Vanadium- and chromium-containing mesoporous MCM-41 molecular sieves with hierarchical structure

Vanadium- and/or chromium-containing MCM-41 molecular sieves were synthesized and characterized by spectroscopic techniques. These materials have bimodal pore size distributions with diameters of approximate to 26 and 39 Angstrom. A hierarchical structure with paintbrush-like morphology was observed by HRTEM. The reason for the formation of such structures might be that there were two types of micelles growing simultaneously in the same direction and in the same particles. V and Cr could be incorporated alone or simultaneously and competitively in the framework through interaction with the silanol groups on the internal walls of the hexagonal tubular silicate MCM-41. (C) 2001 Elsevier Science B.V. All rights reserved.