| Abstract | A series of methane oxidation catalysts were prepared by doping Santa Barbara Amorphous-15 (SBA-15), a highly mesoporous silica sieve, with varying amounts of Zr (5, 10, and 15 wt%) and loading with 2 wt% Pd and 4 wt% Pt. The catalysts were characterized using various techniques, including BET, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and H₂-temperature programmed reduction (H₂-TPR). Fresh and aged catalysts were evaluated for methane oxidation. Aging was performed using a simulated lean burn natural gas (NG) engine exhaust containing water vapor (10% vol) and sulfur (10 ppm). It was found that the catalyst with 15 wt% zirconia was the most active and stable of the series, exhibiting the lowest T₅₀ of 481 °C after 40 h of aging. The Pd–Pt catalyst loaded on pure SBA-15 had a T₅₀ of 583 °C after aging, which was 102 °C higher than that of the Pd–Pt catalyst with 15 wt% Zr. The results suggest that the increased performance was due to the higher amount of reducible PtOₓ species in the proximity of ZrO₂ and the sulfur scavenging effect of zirconia, which protected the active metals from forming inactive sulfur complexes. Overall, the Pd–Pt catalyst with 15 wt% Zr loaded on SBA-15 demonstrated excellent methane oxidation activity, hydrothermal stability, and sulfur resistance and can be considered a viable candidate for reducing the methane slip from a lean burn NG engine exhaust. |
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