TY - JOUR
T1 - Activation of Pd/SSZ-13 catalyst by hydrothermal aging treatment in passive NO adsorption performance at low temperature for cold start application
AU - Ryou, Young Seok
AU - Lee, Jaeha
AU - Cho, Sung June
AU - Lee, Hyokyoung
AU - Kim, Chang Hwan
AU - Kim, Do Heui
N1 - Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2017
Y1 - 2017
N2 - Pd/SSZ-13 catalysts after hydrothermal aging (HTA) treatment at 750 °C for 25 h showed enhanced passive NO adsorption performance at temperature below 120 °C, which will be suitable for cold start application, although those calcined at 500 °C did not possess good NO adsorption capacity irrespective of the preparation methods such as incipient wetness impregnation, wet impregnation, ion-exchange, and solid state ion exchange. NO adsorption ability of HTA treated Pd/SSZ-13 samples increases gradually as a function of the metal content, up to 2 wt% Pd loading, and then decreased implying that there is an optimum chemistry between the metal and zeolite support. Combined H2-TPR and Pd XAFS results clearly demonstrate that PdO mainly existed over the fresh samples, whereas HTA treated samples contained ionic Pd2+ species, indicating the redistribution of PdO into highly dispersed Pd2+ species within the SSZ-13 structure arising from HTA treatment. Such phenomenon was visually confirmed by comparative STEM-EDS analysis of fresh and HTA Pd/SSZ-13 samples. DRIFT results display the formation of two nitrosyl complexes adsorbed on Pd2+ ions, which are directly related to two desorption peaks of NOx at 250 and 400 °C. All combined results provide the unambiguous evidence about the generation of Pd ions in SSZ-13 zeolite induced by HTA treatment, which play as the active sites for NO adsorption at low temperature.
AB - Pd/SSZ-13 catalysts after hydrothermal aging (HTA) treatment at 750 °C for 25 h showed enhanced passive NO adsorption performance at temperature below 120 °C, which will be suitable for cold start application, although those calcined at 500 °C did not possess good NO adsorption capacity irrespective of the preparation methods such as incipient wetness impregnation, wet impregnation, ion-exchange, and solid state ion exchange. NO adsorption ability of HTA treated Pd/SSZ-13 samples increases gradually as a function of the metal content, up to 2 wt% Pd loading, and then decreased implying that there is an optimum chemistry between the metal and zeolite support. Combined H2-TPR and Pd XAFS results clearly demonstrate that PdO mainly existed over the fresh samples, whereas HTA treated samples contained ionic Pd2+ species, indicating the redistribution of PdO into highly dispersed Pd2+ species within the SSZ-13 structure arising from HTA treatment. Such phenomenon was visually confirmed by comparative STEM-EDS analysis of fresh and HTA Pd/SSZ-13 samples. DRIFT results display the formation of two nitrosyl complexes adsorbed on Pd2+ ions, which are directly related to two desorption peaks of NOx at 250 and 400 °C. All combined results provide the unambiguous evidence about the generation of Pd ions in SSZ-13 zeolite induced by HTA treatment, which play as the active sites for NO adsorption at low temperature.
KW - Cold start application
KW - Hydrothermal aging treatment
KW - Low temperature NO adsorption
KW - Pd ion exchange
KW - Pd/SSZ-13
UR - https://www.scopus.com/pages/publications/85018759276
U2 - 10.1016/j.apcatb.2017.04.077
DO - 10.1016/j.apcatb.2017.04.077
M3 - Article
AN - SCOPUS:85018759276
SN - 0926-3373
VL - 212
SP - 140
EP - 149
JO - Applied Catalysis B: Environmental
JF - Applied Catalysis B: Environmental
ER -