STUDIES OF MULTICOMPONENT COMPLEX OXIDE CATALYSTS FOR OXIDATIVE COUPLING OF METHANE VII.EFFECT OF CALCINATION TEMPERATURE ON Ti-La-Li PEROVSKITE-TYPE OXIDE CATALYSTS

The correlations of the calcination temperature.structure and catalvtic activity of the LiLa_（0.5）Ti_（0.5）O_(2-(?)) catalvsts with main phase and major active phase of perovskite-type trmary complex oxide LaTi_(l-y)Li_yO_(3-λ）m the Oxidative coupling of methane(OCM)have been studied The surface and bulk structures of the catalysts were characterized by means of XRD,XPS. IR.BFT and so on. The results clearly indicated that the effect of calcination temperature on the activity for the oxidative coupling of methaneis twofold On one hand.high calcination temperature is favoragble for Lisubstitution for Ti~(3 )into the lattice of LaTiO_3 and the production of moreoxygen vacancies at which active oxygen species are formed However,excessivelv high calcmation temperature makes Li~ substitution for Ti~(3 )less due to a httle change of structure or phases of the catalvst On the otherhand,the conversion of CH_4 drops because of the decrease of surface area,when the calcination temperature is raised.