Ce1–xLaxOy solid solution prepared from mixed rare earth chloride for soot oxidation

Ce1–xLaxOy solid solution was simply prepared using mixed rare earth chloride (RECl3·xH2O, RE=Ce, La>99%, containing unseparated Ce and La from rare earth metallurgical industry) as precursor by ultrasonic-assisted co-precipitation method with different ultrasonic frequencies (CLf, f=200, 400, 600, 800, 1000 Hz). A compared Ce1–xLaxOy solid solution (CL*) was also prepared by the same mothod with 10% less precipitant. X-ray diffraction results confirmed the formation of Ce1–xLaxOy solid solution, and the crystal structures of these catalysts were not very sensitive to ultrasonic frequency and precipitant amount. However, both of the factors had obvious effect on morphology and surface area of CL, and precipitant amount seem to play a more crucial role than ultrasonic frequency for Ce1–xLaxOy solid solution preparation. When soot and catalyst were tight contacted, the peak temperature (Tpeak) of soot oxidation and oxygen reducing temperature for CLf catalysts decreased linearly with increasing surface area. Under loose contact condition, the Tpeak had obvious negative correlation with H2 consumption. It was inferred that good reducibility of the Ce1–xLaxOy solid solution favored the soot oxidation reaction. The Ce1–xLaxOy solid solution prepared from unseparated rare earth chloride showed a good soot oxidaiton activity. Controlling the preparation conditions to prepare a CL catalyst would high surface area will enhance its reducibility and activity.

Surface area, oxygen reducing temperature and Tpeak of CL catalysts under tight contact conditionFigure optionsDownload as PowerPoint slide