PST-20 zeolite, preparation method for the same, and selective separation method for carbon dioxide using the same

Abstract

The present invention relates to a PST-20 zeolite having a novel skeletal structure, its preparation method, and a selective separation and adsorption method for a gas using the PST-20 zeolite. More specifically, the present invention relates to a method of preparing a microporous aluminosilicate PST-20 zeolite having a novel skeletal structure totally different from the skeletal structure of known zeolites and using the PST-20 zeolite as an adsorbent/separator capable of selectively adsorbing/separating carbon dioxide to separate and collect carbon dioxide with high purity from burned gases or natural gases.

Claims

1. A PST-20 zeolite having a composition represented by the following chemical formula (I),
0.110M.sub.xO: 1.0 Al.sub.2O.sub.3: 1.0100SiO.sub.2(I) wherein M is at least one selected from monovalent or divalent metal elements; and X is 1 or 2, the PST-20 zeolite having a skeletal structure according to an XRD pattern presented in the following table 1, TABLE-US-00008 TABLE 1 2 d 100 I/Io 11.3~11.4 7.8~7.7 S~VS 12.0~12.1 7.4~7.3 W 12.7~12.8 7.0~6.9 VS 13.6~13.7 6.5~6.4 S 14.2~14.3 6.3~6.2 W 16.1~16.2 5.5~5.4 M 16.4~16.5 5.4~5.3 W 17.8~17.9 5.0~4.9 VS 19.3~19.4 4.6~4.5 M~S 19.7~19.8 4.5~4.4 VS 21.1~21.2 4.2~4.1 W~M 21.7~21.8 4.1~4.0 M 22.5~22.6 4.0~3.9 W~M 23.8~23.9 3.8~3.7 M~S 25.8~25.9 3.5~3.4 W 27.2~27.3 3.3~3.2 S~VS 27.7~27.8 3.3~3.2 VS 28.3~28.4 3.2~3.1 S 28.7~28.8 3.2~3.1 VS 29.2~29.3 3.1~3.0 M~S 32.2~32.3 2.8~2.7 W~M 32.6~32.7 2.8~2.7 W 33.1~33.2 2.8~2.7 M~S 33.9~34.0 2.7~2.6 M~S 34.0~34.1 2.7~2.6 M~S wherein is the Bragg angle; d is the lattice interval; and I is the intensity of an X-ray diffraction peak, wherein all the powder X-ray diffraction data reported in the present invention including this powder X-ray diffraction pattern are measured using the standard X-ray diffraction method, using copper K radiation as a light source and an X-ray tube operated at 40 kV and 30 mA, wherein the measurement is performed at a rate of 5 degree (2)/min from a powder specimen horizontally compressed, wherein d and I are calculated from the 2 value and the peak height of the observed X-ray diffraction peak, wherein in terms of 100 I/Io, W is for weak (020); M is for medium (2040); S is for strong (4060); and VS is for very strong (60100).

2. The PST-20 zeolite as claimed in claim 1, wherein the PST-20 zeolite has a ratio of Al.sub.2O.sub.3 to SiO.sub.2 in the range of 1:250, wherein 2, d and 100 I/Io of the table 1 are represented as in the following table 2, TABLE-US-00009 TABLE 2 2 d 100 I/Io 11.3~11.4 7.8~7.7 60~65 12.0~12.1 7.4~7.3 10~15 12.7~12.8 7.0~6.9 90~95 13.6~13.7 6.5~6.4 50~55 14.2~14.3 6.3~6.2 15~20 16.1~16.2 5.5~5.4 25~30 16.4~16.5 5.4~5.3 10~15 17.8~17.9 5.0~4.9 65~70 19.3~19.4 4.6~4.5 35~40 19.7~19.8 4.5~4.4 65~70 21.1~21.2 4.2~4.1 15~20 21.7~21.8 4.1~4.0 25~30 22.5~22.6 4.0~3.9 15~20 23.8~23.9 3.8~3.7 40~45 25.8~25.9 3.5~3.4 10~15 27.2~27.3 3.3~3.2 55~60 27.7~27.8 3.3~3.2 100 28.3~28.4 3.2~3.1 50~55 28.7~28.8 3.2~3.1 90~95 29.2~29.3 3.1~3.0 40~45 32.2~32.3 2.8~2.7 15~20 32.6~32.7 2.8~2.7 10~15 33.1~33.2 2.8~2.7 40~45 33.9~34.0 2.7~2.6 40~45 34.0~34.1 2.7~2.6 40~41 wherein is the Bragg angle; d is the lattice interval; and I is the intensity of an X-ray diffraction peak, wherein all the powder X-ray diffraction data reported in the present invention including this powder X-ray diffraction pattern are measured using the standard X-ray diffraction method, using copper K ray as a light source and an X-ray tube operated at 40 kV and 30 mA, wherein the measurement is performed at a rate of 5 degree (2)/min from a powder specimen horizontally compressed, wherein d and I are calculated from the 2 value and the peak height of the observed X-ray diffraction peak.

