Superfund Research Program
Process of Using Layered Double Hydroxides as Low Temperature Recyclable Sorbents for the Removal of SO.sub.x from Flue Gas and Other Gas Streams
Patent Status: Issued
Authors: Pinnavaia, T.J., J. Amarasekera
A process for removing noxious sulfur oxides, nitrous oxides, and chlorine from gas streams, particularly from flue gases of coal-burning power plants, using layered double hydroxide (LDH) sorbents are described. The sorbents are particularly useful for SO.sub.2 absorption at temperatures in the range 100 to less than 400.degree. C. The SO.sub.2 gas absorbs into the hydrotalcite structure as SO.sub.3.sup.2- anions by replacing most of the gallery CO.sub.3.sup.2- anions. The adsorbed SO.sub.2 is driven-off by calcination at elevated temperatures (500.degree. C.) and the LDH sorbents are regenerated by hydrolyzing the calcined product optionally in the presence of CO.sub.2 or CO.sub.3.sup.2-.
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