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Microstructure-Dependent Synergy of Pt-Rh Nanoparticles Charles E. Lyman, Lehigh University, DMR 0506705. Rh-NO. NO. 250 o C.

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  1. Microstructure-Dependent Synergy of Pt-Rh NanoparticlesCharles E. Lyman, Lehigh University, DMR 0506705 Rh-NO NO 250oC In-situ FTIR characterization of a synergistic Pt(95%)-Rh(5%)/g-Al2O3 catalyst for the reduction of NO with H2 revealed important microstructural and mechanistic details about its performance: NO NO Pt-NO NO NO NO NO + H2 4 min Changing back to NO + H2 allows Pt-NO and Rh-NO observation H2 30 min NO NO • Pt and Rh are present on bimetallic nanoparticle surfaces under reaction conditions • Synergy of Pt-Rh catalysts for the reduction of NO with H2 is dependent of having the right Pt:Rh surface ratio. • Synergistic Pt-Rh nanoparticles have a microstructure that minimizes molecularly adsorbed NO by facilitating NO dissociation. NO Absorbance Changing to reducing conditions results in Rh-NO forming H2 4 min Pt Rh NO + H2 60 min g-Al2O3 NO-metal species not present on synergistic Pt –Rh surface after extended exposure to NO + H2 because of efficient NO dissociation Wavenumber (cm-1) In-situ FTIR of 95Pt/5Rh at 250oC and microstructure model Dimick, PS, et al. Appl. Catal. B. (2009) 82. 1-11.

  2. Microstructure-Dependent Synergy of Pt-Rh NanoparticlesCharles E. Lyman, Lehigh University, DMR 0506705 This work uses materials science concepts to design better catalysts. Synthesis, conditioning, testing, and characterization are all accomplished in the same laboratory. Catalyst characterization includes aberration-corrected scanning transmission electron microscopy and analysis. Graduate student experience in this laboratory is truly cross-disciplinary. The previous slide shows for the first time that both Pt and Rh have been identified by FTIR on the surface of Pt-Rh nanoparticles. This work may lead to better design of catalysts for specific reactions. Graduate student Paul Dimick presented this work at the 2008 Fall AIChE. He won first place in the student poster competition at the Catalysis Society of Metropolitan NY.

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