3. The PST-20 zeolite as claimed in claim 2, wherein the PST-20 zeolite belongs to a space group Im3m with a cubic crystal system, wherein the lengths a, b and c of crystal axes of a unit cell are all 50 or greater.

4. The PST-20 zeolite as claimed in claim 3, wherein the lengths a, b and c of crystal axes of a unit cell are 50 .

Description

BRIEF DESCRIPTIONS OF DRAWINGS

(1) FIG. 1 shows the structure of an aluminosilicate PST-20 zeolite prepared in Example 2.

(2) FIG. 2 presents the results of the X-ray diffraction (XRD) analysis of an aluminosilicate PST-20 zeolite prepared in Example 1.

(3) FIG. 3 presents the results of the X-ray diffraction (XRD) analysis of the aluminosilicate PST-20 zeolite prepared in Example 2.

(4) FIG. 4 shows the scanning electron microscope (SEM) image of the aluminosilicate PST-20 zeolite prepared in Example 2.

(5) FIG. 5 presents the results of the X-ray diffraction (XRD) analysis of an aluminosilicate PST-20 containing an analcime zeolite as an impurity as prepared in Comparative Example 2-1.

(6) FIG. 6 presents the results of the X-ray diffraction (XRD) analysis of an aluminosilicate PST-20 zeolite prepared in Example 3.

(7) FIG. 7 presents the results of the X-ray diffraction (XRD) analysis of an aluminosilicate PST-20 zeolite prepared in Example 4.

(8) FIG. 8 presents the results of the X-ray diffraction (XRD) analysis of an aluminosilicate PST-20 zeolite prepared in Example 5.

(9) FIG. 9 presents the results of the X-ray diffraction (XRD) analysis of an aluminosilicate PST-20 zeolite prepared in Example 6.

(10) FIG. 10 presents the results of the adsorption isotherm that measures the adsorbed amount of carbon dioxide while continuously varying the pressure of the carbon dioxide gas at 25 C., according to Example 7.

(11) FIG. 11 presents the results of the adsorption isotherm that measures the adsorbed amount of nitrogen while continuously varying the pressure of the nitrogen gas at 25 C., according to Example 7-1.

(12) FIG. 12 presents the results of the adsorption isotherm that measures the adsorbed amount of methane while continuously varying the pressure of the methane gas at 25 C., according to Example 7-2.

(13) FIG. 13 presents the results of the adsorption isotherm that measures the adsorbed amount of carbon dioxide while continuously varying the pressure of the carbon dioxide gas at 25 C. using a calcined PST-20 zeolite, according to Example 8.

(14) FIG. 14 presents the results of the adsorption isotherm that measures the adsorbed amount of carbon dioxide while continuously varying the pressure of the carbon dioxide gas at C. using a nitrogen ion (Na.sup.+)-exchanged PST-20 zeolite, according to Example 9.

(15) FIG. 15 is the fracture curve showing the results of an analysis on mixed gases of carbon dioxide and nitrogen passing through a reactor containing a PST-20 zeolite at the room temperature with an elapse of time, according to Example 10.

(16) FIG. 16 is the fracture curve showing the results of an analysis on mixed gases of carbon dioxide and methane passing through a reactor containing a PST-20 zeolite at the room temperature with an elapse of time, according to Example 11.

(17) FIG. 17 is a curve plotting the time taken for a PST-20 zeolite to adsorb carbon dioxide and come to the equilibrium pressure of 1.2 bar at the room temperature of 25 C., according to Example 12.

BEST MODES FOR CARRYING OUT THE INVENTION

(18) Hereinafter, the present invention will be described in detail with reference to the following examples, which are only to explain the present invention and not construed to limit the scope of the present invention.

