CO oxidation on Ta-Modified SnO2 solid solution catalysts

• Ta cations can be doped into the matrix of SnO2 to form solid solution structure.
• Ta cations doped into SnO2 improve its CO oxidation activity significantly.
• In comparison, tantala dispersed onto SnO2 surface degrades its activity.
• Sn–Ta solid solution shows improved thermal stability and good water resistance.

Co-precipitation method was adopted to prepare Sn–Ta mixed oxide catalysts with different Sn/Ta molar ratios and used for CO oxidation. The catalysts were investigated by N2-Brunauer–Emmett–Teller (N2-BET), X-ray diffraction patterns (XRD), H2-temperature programmed reduction (H2-TPR), Thermal Gravity Analysis – Differential Scanning Calorimetry (TGA–DSC) techniques. It is revealed that a small amount of Ta cations can be doped into SnO2 lattice to form solid solution by co-precipitation method, which resulted in samples having higher surface areas, improved thermal stability and more deficient oxygen species on the surface of SnO2. As a result, those Sn rich Sn–Ta solid solution catalysts with an Sn/Ta molar ratio higher than 4/2 showed significantly enhanced activity as well as good resistance to water deactivation. It is noted here that if tantala disperses onto SnO2 surface instead of doping into its lattice, it will then have negative effect on its activity.

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