Stock material or miscellaneous articles – Structurally defined web or sheet – Honeycomb-like
Reexamination Certificate
1999-03-31
2001-07-03
Lorin, Francis J. (Department: 1775)
Stock material or miscellaneous articles
Structurally defined web or sheet
Honeycomb-like
C264S631000
Reexamination Certificate
active
06254962
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART STATEMENT
This invention relates to ozone adsorbents having excellent ozone-adsorbing power and exhibiting a low degree of ozone decomposition, and particularly to ozone adsorbents which are suitable for the storage of ozone or for use in a pressure-swinging or temperature-swinging adsorption process for the concentration of ozone. Moreover, this invention also relates to molded products made by molding such an ozone adsorbent into a desired form, and a method of making the same.
Ozone is an oxidizing agent which is so clean as not to cause secondary environmental pollution and can be handled easily. Consequently, it is being widely used in the fields of sterilization, cleansing, oxidation bleaching and the like.
On the other hand, ozone is easily decomposable, so that it cannot be stored in a gas cylinder or the like. Generally, ozone produced by an ozone generator of the silent discharge type, the ultraviolet lamp type, the water electrolysis type or the like is directly used. Thus, it has been conventional practice to install an ozone generator at the site for use and obtain ozone by operating it as required. Ozone supplied directly from an ozone generator cannot be readily accommodated to variation in load on the consumption side.
Accordingly, there is a demand for a storage method in which ozone is previously stored by adsorption to an ozone adsorbent and may be freely desorbed in an amount required for use. However, an ozone adsorbent which can adsorb a large amount of ozone has not been developed as yet. The use of an ozone adsorbent which can adsorb only a small amount of ozone is disadvantageous from an economic point of view in that a large amount of the ozone adsorbent is required and the size of storage equipment is increased.
On the other hand, ozone generators of the silent discharge type, the ultraviolet lamp type, the water electrolysis type and the like fail to produce a high concentration of ozone. Accordingly, when a high concentration of ozone is to be used continuously, it is necessary to concentrate an ozone-containing gas according to a pressure-swinging or temperature-swinging adsorption process. However, an ozone adsorbent which shows a great difference in adsorbing power at different pressures or temperatures has not been developed as yet.
Japanese Patent Laid-Open No. 64690/'78 discloses an oxygen-recycling ozone generation system in which silica gel is used as an ozone adsorbent, ozone is generated by using liquid oxygen as a raw material, the resulting ozone-containing gas is cooled to about −60° C. and fed to an adsorption tower packed with silica gel so as to cause ozone to become adsorbed thereto, and heated dry air is introduced into the adsorption tower having ozone adsorbed therein so as to desorb the ozone by hot purging and thereby produce a gas containing a high concentration of ozone. Generally, silica gel has high moisture-adsorbing power, so that moisture is strongly adsorbed prior to the adsorption of ozone and accumulated in the adsorbent. In a moisture-containing system, therefore, the amount of ozone adsorbed is markedly decreased and a considerable amount of energy is required for the regeneration of the adsorbent. Moreover, ozone is easily decomposed upon contact with silica gel to cause a reduction in ozone recovery or ozone concentration. Furthermore, silica gel may be reduced to powder after repeated adsorption of moisture.
OBJECT AND SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to solve the above-described problems by providing an ozone adsorbent which has high ozone-adsorbing power even in a moisture-containing system and exhibits a high degree of ozone retention (and a low degree of ozone decomposition), as well as a molded product made by molding this ozone adsorbent into a form adapted to practical use, and a method of making the same.
In order to accomplish the above object, the present invention provides:
(1) An ozone adsorbent comprising one or more members selected from the group consisting of high-silica pentasilzeolite having a SiO
2
/Al
2
O
3
ratio of not less than 70 , dealuminized faujasite having a SiO
2
/Al
2
O
3
ratio of not less than 20, and mesoporous silicate having a SiO
2
/Al
2
O
3
ratio of not less than 20.
(2) An ozone-adsorbing molded product made by providing an ozone adsorbent powder comprising one or more members selected from the group consisting of high-silica pentasilzeolite having a SiO
2
/Al
2
O
3
ratio of not less than 70 , dealuminized faujasite having a SiO
2
/Al
2
O
3
ratio of not less than 20, and mesoporous silicate having a SiO
2
/Al
2
O
3
ratio of not less than 20, and molding the powder by use of a SiO
2
binder having an aluminum content of not greater than 2% by weight, the ozone-adsorbing molded product having a porosity in the range of 30 to 70% and a residual carbon content of not greater than 0.1% by weight.
(3) An ozone-adsorbing molded product as described above in (2) wherein the ozone-adsorbing molded product is in the form of a honeycomb.
(4) A method of making an ozone-adsorbing molded product as described above in (2) or (3) which comprises the steps of adding the SiO
2
binder and an organic pore-forming agent to the ozone adsorbent powder, molding the resulting mixture, and drying and firing the molded body to remove the organic pore-forming agent and thereby form pores.
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patent: 5583277 (1996-12-01), Kuehl
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Izumi Jun
Tomonaga Nariyuki
Tsutaya Hiroyuki
Yasutake Akinori
Anderson Kill & Olick P.C.
Lorin Francis J.
Mitsubishi Heavy Industries Ltd.
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