Example 1: Preparation of PST-20 Zeolite

(19) In a plastic beaker, 0.72 g of 50 wt. % sodium hydroxide (NaOH) was added to 4.82 g of deionized water. After adding 0.46 g of aluminum hydroxide (Al(OH).sub.3.H.sub.2O), the resultant mixture was agitated for one hour to prepare an aqueous solution A. Apart from this, 2.57 g of colloidal silica sol (Ludox As-40), 0.25 g of strontium nitrate (Sr(NO.sub.3).sub.2) and 2.66 g of TEABr were added to 9.64 g of deionized water, and the resultant mixture was agitated for one hour to prepare an aqueous solution B. The aqueous solution A was slowly added to the aqueous solution B, and the mixed solution was agitated for 24 hours to obtain a reaction mixture having the composition of the following chemical formula 1.
0.5Sr(NO.sub.3).sub.2:1.9Na.sub.2O:1.0Al.sub.2O.sub.3:5.2TEABr:7.2SiO.sub.2:390H.sub.2O[Chemical Formula 1]

(20) The reaction mixture thus obtained was moved to a Teflon reactor, put into a stainless steel container and heated at 145 C. for 4 days to yield a solid product, which was then repeatedly washed with water and dried at the room temperature.

(21) The solid powder obtained in Example 1 was subjected to an X-ray diffraction analysis. According to the results of the X-ray diffraction analysis, the aluminosilicate PST-20 zeolite had no same X-ray diffraction pattern of the existing zeolites. This implicitly shows that the PST-20 zeolite had a totally new skeletal structure that had never been known. A small amount of ZSM-25 zeolite impurity was also observed.

Example 2: Preparation of PST-20 Zeolite

(22) In a plastic beaker, 0.72 g of 50 wt. % sodium hydroxide (NaOH) was added to 4.82 g of deionized water. After adding 0.46 g of aluminum hydroxide (Al(OH).sub.3.H.sub.2O), the resultant mixture was agitated for one hour to prepare an aqueous solution A. Apart from this, 2.57 g of colloidal silica sol (Ludox As-40), 0.25 g of strontium nitrate (Sr(NO.sub.3).sub.2) and 2.66 g of TEABr were added to 9.64 g of deionized water, and the resultant mixture was agitated for one hour to prepare an aqueous solution B. The aqueous solution A was slowly added to the aqueous solution B. 0.021 g of the PST-20 zeolite obtained in Example 1 was added as a seed to the mixed solution, which was then agitated for 24 hours to obtain a reaction mixture having the composition of the chemical formula 1. Subsequently, the reaction mixture thus obtained was moved to a Teflon reactor, put into a stainless steel container and heated at 145 C. for 48 hours to yield a solid product. The solid product was repeatedly washed with water and dried at the room temperature. The solid powder obtained in Example 2 was subjected to an X-ray diffraction analysis. The results of the X-ray diffraction analysis are presented in Table 7 and FIG. 3.

(23) TABLE-US-00005 TABLE 7 2 d 100 I/Io 11.3~11.4 7.8~7.7 62 12.0~12.1 7.4~7.3 15 12.7~12.8 7.0~6.9 93 13.6~13.7 6.5~6.4 42 14.2~14.3 6.3~6.2 17 16.1~16.2 5.5~5.4 29 16.4~16.5 5.4~5.3 14 17.8~17.9 5.0~4.9 70 19.3~19.4 4.6~4.5 37 19.7~19.8 4.5~4.4 67 21.1~21.2 4.2~4.1 15 21.7~21.8 4.1~4.0 29 22.5~22.6 4.0~3.9 17 23.8~23.9 3.8~3.7 43 25.8~25.9 3.5~3.4 14 27.2~27.3 3.3~3.2 57 27.7~27.8 3.3~3.2 100 28.3~28.4 3.2~3.1 53 28.7~28.8 3.2~3.1 92 29.2~29.3 3.1~3.0 44 32.2~32.3 2.8~2.7 20 32.6~32.7 2.8~2.7 14 33.1~33.2 2.8~2.7 41 33.9~34.0 2.7~2.6 44

(24) The synthesized product was the PST-20 zeolite of the following chemical formula 1-1 without ZSM-25 zeolite as an impurity.
0.48Na.sub.2O:0.46SrO:1.0Al.sub.2O.sub.3:6.68SiO.sub.2(1-1)

(25) According to a thermogravimetric analysis and an element analysis of the solid powder obtained in Example 2, the PST-20 zeolite contained about 10.5 wt. % of water and 5.0 wt. % of TEA cations. Further, an inductive coupled plasma (ICP) analysis showed that the Si/Al ratio of the product was 3.3.

