Combined removal of diesel soot particulates and NOx over CeO2–ZrO2 mixed oxides

✍ Scribed by I. Atribak; A. Bueno-López; A. García-García

• Book ID: 118474420
• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 596 KB
• Volume: 259
• Category: Article
• ISSN: 0021-9517
• DOI: 10.1016/j.jcat.2008.07.016

✦ Synopsis

CeO2 and Ce–Zr mixed oxides with different Ce:Zr ratios were prepared; characterised by Raman spectroscopy, XRD, TEM, N2 adsorption at −196 °C, and H2-TPR; and tested for soot oxidation under NO
x
/O2. Among the different mixed oxides, Ce0.76Zr0.24O2 provided the best results. Ce0.76Zr0.24O2 presented greater activity than pure CeO2 for soot oxidation by NO
x
/O2 when both catalysts were calcined at 500 °C (soot oxidation rates at 500 °C are 14.9 and 11.4 μgsoot/s, respectively), and the catalytic activity of CeO2 decayed significantly with calcination temperature (from 500 to 1000 °C), whereas Ce0.76Zr0.24O2 presented enhanced thermal stability at temperatures as high as 1000 °C. In addition, Ce0.76Zr0.24O2 catalysed the reduction of NO
x
by soot at around 500 °C more efficiently than CeO2, thereby contributing to the decreased NO
x
emission level. The catalytic activity of CeO2 and Ce0.76Zr0.24O2 for soot oxidation by NO
x
/O2 depended on the textural properties (BET area; crystallite size), but other properties of the oxides, such as redox behaviour and/or enhanced lattice oxygen mobility, also played a significant role.