Catalyst – solid sorbent – or support therefor: product or process – Solid sorbent – Silicon containing
Patent
1994-04-26
1996-03-19
Straub, Gary P.
Catalyst, solid sorbent, or support therefor: product or process
Solid sorbent
Silicon containing
423335, 423338, 252194, 2523156, B01J 2010
Patent
active
055004024
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of treating a contact body intended for the exchange of heat, moisture or the like.
2. History of the Related Art
Contact bodies are used in different applications for the exchange of moisture and/or heat, and are normally produced from sheets of paper which are preferably comprised of inorganic material and formed into blocks from which solid contact bodies are produced or wound to form rotors for use in rotary exchangers or contact bodies.
Such bodies contain a moisture and/or heat-exchanging mass of alternating flat and corrugated layers which are so arranged that the corrugations form a large number of fine passages which extend generally parallel with one another. The flat and the corrugated layers are mutually combined and bonded to one another, normally by gluing the layers, whereafter, when a rotor is to be produced, the structure comprised of one flat layer and one corrugated layer is wound to form a generally cylindrical rotor in which the passages extend parallel with the rotor axis. When producing solid contact bodies, a number of such structures are stacked one upon the other to form a block. The turns of the rotor or the structural units forming said block are mutually bonded together in the same way as the flat and the corrugated sheets, for instance by gluing.
It is known in the manufacture of such contact bodies for heat or moisture exchange purposes to impregnate the paper sheets of said bodies with a waterglass solution. The applied waterglass solution is then treated in different ways, e.g. dried by heating or by dipping the contact bodies in a spirit bath (see SE Patent No. 305,170) and then treated with acid, salt or the like to form a silica gel.
When producing a gel with the intention of manufacturing a structure that is suitable for moisture exchange purposes, it is essential to obtain a desired mean pore size and pore size distribution in a controlled fashion. When the exchange element is used to de-moisturize air and thus adsorbs moisture from the air, the moisture content of the air will change as the air passes over an effective adsorption surface, and consequently, in order to be effective, the adsorbent must be effective over a region of the moisture isotherm. When the exchange element is also to be effective over a larger climatic area, the gel must be given corresponding properties. This means that an effective gel is dependent on the availability of a controlled pore size distribution.
The pore distribution of a gel formed from a silicate solution or by converting more or less dry waterglass can be changed by particle growth. This mechanism, however, is not reversible, which means that the pore size will grow during the whole of the pore changing phase. In turn, this means that the mean pore size of the starting gel must be smaller than the desired mean pore size in order to obtain the desired pore structure in a controlled fashion.
It is known from the literature that it is possible to obtain initially a very small particle size with the aid of strong acids and therewith a small pore size. The resultant gelation takes place very quickly and the possibility of controlling the gelation process is very small.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a method for treating a contact body of the aforedescribed kind, and particularly to a method for forming on the contact body a silica gel which will enable the number of pores and the pore size distribution in the gel structure produced to be controlled in a selective fashion.
This is achieved in accordance with the invention by impregnating the body with waterglass, treating the thus impregnated body with acid to produce a gel in a first method step, by causing the gel to mature in an environment of elevated pH to obtain a gel of desired pore structure in a second method step, and by stabilizing the gel with the addition of chemicals in a third method step.
Subsequent to gelation in acid,
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patent: 4886769 (1989-12-01), Kuma et al.
patent: 5254195 (1993-10-01), Tseng et al.
patent: 5328645 (1994-07-01), Lin et al.
patent: 5368833 (1994-11-01), Johansson et al.
patent: 5376348 (1994-12-01), Stoilov et al.
AB Carl Munters
Straub Gary P.
Vanoy Timothy C.
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