(26) The scanning electron microscopy (SEM) was performed to make it sure that the PST-20 zeolite was a pure substance without a physical mixture. As a result, very uniform plate crystals were observed, but no other crystal forms appeared (Refer to FIG. 4).

Comparative Example 2-1: (Increase in Reaction Time)

(27) The procedures were performed in the same manner as described in Example 2, excepting that the final reaction mixture was heated at 145 C. for 14 days to obtain a solid product, which was repeated washed with water and then dried at the room temperature. According to the results (FIG. 5) of the X-ray diffraction analysis of the solid powder obtained in Comparative Example 2-1, the PST-20 zeolite had a great decrease in the degree of crystallization and an analcime zeolite was formed as an impurity.

Example 3: Preparation of PST-20 Zeolite

(28) In a plastic beaker, 0.76 g of 50 wt. % sodium hydroxide (NaOH) was added to 5.04 g of deionized water. After adding 0.48 g of aluminum hydroxide (Al(OH).sub.3.H.sub.2O), the resultant mixture was agitated for one hour to prepare an aqueous solution A. Apart from this, 2.70 g of colloidal silica sol (Ludox As-40), 0.15 g of calcium nitrate (Ca(NO.sub.3).sub.2) and 2.79 g of TEABr were added to 10.08 g of deionized water, and the resultant mixture was agitated for one hour to prepare an aqueous solution B. The aqueous solution A was slowly added to the aqueous solution B, and the mixed solution was agitated for 24 hours to obtain a reaction mixture having the composition of the following chemical formula 2.
0.25Ca(NO.sub.3).sub.2:1.9Na.sub.2O:1.0Al.sub.2O.sub.3:5.2TEABr:7.2SiO.sub.2:390H.sub.2O[Chemical Formula 2]

(29) The reaction mixture thus obtained was moved to a Teflon reactor, put into a stainless steel container and heated at 150 C. for 7 days to yield a solid product, which was then repeatedly washed with water and dried at the room temperature.

(30) The solid powder obtained in Example 3 was subjected to an X-ray diffraction analysis. The results of the X-ray diffraction analysis are presented in FIG. 6. The product of Example 3 contained a small amount of the Na-P1 (GIS) zeolite impurity, but none of the ZSM-25 zeolite impurity.

Example 4: Preparation of PST-20 Zeolite

(31) In a plastic beaker, 0.76 g of 50 wt. % sodium hydroxide (NaOH) was added to 5.06 g of deionized water. After adding 0.48 g of aluminum hydroxide (Al(OH).sub.3.H.sub.2O), the resultant mixture was agitated for one hour to prepare an aqueous solution A. Apart from this, 2.70 g of colloidal silica sol (Ludox As-40), 0.33 g of barium nitrate (Ba(NO.sub.3).sub.2) and 2.79 g of TEABr were added to 10.12 g of deionized water, and the resultant mixture was agitated for one hour to prepare an aqueous solution B. The aqueous solution A was slowly added to the aqueous solution B, and the mixed solution was agitated for 24 hours to obtain a reaction mixture having the composition of the following chemical formula 3.
0.50Ba(NO.sub.3).sub.2:1.9Na.sub.2O:1.0Al.sub.2O.sub.3:5.2TEABr:7.2SiO.sub.2:390H.sub.2O[Chemical Formula 3]

(32) The reaction mixture thus obtained was moved to a Teflon reactor, put into a stainless steel container and heated at 145 C. for 4 days to yield a solid product, which was then repeatedly washed with water and dried at the room temperature.

(33) The solid powder obtained in Example 4 was subjected to an X-ray diffraction analysis. The results of the X-ray diffraction analysis are presented in FIG. 7. The product of Example 4 contained a small amount of the Na-P1 (GIS) zeolite impurity, but none of the ZSM-25 zeolite impurity.

