TY - JOUR
T1 - Effect of reduction treatments (H2 vs. CO) on the NO adsorption ability and the physicochemical properties of Pd/SSZ-13 passive NOx adsorber for cold start application
AU - Ryou, Young Seok
AU - Lee, Jaeha
AU - Kim, Yongwoo
AU - Hwang, Sungha
AU - Lee, Hyokyoung
AU - Kim, Chang Hwan
AU - Kim, Do Heui
N1 - Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2019/1/5
Y1 - 2019/1/5
N2 - Pd/SSZ-13, which has ability to adsorb NO at low temperature, is potentially used as a passive NOx adsorber for cold start application. We investigate the changes in the physicochemical properties and low temperature NO adsorption ability of Pd/SSZ-13 resulting from the reduction treatments with H2 or CO at various temperatures. Treatment with H2 at 500 °C does not give rise to the decrease in NO adsorption ability. However, the ability begins to decrease gradually with the increasing reduction temperature from 600 to 900 °C. On the other hand, CO treatment at 500 °C induces a significant decrease in NO adsorption ability. Combined EXAFS, HAADF-STEM and H2-TPR results clearly demonstrate that CO treatment induced more severe sintering of Pd species than H2 one at the same reduction temperature. After re-oxidation at 500 °C, H2-treated sample generated Pd ion species, which are the active site for NO adsorption at low temperature, more abundantly than CO-treated one, well corresponding to the higher NO adsorption ability over the former sample. Such phenomenon is attributed to the facile sintering behavior due to the high mobility of Pd-carbonyl complex upon the treatment with CO. It can be concluded that the reduction treatments with H2 and CO have different effect on Pd sintering, which is regarded as the main deactivation mechanism of Pd/SSZ-13 passive NOx adsorber.
AB - Pd/SSZ-13, which has ability to adsorb NO at low temperature, is potentially used as a passive NOx adsorber for cold start application. We investigate the changes in the physicochemical properties and low temperature NO adsorption ability of Pd/SSZ-13 resulting from the reduction treatments with H2 or CO at various temperatures. Treatment with H2 at 500 °C does not give rise to the decrease in NO adsorption ability. However, the ability begins to decrease gradually with the increasing reduction temperature from 600 to 900 °C. On the other hand, CO treatment at 500 °C induces a significant decrease in NO adsorption ability. Combined EXAFS, HAADF-STEM and H2-TPR results clearly demonstrate that CO treatment induced more severe sintering of Pd species than H2 one at the same reduction temperature. After re-oxidation at 500 °C, H2-treated sample generated Pd ion species, which are the active site for NO adsorption at low temperature, more abundantly than CO-treated one, well corresponding to the higher NO adsorption ability over the former sample. Such phenomenon is attributed to the facile sintering behavior due to the high mobility of Pd-carbonyl complex upon the treatment with CO. It can be concluded that the reduction treatments with H2 and CO have different effect on Pd sintering, which is regarded as the main deactivation mechanism of Pd/SSZ-13 passive NOx adsorber.
KW - Cold start application
KW - H and CO aging
KW - Low temperature NO adsorption
KW - Pd/SSZ-13
UR - http://www.scopus.com/inward/record.url?scp=85055314248&partnerID=8YFLogxK
U2 - 10.1016/j.apcata.2018.10.016
DO - 10.1016/j.apcata.2018.10.016
M3 - Article
AN - SCOPUS:85055314248
SN - 0926-860X
VL - 569
SP - 28
EP - 34
JO - Applied Catalysis A: General
JF - Applied Catalysis A: General
ER -