Noble metal-free CeO2-based mixed oxides for CO and soot oxidation

Abstract

‘Three-way catalytic technology’ has been successfully implemented in automobile industries for cleaning of auto exhaust gases from 1980’s onward. Supported noble metal catalysts with ceria (CeO2) as the redox promoter have been employed for this technology. However, these catalytic materials have some drawbacks in terms of high light off temperature, catalyst poisoning and drop of activity, heavy metal pollution, etc. Hence, this technology is under active investigation throughout for the sake of better performance. Considerable research efforts have been devoted to develop new advanced materials. Noble metal-free CeO2-based mixed oxides, which can be deployed as potential substitutes, have been investigated at length with the goal to overcome the limitations like loss of stability and activity at elevated temperatures, improvement of oxygen storage/release capacity (OSC), and so on. However, the use of proper dopants at optimum concentration and tuning of the shapes, size and morphology of the nanoparticles via controlled synthesis is a challenging task, since it improves the features of CeO2. In this article, we have reviewed the influence of these factors on the properties of ceria-based materials and their catalytic efficiencies in CO and soot oxidation reactions.