酸化鉄系燃焼触媒のディーゼル排気ガス処理技術への応用

Iron oxides which were supported on three kinds of alumina (γ-Al2O3, χ-Al2O3 and
activated-Al2O3) were prepared for oxidation catalysts on an after-treatment system of diesel engine.
In methane oxidation experiment, we found that the hematite (α-Fe2O3), which was synthesized from
goethite (α-FeOOH), supported on χ-Al2O3 has the highest catalytic activity (over 70% in CH4
conversion) at 227K than the other catalysts. Also in the redox reaction between NOx and
activated-carbon as substitute for soot, the catalyst supported on χ-Al2O3 showed the highest
performance and CO gas was not observed in the products. It is concluded that in α-Fe2O3/χ-Al2O3
catalyst, α-Fe2O3 exists mainly on the surface of the support, because of flatness of the surface of
χ-Al2O3. On the other hand, in the case of α-Fe2O3/γ-Al2O3 catalyst, as the surface of support,
γ-Al2O3, is uneven, α-Fe2O3 do not partially exist on the surface but in the pores.