Novel Pd/SnxZr1−xO2 catalysts for methane total oxidation at low temperature and their 18O-isotope exchange behavior

SnxZr1−xO2 solid solution-supported palladium catalysts were prepared and evaluated for the catalytic combustion of methane at low temperature. Catalyst Pd/Sn0.4Zr0.6O2 with the highest activity (T90% = 378 °C, GHSV = 48,000 h−1) and excellent stability is one of the most active catalysts so far reported. The 18O-isotope exchange measurements show that both partial and complete heterogeneous exchanges, as well as oxygen release, were observed for all catalysts. Compared with other catalysts, Pd/Sn0.4Zr0.6O2 has much higher activity for oxygen-exchange reaction and higher temperature for bulk palladium oxide decomposition. The results of TPR and 18O-isotope exchange experiments demonstrate that the excellent activity of Pd/Sn0.4Zr0.6O2 is due to its high oxygen mobility and moderate reducibility. XPS results indicate that the dispersion of Pd has little influence on the catalytic activity.