Exhast gas cleaning by three way catalytic converters

Karakoç Yıldız, Zuhal
In this study, powder catalysts slurries are washcoated on cordierite monoliths. CeO2-ZrO2 (CZO) and CeO2-ZrO2-Al2O3 (CZAO) mixed oxides are synthesized by co-precipitation. Pd and Rh metals are used as a nobel metals in these supports. Metal loaded CZO is mixed with gamma phase alumina. Powder catalysts are characterized by XRD, BET, ICP-MS and the monolithic catalysts are imaged by SEM. Catalytic activities of monolithic catalysts are tested in dynamic test system which is computerized and basically composed of gas flow control and conditioning units, split furnace, quartz reactor, mass spectrometer and CO analyzer. Gas mixture containing CO, C3H6, C3H8, NO, H2, O2, CO2, SO2, H2O and N2 is used to simulate the exhaust gas automotive. O2 is oscillated at 1 Hz frequency around the stoichiometric condition. Monolithic catalyst in the reactor is heated between 150 ºC and 600 ºC at a rate of 5 ºC/min and then cooled. Gas composition data from mass spectrometer & CO analyzer and temperature data from thermocouple at the monolith entrance, are converted to conversion versus temperature graphs. Catalyst containing co-impregnated support material with metals, showed the lowest loss of catalytic performance after exposure to SO2 during activity tests. As a result, this catalyst has more resistant than Tofas commercial monolithic catalyst.