Nuclear magnetic resonance studies of ruthenium and rhodium exchanged Y-zeolites

TL;DRAbstract

The $\sp{129}$Xe nuclear magnetic resonance (NMR) of xenon gas sorbed in zeolites has been combined with other experimental methods to characterize the state of ruthenium contained in Y-type zeolites at various stages of catalyst treatment. The adsorption of carbon monoxide on ruthenium and rhodium in Y zeolites has been investigated using high resolution magic-angle spinning NMR methods. The xenon NMR experiments, combined with volumetric oxidation/reduction experiments and transmission electron microscopy, reveal that most of the ruthenium is highly dispersed and occupies the faujasite supercages upon initial ion exchange. Initial exposure to hydrogen gas at room temperature causes nearly complete reduction of Ru$\sp{3+}$ to Ru$\sp{0}$. Exposure of the reduced catalyst to oxygen at elevated temperatures results in quantitative oxidation to RuO$\sb2$, and no detectable migration of the ruthenium species accompanies this oxidation. Reduced ruthenium, however, is found to migrate to the

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