A combined experimental and theoretical approach to the study of methane activation over oxide catalysts

We present new results on the activation of methane over pure and doped gallium oxide catalysts. This catalyst was selected from our earlier work on methane to methanol conversion over mixed oxide systems. Calculations show that for defect free surfaces of the beta -Ga2O3 phase only the (010) and (001) facets are stable. Density functional theory level calculations are presented which show that the (010) surface undergoes only a small amount of re-construction from the bulk structure. This suggests that the real crystal surfaces will be defective and we have attempted to increase the surface concentration of defects further by doping with divalent cations. Zn doping leads to an increase in activity compared to beta -Ga2O3, Whilst Mg doping decreased the activity. (C) 2001 Elsevier Science B.V. All rights reserved.