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Title: Surface enrichment of Pt in stable Pt-Ir nano-alloy particles on MgAl 2 O 4 spinel in oxidizing atmosphere

Abstract

With the capability of MgAl2O4 spinel {111} nano-facets in stabilizing small Rh, Ir and Pt particles, bimetallic Ir-Pt catalysts on the same support were investigated, aiming at further lowering the catalyst cost by substituting expensive Pt with cheaper Ir in the bulk. Small Pt-Ir nano-alloy particles (< 2nm) were successfully stabilized on the spinel {111} nano-facets as expected. Interestingly, methanol oxidative dehydrogenation (ODH) rate on the surface Pt atoms increases with oxidizing aging but decreases upon reducing treatment, where Ir is almost inactive under the same reaction conditions. Up to three times enhancement in Pt exposure was achieved when the sample was oxidized at 800 °C in air for 1 week and subsequently reduced by H2 for 2 h, demonstrating successful surface enrichment of Pt on Pt-Ir nano-alloy particles. A dynamic stabilization mechanism involving wetting\nucleation seems to be responsible for the evolution of surface compositions upon cyclic oxidizing and reducing ther-mal treatments.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1355085
Report Number(s):
PNNL-SA-123418
Journal ID: ISSN 1566-7367; 49339; KC0302010
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Catalysis Communications; Journal Volume: 93; Journal Issue: C
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; spinel platinum stabilization iridium; Environmental Molecular Sciences Laboratory

Citation Formats

Li, Wei-Zhen, Nie, Lei, Cheng, Yingwen, Kovarik, Libor, Liu, Jun, and Wang, Yong. Surface enrichment of Pt in stable Pt-Ir nano-alloy particles on MgAl 2 O 4 spinel in oxidizing atmosphere. United States: N. p., 2017. Web. doi:10.1016/j.catcom.2017.01.012.
Li, Wei-Zhen, Nie, Lei, Cheng, Yingwen, Kovarik, Libor, Liu, Jun, & Wang, Yong. Surface enrichment of Pt in stable Pt-Ir nano-alloy particles on MgAl 2 O 4 spinel in oxidizing atmosphere. United States. doi:10.1016/j.catcom.2017.01.012.
Li, Wei-Zhen, Nie, Lei, Cheng, Yingwen, Kovarik, Libor, Liu, Jun, and Wang, Yong. Sat . "Surface enrichment of Pt in stable Pt-Ir nano-alloy particles on MgAl 2 O 4 spinel in oxidizing atmosphere". United States. doi:10.1016/j.catcom.2017.01.012.
@article{osti_1355085,
title = {Surface enrichment of Pt in stable Pt-Ir nano-alloy particles on MgAl 2 O 4 spinel in oxidizing atmosphere},
author = {Li, Wei-Zhen and Nie, Lei and Cheng, Yingwen and Kovarik, Libor and Liu, Jun and Wang, Yong},
abstractNote = {With the capability of MgAl2O4 spinel {111} nano-facets in stabilizing small Rh, Ir and Pt particles, bimetallic Ir-Pt catalysts on the same support were investigated, aiming at further lowering the catalyst cost by substituting expensive Pt with cheaper Ir in the bulk. Small Pt-Ir nano-alloy particles (< 2nm) were successfully stabilized on the spinel {111} nano-facets as expected. Interestingly, methanol oxidative dehydrogenation (ODH) rate on the surface Pt atoms increases with oxidizing aging but decreases upon reducing treatment, where Ir is almost inactive under the same reaction conditions. Up to three times enhancement in Pt exposure was achieved when the sample was oxidized at 800 °C in air for 1 week and subsequently reduced by H2 for 2 h, demonstrating successful surface enrichment of Pt on Pt-Ir nano-alloy particles. A dynamic stabilization mechanism involving wetting\nucleation seems to be responsible for the evolution of surface compositions upon cyclic oxidizing and reducing ther-mal treatments.},
doi = {10.1016/j.catcom.2017.01.012},
journal = {Catalysis Communications},
number = C,
volume = 93,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}