Method of the preparation of macroporous foam comprising...

Catalyst – solid sorbent – or support therefor: product or process – Zeolite or clay – including gallium analogs – And additional al or si containing component

Reexamination Certificate

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C502S060000, C423S704000, C423S705000

Reexamination Certificate

active

06777364

ABSTRACT:

TECHNICAL FIELD
The present invention relates to macroporous foams comprising microporous zeolite or zeotype material, and to a method for the preparation thereof by using polymeric templates having a thread or film form or a sponge structure. More particularly, the present invention relates to macroporous foams which are prepared by using polymeric templates having a thread or film form or a sponge structure to crystallize microporous zeolite or zeotype material in a thread or film form or a sponge structure, and to a method for the preparation thereof.
BACKGROUND ART
The present invention belongs to the inorganic synthesis of synthesizing molecular sieves including zeolite or zeotype materials. “Zeolite” is a generic name of crystalline aluminosilicate, which constitutes the pore skeleton of zeolite molecules and bears an anionic charge for each aluminum atom. Cations for offsetting such anion charges are present within the very fine pore space which is regularly formed and has a size of not more than 2 nm and the remaining pore space is filled with water. The 3-dimensional pore structure of the zeolite molecules varies depending on the shape and size of the pore, and the pore diameter is usually corresponding to the size of molecules. Therefore, based on the shape and size of the pore, zeolite has the size selectivity for a molecule entering into the pore, and thus, zeolite is called as a molecular sieve.
In the context of the present invention, since zeolite and zeotype materials have micropores having a size of from a few nanometers to several tens nanometers, they are considered as being “microporous”.
Microporous zeolite and zeotype materials are widely used in the field of households and various industries as a catalyst, adsorbent, ion exchanger, water-absorbing agent, etc. For examples, zeolite shows diverse chemical and physical properties depending on its chemical composition, structure, pre-treatment method, etc. Especially, zeolite itself has a resistance to high temperature and a modified zeolite in which protons are replaced with other cations represents a strong acidic properties to serve as a strong solid acid, the modified zeolite is widely used as a cracking catalyst of crude oil in the petrochemical industry. In addition, such acidic zeolite is widely used as acid catalyst in various chemical reactions as well as a ion exchanger, water-absorbing agent, adsorbent, gas-purifying agent, carrier for a purifying catalyst of exhausting gases of internal combustion engines, additives for detergent, soil improving agent, additives for animal feed, etc. Further, an extensive study is now being made on its application as a sensor carrier in which zeolite is shaped in the form of a thin membrane.
Meanwhile, there are many known zeotype molecular sieves wherein a part or all of silicon (Si) and/or aluminum (Al) atoms constituting the structural skeleton of zeolite molecule are replaced with other elements. For example, a porous silicalite-type molecular sieve in which aluminum atoms are completely eliminated, an alpo(AlPO
4
)-type molecular sieve in which silicon atoms are replaced with phosphorous atoms, and other molecular sieve or zeotype material wherein skeleton metal atoms are partially replaced with various metal atom such as Ti, Mn, Co, Fe, Zn, etc., have been developed and widely used. In recent, many studies are also being made on mesoporous materials (MCM-series silica) of which pore size is up to several tens nanometers.
Such molecular sieves such as zeolite or zeotype materials are prepared by crystallizing the precursor thereof and generally obtained in the form of fine powder with a diameter of less than about 10 micrometers.
When such zeolite or zeotype materials in the form of powder are filled in a container or reactor, it difficult for a liquid or gaseous fluid to flow through the powder since the spaces between the powder particles are too small. Therefore, a very high pressure is required in order to maintain a sufficient flow velocity in the container or reactor filled with molecular sieve powder, which causes problems that much energy is consumed and the cost for the production of the equipment and reactor is increased. There has been proposed various countermeasures in order to avoid such process problems owing to the pressure dropping phenomena.
A most commonly known method is the method of preparing a zeolite-clay composite, wherein zeolite powder is conglomerated by using clay as a binder to form a paste, which is then granulated to granules with a size of several millimeters, or is extruded in the form of noodle and then cut in a short length [Breck, D. W.
Zeolite Molecular Sieves
725-755 (John Wiley & Sons, New York, 1974)]. However, the above-described method requires a mixing step of mixing zeolite with clay, a shaping step, and subsequent treating steps, which causes problems that the overall procedures are troublesome and overall cost for the production is increased. Further, since clay itself is considered as an impurity, the purity of zeolite in the composite is decreased, which causes a decrease of the zeolite using efficiency. Since pores may be blocked by clay particles, the zeolite using efficiency will be rapidly decreased.
In addition, as to granules or extrudates having a size of more than several micrometers, only the zeolite molecules present in the surface of a granule or extrudate generally participate in a reaction since reactants cannot easily access or penetrate into the inner portion of the granules or extrudates. Therefore, if zeolite is conglomerated by mixing with clay, the zeolite using efficiency will be greatly decreased. In addition, as to granules having a size of more than several micrometers, uniform reactivity at a uniform reaction temperature cannot be obtained since there is a temperature difference between the surface and the inner portion of a granule when a reaction is proceeded.
Another widely known technology is the method of coating zeolite film on a support having macropores of millimeters size, wherein the support is made of aluminum, alumina, stainless steel or the like in the form of honeybee or the like in order to facilitate the spread of molecules and various zeolite is coated thereon in the form of a thin film [Bein,
T. Chem. Mater.
1996, 8, 1636-1653; Caro, J., Noack, M., Klsch, P. & Schfer, R.
Microporous and Mesoporous Materials
2000, 38, 3-24; Clet, G., Jansen, J. C. & van Bekkum, H.
Chem. Mater.
1999, 11, 1696-1702; Boudreau, L. C., Kuck, J. A. & Tsapatsis, M.
J. Membr. Sci.
1999, 152, 41-59; van der Puil, N., Dautzenberg, F. M., van Bekkum, H. & Jansen, J. C.
Microporous and Mesoporous Materials
1999, 27, 95-106; Kormarneni, S., Katsuki, H. & Furuta, S.
J. Mater. Chem.
1998, 8, 2327-2329].
The zeolite-support composite particles thus prepared have advantages that the spread of reactants and products and the thermal transfer in all directions are easy, and the temperature distribution is uniform, etc., whereas the efficiency of zeolite used per unit weight are very small since the amount of zeolite used is much less than that of the support. In addition, since the thermal expansion coefficient of the zeolite is different from that of the support, repeated heating of said composite during the process may cause the deprival of the zeolite particles from the support. Further, since the amount of zeolite coated on the support is much less than that of the zeolite precipitated on the bottom of the reaction vessel during the coating process, there is severe waste of zeolite synthetic gel.
Sterte et al. describe a technology to form macropores in a zeolite mass wherein spherical ion exchange resin and active carbon are used as a support and said support is dipped in a synthetic gel to form zeolite thereon by a secondary crystal growing method and then removed by burning [Tosheva, L., Valtchev, V. & Sterte,
J. Microporous and Mesoporous Materials
2000, 35-36, 621-629; Valtchev, V., Schoeman, B. J., Hedlund, J. Mintova, S. & Sterte, J.
Zeolites
1996,17,

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