Experimental Catalyst preparation The SnO CeO

SnO2-based materials have a lot of active surface oxygen species, as well as oxygen vacancies [15] and [16]. Consequently, they are regarded as one of potential alternatives for noble metal based catalysts in specific catalytic reactions, such as removal of nitrogen oxides [15] and [17] and CO ETP-46464 [18] and [19]. It was reported that doping Cr [20] and Fe [21] into the SnO2 catalyst could enhance the catalytic performance for methane combustion, probably due to the increased amount of the active oxygen species [20] and [21].
The CeO2-based materials are well known because of their high oxygen storage capacity (OSC) [22], [23], [24], [25] and [26], which are strongly related to the reversible Ce4+ ↔ Ce3+ redox reaction [22]. Attempts have been made to increase the amount of the Ce4+/Ce3+ redox couples, and thus, to increase the OSC by substituting a part of Ce with other elements, such as Zr [22], Ti [23], Hf [24], and Sn [25] and [26]. Because the reversible Sn4+ ↔ Sn2+ redox process involves two-electron transfer, the OSC of the Ce1−xSnxO2 materials are higher than other CeO2-based materials, such as Ce1−xZrxO2 [25] and [26] and Ce1−xTixO2 [26]. Accordingly, the SnO2–CeO2 composite oxides may highly active as a potential oxidation catalyst [26].