In this work, slurries of powder catalysts are washcoated on 22 mm diameter
and 13 mm height cordierite monoliths. CeO2-ZrO2 (CZO) and CeO2-ZrO2-
Al2O3 (CZAO) mixed oxides are synthesized by co-precipitation and sol-gel
methods respectively, to be used as support materials of Pd and Rh metals.
Metal loaded CZO is mixed with gamma phase alumina. Powder catalysts
and their slurries 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 of
gasoline vehicles. O2 is oscillated at 1 Hz frequency around the
stoichiometric condition. Monolithic catalyst in the reactor is heated and
cooled between 150 º / C and 600 º / C. Gas composition data from massspectrometer and CO analyzer and temperature data from thermocouple at
the monolith entrance, are converted to conversion versus temperature
graphs. Results of 26 activity tests are compared. Catalyst containing coimpregnated
CZO support material with metals, showed the lowest loss of
catalytic performance after exposure to SO2 during activity tests. Catalyst
containing separately impregnated CZO support material, showed the
highest resistance against thermal aging at 900 º / C and 1000 º / C, and even
improved catalytic activity after aging. These catalysts showed higher
resistances against the applied procedures than the commercial catalyst.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12612546/index.pdf |
| Date | 01 September 2010 |
| Creators | Kandilli, Nur |
| Contributors | Onal, Isik |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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