Chemistry of inorganic compounds – Zeolite
Reexamination Certificate
2002-03-21
2003-03-18
Sample, David (Department: 1755)
Chemistry of inorganic compounds
Zeolite
C423S700000, C423S705000, C095S090000, C095S130000, C095S902000
Reexamination Certificate
active
06534034
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a crystalline zeolitic material having the framework topology of tschörtnelite, an empirical formula of mA
2/11
O: Al
2
O
3
: ySiO
2
where A is a cation such as lithium. The invention also relates to an air separation process using the zeolite.
BACKGROUND OF THE INVENTION
Zeolites are crystalline aluminosilicate compositions which are microporous and which have a three-dimensional oxide framework formed from comer sharing AlO
2
and SiO
2
tetrahedra. Numerous zeolites, both naturally occurring and synthetically prepared are used in various industrial processes. Zeolites are characterized by having pore openings of uniform dimensions, having a significant ion exchange capacity, and being capable of reversibly desorbing an adsorbed phase which is dispersed throughout the internal voids of the crystal without significantly displacing any atoms which make up the permanent zeolite crystal structure.
The number of synthetic zeolites is well over a hundred as evidenced by the
Atlas of Zeolite Structure Types
published by the International Zeolite Association (IZA). As is well known, zeolites are distinguished from each other on the basis of their composition, crystal structure and adsorption properties. One method commonly used in the art to distinguish zeolites is x-ray diffraction.
A mineral discovered in 1993 in the Bellberg volcano, Eifel, Germany was found to be a new zeolite which was named tschörtnerite. The structure was reported by H. Effenberger et al. in
American Mineralogist,
Vol. 83, pp. 607-617, 1998, in which the ideal empirical formula was found to be Ca
4
(K, Ca, Sr, Ba)
3
Cu
3
(OH)
8
[Si
12
Al
12
O
48
]. xH
2
O, x=20. It was also found that the crystal morphology was cubic with a=31.62 Å. Although tschortnerite has a very large cage, the largest pore openings are only single and double eight rings. Also the presence of extra-framework copper diminishes the utility of natural tschörtnerite (along with the fact that only 1 mg of tschörtnerite has been found). In view of tschörtnerite's structure, it would be desirable to prepare a synthetic version, without copper, for use in various separation processes.
SUMMARY OF THE INVENTION
As stated, the present invention relates to a crystalline zeolitic composition having a microporous framework structure containing AlO
2
and SiO
2
tetrahedral units and an empirical formula on an anhydrous and as synthesized basis in terms of molar oxide ratios of:
mA
2/11
O: Al
2
O
3
: ySiO
2
(I)
where A is an exchangeable cation selected from the group consisting of alkali metals, alkaline earth metals, amines, quaternary ammonium ions and mixtures thereof, “m” is the mole ratio of the oxide of A to Al
2
O
3
and varies from about 0.8 to about 1.5, “n” is the valence of A and “y” is the mole ratio of SiO
2
to Al
2
O
3
, the composition characterized in that it has the crystalline structure of TSC and a cubic crystalline cell with a value of a=30 to about 33 Å.
Another embodiment is a process for separating one molecular species from a mixture of molecular species comprising contacting the mixture with the zeolitic composition described above.
A specific embodiment is separating nitrogen from air by contacting air with the above described zeolite to adsorb the nitrogen onto the zeolite.
These and other objects and embodiments will become more apparent after the detailed description of the invention.
REFERENCES:
H. Effenberger et al.American Mineralogist, vol. 83, pp. 607-617 (1998).
Low, J.J., Sherman, J.D., Cheng, L.S., Patton, R.L., Gupta, A., Snurr, R.Q.; Presented at the 7thInternational Conference on Fundamental of Adsorption, Nagasaki, Japan, May 2001.
Lewis Gregory J.
Low John J.
Molinaro Frank S.
Sample David
Tolomei John G.
UOP LLC
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