Catalyst – solid sorbent – or support therefor: product or process – Solid sorbent
Reexamination Certificate
1998-07-31
2001-08-07
Langel, Wayne (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Solid sorbent
C502S344000, C502S340000, C423S230000
Reexamination Certificate
active
06271172
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a carbon dioxide gas absorbent, a method for manufacturing carbon dioxide gas absorbent and an apparatus for separating carbon dioxide gas, which are used for the separation and collection of carbon dioxide gas from a fuel gas or an exhaust gas in an energy plant which uses a fuel whose main component is hydrocarbon.
Known examples of the method of separating carbon dioxide gas from an exhaust gas are a type which utilizes a cellulose acetate film and a type which utilizes the chemical absorption process by an alkanol amine-based solvent.
However, in any of these example methods, it is required to set the upper limit of the temperature of the introduction gas to about 200° C. in consideration of the heat resisting properties of the materials for the film, solvent and the like employed in these methods. Therefore, in the case where carbon dioxide gas is separated from a system which exhaust a high-temperature exhaust gas, it is required to cool down the exhaust gas by a heat exchanger or the like, despite that the heat of the exhaust gas could be utilized in some way. Thus, as a result, the energy consumed for the separation of carbon dioxide gas increases, and therefore the usage of these methods is very much limited.
Under these circumstances, the inventors of the present invention have proposed the method of separating a carbon dioxide gas, which uses lithium zirconia (Jpn. Pat. Appln. KOKAI Publication No. 9-99214). With this method, it is possible to separate a carbon dioxide gas without undergoing a cooling step for cooling the high-temperature exhaust gas.
The above-mentioned KOKAI publication discloses the use of a carbon dioxide gas absorbent in the following manner. That is, lithium zirconia powder is mixed with a solvent and a binder to prepare a slurry, and the slurry is processed by a doctor blade method into a film having a porosity of about 55%. Then, after degreasing, a carbonate salt mixture of lithium carbonate and potassium carbonate are molten and impregnated into the porous film, thus obtaining a carbon dioxide gas absorbent.
However, the carbon dioxide gas absorbent disclosed in the publication does not exhibit a sufficient performance in the absorbing property of carbon dioxide gas at an initial stage of use.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a carbon dioxide gas absorbent exhibiting a high performance in the absorption of carbon dioxide gas from an initial stage of use.
Another object thereof is to provide a method capable of preparing a carbon dioxide gas absorbent exhibiting a high performance in the absorption of carbon dioxide gas from an initial stage of use, at a stable manner.
Still another object thereof is to provide a carbon dioxide gas absorbent capable of absorbing carbon dioxide gas exhausted from an energy plant or the like, efficiency at a relatively low temperature.
Still another object of the present invention is to provide a carbon dioxide gas separation apparatus having a carbon dioxide gas absorbent exhibiting a high performance in the absorption of carbon dioxide gas from an initial stage of use.
According to the present invention, there is provided a carbon dioxide gas absorbent comprising:
primary particles each having lithium zirconia serving as a matrix, and eutectic compound molecules containing lithium carbonate and at least one element selected from the group consisting of alkali metals excluding lithium, and alkali earth metals, which are dispersed in the matrix.
According to the present invention, there is further provided a method of preparing a carbonate gas absorbent, comprising the steps of:
mixing a first raw material component of a powder mixture of zirconia powder and lithium carbonate powder, and a second raw material component containing at least one selected from the group consisting of powder of an oxide and a carbonate salt of an alkali metal except for lithium, and powder of an oxide and a carbonate salt of an alkali earth metal, with each other; and
making the powder mixture to react by heating.
According to the present invention, there is further provided a carbon dioxide gas absorbent comprising:
a first phase made of lithium zirconia represented by formula Li
x
ZrO
y
where x is 2, and y is (x+4)/2; and
a second phase made of at least one lithium zirconia selected from the group consisting of those represented by the formula when x=4, 6 and 8,
wherein the first phase and the second phase coexist.
According to the present invention, there is further provided a carbon dioxide gas separating apparatus comprising:
a reaction tower having a gas inlet section and a gas outlet section; and
a carbon dioxide gas absorbent filled into the reaction tower, the carbon dioxide gas absorbent consisting of primary particles each containing lithium zirconia serving as a matrix, and eutectic compound molecules each containing lithium carbonate and at least one element selected from the group consisting of alkali metals excluding lithium, and alkali earth metals, which are dispersed in the matrix.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
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T. Mimura, et al., Energy Convers. Mgmt., vol. 36, No. 6-9, pp. 397-400, “Research and Development on Energy Saving Technology for Flue Gas Carbon Dioxide Recovery and Steam System in Power Plant”, 1995.
K. Nakagawa, et al., Abstract No. 1073, The Electrochemical Society Meeting Abstracts, Nol. 98-1, “High Temperature CO2Absorption Using Lithium Zirconate Powder”, May 3-8, 1998.
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Akasaka Yoshihiro
Nakagawa Kazuaki
Ohashi Toshiyuki
Ohzu Hideyuki
Tomimatsu Norihiro
Ildebrando Chrishna
Kabushiki Kaisha Toshiba
Langel Wayne
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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