(542b) Characterization of the Silver Phase On Supported Ag/TiO2 Desulfurization Adsorbent Materials Via Multiple X-Ray Techniques

Authors: 
Heinzel, J. - Presenter, Naval Sea Systems Command - Philadelphia
Mansour, A., Naval Surface Warfare Center, Carderock Division
Quinlan, R., Naval Surface Warfare Center, Carderock Division
Tatarchuk, B., Auburn University



This paper explores dispersed silver oxides on TiO2 supports, and intends to identify the electronic and atomic structures and characteristics of the silver phase.  Various parameters are given as result of characterization by XPS, XRD, XANES and EXAFS.  Significant analysis has been performed to understand how the silver structure changes with loading, with the goal to fully understand how the silver phases may effect the selective interaction of heterocyclic sulfur, and how it can be harnessed and optimized to enhance capacity and ultimately process volume.

XPS analysis confirms that AgNO3, which is used as the precursor for preparing the adsorbent, is not present. Ag is mostly present in an oxide form in the near surface region. Linear combination of XANES data for the TiO2 supported Ag adsorbent materials show that for all loadings (1, 2, 4, 8, 12, and 20  wt% Ag), the XANES data can be analyzed with a combination of metallic Ag and the oxide phase in 2wt% Ag/TiO2. For low loadings, 4 wt% and below, only the oxide form is present.  For higher loadings, 8, 12 and 20 wt%, the Ag chemistry consists of the oxide form and the metallic form. The metallic content increases with Ag loading.  At 2 wt% loading, it was verified that the structure of the oxide form varied with the type of the support (TiO2 vs. SiO2).

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