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Title: On the Importance of the Associative Carboxyl Mechanism for the Water-Gas Shift Reaction at Pt/CeO 2 Interface Sites

Periodic density functional theory calculations and microkinetic modeling are used to investigate the associative carboxyl pathways of the water-gas shift (WGS) reaction at the Pt/CeO 2 (111) interface. Analysis of a microkinetic model based on parameters obtained from first principles suggests that the turnover frequencies for the CO-assisted associative carboxyl mechanism are comparable to experimental results. However, this microkinetic model containing various associative carboxyl pathways at interface sites cannot explain the experimentally observed activation barriers and reaction orders of Pt/CeO 2 catalysts. Considering furthermore that a model of an associative carboxyl mechanism with redox regeneration, also derived from first principles and recently published by us, accurately predicts all kinetic parameters while displaying a 2 orders of magnitude higher turnover frequency, we conclude that at Pt/CeO 2 interface sites, the WGS reaction follows a bifunctional Mars-van Krevelen mechanism in which support oxygen vacancies facilitate water dissociation.
Authors:
 [1] ;  [1] ;  [1]
  1. Univ. of South Carolina, Columbia, SC (United States)
Publication Date:
OSTI Identifier:
1227051
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. C; Journal Volume: 118; Journal Issue: 12
Publisher:
American Chemical Society
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Environmental Molecular Sciences Laboratory