(564a) Novel Configured Pt/CeO2(core)@ZrO2(shell) Supported Three-Way Catalysts
AIChE Annual Meeting
2021 Annual Meeting
Catalysis and Reaction Engineering Division
Catalyst Design, Synthesis, and Characterization (Virtual)
Thursday, November 18, 2021 - 12:30pm to 12:50pm
Due to the vehicle engine efficiency improvement, catalysts need to perform effectively at low temperatures to meet the strict emission standards introduced by the Environmental Protection Agency. Therefore, U.S. DRIVE established a goal of achieving 90% conversion of hazardous emissions at 150 ÂºC; so-called â150 ÂºC challengeâ. Fluctuations in the air to fuel ratio in stoichiometric gasoline engine aftertreatment systems result in a decreased efficiency of the catalytic converter.1 CeO2 is a promising catalyst support due to its high oxygen storage capacity (OSC) that buffers O2 during rich/lean cycling.2 However, CeO2 suffers from poor thermal stability, indicated by its surface area loss from 50 (550 oC) to 2 m2/g (800 oC).4 A potential solution for improving the thermal stability of CeO2 is incorporating ZrO2 into CeO2. Herein, CeO2(core)@ZrO2(shell) (Fig. 1(a)) structured supports were synthesized using a solvothermal method to synthesize CeO2 spheres, followed by ZrO2 shell deposition through hydrolysis and condensation of zirconium butoxide. Pt supported on commercial CeO2, ZrO2, CeO2 spheres and Ce0.7Zr0.3O2 solid solution (same composition as CeO2@ZrO2) were synthesized for comparison purposes. The catalytic performance was evaluated using the low temperature oxidation catalyst test protocol defined by U.S. DRIVE under stoichiometric gasoline direct injection (S-GDI) conditions.5 The T90âs of CO, total hydrocarbons (THCs) and NOx over hydrothermally aged 1.8 wt.% Pt/CeO2@ZrO2 were 228, 254 and 265 oC, respectively, lower than the CO, THCs and NOx T90âs over Pt/CeO2 sphere (not able to achieve 90% conversion up to 500 oC). This observation confirms the performance improvement when Zr shell is incorporated on CeO2 spheres (Fig. 1(b-d)). Besides, Pt/CeO2@ZrO2 outperformed Pt/Ce0.7Zr0.3O2 (T90âs at 339, 435 and >500 oC for CO, THC, and NOx, respectively), suggesting the benefit of core@shell catalyst support configuration. Overall, this work illustrates the potential of developing CeO2@ZrO2 supported catalysts for stoichiometric gasoline oxidation reaction.