Perovskite lattice oxygen contributes to low-temperature catalysis for exhaust gas cleaning

摘要

A Pd catalyst supported on Ba-substituted LaAlO3 perovskite (Pd/La0.9Ba0.1AlO3-delta) was investigated for NO reduction at low temperature by propylene, which revealed that Pd/La0.9Ba0.1AlO3-delta has remarkably higher activity than other Pd catalysts at low temperatures (<= 573 K) for NO reduction by propylene. To elucidate the surface reaction pathway, transient response tests were conducted using O-18(2). Also, X-ray photoelectron spectroscopy (XPS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements were conducted. Comparison with a Ba-impregnated catalyst (Pd/Ba/LaAlO3) demonstrated that Pd/La0.9Ba0.1AlO3-delta shows higher activity for the formation of oxygenated species (CxHyOz) as an intermediate for NO reduction because the surface lattice oxygen has improved mobility via Ba2+ substitution in LaAlO3. Therefore, Pd/La0.9Ba0.1AlO3-delta have high activity for NO reduction, even at low temperatures in a humid condition.