Example 5: Preparation of PST-20 Zeolite

(34) In a plastic beaker, 0.30 g of 50 wt. % sodium hydroxide (NaOH) was added to 2.03 g of deionized water. After adding 0.19 g of aluminum hydroxide (Al(OH).sub.3.H.sub.2O), the resultant mixture was agitated for one hour to prepare an aqueous solution A. Apart from this, 1.08 g of colloidal silica sol (Ludox As-40), 0.05 g of potassium nitrate (KNO.sub.3), 0.84 g of TEABr, and 0.35 g of 18-crown-6 were added to 4.05 g of deionized water, and the resultant mixture was agitated for one hour to prepare an aqueous solution B. The aqueous solution A was slowly added to the aqueous solution B, and the mixed solution was agitated for 24 hours to obtain a reaction mixture having the composition of the following chemical formula 4.
1.3 18-crown-6:0.5KNO.sub.3:1.9Na.sub.2O:1.0Al.sub.2O.sub.3:3.9TEABr:7.2SiO.sub.2:390H.sub.2O[Chemical Formula 4]

(35) The reaction mixture thus obtained was moved to a Teflon reactor, put into a stainless steel container and heated at 150 C. for 5 days to yield a solid product, which was then repeatedly washed with water and dried at the room temperature to obtain a solid powder.

(36) The solid powder obtained in Example 5 was subjected to an X-ray diffraction analysis. The results of the X-ray diffraction analysis are presented in FIG. 8. The product of Example 5 contained a small amount of the ZSM-25 zeolite impurity.

Example 6: Preparation of PST-20 Zeolite Using RbNO3 and 18-Crown-6

(37) In a plastic beaker, 0.30 g of 50 wt. % sodium hydroxide (NaOH) was added to 2.03 g of deionized water. After adding 0.19 g of aluminum hydroxide (Al(OH).sub.3.H.sub.2O), the resultant mixture was agitated for one hour to prepare an aqueous solution A. Apart from this, 1.08 g of colloidal silica sol (Ludox As-40), 0.08 g of rubidium nitrate (RbNO.sub.3), 0.84 g of TEABr, and 0.35 g of 18-crown-6 were added to 4.05 g of deionized water, and the resultant mixture was agitated for one hour to prepare an aqueous solution B. The aqueous solution A was slowly added to the aqueous solution B, and the mixed solution was agitated for 24 hours to obtain a reaction mixture having the composition of the following chemical formula 5.
1.3 18-crown-6:0.5RbNO.sub.3:1.9Na.sub.2O:1.0Al.sub.2O.sub.3:3.9TEABr:7.2SiO.sub.2:390H.sub.2O[Chemical Formula 5]

(38) The reaction mixture thus obtained was moved to a Teflon reactor, put into a stainless steel container and heated at 150 C. for 5 days to yield a solid product, which was then repeatedly washed with water and dried at the room temperature.

(39) The solid powder obtained in Example 6 was subjected to an X-ray diffraction analysis. The results of the X-ray diffraction analysis are presented in FIG. 9. The product of Example 6 contained a small amount of the ZSM-25 zeolite impurity.

Example 7: Adsorption of Carbon Dioxide

(40) To evaluate the PST-20 zeolite prepared in Example 2 in regards to the adsorption of carbon dioxide gas, 100 mg of the zeolite specimen was put into a quartz tube, which was then heated up to 250 C. at the rate of 10 C./min under the reduced pressure of 0.009 torr and maintained at 250 C. for 2 hours to achieve a complete dehydration. The dehydrated zeolite was cooled down to the room temperature under vacuum and maintained at 25 C. using a water circulator to measure the adsorbed amount of carbon dioxide while the pressure of the carbon dioxide gas was continuously varied. The measurement results are presented in FIG. 10, according to which the adsorbed amount of carbon dioxide was 1.7 mmol/g (37.8 cm.sup.3/g) at 0.1 bar (75 Torr) and 2.8 mmol/g (62.6 cm.sup.3/g) at 1.0 bar (750 Torr).

Example 7-1: Adsorption of Nitrogen

(41) To evaluate the PST-20 zeolite prepared in Example 2 in regards to the adsorption of nitrogen gas, the procedures were performed in the same manner as described in Example 7 to measure the adsorbed amount of nitrogen by the PST-20 zeolite at 25 C. while the pressure of the nitrogen gas was continuously varied. The measurement results are presented in FIG. 11, according to which the adsorbed amount of nitrogen was 0.07 mmol/g (1.6 cm.sup.3/g) at 0.1 bar (75 Torr) and 0.4 mmol/g (9.0 cm.sup.3/g) at 1.0 bar (750 Torr).

