Chemistry: electrical and wave energy – Apparatus – Electrolytic
Patent
1998-10-06
2000-08-08
Bell, Bruce F.
Chemistry: electrical and wave energy
Apparatus
Electrolytic
204282, 204283, 204290R, 204294, 252502, 252503, 252500, 25251933, 2525203, 427122, 4271261, 427180, 427201, 427245, 427295, 427352, 4273722, 427304, C25B 1104
Patent
active
060997044
DESCRIPTION:
BRIEF SUMMARY
The subject-matter of the present invention is a cathode component devoid of asbestos fibres, its process of preparation and its use in the production of alkali metal hydroxide solution.
The materials used for the preparation of the cathode component of an electrolysis cell must correspond to several specific characteristics. Thus, they must exhibit a low electrical resistivity, compatible with the operation, at an acceptable energy level, of the electrolyser equipped with such a cathode component. Furthermore, they must also make it possible to obtain a component which is low in thickness while conferring on the said component a high specific surface which can exceed several square meters.
Such cathode components are generally obtained by depositing, by filtration through a porous support, a dispersion of the materials used. One of the difficulties of this type of process is to be able to control the amount of product effectively retained at the surface of the porous support, the latter exhibiting a level of opening or diameters of holes which are large with respect to the size of the materials used. In addition, the sheet must exhibit controlled and reproducible characteristics of porosity and of homogeneity, in terms of thickness of the sheet and of distribution of these constituents, if cathode components which are unusable or poor in performance are not to be obtained.
One of the first generations of cathode component consisted in depositing a suspension comprising carbon fibres, asbestos fibres, a fluorinated polymer binding the fibres, an electrocatalytic agent and a pore-forming agent.
The advantage of this type of cathode component is now limited because of anticipated new regulations relating to asbestos fibres. This is because the toxicity of these fibres is now recognized and there is a tendency to no longer allow the use of such a material.
Furthermore, it has been found that the long-term stability of asbestos fibres in the electrolytic medium comprising a concentrated base and a salt was to be improved, so as to limit the replacement, regarded as excessively frequent, of the cathode components.
Firstly, provision was made to dispense purely and simply with the asbestos fibres in the fibrous suspension. However, the resulting sheet proved to be unusable in industrial-scale electrolysis because it was not possible to efficiently control the thickness and the porosity of the said sheet. In addition, its cohesion with the cathode was not satisfactory either.
In the light of such results, one suggestion consisted in substituting the asbestos fibres by organic fibres of the fluorinated polymer type. However, the performances of the cathode component were not satisfactory either. This is because the porosity and the thickness could not always be controlled, essentially after the stage of consolidation of the said sheet (or sintering).
Given these facts, a novel type of asbestos-free cathode component has been provided in which these fibres were replaced by a mixture of organic fibres, of the fluorinated polymer type, and of inorganic fibres, such as, in particular, titanate fibres.
Just like the preceding generation of cathode component based on asbestos fibres, this novel composition of the fibrous sheet makes it possible to obtain highly satisfactory properties in electrolysis of sodium chloride solutions.
However, the disadvantage of this latter sheet composition is its high cost, due mainly to the organic and inorganic fibres, which represent a not insignificant part of the composition.
The aim of the present invention is to provide a fibrous sheet composition devoid of asbestos and of organic and inorganic fibres, such as those which have just been mentioned.
Thus, the invention relates to a cathode component devoid of asbestos fibres which is capable of being obtained by deposition, by filtration through a porous support, of an aqueous suspension comprising electrically conducting fibres, at least one cationic polymer, at least one electrocatalytic agent, at least one pore-forming agent and a
REFERENCES:
patent: 5584977 (1996-12-01), Bachot et al.
patent: 5626905 (1997-05-01), Bachot et al.
Bacquet Gerard
Kuntzburger Frederic
Bell Bruce F.
Chloralp
LandOfFree
Asbestos-free cathodic element suitable for electrolysis of sodi does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Asbestos-free cathodic element suitable for electrolysis of sodi, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Asbestos-free cathodic element suitable for electrolysis of sodi will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1146877