The removal of sulfur from petroleum feedstocks is of great importance to the oil industry. The process, known as hydrodesulfurization (HDS), is typically catalyzed by Group VIB metal oxides. The workhorse of the industry today is an alumina supported CoO-MoO3 catalyst. Recently, several models have been proposed for the active site responsible for HDS activity, but despite extensive research efforts there is still no clear relationship between structure and activity. We have prepared promoted and non-stoichiometric catalyst samples via a novel solid state synthesis route. These catalysts are not only quite active in the HDS of thiophene, but are also more thermally stable and consequently easier to characterize than the standard HDS materials prepared by wet chemistry methods. Most studies on HDS catalysts rely on bulk techniques for characterization analysis, however, these do not provide any information at the microscopic level where catalysis occurs. For that reason we have used analytical and high resolution electron microscopy to obtain information at the atomic level, coupled with bulk techniques such as x-ray diffraction and surface area measurements. The objective was to develop a link between the microstructure of our solid state catalysts and their HDS activity.
