Catalyst – solid sorbent – or support therefor: product or process – Zeolite or clay – including gallium analogs
Patent
1989-10-30
1992-02-04
Konopka, Paul E.
Catalyst, solid sorbent, or support therefor: product or process
Zeolite or clay, including gallium analogs
623241, 16510412, 237 2B, 252 69, 502 64, 502 80, 502410, 502411, 502413, 502417, B01J 2018, B01J 2020, B01J 2004, C09K 500
Patent
active
050860224
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for improving the characteristics of absorption and of desorption of a gas by a reaction medium and to the reaction medium thus obtained for applications to chemical heat pumps.
Patent Application 87/12,389, filed in the name of the Elf Aquitaine company on 7 Sept. 1987 discloses a process for constituting a reaction medium for conducting an absorption and desorption reaction in a chemical heat pump. This process teaches the packing percentages of a salt relative to the optimum packing of the salt as a function of the mass percentage of the reaction product of a porous product, which makes it possible to obtain an optimization of the energy densities of the reaction medium. Thus, a maximum packing (Tmax, FIG. 1) enables a maximum energy density to be obtained as a function of a given salt (1). This value is called the optimum packing of the reaction without graphite and expresses the maximum energy which can be introduced into a chemical storage system employing a salt and a gas. A maximum energy density and a maximum packing correspond to a first salt, shown by curve (1) in FIG. 1, and other values of packing and of energy density correspond to a second salt, represented by curve (2). In the above application an investigation was made, in the case of reaction media consisting of expanded graphite and of one or more salts, of the percentages (X, Y, FIG. 2) of optimum packing which, as a function of the percentage of expanded graphite, made it possible to obtain a reaction medium whose operating region was situated in the energy densities and powers which were advantageous for heat storage and release applications. Thus, as can be seen in FIG. 2, in the case of a reaction medium represented by curve (3), consisting of a mixture of salt with 25 mass % of expanded graphite, a maximum specific power is obtained for a given percentage X of optimum packing. As expressed in the above patent application, it is found that one remains in the specific power regions which are high and capable of being employed for heat storage and release reactions, in the case of a packing value expressed as the number of kilograms of mixture per m.sup.3 of between 20% and 60% of the optimum packing of the reaction without graphite. Similarly, in the case of a reaction medium represented by curve (4), containing 35 mass % of expanded graphite, it has been possible to establish that the salt packing had to be chosen between 15 and 50% of the optimum packing. We shall recall, furthermore, that expanded graphite is employed as a good heat conductor and for its porosity, which makes it easier for the reaction gas to pass through the reaction medium during the absorption or desorption reaction. This is important, because the metal or alkaline-earth metal halides employed as salt are poor conductors. Furthermore, these salts begin to swell when they react with a gas such as, for example, ammonia or methylamine, which react with calcium chloride.
However, as can be seen from the curves in FIG. 2, the power depends enormously on the packing and varies very rapidly as a function of the latter. This phenomenon, related to the salt swelling phenomenon, which can give rise to a blockage of the reaction medium in the thermochemical reactor, is a major disadvantage.
An object of the invention is to propose a process for improving the characteristics of absorption or of desorption of a gas by a reaction medium, to make them relatively independent of the packing of the reaction medium.
This object is attained by the fact that the process for improving the characteristics of absorption and of desorption of a gas by a reaction medium consisting of one or more salts in a pulverulent form and of a porous solid product, consists in mixing between 0 and 60 mass % of the porous product with the pulverulent salt(s), the porous product consisting of a mixture of expanded graphite and of a second expanded product of rigid structure and high permeability.
According to another characteristic, the second expanded produc
REFERENCES:
patent: 2986525 (1961-05-01), Hughes
patent: 4595774 (1986-06-01), Coste et al.
patent: 4660629 (1987-04-01), Maier-Larhvber et al.
patent: 4754805 (1988-07-01), Rothmayer
patent: 4906258 (1990-03-01), Balat et al.
Mauran Sylvain
Roca Alain
Spinner Bernard
Konopka Paul E.
Societe Nationale Elf Aquitaine
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