Abstract: The Pd-MnO_x/Al₂O₃ catalyst has been prepared by the urea hydrolysis method and characterized by low temperature nitrogen adsorption-desorption and X-ray diffraction. Its catalytic activity for decomposing ground-level ozone has been studied. The catalyst showed a high activity at low temperature and high relative humidity. At gas hourly space velocity (GHSV) of 660000 h^-1 and relative humidity of 85%–90%, the ozone conversion over the catalyst reached 91.7% at 20 °C and the temperature for complete decomposition of ozone was only 24 °C. Furthermore, the prepared catalyst can completely decompose ground-level ozone when it is coated on the wave shaped heat patches of automobile water tanks.

Key words: palladium, manganese oxide, urea hydrolysis method, relative humidity, ground-level ozone, catalytic decomposition, completely decompose