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Effect of Ag loading on praseodymium doped ceria catalyst for soot oxidation activity
Pandurangappa Govardhan,Anjana Payyalore Anantharaman,Sunaina Shivasharanappa Patil,Hari Prasad Dasari,Harshini Dasari,Atmuri Shourya 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.2
Silver-loaded praseodymium doped ceria (XAg/PDC) was synthesized by microwave-assisted co-precipitation and wetness impregnation. XRD confirms the fluorite structure of ceria without secondary phase, and Raman spectroscopy represents the increased generation of oxygen vacancies with Ag loading. The TEM analysis shows lattice fringes corresponding to both CeO2 and Ag on the surface. The BET and BJH analysis of catalyst confirms the high porosity accompanied by high surface area and pore diameter of 5Ag/PDC and 15Ag/PDC, making it more active for the oxidation reaction. From the XPS analysis the amount of surface Ce3+ concentration and the surface chemisorbed oxygen species (O2 2) is high for 5Ag/PDC and 15Ag/PDC, in line with XRD and Raman results. The soot oxidation T50 temperature follows the trend: 5Ag/PDC~15Ag/PDC>10Ag/PDC>20Ag/PDC>0Ag/PDC. The Ag loading increased the surface reducibility of cerium ions and thus 5 wt% was optimized.
Hari Prasad Uppara,Sunit Kumar Singh,Nitin Kumar Labhsetwar,Mudiyaru Subrahmanya Murari,Harshini Dasari 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.7
The synthesis of binary mixed oxide Ce-Hf (CH), ternary mixed oxide Ce-Hf-Ru (CHR), and Ce-Hf-Mg (CHM) has been attempted using the PVP-assisted sol-gel method. The structural and surface morphology of the prepared catalysts were investigated and studied for the generation of superoxides (O2 )/peroxides (O2 2) species and availability of lattice oxygen (O) during soot oxidation reactions. The successfully incorporated Hf4+/Mg2+ into ceria (CH, CHM) enhances the redox potential sites on nano-flake morphology, thus produces more oxygen vacancies (□). However, Ru4+/Hf4+ was not doped into the ceria structure in CHR catalyst; it showed lesser structural distortions generating fewer oxygen vacancies. In addition, it was observed that better performing catalysts should possess lower oxidation temperature and be catalytically stable. Indeed, the ternary oxide CHR featured excellent catalytic properties when compared with the others. However, CHM was found structurally and catalytically stable with self-regenerative capability even after the repeated soot oxidation experiments. Thus, the possible soot oxidation mechanism has been proposed on the prepared catalysts.