HRTEM, Synchrotron, and Simulation Techniques Applied to Activity and Selectivity Correlation in Hydrodesulfurization Catalysts

Faced with heavier crudes and increasingly strict regulations regarding sulfur content of fuels, better HDS, HDN, and HDM catalysts are sought requiring a deeper understanding of the structure and function of transition metal sulfide based catalysts. Small angle scattering, wide-angle scattering, high resolution transmission electron microscopy (HRTEM), and simulation techniques using CERIUS software were applied to commercial alumina supported and unsupported CoMo catalysts stabilized in real feeds. Scattering from the active phases was easily obtained by subtraction of the alumina support. Analysis of the active phase scattering showed that the catalyst consisted of mainly single layers of MoS ₂ in contrast to HRTEM studies that "see" only stacked layers. Catalysts that were run for long periods of time under high-pressure conditions tended to "destack".