the zeolite comprises at least one structure selected from the group consisting of CHA-type, FER-type, HEU-type, and MWW-type.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is an ultraviolet-visible absorption spectrum of a xenon adsorbent containing silver.

(2) FIG. 2 is an enlarged view of the absorbance peak near 320 nm of FIG. 1.

EXAMPLES

(3) Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

(4) <Measurement of Amount of Xenon Adsorbed and Amount of Nitrogen Adsorbed>

(5) Amounts of adsorbed were measured by using a adsorption measurement apparatus of fixed displacement type (BELSORP 28SA: manufactured by MicrotracBEL Corp.). An adsorbent was pretreated at 350° C. under a vacuum of 0.01 Pa or less for 2 hours. Amounts of adsorbed were measured at a temperature of 25° C. The amount of xenon adsorbed was measured at a pressure of 1 kPa, and the amount of nitrogen adsorbed was measured at a pressure of 100 kPa.

(6) <Xenon Selectivity>

(7) The xenon selectivity was calculated by the expression (1).
Xenon selectivity=(amount of xenon adsorbed at 1 kPa/1 kPa)/(amount of nitrogen adsorbed at 100 kPa/100 kPa)  (1)
<Measurement of Ultraviolet-Visible Absorption Spectrum>

(8) An ultraviolet-visible absorption spectrum of a xenon adsorbent containing silver was measured by raising the temperature of a muffle furnace having an internal volume of 30 L over 1 hour and 40 minutes while dry air was blown thereto at a flow rate of 25 L/min, performing calcination at 500° C. for 3 hours to thereby obtain a sample, and measuring the sample by a diffuse reflection method with use of a UV-visible spectrophotometer (V-650: manufactured by JASCO Corporation) equipped with an integrating sphere unit at room temperature.

(9) As for the measurement condition, the measurement was performed in a wavelength range of 200 to 400 nm for 2 minutes.

Example 1

(10) 7.5 g of a 25% N,N,N-trimethyladamantane ammonium hydroxide aqueous solution, 37.0 g of pure water, 1.0 g of a 48% sodium hydroxide aqueous solution, 1.4 g of a 48% potassium hydroxide aqueous solution, and 9.3 g of amorphous aluminosilicate gel were added and sufficiently mixed to obtain a raw material composition. The composition of the raw material composition, as a molar ratio in the case where SiO.sub.2 was set to 1, was Al.sub.2O.sub.3: 0.072, N,N,N-trimethyladamantane ammonium hydroxide: 0.065, Na.sub.2O: 0.044, K.sub.2O: 0.044, and H.sub.2O: 18.

(11) This raw material composition was sealed in an 80 cc stainless autoclave and heated at 150° C. for 70 hours while rotated at 55 rpm. A product after heated was subjected to solid-liquid separation, and the solid phase obtained was washed with a sufficient amount of pure water and dried at 110° C. to thereby obtain a product. It was found that the product was a CHA-type zeolite single phase by X-ray powder diffraction and fluorescent X-ray analysis. The dried powder of the CHA-type zeolite obtained was calcined under air flowing at 600° C. for 2 hours (pore size of the CHA-type zeolite: 3.8 Å). The CHA-type zeolite had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 13, a Na/Al ratio of 0.2, and a K/Al ratio of 0.4 (amount of metal (Na+K) relative to aluminum: 0.6 equivalent amount).

(12) This CHA-type zeolite (xenon adsorbent) had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.14 mol/kg and an amount of nitrogen adsorbed at 25° C. and 100 kPa of 0.47 mol/kg. The xenon selectivity was 29.8.

Example 2

(13) 825 g of pure water, 4.9 g of a 48% sodium hydroxide aqueous solution, 13.5 g of a 48% potassium hydroxide aqueous solution, and 557 g of amorphous aluminosilicate gel were added and sufficiently mixed to obtain a raw material composition. The composition of the raw material composition, as a molar ratio in the case where SiO.sub.2 was set to 1, was Al.sub.2O.sub.3: 0.051, Na.sub.2O: 0.071, K.sub.2O: 0.019, and H.sub.2O: 21.

