HRTEM investigation of mesoporous molecular sieves

High resolution transmission electron microscopic (HRTEM) studies of some typical mesoporous molecular sieves, such as MCM-41, SBA-2 and STAC-1, etc. are presented. Since the materials consist of amorphous silica and their unit cell dimensions are in a range of 1.5 to over 10 nm, the conventional X-ray diffraction method gives us very limited information about the detailed structures. On the other hand, HRTEM has been found to be the most powerful technique to detect the local structures and to image metal clusters inside the channels of these materials.