Specific selectivity of simple oxides towards CH4 activation

Simple metal oxides exhibit noticeable catalytic activity in methane conversion reactions. However, their catalytic role in the selective activation of CH 4 to more valuable products (CO, H 2 , olefins) is often masked by the highly oxidative reaction conditions and by complex catalyst formulations. Transient studies of the direct interaction of CH 4 with simple catalytic systems, including rare-earth (La 2 O 3 , Nd 2 O 3 , Y 2 O 3 ), alkali-earth (MgO) and reducible (TiO 2 ), reveal peculiar selectivity for different monometallic oxides. Rare-earth metal oxides show high initial activity towards partial oxidation products (CO, H 2 ), while MgO possesses unique selectivity towards coupling products (C 2 H 6 and C 2 H 4 ) with remarkable activity in dehydrogenation reactions. A continuous supply of lattice oxygen species for the selective oxidation of CH 4 to CO is provided by TiO 2 , which can effectively prevent accumulation of C deposits. The results indicate the roles played by the metal oxide materials and provide a basis for rational design of catalysts and reaction conditions for the selective conversion of CH 4 . • Transient activity studies highlight the specific selectivity of catalytic systems. • Simple metal oxides exhibit distinct activity in methane conversion reactions. • Rare-earth metal oxides show high initial activity towards CO and H 2 . • MgO exhibits unique selectivity towards coupling products C 2 H 6 and C 2 H 4 . • TiO 2 lattice oxygen selectively oxidises CH 4 to CO and prevents carbon deposition.