Effect of reducing atmosphere on the structure of ceria-supported nano-pt catalysts |
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Authors: | M Shamsuzzoha E T Ada R G Reddy |
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Institution: | (1) School of Mines and Energy Development, The University of Alabama, 35487 Tuscaloosa, Al;(2) Department of Metallurgical and Materials Engineering, The University of Alabama, USA |
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Abstract: | Bulk platinum has been known to be chemically inert, but shows remarkably high activity as a catalyst when finely dispersed
as nano particles (10 nm) in ceramic substrates. In order to understand this mechanism, we have studied the effect of a reducing
environment on the structure, morphology, and distribution of these Pt nano particles as well as of oxide support in gadolinium-doped
ceria catalysts by transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS) methods. In fresh catalysts
prepared by calcinations, the Pt nano particles were found to be crystalline with many of them twinned and distributed randomly
in the microstructure of crystalline ceria support. The size of the Pt nano particles ranged between 20 and 50 nm. A special
feature found in these catalysts is that no constituting Pt particle is partially or fully embedded in the ceria grain. Upon
reduction with hydrogen gas at high temperatures, both Pt and ceria crystals showed evidence of crystalline defects. The Pt
nano particles in reduced catalysts appeared similar in size and shape to those observed in the fresh catalysts, and they
resided on the surface of the ceria crystal. The results are discussed in relation to their expected catalytic activity in
autothermal reforming of iso-octane. |
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Keywords: | Platinum catalyst ceria gadolinium autothermal reforming |
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