RELATIONSHIP BETWEEN MORPHOLOGY AND CATALYTIC PERFORMANCE OF LITHIUM AND GOLD DOPED MAGNESIUM-OXIDE CATALYSTS FOR THE OXIDATIVE COUPLING OF METHANE

A detailed study is presented of the relationship between morphology and catalytic performance of Li and Au doped Mgo prepared by the thermal decomposition of the hydroxide. Addition of Li to MgO causes a loss of the characteristic morphology of the precursor MgO due to grain growth via agglomeration of crystallites and grain boundary dislocations are evident. In contrast, Au doping of Mgo does not lead to an increase in grain size. For both Li and Au doped MgO, dislocations are observed that are immobile and are proposed to be of the type a/2(110) which are probably pinned by Li or Au ions segregating to the line of the defect. The importance of these dislocations is discussed with respect to the catalytic performance of Li and Au doped MgO catalysts for the oxidative coupling of methane.