Iron, removal from molecular sieve

When dichloromethane solutions of Cp2 or FePc are impregnated on NaY or VPI-5, and heated at 423 and 523 K respectively, the application of the standard soxhlet extraction procedure removes all iron from the solids. The same is true for ferricenium-Y and ferrocenium-VPI-5. When in situ synthesis of FePc is made in both molecular sieve structures, the extraction procedure removes only part of the iron. Thus all residual iron present is associated with encaged FePc. 

The key property required of the inorganic species is ability to build up (polymerize) around the template molecules into a stable framework. As is already evident in this article, the most commonly used inorganic species are silicate ions, which yield a silica framework. The silica can be doped with a wide variety of other elements (heteroatoms), which are able to occupy positions within the framework. For example, addition of an aluminium source to the synthesis gel provides aluminosilicate ions and ultimately an aluminosilicate mesoporous molecular sieve. Other nonsilica metal oxides can also be used to construct stable mesoporous materials. These include alumina, zirconia, and titania. Metal oxide mesophases, of varying stability, have also been obtained from metals such as antimony (Sb), iron (Fe), zinc (Zn), lead (Pb), tungsten (W), molybdenum (M), niobium (Nb), tantalum (Ta), and manganese (Mn). The thermal stability, after template removal, and structural ordering of these mesostructured metal oxides, is far lower, however, than that of mesoporous silica. Other compositions that are possible include mesostructured metal sulfides (though these are unstable to template removal) and mesoporous metals (e.g., platinum, Pt). 

---