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Title: Microkinetic modeling of H 2SO 4 formation on Pt based diesel oxidation catalysts

The presence of water vapor and sulfur oxides in diesel engine exhaust leads to the formation of sulfuric acid (H 2SO 4), which severely impacts the performance of Pt/Pd based emissions aftertreatment catalysts. In this study, a microkinetic model is developed to investigate the reaction pathways of H 2SO 4 formation on Pt based diesel oxidation catalysts (DOCs). The microkinetic model consists of 14 elementary step reactions (7 reversible pairs) and yields prediction in excellent agreement with data obtained from experiments at practically relevant sulfur oxides environment in engine exhaust. The model simulation utilizing a steady-state plug flow reactor demonstrates that it matches experimental data in both kinetically and thermodynamically controlled regions. Results clearly show the negative impact of SO 3 on the SO 2 oxidation light-off temperature, consistent with experimental observations. A reaction pathway analysis shows that the primary pathway of sulfuric acid formation on Pt surface involves SO 2* oxidation to form SO 3* with the subsequent interaction of SO 3* with H 2O* to form H 2SO 4*.
Authors:
 [1] ;  [1] ;  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-730597
Journal ID: ISSN 0926-3373
Grant/Contract Number:
AC52-07NA27344; FP917501
Type:
Accepted Manuscript
Journal Name:
Applied Catalysis. B, Environmental
Additional Journal Information:
Journal Volume: 220; Journal ID: ISSN 0926-3373
Publisher:
Elsevier
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE; USEPA
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Pt catalyst; sulfuric acid poisoning; diesel oxidation catalyst; sulfur oxides; microkinetic modeling
OSTI Identifier:
1438632