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Title: Effects of Sulfation Level on the Desulfation Behavior of Presulfated Pt-BaO/Al2O3 Lean

Abstract

Desulfation by hydrogen of presulfated Pt (2 wt %)-BaO(20 wt %)/Al2O3 with various sulfur loading (S/Ba = 0.12, 0.31, and 0.62) were investigated by combining H2 temperature programmed reaction (TPRX), X-ray photoelectron spectroscopy (XPS), in situ sulfur K-edge X-ray absorption near-edge spectroscopy (XANES), and synchrotron time-resolved X-ray diffraction (TR-XRD) techniques. We find that the amount of H2S desorbed during the desulfation in the H2 TPRX experiments is not proportional to the amount of initial sulfur loading. The results of both in situ sulfur K-edge XANES and TR-XRD show that at low sulfur loadings, sulfates were transformed to a BaS phase and remained in the catalyst rather than being removed as H2S. On the other hand, when the deposited sulfur level exceeded a certain threshold (at least S/Ba = 0.31) sulfates were reduced to form H2S, and the relative amount of the residual sulfide species in the catalyst was much less than at low sulfur loading. Unlike samples with high sulfur loading (e.g., S/Ba = 0.62), H2O did not promote the desulfation for the sample with S/Ba of 0.12, implying that the formed BaS species originating from the reduction of sulfates at low sulfur loading are more stable to hydrolysis. Themore » results of this combined spectroscopy investigation provide clear evidence to show that sulfates at low sulfur loadings are less likely to be removed as H2S and have a greater tendency to be transformed to BaS on the material, leading to the conclusion that desulfation behavior of Pt-BaO/Al2O3 lean NOx trap catalysts is markedly dependent on the sulfation levels.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
980171
Report Number(s):
BNL-93089-2010-JA
Journal ID: ISSN 1932-7447; TRN: US1005424
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry C
Additional Journal Information:
Journal Volume: 113; Journal ID: ISSN 1932-7447
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 43 PARTICLE ACCELERATORS; ABSORPTION; CATALYSTS; HYDROGEN; HYDROLYSIS; SPECTROSCOPY; SULFATES; SULFATION; SULFIDES; SULFUR; SYNCHROTRONS; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY; national synchrotron light source

Citation Formats

Kim, D, Szanyi, J, Kwak, J, Wang, X, Hanson, J, Engelhard, M, and Peden, C. Effects of Sulfation Level on the Desulfation Behavior of Presulfated Pt-BaO/Al2O3 Lean. United States: N. p., 2009. Web. doi:10.1021/jp900304h.
Kim, D, Szanyi, J, Kwak, J, Wang, X, Hanson, J, Engelhard, M, & Peden, C. Effects of Sulfation Level on the Desulfation Behavior of Presulfated Pt-BaO/Al2O3 Lean. United States. doi:10.1021/jp900304h.
Kim, D, Szanyi, J, Kwak, J, Wang, X, Hanson, J, Engelhard, M, and Peden, C. Thu . "Effects of Sulfation Level on the Desulfation Behavior of Presulfated Pt-BaO/Al2O3 Lean". United States. doi:10.1021/jp900304h.
@article{osti_980171,
title = {Effects of Sulfation Level on the Desulfation Behavior of Presulfated Pt-BaO/Al2O3 Lean},
author = {Kim, D and Szanyi, J and Kwak, J and Wang, X and Hanson, J and Engelhard, M and Peden, C},
abstractNote = {Desulfation by hydrogen of presulfated Pt (2 wt %)-BaO(20 wt %)/Al2O3 with various sulfur loading (S/Ba = 0.12, 0.31, and 0.62) were investigated by combining H2 temperature programmed reaction (TPRX), X-ray photoelectron spectroscopy (XPS), in situ sulfur K-edge X-ray absorption near-edge spectroscopy (XANES), and synchrotron time-resolved X-ray diffraction (TR-XRD) techniques. We find that the amount of H2S desorbed during the desulfation in the H2 TPRX experiments is not proportional to the amount of initial sulfur loading. The results of both in situ sulfur K-edge XANES and TR-XRD show that at low sulfur loadings, sulfates were transformed to a BaS phase and remained in the catalyst rather than being removed as H2S. On the other hand, when the deposited sulfur level exceeded a certain threshold (at least S/Ba = 0.31) sulfates were reduced to form H2S, and the relative amount of the residual sulfide species in the catalyst was much less than at low sulfur loading. Unlike samples with high sulfur loading (e.g., S/Ba = 0.62), H2O did not promote the desulfation for the sample with S/Ba of 0.12, implying that the formed BaS species originating from the reduction of sulfates at low sulfur loading are more stable to hydrolysis. The results of this combined spectroscopy investigation provide clear evidence to show that sulfates at low sulfur loadings are less likely to be removed as H2S and have a greater tendency to be transformed to BaS on the material, leading to the conclusion that desulfation behavior of Pt-BaO/Al2O3 lean NOx trap catalysts is markedly dependent on the sulfation levels.},
doi = {10.1021/jp900304h},
journal = {Journal of Physical Chemistry C},
issn = {1932-7447},
number = ,
volume = 113,
place = {United States},
year = {2009},
month = {1}
}