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Title: Effects of Reduction Temperature and Metal-support Interactions on the Catalytic Activity of Pt/γ-Al2O3 and Pt/TiO2 for the Oxidation of CO in the Presence and Absence of H2

Abstract

TiO2- and ?-Al2O3-supported Pt catalysts were characterized by HRTEM, XPS, EXAFS, and in-situ FTIR after activation at various conditions and their catalytic properties were examined for the oxidation of CO in the absence and presence of H2 (PROX). When ?-Al2O3 was used as the support, the catalytic, electronic, and structural properties of the Pt particles formed were not affected substantially by the pretreatment conditions. In contrast, the surface properties and catalytic activity of Pt/TiO2 were strongly influenced by the pretreatment conditions. In this case, an increase in the reduction temperature led to higher electron density on Pt, altering its chemisorptive properties, weakening the Pt-CO bonds, and increasing its activity for the oxidation of CO. The in-situ FTIR data suggest that both the terminal and bridging CO species adsorbed on fully reduced Pt are active for this reaction. The high activity of Pt/TiO2 for the oxidation of CO can also be attributed to the ability of TiO2 to provide or stabilize highly reactive oxygen species at the metal-support interface. However, such species appear to be more reactive towards H2 than CO. Consequently, Pt/TiO2 shows substantially lower selectivities towards CO oxidation under PROX conditions than Pt/?-Al2O3.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
878276
Report Number(s):
PNNL-SA-47758
Journal ID: ISSN 1089-5647; JPCBFK; 3521; KP1303000; TRN: US200611%%56
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical; Journal Volume: 109; Journal Issue: 49
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CATALYSTS; ELECTRON DENSITY; OXIDATION; OXYGEN; SURFACE PROPERTIES; X-RAY PHOTOELECTRON SPECTROSCOPY; Environmental Molecular Sciences Laboratory

