OXIDATIVE COUPLING OF METHANE OVER ALKALI-PROMOTED TI-LA OXIDE CATALYSTS - EFFECT OF BULK AND SURFACE-PROPERTIES ON CATALYTIC PERFORMANCE

The reactivity of lanthanum titanate catalysts is investigated in the oxidative coupling of methane (OCM) under lean-oxygen conditions. The catalyst performances are influenced by the catalyst preparation metho d and by the amounts of the alkali dopant. A transient method was also used to study the mobility of lattice oxygen species under OCM reacti on conditions. It is found that (i) in the absence of gas phase oxygen the sample does not possess lattice oxygen species which participate in the reaction; (ii) the alkali doping does not appreciably modify th e mobility of lattice oxygen; and (iii) the role of the alkali promote r in the reaction is that of modifying the surface acid/base and oxidi zing properties.