Method for the preparation of highly reactive clay composites for the removal of sox from flue gas streams
First Claim
1. A method for removing SOx from a flue gas stream of a coal-burning power plant and other gas streams which comprises:
- (a) providing a dried mixture of a basic compound selected from the group consisting of alkaline earth metal oxides, hydroxides, carbonates and mixtures thereof, uniformly dispersed in a smectite clay, wherein the clay and the basic compound have been mixed in water and dried, and a second metal ion in a form selected from the group consisting of metal oxides, metal oxide precursors and mixtures thereof dispersed in the clay, wherein the metal ion is present in an amount which promotes oxidation of sulfur dioxide to sulfur trioxide; and
(b) heating the composite mixture in the presence of the flue gas containing SOx to remove the SOx.
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Abstract
The use of base/clay composites materials as sorbents for the removal of SO2 and SO3 (SOx) from flue gas and other sulfur containing gas streams is described. The base is either an alkaline earth metal carbonate (eg. CaCO3) or hydroxide (eg. Ca(OH)2) is incorporated onto the clay by precipitating from corresponding metal oxide (eg. CaO) in an aqueous clay slurry. A second metal oxide or oxide precursor, preferably selected from transition metal ions, capable of promoting the oxidation of sulfur dioxide to sulfur trioxide, is incorporated to the base/clay composite during the synthesis in the form of finely divided metal oxide powder, metal oxide sol, water soluble metal salt or as clay-intercalated metal cation. The use of clay as dispersing agent for both the basic oxide and the second metal oxide component decreases the particle agglomeration of base particles and increases the rate of SOx uptake compared to the bulk bases in current use.
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Citations
11 Claims
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1. A method for removing SOx from a flue gas stream of a coal-burning power plant and other gas streams which comprises:
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(a) providing a dried mixture of a basic compound selected from the group consisting of alkaline earth metal oxides, hydroxides, carbonates and mixtures thereof, uniformly dispersed in a smectite clay, wherein the clay and the basic compound have been mixed in water and dried, and a second metal ion in a form selected from the group consisting of metal oxides, metal oxide precursors and mixtures thereof dispersed in the clay, wherein the metal ion is present in an amount which promotes oxidation of sulfur dioxide to sulfur trioxide; and (b) heating the composite mixture in the presence of the flue gas containing SOx to remove the SOx.
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2. A method for removing SOx from a flue gas stream of a coal-burning power plant and other gas streams which comprises:
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(a) providing a calcined mixture of a basic compound selected from the group consisting of metal oxides, metal oxide precursors and mixtures thereof dispersed in a smectite clay, wherein the clay and the basic compound have been mixed in water and dried, and a second metal ion, wherein the second metal ion is present in an amount which promotes oxidation of sulfur dioxide to sulfur trioxide wherein the ratio of basic compound to clay is between about 1;
10 and 10;
1 and the second metal ion is present in an amount between about 0.1 add 20 percent by weight based upon the basic compound; and(b) heating the composite mixture in the presence of the flue gas containing SOx to remove the SOx. - View Dependent Claims (3, 4, 5, 6)
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7. A method for for removing SOx from a flue gas stream of a coal-burning power plant and other gas streams which comprises:
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(a) providing a dried mixture of a basic compound selected from the group consisting of alkaline earth metal oxides, hydroxides, carbonates and mixtures thereof, dispersed in a smectite clay, wherein the clay and the basic compound have been mixed in water and dried, and a second metal ion in a form selected from the group consisting of metal oxides, metal oxide precursors and mixtures thereof dispersed in the clay, wherein the second metal ion is present in an amount which promotes oxidation of sulfur dioxide to sulfur trioxide wherein the ratio of basic compound to clay is between about 1;
10 and 10;
1 and the second metal ion is present in an amount between about 0.1 and 20 percent by weight based upon the basic compound; and(b) heating the composite mixture in the presence of the flue gas containing SOx to remove the SOx. - View Dependent Claims (8, 9, 10, 11)
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Specification