Production of Porous Materials by Dealumination of Alumina-Rich Zeolites

A comparative study of chemical and textural properties for materials obtained by three different methods of dealumination of alumina-rich parent Ca-A zeolite showed that the method using ammonium hexafluorosilicate (AFS) resulted in the most interesting developments of mesoporous materials, with much higher void volumes and cation exchange properties than obtained by acid leaching or hydrothermal treatment. AFS treatment on both the Na and Ca forms of zeolite A resulted in materials with 12 nm sized mesopores, whereas smaller mesopores of about 4 nm were obtained when using the higher Si/Al ratio parent zeolite Na-X. Pore size distribution profiles obtained for these new materials are fairly narrow, indicating homogeneous mesopore sized solids.