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

A Pd catalyst supported on Ba-substituted LaAlO(3) perovskite (Pd/La(0.9)Ba(0.1)AlO(3−δ)) was investigated for NO reduction at low temperature by propylene, which revealed that Pd/La(0.9)Ba(0.1)AlO(3−δ) 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 (18)O(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/LaAlO(3)) demonstrated that Pd/La(0.9)Ba(0.1)AlO(3−δ) shows higher activity for the formation of oxygenated species (C(x)H(y)O(z)) as an intermediate for NO reduction because the surface lattice oxygen has improved mobility via Ba(2+) substitution in LaAlO(3). Therefore, Pd/La(0.9)Ba(0.1)AlO(3−δ) have high activity for NO reduction, even at low temperatures in a humid condition.