Liquid purification or separation – Filter – Material
Reexamination Certificate
2000-02-28
2003-09-16
Fortuna, Ana (Department: 1723)
Liquid purification or separation
Filter
Material
C210S500260, C210S490000, C264S045100, C055S523000, C055S524000
Reexamination Certificate
active
06620320
ABSTRACT:
The present invention relates to a permeable composite material having ion-conducting properties.
Ion-conducting materials of the prior art are in service in very broad scope in technology and are used for the most diverse applications. In this context there could be cited in particular not only the applications in electrodialysis as anion or cation exchange membranes but also the application as diaphragms in electrolysis or membrane-electrolysis cells as well as the membrane in pervaporation modules. Further fields of application can be found in the area of energy production with fuel cells. There is also known, however, an entire series of electrochemical or catalyzed reactions which take place on ion-conducting materials or are catalyzed thereby.
At present, predominantly polymer materials bearing ionic groups are used for these applications. The modified polysulfones, polyether sulfones, polystyrenes and modified polyvinylidine fluoride and polytetrafluoroethylene in particular could be cited in this context. These materials have performances completely adequate for most applications. Nevertheless, these polymers are subject to limits as regards the temperature range in which they can be used. At a temperature of about 120° C. or above, for example, either softening of the material occurs or the materials are no longer sufficiently swellable to ensure good ion conduction.
Inorganic materials such as zeolites or other aluminosilicates are indeed characterized by better thermal stability, but frequently are not sufficiently stable in acid media, with the result that slow decomposition of the materials takes place during operation. Thus they also have fields of application only in a limited area, such as in the sodium sulfide/sulfur cell (energy storage) or in some electrolysis apparatuses.
PCT/EP98/05939 describes a permeable composite material and a process for making the same. This permeable composite material is characterized by high thermal stability, but it lacks ion-conducting properties.
The purpose of the present invention was to find a material which still has good ion conduction even at temperatures of up to 250° C. and which at the same time is insensitive to relatively high acid concentrations.
It has been surprisingly found that it is possible to impart ion-conducting properties to a permeable composite material based on at least one porous and permeable support, which is provided on at least one side of the support and in the interior of the support with at least one inorganic component, which contains substantially at least one compound of a metal, a semi-metal or a mixed metal with at least one element of Group 3 to Group 7, while retaining its good thermal stability and resistance to acids.
The subject matter of the present invention is therefore a permeable composite material based on at least one porous and permeable support, which is provided on at least one side of the support and in the interior of the support with at least one inorganic component, which contains substantially at least one compound of a metal, a semi-metal or a mixed metal with at least one element of Group 3 to Group 7, which composite material is characterized in that it exhibits ion-conducting properties.
Also subject matter of the present invention is a process for making a composite material based on at least one porous and permeable support, which is provided on at least one side of the support and in the interior of the support with at least one inorganic component, which contains substantially at least one compound of a metal, a semi-metal or a mixed metal with at least one element of Group 3 to Group 7, which process is characterized in that a composite material with ion-conducting properties is made.
Further subject matter of the present invention is the use of a composite material according to at least one of claims
1
to
20
as a catalyst for acid or base catalyzed reactions.
The ion-conducting composite material according to the invention is characterized by good ion-conducting properties. Contrary to the general assumption that materials having good ion conduction must be pore-free, it has been found that materials having good ion conduction do not absolutely have to be pore-free, but instead the pore size merely has to be smaller than a certain limit value. If the pore surfaces contain ionogenic groups, ion conduction takes place in the form of a surface diffusion mechanism. Provided the porosity is quite high, this mechanism of ion migration leads to high ion fluxes through the material, so that current densities of greater than 50 mA·cm
−2
can be achieved.
Not only good conductivity but also the greatest possible permselectivity is necessary for use of membranes in electrodialysis or as a proton-conducting membrane in fuel cells. This requirement is also thoroughly satisfied by the composite material according to the invention. The permselectivities of the ion-conducting composite materials according to the invention and used as membrane materials lie in the range of 0.75 to 0.98 depending on the material used.
The composite material according to the invention will be described hereinafter by reference to an example, without being limited thereto.
The permeable composite material according to the invention based on at least one porous and permeable support, which on at least one side of the support and in the interior of the support is provided with at least one inorganic component, which substantially contains at least one compound of a metal, a semi-metal or a mixed metal with at least one element of Group 3 to Group 7, exhibits ion-conducting properties. As used in the present invention, the term interior of a support refers to cavities or pores in a support.
According to the invention, the porous and permeable support can have interstices with a size of 0.02 to 500 &mgr;m. The interstices can be pores, meshes, holes, crystal lattice interstices or cavities. The support can contain at least one material chosen from carbon, metals, alloys, glass, ceramics, minerals, plastics, amorphous substances, natural products, composite substances or from at least one combination of these materials. It is permissible for supports which can contain the said materials to have been modified by a chemical, thermal or mechanical treatment method or a combination of treatment methods. Preferably the composite material is provided with a support which contains at least one metal, one natural fiber or one plastic, which was modified by at least one mechanical forming technique or treatment method, such as drawing, upsetting, fulling, rolling, stretching or forging. Quite particularly preferably the composite material is provided with at least one support which contains at least woven, bonded, felted or ceramically bound fibers or at least sintered or bonded shapes, globules or particles. In a further preferred embodiment there can be used a perforated support. Permeable supports can also be such which become or have been made permeable by laser treatment or ion beam treatment.
It can be advantageous if the support contains fibers of at least one material chosen from carbon, metals, alloys, ceramics, glass, minerals, plastics, amorphous substances, composite substances and natural products or fibers of at least one combination of these materials, such as asbestos, glass fibers, carbon fibers, metal wires, steel wires, steel-wool fibers, polyamide fibers, coconut fibers, coated fibers. Preferably there are used supports containing woven fibers of metal or alloys. Wires can also be used as metal fibers. Quite especially preferably the composite material is provided with a support which contains at least one fabric of steel or stainless steel, such as a fabric made by weaving from steel wires, steel fibers, stainless-steel wires or stainless-steel fibers, which fabric preferably has mesh widths of 5 to 500 &mgr;m, especially preferably mesh widths of 50 to 500 &mgr;m, and quite especially preferably mesh widths of 70 to 120 &mgr;m.
The support of the composite material, however, ca
Hörpel Gerhard
Hying Christian
Penth Bernd
CREAVIS Gesellschaft fuer Technologie und Innovation mbH
Fortuna Ana
LandOfFree
Ion-conducting composite which is permeable to matter,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ion-conducting composite which is permeable to matter,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ion-conducting composite which is permeable to matter,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3015306