Oxidative coupling of methane with peroxide ions over barium-lanthanum-oxygen mixed oxide

✍ Scribed by Hiromi Yamashita; Yoshihiro Machida; Akira Tomita

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 743 KB
• Volume: 79
• Category: Article
• ISSN: 0926-860X
• DOI: 10.1016/0926-860x(91)80006-k

✦ Synopsis

The oxidative coupling of methane on a mixed oxide of LasOs and an alkaline earth metal oxide was investigated. The formation and decomposition behaviors of surface oxygen species were studied by measuring the weight change in the oxygen atmosphere with thermogravimetry (TG) and by recording X-ray photoelectron spectroscopy (XPS). An active and selective catalyst for methane coupling was prepared by mixing La.jO, with 15 atom-% BaO (15BLO). The XPS study showed the existence of OFj-species on the surface of La,Os and 15BL0. The barium species were well dispersed in 15BL0 and they increased the concentration of the Oz-species. The high catalytic ability of 15BLG is ascribed to this dispersed O:-species on the surface. On the other hand, La,O, with 50 atom-% BaO (50BLO) exhibited little activity in spite of a larger content of Oi-than 15BL0, because the dispersion of the O:-species was poor. In the actual methane coupling reaction, the surface O:-would be decomposed into active oxygen species, probably 20-, before interacting with methane. The importance of barium dispersion may relate to this step of O$-splitting.