Method for the preparation of highly reactive clay composites for the removal of SO.sub.x from flue gas streams

A method for preparing a composite material useful for SO.sub.x removal from a flue gas stream of a coal-burning power plant and other gas streams which comprises:

• (a) providing a suspension of a smectite clay in water;
• (b) adding a quantity of basic compound selected from the group consisting of alkaline earth metal oxides, hydroxides, carbonates and mixtures thereof to the clay suspension;
• (c) adding a quantity of second metal ion in the form of a metal oxide or oxide precursor and mixtures thereof, which metal ion provides oxidation of sulfur dioxide to sulfur trioxide, in an amount sufficient that said composite material promotes the oxidation of the sulfur dioxide to sulfur trioxide at sulfur dioxide oxidation conditions to provide a resulting suspension;
• (c) mixing the resulting suspension and allowing a precipitate to form;
• (d) removing the precipitate from at least some of the water;
• and
• (e) heating the precipitate in air to provide the composite material, wherein when the composite material is heated to a temperature of 500.degree. C. or above in the presence of the SO.sub.x in the gas stream, the SO.sub.x is removed by the composite material.

A method for preparing a composite material useful for SO.sub.x removal from a flue gas stream of a coal-burning power plant and other gas streams which comprises:

• (a) providing a suspension of a smectite clay in water;
• (b) adding a quantity of a basic compound selected from the group consisting of an alkaline earth metal hydroxide and alkaline earth oxide and mixtures thereof to the clay suspension;
• (c) adding a quantity of second metal ion in the form selected from the group consisting of a metal oxide, a metal oxide precursor and mixtures thereof, which provide oxidation of sulfur dioxide to sulfur trioxide in an amount sufficient that said composite material promotes the oxidation of the sulfur dioxide to sulfur trioxide at sulfur dioxide oxidation conditions to provide a resulting suspension;
• (d) providing carbon dioxide in the resulting suspension to form an alkali metal carbonate from at least some of the basic compound so that the alkali metal carbonate precipitates;
• (e) removing the precipitate from at least some of the water;
• and
• (f) heating the precipitate in air to provide the composite material, wherein when the composite is heated to a temperature of 500.degree. C. or above in the presence of SO.sub.x in the gas stream, the SO.sub.x is removed by the composite material.

A method for preparing a composite material useful for SO.sub.x removal from a flue gas stream of a coal-burning power plant and other gas streams which comprises:

• (a) providing a suspension of a smectite clay in water;
• (b) adding a quantity of basic compound selected from the group consisting of alkaline earth metal oxides, hydroxides, carbonates and mixtures thereof to the clay suspension to provide a resulting suspension;
• (c) mixing the resulting suspension by stirring and allowing a precipitate to form;
• (d) recovering the precipitate from the water by filtration, by centrifugation or as a slurry;
• (e) drying the precipitate in air;
• (f) adding a second metal cation to the precipitate, which provides oxidation of sulfur dioxide to sulfur trioxide in an amount sufficient that the composite promotes the oxidation of the sulfur dioxide to sulfur trioxide at sulfur dioxide oxidation conditions, as a metal salt by impregnating the dried precipitate with an aqueous solution of a metal salt containing the metal ion;
• and
• (g) heating to form the composite material, wherein when the composite material is heated to a temperature of 500.degree. C. or above in the presence of the SO.sub.x in the gas stream, the SO.sub.x is removed by the composite material upon contacting with the said gas stream at that temperature.

A method for preparing a composite material useful for SO.sub.x removal from a flue gas of a coal-burning power plant and other gas streams which comprises:

• (a) providing a suspension of a smectite clay in water;
• (b) adding a quantity of a basic compound selected from the group consisting of an alkaline earth metal hydroxide and alkaline earth metal oxide and mixtures thereof to the clay suspension;
• (c) providing carbon dioxide in the suspension to form an alkaline earth metal carbonate from the basic compound, wherein the alkaline earth metal carbonate precipitates with the clay from the suspension containing some alkaline earth metal hydroxide;
• (d) recovering the precipitate from at least some of the water;
• (e) drying the precipitate in air;
• (f) adding a second metal ion, which provide oxidation of sulfur dioxide to sulfur trioxide in an amount sufficient that said composite promotes the oxidation of the sulfur dioxide to sulfur trioxide at sulfur dioxide oxidation conditions, in the form of metal salt by impregnating the precipitate with an aqueous solution of metal salt;
• and
• (g) heating to provide the composite material, wherein when the composite material is heated to a temperature of 500.degree. C. or above in the presence of SO.sub.x in the gas stream, the SO.sub.x is removed by the composite material.

A method for preparing a composite material useful for SO.sub.x removal from a flue gas stream of a coal-burning power plant and other gas streams which comprises:

• (a) providing an aqueous suspension of a pillared smectite clay containing a pillared transition metal, wherein the said transition metal promotes the oxidation of the sulfur dioxide to sulfur trioxide at sulfur dioxide oxidation conditions;
• (b) adding a quantity of basic compound selected from the group consisting of alkaline earth metal oxides, hydroxides, carbonates and mixtures thereof to the clay suspension;
• (c) mixing the resulting suspension by stirring and allowing a precipitate to form;
• (d) removing the precipitate from at least some of the water;
• and
• (e) heating the precipitate in air to provide the composite material, wherein when the composite material is heated to a temperature of 500.degree. C. or above in the presence of SO.sub.x in the gas stream, the SO.sub.x is removed by the composite material.

A method for preparing a composite material useful for SO.sub.x removal from a flue gas stream of a coal-burning power plant and other gas streams which comprises:

• (a) providing a suspension in water of a smectite clay containing a pillared transition metal, wherein the said transition metal promotes the oxidation of the sulfur dioxide to sulfur trioxide at sulfur dioxide oxidation conditions;
• (b) adding a quantity of a basic compound selected from the group consisting of an alkaline earth metal hydroxide and alkaline earth oxide and mixtures thereof to the clay suspension;
• (c) providing carbon dioxide in the suspension to form alkaline earth metal carbonate and allowing a precipitate to form;
• (d) removing the precipitate from at least some of the water;
• and
• (e) heating the precipitate in air to provide the composite material, wherein when the composite material is heated to a temperature of 500.degree. C. or above in the presence of SO.sub.x in the gas stream, the SO.sub.x is removed by the composite material.