TY - JOUR
T1 - Improvement in heat resistance of NOx trap catalyst using Ti-Na binary metal oxide as NOx trap material
AU - Iizuka, Hidehiro
AU - Kaneeda, Masato
AU - Shinotsuka, Norihiro
AU - Kuroda, Osamu
AU - Higashiyama, Kazutoshi
AU - Miyamoto, Akira
PY - 2010/4/6
Y1 - 2010/4/6
N2 - The purpose of this study was to identify suitable base materials for NOx trap catalysts from the viewpoint of heat resistance. First, suitable elements among alkali metals (M: K, Na, Li) and alkaline earth metals (M: Ba, Ca, Sr, Mg) were evaluated using M-Rh,Pt/Al2O3. Na was found to be the most suitable element that combines NOx trap performance with hydrocarbon purification performance after heat treatment at 973 K. Moreover, the effects of binary metal oxides with Na and M′ (Zr, Fe, W, Mo, Ti) were evaluated to improve the heat resistance of Na-Rh,Pt/Al2O3. The ranking of the NOx trap activity of M′ was Ti > none > Fe > W > Zr > Mo; Ti was the most suitable additional element for improving heat resistance of Na-Rh,Pt/Al2O3. The maximum amount of NOx conversion and the maximum number of base sites of Ti,Na-Rh,Pt/Al2O3 were reached at a Ti/Na mol ratio of 0.1. It was inferred that the addition of Ti to Na-Rh,Pt/Al2O3 formed a Ti-Na binary metal oxide from catalyst characterisation by X-ray diffraction and X-ray photoelectron spectrometry, and this Ti-Na binary metal oxide improved the thermal stability of Na-Rh,Pt/Al2O3. Finally, from vehicle tests, it was clear that the NOx trap catalyst, which supported Ti-Na binary metal oxide, exhibited high heat resistance.
AB - The purpose of this study was to identify suitable base materials for NOx trap catalysts from the viewpoint of heat resistance. First, suitable elements among alkali metals (M: K, Na, Li) and alkaline earth metals (M: Ba, Ca, Sr, Mg) were evaluated using M-Rh,Pt/Al2O3. Na was found to be the most suitable element that combines NOx trap performance with hydrocarbon purification performance after heat treatment at 973 K. Moreover, the effects of binary metal oxides with Na and M′ (Zr, Fe, W, Mo, Ti) were evaluated to improve the heat resistance of Na-Rh,Pt/Al2O3. The ranking of the NOx trap activity of M′ was Ti > none > Fe > W > Zr > Mo; Ti was the most suitable additional element for improving heat resistance of Na-Rh,Pt/Al2O3. The maximum amount of NOx conversion and the maximum number of base sites of Ti,Na-Rh,Pt/Al2O3 were reached at a Ti/Na mol ratio of 0.1. It was inferred that the addition of Ti to Na-Rh,Pt/Al2O3 formed a Ti-Na binary metal oxide from catalyst characterisation by X-ray diffraction and X-ray photoelectron spectrometry, and this Ti-Na binary metal oxide improved the thermal stability of Na-Rh,Pt/Al2O3. Finally, from vehicle tests, it was clear that the NOx trap catalyst, which supported Ti-Na binary metal oxide, exhibited high heat resistance.
KW - Alkali metals
KW - Alkaline earth metals
KW - Binary metal oxide
KW - Heat resistance
KW - NOx trap catalyst
KW - Na
KW - Ti
UR - http://www.scopus.com/inward/record.url?scp=77949296658&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=77949296658&partnerID=8YFLogxK
U2 - 10.1016/j.apcatb.2010.01.010
DO - 10.1016/j.apcatb.2010.01.010
M3 - Article
AN - SCOPUS:77949296658
SN - 0926-3373
VL - 95
SP - 320
EP - 326
JO - Applied Catalysis B: Environmental
JF - Applied Catalysis B: Environmental
IS - 3-4
ER -