Tuning surface active oxygen of lanthanum oxide via partial dissolution and regrowth of crystallites

A commercial lanthanum oxide was modified into X-La₂O ₃ samples via partial dissolution and regrowth of crystallites, wherein the X value denotes the weight percent of the initial metal oxide powder dissolved by nitric acid. BET measurements and TEM observations indicate that the 20-La₂O₃ sample has an increased specific surface area, relatively thin and small crystallites in size. TPD/TPR profiles also show that the 20-La₂O₃ sample has more surface active oxygen than the 0-La₂O₃ sample. Among the four X-La ₂O₃ samples, the highest activity for methane oxidation was obtained over the 20-La₂O₃ sample. Therefore, the present work proves that the method of partial dissolution and regrowth of crystallites are effective to modify surface property of lanthanum oxide.