TY - JOUR
T1 - Effects of nanocrystalline CeO2 supports on the properties and performance of Ni-Rh bimetallic catalyst for oxidative steam reforming of ethanol
AU - Kugai, Junichiro
AU - Subramani, Velu
AU - Song, Chunshan
AU - Engelhard, Mark H.
AU - Chin, Ya Huei
N1 - Funding Information:
The authors are grateful to the Nippon Shokubai Co., Ltd, and Pennsylvania State University for supporting this work and to Rhodia Chemicals Company for its generous gift of the CeO 2 samples. The Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility at Pacific Northwest National Laboratory (PNNL), Richland, WA is gratefully acknowledged for XPS measurements under proposal 6300. Chunshan Song thanks the U.S. Department of State and the U.S.–U.K. Fulbright Commission for the Fulbright Distinguished Scholar award in conjunction with his sabbatical stay at Imperial College London, University of London.
PY - 2006/3/10
Y1 - 2006/3/10
N2 - This study focuses on the effects of the CeO2 support properties on the catalyst properties and performance of bimetallic Ni-Rh/CeO2 catalysts containing 5 wt% Ni and 1 wt% Rh for the oxidative steam reforming (OSR) of ethanol for hydrogen production and fuel cell applications. Three CeO2 supports with different crystal sizes and surface areas were examined. The surface areas of these supports increases in the order of CeO2-I (74 m2/g) < CeO2-II (92 m2/g) < CeO2-III (154 m2/g), but their crystallite sizes were about 10.2, 29.3, and 6.5 nm, respectively. The properties of Ni-Rh/CeO2 catalysts were investigated by XRD, TPR, H2 chemisorption, and in situ XPS techniques. The Rh metal dispersion increased while the Ni metal dispersion decreased with decreasing crystallite sizes of CeO2. TPR studies revealed the existence of a Rh-CeO2 metal-support interaction as well as Ni-Rh interaction in the Ni-Rh bimetallic catalyst supported on CeO2-III with a crystallite size of about 6.5 nm. The in situ XPS studies corroborated the TPR results. The reduced Ni and Rh species were reversibly oxidized, suggesting the existence of Ni-Rh redox species rather than NiRh surface alloy in the present catalyst system. The Rh species became highly dispersed when the crystallite size of CeO2 support was smaller. Comparing the catalytic performance in the OSR of ethanol with the properties of the catalysts demonstrated that both ethanol conversion and H2 selectivity increased and the selectivity for undesirable byproducts decreased with increasing Rh metal dispersion. Best catalytic performance for OSR was achieved by supporting Ni-Rh bimetallic catalysts on the nanocrystalline CeO 2-III. The Ni-Rh/CeO2-III catalyst exhibited stable activity and selectivity during on-stream operations at 450 °C and as well as at 600 °C.
AB - This study focuses on the effects of the CeO2 support properties on the catalyst properties and performance of bimetallic Ni-Rh/CeO2 catalysts containing 5 wt% Ni and 1 wt% Rh for the oxidative steam reforming (OSR) of ethanol for hydrogen production and fuel cell applications. Three CeO2 supports with different crystal sizes and surface areas were examined. The surface areas of these supports increases in the order of CeO2-I (74 m2/g) < CeO2-II (92 m2/g) < CeO2-III (154 m2/g), but their crystallite sizes were about 10.2, 29.3, and 6.5 nm, respectively. The properties of Ni-Rh/CeO2 catalysts were investigated by XRD, TPR, H2 chemisorption, and in situ XPS techniques. The Rh metal dispersion increased while the Ni metal dispersion decreased with decreasing crystallite sizes of CeO2. TPR studies revealed the existence of a Rh-CeO2 metal-support interaction as well as Ni-Rh interaction in the Ni-Rh bimetallic catalyst supported on CeO2-III with a crystallite size of about 6.5 nm. The in situ XPS studies corroborated the TPR results. The reduced Ni and Rh species were reversibly oxidized, suggesting the existence of Ni-Rh redox species rather than NiRh surface alloy in the present catalyst system. The Rh species became highly dispersed when the crystallite size of CeO2 support was smaller. Comparing the catalytic performance in the OSR of ethanol with the properties of the catalysts demonstrated that both ethanol conversion and H2 selectivity increased and the selectivity for undesirable byproducts decreased with increasing Rh metal dispersion. Best catalytic performance for OSR was achieved by supporting Ni-Rh bimetallic catalysts on the nanocrystalline CeO 2-III. The Ni-Rh/CeO2-III catalyst exhibited stable activity and selectivity during on-stream operations at 450 °C and as well as at 600 °C.
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U2 - 10.1016/j.jcat.2006.01.001
DO - 10.1016/j.jcat.2006.01.001
M3 - Article
AN - SCOPUS:32444447286
SN - 0021-9517
VL - 238
SP - 430
EP - 440
JO - Journal of Catalysis
JF - Journal of Catalysis
IS - 2
ER -