Example 7-2: Adsorption of Methane

(42) To evaluate the PST-20 zeolite prepared in Example 2 in regards to the adsorption of methane gas, the procedures were performed in the same manner as described in Example 7 to measure the adsorbed amount of methane by the PST-20 zeolite at 25 C. while the pressure of the methane gas was continuously varied. The measurement results are presented in FIG. 12, according to which the adsorbed amount of methane was 0.014 mmol/g (0.32 cm.sup.3/g) at 0.1 bar (75 Torr) and 0.15 mmol/g (3.3 cm.sup.3/g) at 1.0 bar (750 Torr).

(43) Table 5 shows the selectivity for carbon dioxide against nitrogen and methane at pressure of 0.1 bar or 1.0 bar based on the adsorption for different gases as measured in Examples 78, 87-1 and 78-2. Particularly, the PST-20 zeolite had a very high selectivity for carbon dioxide at low pressure.

(44) TABLE-US-00006 TABLE 5 0.1 bar 1.0 bar CO.sub.2/N.sub.2 selectivity 24 7 CO.sub.2/NH.sub.4 selectivity 120 19

Example 8: Calcined PST-20 and Adsorption of Carbon Dioxide Using the Same

(45) 100 mg of the PST-20 zeolite prepared in Example 2 was put into a stationary microreactor having an inner diameter of 0.64 cm. While an ammonium (NH.sub.3) gas was flowing into the reactor at a rate of 50 cc/min, the reactor was heated up to 500 C. at a rate of 1 C./min and maintained at 500 C. for 4 hours to completely calcine the specimen. According to a thermogravimetric analysis and an element analysis, all the TEA cations in the PST-20 zeolite were combusted and the PST-20 zeolite contained 14.2 wt. % of water alone. The solid powder thus obtained was subjected to an X-ray diffraction analysis. The results are presented in Table 6.

(46) TABLE-US-00007 TABLE 6 2 d 100 I/Io 11.5 7.7 100 12.8 6.9 79 13.1 6.7 43 14.0 6.3 45 14.1 6.3 35 16.4 5.4 37 18.1 4.9 37 19.7 4.5 30 20.1 4.4 53 20.5 4.3 26 21.6 4.1 15 22.2 4.0 16 24.2 3.7 38 26.8 3.3 16 27.7 3.2 41 28.2 3.2 82 29.3 3.0 66 29.8 3.0 47 33.7 2.7 20 34.6 2.6 27

(47) To evaluate the calcined PST-20 zeolite in regards to the adsorption of carbon dioxide gas, the procedures were performed in the same manner as described in Example 7 to measure the adsorbed amount of carbon dioxide by the PST-20 zeolite at 25 C. while the pressure of the carbon dioxide gas was continuously varied. The measurement results are presented in FIG. 13, according to which the adsorbed amount of carbon dioxide was 1.1 mmol/g (24.0 cm.sup.3/g) at 0.1 bar (75 Torr) and 2.2 mmol/g (48.9 cm.sup.3/g) at 1.0 bar (750 Torr). The calcined PST-20 zeolite (Example 8) had the lower adsorption of carbon dioxide than the non-calcined PST-20 zeolite (Example 7). This result presumably comes down to the fact that the crystallinity of the PST-20 zeolite was deteriorated due to the heat generated from the combustion of the organic substances by the oxygen in the air at 500 C.

Example 9: Adsorption of Carbon Dioxide Using Ion-Exchanged and Dehydrated PST-20

(48) 1.0 g of the PST-20 zeolite prepared in Example 2 was added to 50 ml of a 1.0M solution of sodium nitrate (NaNO.sub.3) and subjected to ion exchange at 80 C. for 6 hours to yield a solid product. The solid product thus obtained was repeatedly washed with water and dried at the room temperature. 100 mg of the zeolite specimen (Na-PST-20) prepared by performing these procedures twice was put into a quartz tube, which was then heated up to 250 C. at the rate of 10 C./min under the reduced pressure of 0.009 torr and maintained at 250 C. for 2 hours to achieve a complete dehydration. The dehydrated zeolite was cooled down to the room temperature under vacuum and maintained at 25 C. using a water circulator to measure the adsorbed amount of carbon dioxide while the pressure of the carbon dioxide gas was continuously varied. The measurement results are presented in FIG. 14, according to which the adsorbed amount of carbon dioxide was 1.8 mmol/g (41.3 cm.sup.3/g) at 0.1 bar (75 Torr) and 3.0 mmol/g (67.8 cm.sup.3/g) at 1.0 bar (750 Torr).

