Abstract:

The effect of Li content in a series of multicomponent oxides Li_xLa_(0.5)Ti_(0.5) for methane oxidative coupling has been studied. The catalytic activities of LiLa_(0.5)Ti_(0.5) catalyst befroe and after washing with boiling water have been compared. The surface and bulk structure of the catalysts were characterized by means of XRD、XPS、IR、BET and so on. The results clearly indicated that the role of Li on the surface is to decrease the sruface area of the catalysts and to cover the deep oxidative active sites thus increasing the C_2 selectivity. However, the role of lithium in the bulk is to produce active phase LaTi_(1-y)Li_yO_(3-λ) in which the defect clusters Li~+-O~--Ti~(3+) act as the active sites for methane oxidative coupling.

Key words: Methane oxidative coupling, Catalyst, Titanium-lanthanum-lithium, Role of lithium