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Title: Effects of sulfation level on the desulfation behavior of pre-sulfated Pt BaO/Al2O3 lean NOx trap catalysts: a combined H2 Temperature-Programmed Reaction, in-situ sulfur K-edge X-ray Absorption Near-Edge Spectroscopy, X-ray Photoelectron Spectroscopy, and Time-Resolved X-ray Diffraction Study

Abstract

Desulfation by hydrogen of pre-sulfated Pt(2wt%) BaO(20wt%)/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 investigationmore » 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.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
958458
Report Number(s):
PNNL-SA-64098
Journal ID: ISSN 1932-7447; 19800; VT0401000; TRN: US1000384
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry C, 113(17):7336-7341
Additional Journal Information:
Journal Volume: 113; Journal Issue: 17; Journal ID: ISSN 1932-7447
Country of Publication:
United States
Language:
English
Subject:
08 HYDROGEN; 43 PARTICLE ACCELERATORS; ABSORPTION; CATALYSTS; HYDROGEN; HYDROLYSIS; SPECTROSCOPY; SULFATES; SULFATION; SULFIDES; SULFUR; SYNCHROTRONS; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY; Environmental Molecular Sciences Laboratory

Citation Formats

Kim, Do Heui, Szanyi, Janos, Kwak, Ja Hun, Wang, Xianqin, Hanson, Jonathan C, Engelhard, Mark H, and Peden, Charles HF. Effects of sulfation level on the desulfation behavior of pre-sulfated Pt BaO/Al2O3 lean NOx trap catalysts: a combined H2 Temperature-Programmed Reaction, in-situ sulfur K-edge X-ray Absorption Near-Edge Spectroscopy, X-ray Photoelectron Spectroscopy, and Time-Resolved X-ray Diffraction Study. United States: N. p., 2009. Web. doi:10.1021/jp900304h.
Kim, Do Heui, Szanyi, Janos, Kwak, Ja Hun, Wang, Xianqin, Hanson, Jonathan C, Engelhard, Mark H, & Peden, Charles HF. Effects of sulfation level on the desulfation behavior of pre-sulfated Pt BaO/Al2O3 lean NOx trap catalysts: a combined H2 Temperature-Programmed Reaction, in-situ sulfur K-edge X-ray Absorption Near-Edge Spectroscopy, X-ray Photoelectron Spectroscopy, and Time-Resolved X-ray Diffraction Study. United States. doi:10.1021/jp900304h.
Kim, Do Heui, Szanyi, Janos, Kwak, Ja Hun, Wang, Xianqin, Hanson, Jonathan C, Engelhard, Mark H, and Peden, Charles HF. Fri . "Effects of sulfation level on the desulfation behavior of pre-sulfated Pt BaO/Al2O3 lean NOx trap catalysts: a combined H2 Temperature-Programmed Reaction, in-situ sulfur K-edge X-ray Absorption Near-Edge Spectroscopy, X-ray Photoelectron Spectroscopy, and Time-Resolved X-ray Diffraction Study". United States. doi:10.1021/jp900304h.
@article{osti_958458,
title = {Effects of sulfation level on the desulfation behavior of pre-sulfated Pt BaO/Al2O3 lean NOx trap catalysts: a combined H2 Temperature-Programmed Reaction, in-situ sulfur K-edge X-ray Absorption Near-Edge Spectroscopy, X-ray Photoelectron Spectroscopy, and Time-Resolved X-ray Diffraction Study},
author = {Kim, Do Heui and Szanyi, Janos and Kwak, Ja Hun and Wang, Xianqin and Hanson, Jonathan C and Engelhard, Mark H and Peden, Charles HF},
abstractNote = {Desulfation by hydrogen of pre-sulfated Pt(2wt%) BaO(20wt%)/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, 113(17):7336-7341},
issn = {1932-7447},
number = 17,
volume = 113,
place = {United States},
year = {2009},
month = {4}
}