Citation Formats

Alexeev, Oleg S., Chin, Soo Yin, Engelhard, Mark H., Ortiz-Soto, Lorna, and Amiridis, Michael D. Effects of Reduction Temperature and Metal-support Interactions on the Catalytic Activity of Pt/γ-Al2O3 and Pt/TiO2 for the Oxidation of CO in the Presence and Absence of H2. United States: N. p., 2005. Web. doi:10.1021/jp054888v.
Alexeev, Oleg S., Chin, Soo Yin, Engelhard, Mark H., Ortiz-Soto, Lorna, & Amiridis, Michael D. Effects of Reduction Temperature and Metal-support Interactions on the Catalytic Activity of Pt/γ-Al2O3 and Pt/TiO2 for the Oxidation of CO in the Presence and Absence of H2. United States. doi:10.1021/jp054888v.
Alexeev, Oleg S., Chin, Soo Yin, Engelhard, Mark H., Ortiz-Soto, Lorna, and Amiridis, Michael D. Thu . "Effects of Reduction Temperature and Metal-support Interactions on the Catalytic Activity of Pt/γ-Al2O3 and Pt/TiO2 for the Oxidation of CO in the Presence and Absence of H2". United States. doi:10.1021/jp054888v.
@article{osti_878276,
title = {Effects of Reduction Temperature and Metal-support Interactions on the Catalytic Activity of Pt/γ-Al2O3 and Pt/TiO2 for the Oxidation of CO in the Presence and Absence of H2},
author = {Alexeev, Oleg S. and Chin, Soo Yin and Engelhard, Mark H. and Ortiz-Soto, Lorna and Amiridis, Michael D.},
abstractNote = {TiO2- and ?-Al2O3-supported Pt catalysts were characterized by HRTEM, XPS, EXAFS, and in-situ FTIR after activation at various conditions and their catalytic properties were examined for the oxidation of CO in the absence and presence of H2 (PROX). When ?-Al2O3 was used as the support, the catalytic, electronic, and structural properties of the Pt particles formed were not affected substantially by the pretreatment conditions. In contrast, the surface properties and catalytic activity of Pt/TiO2 were strongly influenced by the pretreatment conditions. In this case, an increase in the reduction temperature led to higher electron density on Pt, altering its chemisorptive properties, weakening the Pt-CO bonds, and increasing its activity for the oxidation of CO. The in-situ FTIR data suggest that both the terminal and bridging CO species adsorbed on fully reduced Pt are active for this reaction. The high activity of Pt/TiO2 for the oxidation of CO can also be attributed to the ability of TiO2 to provide or stabilize highly reactive oxygen species at the metal-support interface. However, such species appear to be more reactive towards H2 than CO. Consequently, Pt/TiO2 shows substantially lower selectivities towards CO oxidation under PROX conditions than Pt/?-Al2O3.},
doi = {10.1021/jp054888v},
journal = {Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical},
number = 49,
volume = 109,
place = {United States},
year = {Thu Dec 15 00:00:00 EST 2005},
month = {Thu Dec 15 00:00:00 EST 2005}
}
  • TiO2- and -Al2O3-supported Pt catalysts were characterized by HRTEM, XPS, EXAFS, and in situ FTIR spectroscopy after activation at various conditions, and their catalytic properties were examined for the oxidation of CO in the absence and presence of H2 (PROX). When {gamma}-Al{sub 2}O{sub 3} was used as the support, the catalytic, electronic, and structural properties of the Pt particles formed were not affected substantially by the pretreatment conditions. In contrast, the surface properties and catalytic activity of Pt/TiO2 were strongly influenced by the pretreatment conditions. In this case, an increase in the reduction temperature led to higher electron density onmore » Pt, altering its chemisorptive properties, weakening the Pt-CO bonds, and increasing its activity for the oxidation of CO. The in situ FTIR data suggest that both the terminal and bridging CO species adsorbed on fully reduced Pt are active for this reaction. The high activity of Pt/TiO2 for the oxidation of CO can also be attributed to the ability of TiO2 to provide or stabilize highly reactive oxygen species at the metal-support interface. However, such species appear to be more reactive toward H{sub 2} than CO. Consequently, Pt/TiO{sub 2} shows substantially lower selectivities toward CO oxidation under PROX conditions than Pt/{gamma}-Al{sub 2}O{sub 3}.« less
  • Low temperature (308 K) hydrogenation of acetone was used as a probe reaction to investigate the support effect on the hydrogenation activity of Pt/Ni bimetallic catalysts supported on TiO{sub 2}, SiO{sub 2} and {gamma}-Al{sub 2}O{sub 3}. The oxide supports significantly affected the catalytic properties of Pt/Ni catalysts, in which Pt/Ni/SiO2 bimetallic catalysts exhibited significantly higher activity than the other two bimetallic catalysts. TEM measurements revealed that the three supported Pt/Ni bimetallic catalysts have similar particle size distribution, while CO chemisorption measurements showed very different chemisorption capacity. Extended X-Ray absorption fine structure (EXAFS) measurements of the Pt L{sub III}-edge indicated thatmore » Pt atoms were fully reduced and the Pt-Ni bimetallic bonds were formed on all three catalysts. The extent of Pt-Ni bond formation followed the trend of SiO{sub 2} > {gamma}-Al{sub 2}O{sub 3} > TiO{sub 2}, which correlated very well with the hydrogenation activity.« less
  • Low temperature (308 K) hydrogenation of acetone was used as a probe reaction to investigate the support effect on the hydrogenation activity of Pt/Ni bimetallic catalysts supported on TiO{sub 2}, SiO{sub 2} and γ-Al{sub 2}O{sub 3}. The oxide supports significantly affected the catalytic properties of Pt/Ni catalysts, in which Pt/Ni/SiO{sub 2} bimetallic catalysts exhibited significantly higher activity than the other two bimetallic catalysts. TEM measurements revealed that the three supported Pt/Ni bimetallic catalysts have similar particle size distribution, while CO chemisorption measurements showed very different chemisorption capacity. Extended X-Ray absorption fine structure (EXAFS) measurements of the Pt LIII-edge indicated thatmore » Pt atoms were fully reduced and the Pt–Ni bimetallic bonds were formed on all three catalysts. The extent of Pt–Ni bond formation followed the trend of SiO{sub 2} > γ-Al{sub 2}O{sub 3} > TiO{sub 2}, which correlated very well with the hydrogenation activity.« less