Mesoporous aluminosilicates: preparation from Ca-A zeolite by treatment with ammonium fluorosilicate

Abstract

Ammonium hexafluorosilicate (AFS) in aqueous solution under mild conditions can modify drastically the textural properties of Ca-A zeolite. Open slit-shaped mesopores with a pore-size distribution showing a maximum at 14–20 nm are formed. The average pore diameter depends on the rate of addition of the AFS solution to the leaching medium. If such a treatment is combined with acid leaching or hydrothermal treatment, the mesoporous materials obtained exhibit similar pore-size distribution. However, their adsorption capacity for nitrogen is significantly increased.