(14) This raw material composition was sealed in a 2000 cc stainless autoclave and heated at 180° C. for 72 hours under stirring. A product after heated was subjected to solid-liquid separation, and the solid phase obtained was washed with a sufficient amount of pure water and dried at 110° C. to thereby obtain a product. It was found that the product was a FER-type zeolite (pore size: 4.2 Å) single phase by X-ray powder diffraction and fluorescent X-ray analysis. The FER-type zeolite had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 18, a Na/Al ratio of 0.3, and a K/Al ratio of 0.7 (amount of metal (Na+K) relative to aluminum: 1.0 equivalent amount).

(15) To the 100 parts by weight of the FER-type zeolite obtained, 20 parts by weight of attapulgite clay (MIN-U-GEL MB: manufactured by Active Minerals International LLC.), 3 parts by weight of carboxymethyl cellulose, 1 part by weight of RHEODOL (TWL-120: manufactured by Kao Corporation), and 110 parts by weight of pure water were added and kneaded by a Mix Muller. The kneaded product was extruded and molded into a cylinder having a diameter of 1.5 mmϕ. The molded product was dried at 110° C. and then calcined at 650° C. for 3 hours in air to obtain a xenon adsorbent (molded body).

(16) The xenon adsorbent obtained had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.34 mol/kg and an amount of nitrogen adsorbed at 25° C. and 100 kPa of 0.60 mol/kg. The xenon selectivity was 56.7.

Example 3

(17) The CHA-type zeolite after calcination obtained in Example 1 (pore size: 3.8 Å) was ion-exchanged with a sodium nitrate solution. The sodium-exchanged CHA-type zeolite obtained had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 13 and a Na/Al ratio of 0.8 (amount of metal (Na) relative to aluminum: 0.8 equivalent amount) and contained no K. The Na/Al ratio was 0.2 and the K/Al ratio was 0.4 before the ion exchange.

(18) This sodium-exchanged CHA-type zeolite (xenon adsorbent) had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.17 mol/kg and an amount of nitrogen adsorbed at 25° C. and 100 kPa of 0.64 mol/kg. The xenon selectivity was 26.6.

Examples 4 to 7

(19) The FER-type zeolite after crystallization obtained in Example 2 (pore size: 4.2 Å, powder before molded, Example 6) was ion-exchanged with a sodium nitrate solution (Examples 4 and 5) or potassium nitrate (Example 7) to prepare four FER-type zeolites each having different Na and K contents (SiO.sub.2/Al.sub.2O.sub.3 molar ratio: 18). The amount of xenon adsorbed at 25° C. and 1 kPa, amount of nitrogen adsorbed at 25° C. and 100 kPa, and xenon selectivity of each sample are shown in Table 1.

(20) TABLE-US-00001 TABLE 1 Composition Equivalent Adsorption performance amount Amount Amount Xe relative to of Xe of N.sub.2 selec- Na/Al K/Al metal Al adsorbed adsorbed tivity Example 4 1.0 0.0 1.0 0.57 0.94 60.6 Example 5 0.7 0.3 1.0 0.52 0.86 60.5 Example 6 0.3 0.7 1.0 0.42 0.74 56.8 Example 7 0.0 1.0 1.0 0.28 0.65 43.1

(21) As shown in Table 1, with a larger amount of sodium exchange, the amount of xenon adsorbed was larger and the xenon selectivity was more excellent.

Example 8

(22) 1.07 g of a sodium aluminate aqueous solution (manufactured by Asada Chemical INDUSTRY Co., Ltd., Al.sub.2O.sub.3 19.3%, Na.sub.2O 19.6%), 0.39 g of a 48% sodium hydroxide aqueous solution, and 51.6 g of pure water were sufficiently mixed. To this solution, 2.27 g of hexamethyleneimine and 4.40 g of amorphous silica (Nipsil-VN3: manufactured by TOSOH SILICA CORPORATION, SiO.sub.2 90.2%, Al.sub.2O.sub.3 0.38%, Na.sub.2O 0.25%) were added, and the mixture was further mixed sufficiently to obtain a raw material composition. The composition of the raw material composition, as a molar ratio in the case where SiO.sub.2 was set to 1, was Al.sub.2O.sub.3: 0.033, hexamethyleneimine: 0.35, Na.sub.2O: 0.09, and H.sub.2O: 45.

