Hidden crystalline components in mesoporous silicate

Abstract

As reported in a previous paper (J. Mater. Chem., 2008, 18, 1383), mesoporous silicate plates displaying a single crystal like property can be prepared from the intercalation of the crystalline layered precursor, Na-RUB-18 with cetyltrimethylammonium (CTA) molecules followed by the removal of CTA via a solvent extraction method. Further investigation of the microstructures of these materials using transmission electron microscopy as the principal characterisation technique indicates that solvent extraction in an acidified ethanol solution resulted in the silicate layers collapsing to form mesoporous plates with crystalline zeolite RUB-24 surface regions. New electron microscopic images and selected area electron diffraction patterns found the previously reported conclusion of one-phase crystalline mesoporous silicate plates is unlikely to be correct. An alternative conclusion regarding the location of hidden crystalline regions within the silicate plates is proposed.