Catalyst – solid sorbent – or support therefor: product or process – Zeolite or clay – including gallium analogs – Including organic component
Patent
1992-09-30
1995-02-07
Green, Anthony
Catalyst, solid sorbent, or support therefor: product or process
Zeolite or clay, including gallium analogs
Including organic component
501128, 501141, 501153, 502 68, 2641761, 26417712, 264211, 26421112, 2642112, B01J 2904
Patent
active
053875648
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to molding and calcining of zeolite powder. More particularly, the invention relates to a plastic and moldable composition of zeolite, a molded article and a calcined article of zeolite obtained by use of the composition, and a method of production of such a molded article and a calcined article of zeolite.
2. Background Art
A zeolite powder is usually formed to various shapes, for example, spherical, columnar, granular or honeycomb, and is used in various fields. As well known, zeolite powder has no plasticity, and a mixture with water provides no plastic material like a clay-water mixture. Accordingly, zeolite per se can not be plastic-molded or sintered.
It is already known that zeolite powder can be made plastic by mixing and kneading with an inorganic binder such as natural clay, bentonite, kaolin or colloidal silica, or an organic binder such as cellulose derivatives, and thus can be plastic-molded and calcined.
For instance, the use of crystalline cellulose as an organic binder is described in Japanese Patent/Application Laid-open No. 48-39399. There is also described in Japanese Patent/Application Laid- open No. 59-26923 and No. 2-6846 that zeolite powder is mixed with an inorganic binder such as natural clay, bentonite, kaolin or colloidal silica, or an organic binder such as cellulose derivatives, together with water, to provide an aqueous composition, and then the composition is molded, dried, and calcined to pellet-like calcined artcles.
However, the known method as above has disadvantages in that, for example, when natural clay is used as a plasticizing agent, it is necessary to use a comparatively large amount. Consequently, the resultant molded article contains a comparatively large amount of natural clay, and thus the resultant molded article is greatly affected in its properties as zeolites, such as adsorption power per unit weight, compared with zeolite powder itself. Also finely divided particles of clay may clog micropores of zeolite powder to further reduce adsorption power of zeolites.
There is also described a method of producing a calcined article of honeycomb structure in Japanese Patent Application Laid-open No. 61-171539. According to the method, a composition is prepared by admixing zeolite powder with an organic binder and inorganic fibers as a reinforcing material so that the resultant product has such a mechanical strength as is required in industrial use. The composition is molded, dried, and calcined while preventing the generation of cracks, to provide a calcined honeycomb article of zeolite powder. However, it has been found that the organic binder used fails to provide sufficient plasticity and moldability with the composition. In addition, the generation of cracks during the calcining is not sufficiently prevented.
It is further known that a kind of polysaccharide, pullulan, is used as a plasticizing agent when a powder of a ceramic material such as alumina is molded and calcined, as disclosed in Japanese Patent Application Laid-open No. 53-6309. The use of a natural polysaccharide including succinoglycan is also known in the production of molded and heat-treated article of powder of such a ceramic material as alumina or titanium oxide, as disclosed in Japanese Patent Application Laid-open No. 64-65066. As zeolite is useful as, for example, an adsorbent or a catalyst, however, no molding aid has hitherto been known which is effectively used through the steps of molding, drying and calcining zeolite powder to provide sufficient strength in the molded article.
The present inventors have made intensive investigations to solve such problems as above described involved in the conventional methods of plastic molding of zeolite powder, and found that the addition of a small amount of a .beta.-1,3-glucan to the powder provides an aqueous plastic composition of zeolite powder. It has been further found that when a composition of zeolite comprising an inorganic sintering agent is molded, dried and calcined to produce a molded
REFERENCES:
patent: 5132255 (1992-07-01), Takeuchi et al.
Weaver, Charles et al., "The Chemistry of Clay Minerals", pp. 1-2, (1973) no month.
Database WPIL Week 8637, Derwent Publications Ltd., London, AN 86-242417 (Aug. 1986).
Chemical Abstracts, vol. 115, No. 20, Abstract No. 213556r (Jun. 1991).
Supplementary European Search Report (Apr. 1993).
Miyamura Shoichi
Mouri Motoya
Okabayashi Saji
Takeuchi Tatsuro
Green Anthony
Mizusawa Industrial Chemicals Ltd.
Takeda Chemical Industries Ltd.
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