(23) This raw material composition was sealed in an 80 cc stainless autoclave and heated at 150° C. for 7 days while rotated at 55 rpm. A product after heated was subjected to solid-liquid separation, and the solid phase obtained was washed with a sufficient amount of pure water, dried at 110° C., and further, calcined under air flowing at 600° C. for 2 hours. It was found that the product was an MWW-type zeolite (pore size: 4.0 Å) by X-ray powder diffraction. Additionally, it was found that the MWW-type zeolite had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 20 by fluorescent X-ray analysis.

(24) The MWW-type zeolite calcined product obtained was ion-exchanged with a sodium nitrate solution. The sodium-exchanged MWW-type zeolite obtained had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 20 and a Na/Al ratio of 0.6 (amount of metal (Na) relative to aluminum: 0.6 equivalent amount).

(25) This sodium-exchanged MWW-type zeolite (xenon adsorbent) had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.17 mol/kg and an amount of nitrogen adsorbed at 25° C. and 100 kPa of 0.47 mol/kg. The xenon selectivity was 36.2.

Example 9

(26) The CHA-type zeolite after calcination obtained in Example 1 (pore size: 3.8 Å) was ion-exchanged with a silver nitrate solution. The silver-exchanged CHA-type zeolite obtained had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 13 and a Ag/Al ratio of 0.6 (amount of metal (Ag) relative to aluminum: 0.6 equivalent amount), and contained no Na and K. The ultraviolet-visible absorption spectrum of this silver-exchanged CHA-type zeolite is shown in FIGS. 1 and 2. As seen from the figures, the zeolite had an absorbance peak having a peak top in the range of 310 to 330 nm.

(27) This silver-exchanged CHA-type zeolite (xenon adsorbent) had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.88 mol/kg and an amount of nitrogen adsorbed at 25° C. and 100 kPa of 0.65 mol/kg. The xenon selectivity was 135.

Example 10

(28) The FER-type zeolite after crystallization obtained in Example 2 (pore size: 4.2 Å, powder before molded) was ion-exchanged with a silver nitrate solution. The silver-exchanged FER-type zeolite obtained had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 18 and a Ag/Al ratio of 0.5 (amount of metal (Ag) relative to aluminum: 0.5 equivalent amount), and contained no Na and K. The ultraviolet-visible absorption spectrum of this silver-exchanged FER-type zeolite is shown in FIGS. 1 and 2. As seen from the figures, the zeolite had an absorbance peak having a peak top in the range of 310 to 330 nm.

(29) This silver-exchanged FER-type zeolite (xenon adsorbent) had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.79 mol/kg and an amount of nitrogen adsorbed at 25° C. and 100 kPa of 0.63 mol/kg. The xenon selectivity was 125.

(30) This silver-exchanged FER-type zeolite was calcined in a dry air atmosphere at 400, 500, and 600° C. for 3 hours (temperature raising rate: 5° C./rain in any of the cases). The amount of xenon adsorbed at 25° C. and 1 kPa, amount of nitrogen adsorbed at 25° C. and 100 kPa, and xenon selectivity of each calcined silver-exchanged zeolite are shown in Table 2.

(31) TABLE-US-00002 TABLE 2 Adsorption performance Calcination Amount of Amount of Xe temperature Xe adsorbed N.sub.2 adsorbed selectivity Silver-exchanged Example 10 0.79 0.63 125 FER of 400° C. 0.91 0.73 125 Example 10 500° C. 0.92 0.74 124 600° C. 0.89 0.73 122 Silver-exchanged Example 11 0.98 0.74 132 FER of 500° C. 1.13 0.91 124 Example 11 Silver-exchanged Example 13 0.79 0.59 134 CHA of 400° C. 0.80 0.63 127 Example 13 500° C. 0.85 0.66 129

(32) As shown in Table 2, calcination in the range of 400° C. to 600° C. led to an increase in the amount of xenon adsorbed of the silver-exchanged zeolite.

Example 11

(33) The silver-exchanged FER-type zeolite obtained in Example 10 was ion-exchanged again with a silver nitrate solution. The silver-exchanged FER-type zeolite obtained had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 18 and a Ag/Al ratio of 0.8 (amount of metal (Ag) relative to aluminum: 0.8 equivalent amount), and contained no Na and K. The ultraviolet-visible absorption spectrum of this silver-exchanged FER-type zeolite is shown in FIGS. 1 and 2. As seen from the figures, the zeolite had an absorbance peak having a peak top in the range of 310 to 330 nm.

