Liquid purification or separation – Processes – Chemical treatment
Patent
1994-09-12
1997-09-02
Silverman, Stanley S.
Liquid purification or separation
Processes
Chemical treatment
210763, 210903, C02F 170
Patent
active
056628099
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for the catalytic treatment of aqueous liquids containing germs.
A number of processes are known in which aqueous liquids are treated catalytically. It may, for example, be desirable to reduce or remove the oxygen content of aqueous liquids. Thus, it is known to lower the oxygen content in water which is used is a coolant in technical equipment and therefore reduce the corrosiveness of the water. The oxygen content is also advantageously reduced in drinking water or in water used for the manufacturing of food products and semi-luxury food items, such as alcoholic or non-alcoholic beverages. It is also known that the nitrite and/or nitrate content in drinking, commercial or waste water must be reduced. A corresponding catalytically operating process is described in European Patent Document EP-A-0 359 074 (U.S. Pat. No. 4,990,266).
The catalytic treatment for reducing the oxygen, nitrite and/or nitrate content in aqueous liquids, for example, is carried out such that the aqueous liquid is mixed with hydrogen and is then guided through a suitable catalyst. Normally, carrier catalysts are used which contain one or several platinum group metals as well as optionally, in addition, other metals, such as metals of the copper group.
It presents a problem that aqueous liquids, such as well water, drinking water, commercial water or waste water, which are to be treated catalytically, normally contain microorganisms. A gradual contamination of the catalyst can then be observed. The treatment of the aqueous liquids with UV-light, for example, is no perfect remedy. Other measures, such as the addition of biocides, are not appropriate, particularly in the drinking water field.
The published Japanese Patent Application JP 60/129188 (Patent Abstracts of Japan 9, No. 283, C-313 (1985)), discloses the decomposition of reducing substances such as hydrazine, hydrazide or hydrazone in waste water from steam boilers, whereby the catalyst is contained in a fixed bed or in a fluidized bed.
The EP-A 345,822 discloses catalyst resins with high stability and catalytic activity of long duration. The resins can be used for removing the oxygen from drinking water, sea water and brackish water as well as from condensate.
It is an object of the invention to provide a process by means of which it is possible to catalytically treat aqueous liquids without any contamination of the catalyst. This object is achieved by means of the process indicated in the claims.
Surprisingly, it was found that a contamination of the catalyst during the catalytic treatment of aqueous liquids containing germs can be prevented when the process is carried out in a fluidized bed. The process according to the invention for the catalytic treatment of aqueous liquids containing germs, during which the aqueous liquid is guided through a catalyst, is characterized in that particle-shaped carrier catalysts are used which have a particle size of from 0.1 to 10 mm, and the catalytic treatment is carried out in the fluidized bed in the absence of hydrazine, hydrazide and hydrazone and while the liquid to be treated flows through a reactor.
Preferably, carrier catalysts are used, particularly spherical carrier catalysts. The diameter preferably amounts to from 0.1 mm to 1.0 mm, particularly preferably from 0.3 to 0.8 mm.
The process according to the invention is particularly advantageously used in the case of such aqueous liquids which are used for the manufacturing of food products or semi-luxury food items, for example, for the treatment of drinking water or well water, for the manufacturing of food products or of beverages, such as alcoholic and non-alcoholic beverages.
According to a variant, the process is applied to the reductive removal of oxygen from aqueous liquids. Carrier catalysts will then preferably be used which comprise one or several platinum group metals, such a platinum or palladium, and optionally other additions on conventional ceramic carrier material which promote the catalytic activity, such as silicon dioxide, alu
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Bischoff Michael
Bonse Dirk
Sell Michael
Green Theodore M.
Silverman Stanley S.
Solvay Umweltchemie GmbH
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