We will discuss our recent investigations using INS and quasielastic neutron scattering QENS to examine the interaction of hydrogen with pure and metal decorated metal oxide materials. These find widespread use as energy materials especially as oxidation and hydrogenation catalysts. Our studies are geared toward illuminating the microscopic details of the process(es) that underlie the phenomena often referred to as �hydrogen spillover� in order to identify what, if any, role it plays in the catalytic cycle. The term �hydrogen spillover� refers to the diffusion of hydrogen from a surface capable of disassociating H2, onto the surface of an adjoining solid. One of the characteristics of this diffusing hydrogen is that it possesses an electron capable of pairing with an unpaired free radical electron on an adjacent surface noted above, that spillover of hydrogen from a metal to a metal oxide or carbon surface is primarily of interest because most commercial catalysts consist of nanometer sized metal clusters supported on either high surface area metal oxides or carbon, and many catalytic reactions involve hydrogen. Because hydrogen spillover is the fastest of the many spillover processes (e.g. oxygen spillover), and because H2 adsorption is a commonly used method to measure the surface area of supported metal catalysts, it is an important process to understand and clarify.         We will present recent INS observations that show that hydroxyl formation on these metal oxide supports takes place only when the metal catalyst is present even at low temperatures.  Spectral signatures in both the rotational and vibrational portions of the INS signals underscore this behavior.  QENS data establishes that there is substantial translational diffusion at temperatures well below 50K.  Similarities and differences of the various support materials will be highlighted.  Implications for improving the catalytic performance of these materials will be presented.

Inelastic neutron scattering(INS) studies of hydrogen spillover on pure and Pd decorated metal oxides

246th National Meeting (2013)

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