Effect of oxide supports on palladium based catalysts for NO reduction by H2-SCR

The present work shows the synthesis of various mixed oxide catalysts prepared by co-precipitation followed by impregnation of palladium metal. The catalysts are denoted as Pd/MgO-CeO2, Pd/ZrO2-CeO2, Pd/Al2O3-CeO2, and Pd/TiO2-CeO2 and examined for selective catalytic reduction (SCR) of NO with H2 in the presence of excess oxygen (6% O2). The properties of catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), BET, transmission electron microscopy (TEM), H2-temperature-programmed reduction (H2TPR), and Raman spectroscopy. The synthesized catalysts exhibit notable NO reduction potential at 175 degrees C and in a wide temperature range from 100 to 400 degrees C. Compared to bare CeO2 support, the Pd/ZrO2-CeO2 catalyst greatly enhances the SCR activity with a wide temperature range (100-400 degrees C). The experimental results showed that the Pd/ZrO2-CeO2 catalyst had the best catalytic activity with 92 % NO reduction and a wide temperature reduction window (150-400 degrees C) at the gas hour space velocity (GHSV) of 20,000 h-1.