(34) This silver-exchanged FER-type zeolite (xenon adsorbent) had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.98 mol/kg and an amount of nitrogen adsorbed at 25° C. and 100 kPa of 0.74 mol/kg. The xenon selectivity was 132.

(35) This silver-exchanged FER-type zeolite was calcined in a dry air atmosphere at 500° C. for 3 hours (temperature raising rate: 5° C./min in any of the cases). The amount of xenon adsorbed at 25° C. and 1 kPa, amount of nitrogen adsorbed at 25° C. and 100 kPa, and xenon selectivity of each calcined silver-exchanged zeolite are shown in Table 2.

(36) As shown in Table 2, calcination at 500° C. led to an increase in the amount of xenon adsorbed of the silver-exchanged zeolite.

Example 12

(37) The MWW-type zeolite obtained in Example 8 (pore size: 4.0 Å) was ion-exchanged with a silver nitrate solution. The silver-exchanged MWW-type zeolite obtained had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 20 and a Ag/Al ratio of 0.5 (amount of metal (Ag) relative to aluminum: 0.5 equivalent amount), and contained no Na. The ultraviolet-visible absorption spectrum of this silver-exchanged MWW-type zeolite is shown in FIGS. 1 and 2. As seen from the figures, the zeolite had an absorbance peak having a peak top in the range of 310 to 330 nm.

(38) This silver-exchanged MWW-type zeolite (xenon adsorbent) had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.49 mol/kg and an amount of nitrogen adsorbed at 25° C. and 100 kPa of 0.38 mol/kg. The xenon selectivity was 129.

Example 13

(39) The CHA-type zeolite after calcination obtained in Example 1 (pore size: 3.8 Å) was ion-exchanged with a silver nitrate solution. The silver-exchanged CHA-type zeolite obtained had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 13 and a Ag/Al ratio of 0.5 (amount of metal (Ag) relative to aluminum: 0.5 equivalent amount), and contained no Na and K. The ultraviolet-visible absorption spectrum of this silver-exchanged CHA-type zeolite is shown in FIGS. 1 and 2. As seen from the figures, the zeolite had an absorbance peak having a peak top in the range of 310 to 330 nm.

(40) This silver-exchanged CHA-type zeolite (xenon adsorbent) had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.79 mol/kg and an amount of nitrogen adsorbed at 25° C. and 100 kPa of 0.59 mol/kg. The xenon selectivity was 134.

(41) This silver-exchanged CHA-type zeolite was calcined in a dry air atmosphere at 400 and 500° C. for 3 hours (temperature raising rate: 5° C./min in any of the cases). The amount of xenon adsorbed at 25° C. and 1 kPa, amount of nitrogen adsorbed at 25° C. and 100 kPa, and xenon selectivity of each calcined silver-exchanged zeolite are shown in Table 2.

(42) As shown in Table 2, calcination in the range of 400° C. to 500° C. led to an increase in the amount of xenon adsorbed of the silver-exchanged zeolite.

Example 14

(43) The FER-type zeolite after crystallization obtained in Example 2 (pore size: 4.2 Å, powder before molded) was ion-exchanged with an ammonium chloride solution and then ion-exchanged with a calcium nitrate solution. The calcium-exchanged FER-type zeolite obtained had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 18 and a Ca/Al ratio of 0.45 (amount of metal (Ca) relative to aluminum: 0.90 equivalent amount), and contained no Na and K.

(44) This calcium-exchanged FER-type zeolite (xenon adsorbent) had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.55 mol/kg and an amount of nitrogen adsorbed at 25° C. and 100 kPa of 0.70 mol/kg. The xenon selectivity was 78.6.

Example 15

(45) The FER-type zeolite after crystallization obtained in Example 2 (pore size: 4.2 Å, powder before molded) was ion-exchanged with an ammonium chloride solution and then ion-exchanged with a magnesium nitrate solution. The magnesium-exchanged FER-type zeolite obtained had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 18 and a Mg/Al ratio of 0.45 (amount of metal (Mg) relative to aluminum: 0.90 equivalent amount), and contained no Na and K.

(46) This magnesium-exchanged FER-type zeolite (xenon adsorbent) had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.36 mol/kg and an amount of nitrogen adsorbed at 25° C. and 100 kPa of 0.50 mol/kg. The xenon selectivity was 72.0.

