Novel Approach to the Sol-Gel Synthesis of Molybdenum Oxide Catalysts

Hydrolysis rate and ratio as well as the hydrolysis method are known to greatly influence the sol-gel process of alkoxide precursors. UV/vis-spectroscopy is a valuable tool for the study of hydrolysis and condensation especially for analyzing valencies and degree of condensation. Anyhow additional spec-troscopic methods (particularly Raman spectroscopy) are in preparation and will help to determine local structural de-velopment. Besides the effects of hydrolysis and condensation in solution the influence of the heating rate can clearly be seen. The slower heating rate (1 K/min) yields a nanocrystalline material (~50-100nm) which basically consists of MoO3 (XRD). TEM images reveal the probable exis-tence of shear structures (defective short range structures) and electron diffraction patterns (not shown) indicate additional molybdenum oxide phases. This novel synthesis approach to MoO3 has proved to be very versatile. Though not presented in detail on this poster first results on nanoparticles and thin films are promising (see images on top of the poster). The aim of this work, to start with a molecular precursor and follow the entire preparation route by in situ techniques leading to a well defined solid catalyst is a challenge but never-theless possible. Final comparison of the catalytic performance of thin films, powders and nanoparticles prepared all from the same molecular precursor will help to get a better understanding of molybdenuim oxide based c