Example 10: Adsorption of Carbon Dioxide Using Dehydrated PST-20

(49) 300 mg of the PST-20 zeolite prepared in Example 2 was put into a stationary microreactor having an inner diameter of 0.64 cm. While a helium gas was flowing into the reactor at a rate of 100 cc/min, the reactor was heated up to 250 C. at a rate of 2 C./min and maintained at 250 C. for 6 hours to completely dehydrate the specimen. The specimen was cooled down to the room temperature in an atmosphere of helium. Subsequently, mixed gases of carbon dioxide and nitrogen were flowed into the reactor at a rate of 20 cc/min. The amount of the gas passing through the reactor was analyzed using a mass spectrometer (Pfeiffer Prisma QMS 200). The results are presented in FIG. 15. The mixed gases of carbon dioxide and nitrogen passing through the reactor were adsorbed onto the PST-20 zeolite at once, so both of them were not detected by the mass spectrometer. As the PST-20 zeolite stopped adsorbing nitrogen and selectively adsorbed carbon dioxide, the mass spectrometer detected the nitrogen alone. Such a selective adsorption for carbon dioxide was performed for 60 seconds, and the carbon dioxide together with the nitrogen was detected by the mass spectrometer immediately after the completion of the adsorption (saturation) of carbon dioxide into the zeolite. This shows the excellent selective adsorption and separation performance of the PST-20 zeolite for carbon dioxide out of the mixed gases of carbon dioxide and nitrogen. Accordingly, there is provided the use of the PST-20 zeolite as a separator and/or adsorbent considerably available in the process of separating and collecting carbon dioxide.

Example 11

(50) 300 mg of the PST-20 zeolite prepared in Example 2 was put into a stationary microreactor having an inner diameter of 0.64 cm. While a helium gas was flowing into the reactor at a rate of 100 cc/min, the reactor was heated up to 250 C. at a rate of 2 C./min and maintained at 250 C. for 6 hours to completely dehydrate the specimen. The specimen was cooled down to the room temperature in an atmosphere of helium. Subsequently, mixed gases of carbon dioxide and nitrogen were flowed into the reactor at a rate of 20 cc/min. The amount of the gas passing through the reactor was analyzed using a mass spectrometer (Pfeiffer Prisma QMS 200). The results are presented in FIG. 16. The mixed gases of carbon dioxide and nitrogen passing through the reactor were adsorbed onto the PST-20 zeolite at once, so both of them were not detected by the mass spectrometer. As the PST-20 zeolite stopped adsorbing nitrogen and selectively adsorbed carbon dioxide, the mass spectrometer detected the nitrogen alone. Such a selective adsorption for carbon dioxide was performed for 60 seconds, and the carbon dioxide together with the nitrogen was detected by the mass spectrometer immediately after the completion of the adsorption (saturation) of carbon dioxide into the zeolite. This shows the excellent selective adsorption and separation performance of the PST-20 zeolite for carbon dioxide out of the mixed gases of carbon dioxide and nitrogen. Accordingly, there is provided the use of the PST-20 zeolite as a separator and/or adsorbent considerably available in the process of separating and collecting carbon dioxide.

Example 12

(51) 130 mg of the PST-20 zeolite prepared in Example 2 was put into a 5 ml autoclave. Under the reduced pressure of 0.009 torr, the autoclave was heated up to 200 C. at a rate of 10 C./min and maintained at 200 C. for 6 hours to achieve a complete dehydration. The dehydrated specimen was cooled down to the room temperature under vacuum and maintained at 25 C. using a water circulator. Subsequently, a pressure of 2.7 bar was applied to the autoclave containing the specimen in a 12.39 ml reservoir, and a measurement was performed to determine the time taken for the final equilibrium pressure of the reservoir and the autoclave to reach 1.2 bar due to the adsorption of carbon dioxide by the specimen under the defined pressure. The measurement results are presented in FIG. 17. The equilibrium pressure of 1.2 bar was maintained as the PST-20 zeolite adsorbed carbon dioxide to reach a saturation of carbon dioxide within 3 minutes. This implicitly shows that the PST-20 zeolite adsorbed carbon dioxide very fast.