Abstract
This paper describes the investigations of the catalytic activity in soot oxidation over well-defined iron oxide based materials. The nanostructuration of iron oxide by potassium into tunnelled (KFeO2) and layered (K2Fe22O34) ferrites and the surface promotion with CeO2 results in the marked increase in the catalytic activity (decrease of the ignition temperature down to 210 °C and T 10 % to 310 °C). The measurements of the catalysts work function showed that both nanostructuration and surface promotion with ceria of the best KFeO2 phase led to increase of the electron availability (decrease of the work function). Strong correlation of the catalytic activity in soot combustion of the Ce–K–Fe–O systems with the work function value was revealed for the first time in the model studies, and can be used as a guideline for optimisation of the real catalytic filters.
Highlights
Soot particles emitted from diesel engines, due to their submicron size and specific chemical composition, are among the most hazardous urban air pollutants [1]
This paper describes the investigations of the catalytic activity in soot oxidation over well-defined iron oxide based materials
Strong correlation of the catalytic activity of the Ce–K–Fe– O systems with the catalyst work function value was revealed for the first time
Summary
Soot particles emitted from diesel engines, due to their submicron size and specific chemical composition, are among the most hazardous urban air pollutants [1]. Its positive role on soot combustion has been discussed in terms of: (i) an electron donor effect, increasing the oxygen reactivity; (ii) autogenic formation of low melting point compounds, or eutectics with other components of the catalyst, wetting the soot surface to increase the contact with the catalyst, (iii) the formation of a superficial carbonate intermediate and (iv) nanostructurization of the parent oxide. The latter case is may be illustrated by the transformation of Fe2O3 into tunnelled and layered ferrites of KFeO2, and K2Fe22O34 structures. Both effects were discussed in terms of electronic factor-structure– activity relationship
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