Tuning Al2O3 Surface with SnO2 to Prepare Improved Supports for Pd for CO Oxidation

SnO2/Al2O3 supports with different SnO2 loadings were prepared by using a deposition-precipitation method and characterized by using N-2 and CO adsorption-desorption, XRD, H-2 temperature-programmed reduction, and X-ray photoelectron spectroscopy techniques. SnO2 dispersed finely on the Al2O3 surface with a capacity of 0.172 mmol 100 m(-2), which equals 6.4% SnO2 loading. Below this loading, no crystalline SnO2 can be detected owing to the formation of the sub-monolayer-or monolayer-dispersed SnO2 phase. Crystalline SnO2 can be ob-served only if the SnO2 loading reaches 9%. With use of these SnO2/Al2O3 supports, all prepared Pd/SnO2/Al2O3 catalysts demonstrate increased activity compared to Pd/SnO2 and Pd/Al2O3 owing to the presence of more active oxygen species on SnO2/Al2O3 supports as well as their higher surface areas, which improve Pd dispersion. This result indicates that with SnO2/Al2O3 supports, less amount of Pd can be used to obtain catalysts with competitive performance.