Catalytic combustion of methane over Ce 1− xLa xO 2− x/2 /Al 2O 3/FeCrAl catalysts

Abstract

A series of the Ce 1− x La x O 2− x/2 /Al 2O 3/FeCrAl monolithic catalysts ( x = 0–1) were prepared. The structure of the catalysts was characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and temperature-programmed reduction (TPR). The catalytic activity of the catalysts for the methane combustion was evaluated with a fixed bed reactor. The results showed that in the Ce 1− x La x O 2− x/2 /Al 2O 3/FeCrAl catalysts the phase structure was the Ce 1− x La x O 2− x/2 solid solutions, α-Al 2O 3 and γ-Al 2O 3. The molar ratio of Ce to La in the Ce 1− x La x O 2− x/2 solid solutions significantly influenced the surface particle shape and size of the catalysts. The catalytic activity for the methane combustion strongly depended on the La component of the Ce 1− x La x O 2− x/2 /Al 2O 3/FeCrAl catalysts, and the order of the catalytic activity in terms of x was 0.7 > 0.9 > 0.5 > 0.3 > 0 > 1. TPR analyses of the catalysts revealed the existence of a strong interaction among the Ce 1− x La x O 2− x/2 solid solutions, the Al 2O 3 washcoats and the FeCrAl support. This interaction remarkably enhanced the redox properties of the catalysts resulting in the higher catalytic activity.