TY - JOUR
T1 - Preferential CO oxidation in hydrogen-rich stream over Pt catalysts modified with alkali metals. Part II. Catalyst characterization and role of alkali metals
AU - Tanaka, Hisanori
AU - Kuriyama, Masatoshi
AU - Ishida, Yoichi
AU - Ito, Shin ichi
AU - Kubota, Takeshi
AU - Miyao, Toshihiro
AU - Naito, Shuichi
AU - Tomishige, Keiichi
AU - Kunimori, Kimio
PY - 2008/7/1
Y1 - 2008/7/1
N2 - The addition of alkali metals over Pt/Al2O3 has both promoting and negative effects on the catalytic performance in the preferential CO oxidation in H2-rich stream (PROX), therefore there is an optimum amount of alkali metal. The Pt/Al2O3 catalysts modified with Na, K, Rb and Cs were characterized by means of transmission electron microscopy (TEM), extended X-ray absorption fine structure (EXAFS), X-ray absorption near-edge structure (XANES), and Fourier transform infrared spectroscopy (FTIR). The results show that the addition of larger amount of alkali metals with stronger basicity causes the aggregation of Pt metal particles. The Pt particles on Pt/Al2O3 modified with alkali metals are more electron-deficient than those on Pt/Al2O3, and this weakens the strength of CO adsorption on Pt/Al2O3 modified with alkali metals, which is related to the enhancement of turnover frequency of the PROX. In addition, in situ FTIR observation suggests that the coadsorbed species originating from H2 and O2 (e.g., the OH species) under the PROX condition, which promote the CO oxidation, can be found on highly active catalysts.
AB - The addition of alkali metals over Pt/Al2O3 has both promoting and negative effects on the catalytic performance in the preferential CO oxidation in H2-rich stream (PROX), therefore there is an optimum amount of alkali metal. The Pt/Al2O3 catalysts modified with Na, K, Rb and Cs were characterized by means of transmission electron microscopy (TEM), extended X-ray absorption fine structure (EXAFS), X-ray absorption near-edge structure (XANES), and Fourier transform infrared spectroscopy (FTIR). The results show that the addition of larger amount of alkali metals with stronger basicity causes the aggregation of Pt metal particles. The Pt particles on Pt/Al2O3 modified with alkali metals are more electron-deficient than those on Pt/Al2O3, and this weakens the strength of CO adsorption on Pt/Al2O3 modified with alkali metals, which is related to the enhancement of turnover frequency of the PROX. In addition, in situ FTIR observation suggests that the coadsorbed species originating from H2 and O2 (e.g., the OH species) under the PROX condition, which promote the CO oxidation, can be found on highly active catalysts.
KW - Alkali metals
KW - FTIR
KW - OH group
KW - Platinum
KW - Potassium
KW - Preferential CO oxidation
KW - X-ray absorption fine structure
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U2 - 10.1016/j.apcata.2008.03.029
DO - 10.1016/j.apcata.2008.03.029
M3 - Article
AN - SCOPUS:43849091137
SN - 0926-860X
VL - 343
SP - 125
EP - 133
JO - Applied Catalysis A: General
JF - Applied Catalysis A: General
IS - 1-2
ER -