Well-defined, single site heterogeneous catalysts are emerging as highly selective and active catalysts that have the potential to merge the tunability of homogeneous platforms with the stability of heterogeneous catalysts.  In order to realize these potential benefits, mechanistic studies must be performed with similar detail to homogeneous catalysts.  Recently we have developed selective syntheses to highly uniform-in-function single site catalysts with high selectivity and stability for nonoxidatiave propane dehydrogenation.  This system provides an excellent platform upon which to vary the support (ligand) effects and elucidate the effect of ligand or promoters upon the catalytic function.  X-ray absorption spectroscopy (XAS) is a powerful tool for the study of catalyst formation and turnover mechanisms.  However, the results can be challenging to rationalize for a wide variety of reasons.  In some cases it can be difficult to even tell if the metal is changing oxidation state!    In this talk we will detail our approach and use of <i>in situ </i>x-ray absorption spectroscopy of dehydrogenation catalysts and organometallic model complexes, combined with vibrational spectroscopy, computational analysis, and other techniques yields further insight in to the mechanism of these catalysts.  In particular, we address the question of metal-based redox in gallium catalysts, ligand effects in cobalt catalysts for alkane dehydrogenation, and other sources of uncertainty in x-ray absorption spectroscopy interpretation (and strategies for their resolution) as time permits.<br/>

Using organometallic model complexes to assist in interpreting x-ray absorption spectra of single-site catalysts

253rd National Meeting (2017)

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