Promotional effect of alkyl acids on thermal stability of nanostructured CeO2-ZrO2-Y2O3-La2O3 and its application in automotive three-way catalysts

- Alkyl acids assisted co-precipitation is employed to synthesize CeO2-ZrO2-La2O3-Y2O3.
- Better properties are obtained in CZ-C12 compared with the commercial material SO-2.
- The supported Rh/CZ-C12 shows higher three-way catalytic activity than Rh/SO-2.

A series of nanostructured CeO2-ZrO2-Y2O3-La2O3 quaternary solid solutions (CZ-C10, CZ-C12, CZ-C14 and CZ-C16) were synthesized by simultaneous co-precipitation method with the assistance of alkyl acids CnH2n+1COOH (n = 9, 11, 13 and 15). The obtained materials exhibit greatly enhanced oxygen storage capacity, textural properties and thermal stability. After aging at 1000 °C, CZ-C12-a presents a high surface area of 47 m2 g−1 and a large cumulative pore volume of 0.28 mL g−1. A comparison between CZ-C12 and the commercial material SO-2 in terms of the catalytic performance of supported Rh-only three-way catalysts indicates that Rh/CZ-C12 owns significantly higher catalytic activity than Rh/SO-2. After aging at 1050 °C for 12 h, the light-off temperatures (T50) of C3H8, CO and NO for Rh/CZ-C12-a are 314 °C, 263 °C and 322 °C, respectively, which are much lower than those (360 °C, 290 °C and 386 °C) for Rh/SO-2-a.

Alkyl acids CnH2n+1COOH (n = 9, 11, 13 and 15) are applied to synthesize highly thermal stable nanostructured CeO2-ZrO2-Y2O3-La2O3 quaternary solid solutions. The results indicate that the dodecanoic acid assisted material CZ-C12 exhibits better properties than the commercial material SO-2 provided by Rhodia. The investigation of supported Rh-only three-way catalysts for gasoline engine exhaust purification show that Rh/CZ-C12 presents higher catalytic activity and better thermal stability with respect to Rh/SO-2.170