Abstract: The present invention relates to a capture agent for the treatment of gases, having an active phase that comprises a calcium silicate hydrate of (CaO)x(SiO2)y(H2O)z type with a Ca/Si molar ratio between 1.55 and 1.72, preferably between 1.65 and 1,72 and an H2O/Ca molar ratio between 1 and 1.4, preferably between 1.1 and 1.3, “z” being between 0.3 and 0.8, the capture agent having a specific surface area greater than 120 m2/g, preferably greater than 150 m2/g and particularly preferably greater than 200 m2/g and a pore volume greater than 0.4 cm3/g, preferably greater than 0.6 cm3/g and particularly preferably greater than 0.8 cm3/g.

Abstract: A hydrated lime, especially suited for removal of acid gases, such as SO3, from flue gases, is produced by the method of hydrating quicklime while controlling the temperature increase of the reaction, caused by the hydration reaction of the quicklime with water, sufficient to form a hydrated lime having a high pore volume of between about 0.1 to 0.25 cm3/g and a specific surface area of between about 20 to 50 m2/g, and then drying the resultant hydrated lime by indirect heating to provide a residual water content of less than 2.0 weight percent of the hydrated lime product.