Chemistry of inorganic compounds – Zeolite – Synthesized from naturally occurring product
Patent
1998-05-26
1999-11-02
Bell, Mark L.
Chemistry of inorganic compounds
Zeolite
Synthesized from naturally occurring product
423716, 502 68, C01B 3902, B01J 2010
Patent
active
059764902
DESCRIPTION:
BRIEF SUMMARY
This invention relates to expanded ceramic zeolitic particles which comprise various zeolitic cation exchangers with the common property that they consist of macroporous, 0.1-10 mm ceramic aggregates containing zeolite as an active component, and the application of said aggregates primarily in connection with water purification, e.g., removal of ammonium and heavy metals.
Zeolite is in its original form a class of naturally occurring silicate minerals which have the property of being microporous. The pores form a continuous network through the structure, and are most often saturated with water which evaporates when heated. The name "zeolite" means "boiling rock," suggesting that very property. Approx. 50 different zeolites are found in nature, but only 5 or 6 of these occur in commercial quantities. In addition, approx. 50 structures have been synthetically produced, but only a few of those have had any industrial significance. In all, there are about 10 different structures which will be assessed in connection with applications where requirements are set for a relatively low price, i.e. less than NOK 10,000/tonne.
Microporosity is the most interesting and unique property of zeolite. Zeolite pores run through the structure, frequently forming a 3-dimensional network throughout the zeolite crystal. Because the pores are so small the zeolite will typically have one pore opening per nm.sup.2 of surface area, i.e. 10.sup.18 pore openings per m.sup.2 of surface area. Consequently, the combined length of all the pores in one kilo of zeolite will typically be 10.sup.12 km, which corresponds to 25 million times around the earth. For many zeolites there is only one well-defined pore diameter, making them well-suited for gas separation, in that only molecules that are smaller than the pore opening are allowed into the zeolite's pore system.
Another very important property shared by many zeolites is the cation-exchange capacity. That is because the zeolite's lattice is negatively charged, and this negative charge is compensated by free cations in the pores. These free cations can be exchanged with other cations, and in many cases with hydronium ions. Zeolite on H.sup.+ form has highly acidic properties, and some of those H.sup.- zeolites have had major significance as catalysts in industry, particularly in catalytic cracking of oil to gasoline. Furthermore, A-zeolite on Na.sup.+ form is used in detergents where it acts as a softener by capturing Mg.sup.2+ and Ca.sup.2+, and releasing Na.sup.+. The same zeolite is also used in air separation. In water purification the cation-exchanger properties are used to remove particularly NH.sub.4.sup.+ and heavy metals. Zeolites are also used as feed additives, dehydrating agents, soil-enhancement agents, substrates for yeast and bacteria, etc.
It is known from the literature, e.g., U.S. Pat. No. 5,451,391 and U.S. Pat. No. 4,891,200, that zeolite can be produced on the basis of raw materials containing oxides or other compounds of silicon and aluminum through their reaction with a relatively concentrated alkaline solution over a sufficiently long period, usually 6 hours to 1 month, and at a sufficiently high temperature, usually >70.degree. C. It will often be unfavorable to have substances other than Si oxide, Al oxide, water and alkali present, but selected other substances can also serve to steer the synthesis in the direction of specific products. It is also known that raw materials for producing zeolite may comprise clay, e.g., kaolin which consists of SiO.sub.2 and Al.sub.2 O.sub.3 at a 2-to-1 ratio. When this material reacts with alkali, for example at 100.degree. C. zeolite A can be produced. An example of such production of zeolite-A is given in U.S. Pat. No. 3,058,805. One type of zeolite can also be recrystallized into a different type of zeolite through hydrothermal treatment, e.g., as shown in U.S. Pat. No. 5,451,391 where Y zeolite is recrystallized to mazzite zeolite. However, in this and other methods for producing zeolite the product is obtained in powder fo
REFERENCES:
patent: 3008803 (1961-11-01), Milton
patent: 3058805 (1962-10-01), Weber
patent: 3065054 (1962-11-01), Haden, Jr. et al.
patent: 3647718 (1972-03-01), Haden, Jr. et al.
patent: 3649178 (1972-03-01), Wang et al.
patent: 4058586 (1977-11-01), Chi et al.
patent: 4344851 (1982-08-01), Sherman et al.
patent: 4522727 (1985-06-01), Weber
patent: 4818508 (1989-04-01), Flank et al.
patent: 4891200 (1990-01-01), Fajula et al.
patent: 4980323 (1990-12-01), Bedard et al.
patent: 5023220 (1991-06-01), Dight et al.
patent: 5064790 (1991-11-01), Bedard et al.
patent: 5169825 (1992-12-01), Okubo et al.
patent: 5179051 (1993-01-01), Bedard et al.
patent: 5451391 (1995-09-01), DiRenzo et al.
patent: 5470557 (1995-11-01), Garney
patent: 5552129 (1996-09-01), Farnos et al.
patent: 5558851 (1996-09-01), Miller
Meier et al., Atlas of Zeolite Structure Types, pp. 100-101, 1992.
Bell Mark L.
Norsk Leca AS
Sample David
LandOfFree
Zeolite containing cation exchangers methods for preparation and does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Zeolite containing cation exchangers methods for preparation and, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Zeolite containing cation exchangers methods for preparation and will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2131174