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

摘要

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° 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° 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-.