Influence of Surface Properties of Nanostructured Ceria-Based Catalysts on Their Stability Performance.

Boyu Li,Eric Croiset,John Z. Wen

doi:10.3390/nano12030392

Abstract

As the poor cycling stability of CeO2 catalysts has become the major obstacle for applications of diesel particulate filters (DPF), it is necessary to investigate how to reduce their structural and compositional changes during soot oxidation. In this study, different ratios of Samarium (Sm) were doped into the lattice of CeO2 nanoparticles to improve the catalytic performance as well as surface properties. The stability was investigated by recycling the catalyst, mixing it with soot again, and repeating the thermogravimetric analysis (TGA) tests seven times. Consistent observations were expected for more cycles. It was found that doping 5%, 10%, and 20% samarium into the CeO2 lattice can improve the catalyst stability but at the cost of losing some activity. While the catalyst became more stable with the increasing Sm doping, the 10% Sm-doped catalyst showed the best compromise between stability and activity. Ce3+ and Oα were found to play important roles in controlling catalytic soot oxidation activity. These two species were directly related to oxygen vacancies and oxygen storage capacity of the catalyst. Sm-doped catalysts showed a minimized decrease in the Ce3+ and Oα content when the fresh and spent catalysts were compared.

Highlights

Ceria has already been widely studied in soot oxidation because of its excellent redox properties and oxygen storage capacity (OSC)
In a previous study that investigated the activities of iron-doped ceria catalysts at different doping ratios, we showed 5% iron doping prepared with the solution combustion synthesis (SCS) method performed best due to its highly reactive Fe–O–Ce sites [2]
The present study aims to develop an optimum ratio of Sm doping into the CeO2 catalyst to improve catalyst stability for soot oxidation

Summary

Introduction

Ceria has already been widely studied in soot oxidation because of its excellent redox properties and oxygen storage capacity (OSC). Liang et al [3] have studied the thermal stability of CeO2 for soot oxidation by aging the catalyst at 800 ◦ C for 20 h in air. They found that the temperature corresponding to the maximum rate for CO2 production with an aged catalyst increased by about 60 ◦ C compared to a fresh catalyst because of the highly reduced surface area and sintering. Liu et al [5]

Methods

Results

Conclusion