Clay composites for the removal of SO.sub.x from flue gas streams
First Claim
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1. A method for preparing a composite material useful for SOx removal from the flue gas of a coal-burning power plant and other gas streams which comprises:
- (a) providing a suspension of a smectite clay containing 0.1 to 5% by weight of clay in water;
(b) adding a basic material selected from the group consisting of alkaline earth metal oxides and hydroxides to the clay suspension to provide a resulting suspension;
(c) mixing the resulting suspension;
(d) recovering a precipitate from the resulting suspension; and
(e) drying the precipitate at a temperature between 100°
-120°
C. to provide the composite material, wherein when the composite material is heated to a temperature of 500°
C. or above, the SOx components from a gas stream are removed by the composite material upon contacting with the said gas stream at that temperature.
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Abstract
A method for preparing smectite clay alkaline earth metal hydroxide and carbonate composite materials is described. The method uses low amounts of the clay added to water to which is added calcium oxide or calcium hydroxide. Optionally the calcium carbonate is formed in situ by exposure to air or to carbon dioxide in the solution. The product is dried to form the composite material which is used to remove SOx from flue gases.
79 Citations
18 Claims
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1. A method for preparing a composite material useful for SOx removal from the flue gas of a coal-burning power plant and other gas streams which comprises:
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(a) providing a suspension of a smectite clay containing 0.1 to 5% by weight of clay in water; (b) adding a basic material selected from the group consisting of alkaline earth metal oxides and hydroxides to the clay suspension to provide a resulting suspension; (c) mixing the resulting suspension; (d) recovering a precipitate from the resulting suspension; and (e) drying the precipitate at a temperature between 100°
-120°
C. to provide the composite material, wherein when the composite material is heated to a temperature of 500°
C. or above, the SOx components from a gas stream are removed by the composite material upon contacting with the said gas stream at that temperature. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for preparing a composite material useful for SOx removal from the flue gas of a coal-burning power plant and other gas streams which comprises:
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(a) providing a suspension of a smectite clay containing 0.1 to 5% by weight of clay in water; (b) adding a basic material selected from the group consisting of alkaline earth metal oxides and hydroxides to the clay suspension to provide a resulting suspension; (c) mixing the resulting suspension by stirring with CO2 gas present in water to convert at least some of the basic material to alkaline metal carbonate; (d) recovering a precipitate from the resulting suspension; and (e) drying the precipitate in air at ambient temperatures to provide the composite material, wherein when the composite material is heated to a temperature of 500°
C. or above, the SOx components from a gas stream are removed by the composite material upon contacting with the said gas stream at that temperature. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for preparing a composite material useful for SOx removal from the flue gas of a coal-burning power plant and other gas streams which comprises:
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(a) providing a suspension of a smectite clay containing 0.1 to 5% by weight of clay in water; (b) adding a basic material seelcted from the group consisting of alkaline earth metal oxides and hydroxides to the clay suspension as a resulting suspension; (c) mixing the resulting suspension by stirring while bubbling CO2 gas through the suspension to convert at least some of the basic material to alkaline metal carbonate in the resulting suspension; (d) recovering a precipitate from the water by filtration or by centrifugation; and (e) drying the precipitate in air at ambient temperatures or in an oven at 110°
C. to prvoide the composite material, wherein when the composite material is heated to a temperature of 500°
C. or above, the SOx components from a gas stream are removed by the composite material upon contacting with the said gas stream at that temperature. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification