Impact of iso/aliovalent dopants in ceria solid solutions for improved CO oxidation

Ceria based solid solution (Cu0.08Mn0.02MxCe0.9-xO2) were synthesized by the co-precipitation method, followed by calcination at the temperature of 500 degrees C. These catalysts were examined for low-temperature oxidation of CO. A small content of iso/aliovalent dopants (Bi, Ti, Sn) resulted in an increase of the catalytic activity in CO oxidation. The addition of the dopant leads to a positive effect, while a further increase of its concentration leads to a decrease in activity possibly due to the dilution of the active surface with less active catalytic centers (Sn, Ti, and Bi replace Cu and Mn). CO is adsorbed on the Cu+, Mn2+, Mn3+, Sn2+ surface sites and directly oxidized by the oxygen species activated on the oxygen vacancies of ceria solid solution from the molecular oxygen in the reaction gas, so the activity for CO oxidation may be correlated with the concentration of these sites and oxygen vacancies.

Automated summary

Ceria based solid solution catalysts were synthesized and studied for CO oxidation, with the addition of a small amount of iso/aliovalent dopants (Bi, Ti, Sn) resulting in increased catalytic activity. However, a further increase in dopant concentration may decrease activity due to the dilution of active surface with less active catalytic centers.