Supported silver species are active catalytic materials for reactions including NO reduction, CO oxidation, ethylene epoxidation and diesel soot oxidation. Determining what the active phases are during reactions are critical for materials design and challenging as multiple silver species may exist in the system including the silver cation, charged silver clusters and nanoparticles. A controlled synthesis of silver catalysts will facilitate understanding reaction mechanism and designing catalysts for better activity. The silver species can be manipulated by thermal treatment in inert or reducing environment with various zeolites supports. Zeolites with well-defined structure can not only provide confined environment for Ag particles, but their surface chemistry also impacts the morphology and charges of the silver species. Perception on both the evolution of the catalysts structure and the changes of surface chemistry at the same time in the same condition is of prime importance for controlling the synthesis. Quantitatively delineated the structures and kinetics of Ag species during reduction have obtained using pair distribution function (PDF) methods. Combed PDF with diffuse reflection infrared Fourier transformed spectroscopy (DRIFTS) will provide comprehensive structural information and surface chemistry evolution for silver ion-exchanged zeolites upon dehydration and reduction.

Investigating silver ion exchanged zeolites using in-situ pair distribution function and diffuse reflectance infrared spectroscopy techniques

247th National Meeting (2014)

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