TY - JOUR
T1 - Pd-, Pt-, and Rh-loaded Ce0.6Zr0.35Y0.05O2 three-way catalysts
T2 - An investigation on performance and redox properties
AU - He, H.
AU - Dai, H. X.
AU - Ng, L. H.
AU - Wong, K. W.
AU - Au, C. T.
N1 - Funding Information:
The work described in this paper was supported by a grant from the Hong Kong Baptist University (FRG/00-01/I-15).
PY - 2002
Y1 - 2002
N2 - The redox behaviors, oxygen mobilities, and oxygen storage capacities of Ce0.6Zr0.4O2 (CZ), Ce0.6Zr0.35Y0.05O2 (CZY), and 0.5 wt% M/CZY (M = Pd, Pt, Rh) as well as the three-way catalytic performance of the noble metal-loaded CZY materials have been investigated. It is observed that at a space velocity of 60, 000 h−1 and in an atmosphere close to the theoretical air-to-fuel ratio (i.e., 14.6), the CZY-supported precious metal catalysts showed good three-way catalytic activity. X-ray diffraction investigations revealed that there are two phases (cubic Ce0.75Zr0.25O2, major; cubic ZrO1.87, minor) in CZ, CZY, and 0.5 wt% M/CZY. These materials are porous and large in surface area. According to the results of Ce 3d X-ray photoelectron spectroscopic studies, the doping of Y3+ ions into the CZ lattice would cause the concentrations of oxygen vacancies and Ce3+ ions to increase. The results of H2(or CO)-O2 titration and temperature-programmed reduction-reoxidation experiments indicate the presence of a reversible redox behavior of Ce4+/Ce3+ couples. The results of 18O/16O isotope exchange studies show that in the presence of oxygen vacancies and noble metals, the mobility of lattice oxygen on/in CZY is promoted. Based on the above outcomes, we suggest that by incorporating Y3+ ions into CZ and loading Pd, Pt, or Rh on CZY, one can enhance (i) lattice oxygen mobility, (ii) Ce3+ ion concentration, and (iii) oxygen uptake capacity of the CZY solid solution, generating a class of materials suitable for the catalytic conversion of automotive exhaust.
AB - The redox behaviors, oxygen mobilities, and oxygen storage capacities of Ce0.6Zr0.4O2 (CZ), Ce0.6Zr0.35Y0.05O2 (CZY), and 0.5 wt% M/CZY (M = Pd, Pt, Rh) as well as the three-way catalytic performance of the noble metal-loaded CZY materials have been investigated. It is observed that at a space velocity of 60, 000 h−1 and in an atmosphere close to the theoretical air-to-fuel ratio (i.e., 14.6), the CZY-supported precious metal catalysts showed good three-way catalytic activity. X-ray diffraction investigations revealed that there are two phases (cubic Ce0.75Zr0.25O2, major; cubic ZrO1.87, minor) in CZ, CZY, and 0.5 wt% M/CZY. These materials are porous and large in surface area. According to the results of Ce 3d X-ray photoelectron spectroscopic studies, the doping of Y3+ ions into the CZ lattice would cause the concentrations of oxygen vacancies and Ce3+ ions to increase. The results of H2(or CO)-O2 titration and temperature-programmed reduction-reoxidation experiments indicate the presence of a reversible redox behavior of Ce4+/Ce3+ couples. The results of 18O/16O isotope exchange studies show that in the presence of oxygen vacancies and noble metals, the mobility of lattice oxygen on/in CZY is promoted. Based on the above outcomes, we suggest that by incorporating Y3+ ions into CZ and loading Pd, Pt, or Rh on CZY, one can enhance (i) lattice oxygen mobility, (ii) Ce3+ ion concentration, and (iii) oxygen uptake capacity of the CZY solid solution, generating a class of materials suitable for the catalytic conversion of automotive exhaust.
KW - Lattice oxygen mobility
KW - Noble metal (Pd, Pt, Rh)-loaded CeZrYO catalysts
KW - Oxygen storage capacity
KW - Three-way exhaust catalysts
KW - Yttrium-incorporated CeO-ZrO solid solutions
UR - http://www.scopus.com/inward/record.url?scp=85006932917&partnerID=8YFLogxK
U2 - 10.1006/jcat.2001.3466
DO - 10.1006/jcat.2001.3466
M3 - Journal article
AN - SCOPUS:85006932917
SN - 0021-9517
VL - 206
SP - 1
EP - 13
JO - Journal of Catalysis
JF - Journal of Catalysis
IS - 1
ER -