Example 16

(47) The FER-type zeolite after crystallization obtained in Example 2 (pore size: 4.2 Å, powder before molded) was ion-exchanged with an ammonium chloride solution and then ion-exchanged by a lithium chloride solution. The lithium-exchanged FER-type zeolite obtained had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 18 and a Li/Al ratio of 1.0 (amount of metal (Li) to relative to aluminum: 1.0 equivalent amount), and contained no Na and K.

(48) This lithium-exchanged FER-type zeolite (xenon adsorbent) had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.63 mol/kg and an amount of nitrogen adsorbed at 25° C. and 100 kPa of 1.08 mol/kg. The xenon selectivity was 58.3.

Comparative Example 1

(49) The amount of xenon adsorbed and amount of nitrogen adsorbed of a NaX-type zeolite molded body (ZEOLUM® F-9HA: manufactured by TOSOH CORPORATION, pore size of zeolite: 7.4 Å, silica alumina molar ratio: 2.5) were measured. The amount of xenon adsorbed at 25° C. and 1 kPa was 0.03 mol/kg and the amount of nitrogen adsorbed at 25° C. and 100 kPa was 0.43 mol/kg. The xenon selectivity was 7.0.

Comparative Example 2

(50) The amount of xenon adsorbed and amount of nitrogen adsorbed of a LiLSX-type zeolite molded body (ZEOLUM® NSA-700: manufactured by TOSOH CORPORATION, pore size of zeolite: 7.4 Å, silica alumina molar ratio: 2.0) were measured. The amount of xenon adsorbed at 25° C. and 1 kPa was 0.03 mol/kg and the amount of nitrogen adsorbed at 25° C. and 100 kPa was 1.13 mol/kg. The xenon selectivity was 2.7.

Comparative Example 3

(51) The amount of xenon adsorbed and amount of nitrogen adsorbed of a CaX-type zeolite molded body (ZEOLUM® SA-600A: manufactured by TOSOH CORPORATION, pore size of zeolite: 7.4 Å, silica alumina molar ratio: 2.5) were measured. The amount of xenon adsorbed at 25° C. and 1 kPa was 0.11 mol/kg and the amount of nitrogen adsorbed at 25° C. and 100 kPa was 1.14 mol/kg. The xenon selectivity was 9.6.

Comparative Example 4

(52) The amount of xenon adsorbed and amount of nitrogen adsorbed of a CaA-type zeolite molded body (ZEOLUM® SA-500A: manufactured by TOSOH CORPORATION, pore size of zeolite: 4.1 Å, silica alumina molar ratio: 2.0) were measured. The amount of xenon adsorbed at 25° C. and 1 kPa was 0.05 mol/kg and the amount of nitrogen adsorbed at 25° C. and 100 kPa was 0.57 mol/kg. The xenon selectivity was 8.8.

Comparative Example 5

(53) A NaY-type zeolite (HSZ-320NAA: manufactured by TOSOH CORPORATION, pore size of zeolite: 7.4 Å, silica alumina molar ratio: 5.7) was ion-exchanged with an ammonium chloride solution and then ion-exchanged with a silver nitrate solution. The silver-exchanged FAU-type zeolite obtained had a SiO.sub.2/Al.sub.2O.sub.3 molar ratio of a 5.7, a Ag/Al ratio of 0.2, and a Na/Al ratio of 0.2.

(54) This silver-exchanged FAU-type zeolite (xenon adsorbent) had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.02 mol/kg.

(55) This silver-exchanged FAU-type zeolite was calcined in a dry air atmosphere at 500° C. for 3 hours (temperature raising rate: 5° C./min in any of the cases). The silver-exchanged zeolite after calcination had an amount of xenon adsorbed at 25° C. and 1 kPa of 0.02 mol/kg. Calcination at 500° C. led to no increase in the amount of xenon adsorbed of the silver-exchanged zeolite.

(56) The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2017-1299, filed on Jan. 6, 2017, Japanese Patent Application No. 2017-125856, filed on Jun. 28, 2017, and Japanese Patent Application No. 2017-218780, filed on Nov. 14, 2017 are incorporated by reference herein as a disclosure of the specification of the present invention.

INDUSTRIAL APPLICABILITY

(57) The xenon adsorbent of the present invention, which adsorbs a large amount of xenon at a low concentration, can efficiently adsorb xenon from a mixture gas.