TY - JOUR
T1 - Size-dependent activity of Pt/yttria-stabilized zirconia catalyst for ethylene and carbon monoxide oxidation in oxygen-free gas environment
AU - Isaifan, Rima J.
AU - Ntais, Spyridon
AU - Couillard, Martin
AU - Baranova, Elena A.
N1 - Publisher Copyright:
© 2015 Elsevier Inc. All rights reserved.
PY - 2015/4/1
Y1 - 2015/4/1
N2 - The effect of Pt average particle size (1.9-6.7 nm) on the catalytic activity of 909 ppm carbon monoxide and ethylene oxidation by O2- from yttria-stabilized zirconia (YSZ) was studied at 25-400 °C. The results show that CO and C2H4 oxidation in the absence of oxygen in the gas feed is strongly size dependent in analogy to their catalytic oxidation in oxygen-rich environment. Without oxygen, the local nano-galvanic cell mechanism is proposed, where CO and C2H4 electrooxidation at the three-phase boundary (tpb) is accompanied by partial surface electroreduction of zirconia. The smallest Pt nanoparticles (NPs) (1.9 ± 0.4 nm) have higher TOF, higher intrinsic rates and lower activation energies compared with the larger Pt NPs (4.4 ± 0.3 nm), for example 30.3 vs. 64.8 kJ mol-1 for CO and 12.5 vs. 38.4 kJ mol-1 for C2H4 oxidation, respectively. In the presence of oxygen, the catalytic oxidation occurs at significantly lower temperatures than without O2. In this case, the oxidation reaction takes place via a sacrificial promoter-type mechanism, proposed earlier for catalyst nanoparticles supported on YSZ, where thermally induced O2- backspillover migrates from YSZ to the gas-exposed surface of Pt NPs in parallel with the electrooxidation reaction at tpb.
AB - The effect of Pt average particle size (1.9-6.7 nm) on the catalytic activity of 909 ppm carbon monoxide and ethylene oxidation by O2- from yttria-stabilized zirconia (YSZ) was studied at 25-400 °C. The results show that CO and C2H4 oxidation in the absence of oxygen in the gas feed is strongly size dependent in analogy to their catalytic oxidation in oxygen-rich environment. Without oxygen, the local nano-galvanic cell mechanism is proposed, where CO and C2H4 electrooxidation at the three-phase boundary (tpb) is accompanied by partial surface electroreduction of zirconia. The smallest Pt nanoparticles (NPs) (1.9 ± 0.4 nm) have higher TOF, higher intrinsic rates and lower activation energies compared with the larger Pt NPs (4.4 ± 0.3 nm), for example 30.3 vs. 64.8 kJ mol-1 for CO and 12.5 vs. 38.4 kJ mol-1 for C2H4 oxidation, respectively. In the presence of oxygen, the catalytic oxidation occurs at significantly lower temperatures than without O2. In this case, the oxidation reaction takes place via a sacrificial promoter-type mechanism, proposed earlier for catalyst nanoparticles supported on YSZ, where thermally induced O2- backspillover migrates from YSZ to the gas-exposed surface of Pt NPs in parallel with the electrooxidation reaction at tpb.
KW - Local nano-galvanic cells
KW - Metal-support interaction
KW - Particle size
KW - Platinum nanoparticles
KW - Yttria-stabilized zirconia
UR - http://www.scopus.com/inward/record.url?scp=84923013452&partnerID=8YFLogxK
U2 - 10.1016/j.jcat.2015.01.010
DO - 10.1016/j.jcat.2015.01.010
M3 - Article
AN - SCOPUS:84923013452
SN - 0021-9517
VL - 324
SP - 32
EP - 40
JO - Journal of Catalysis
JF - Journal of Catalysis
ER -