SELECTIVE OXIDATIVE DEHYDROGENATION OF PROPANE OVER SURFACE MOLYBDENUM-ENRICHED MGMOO4 CATALYST

Drastic activity increases were observed by the treatments of the magn esium-rich MgMo0.99Oy catalysts, which are poorly active for the oxida tive dehydrogenation of propane, with inorganic or organic acid to rem ove excess magnesium on the surface. MoO3 loading on magnesium-rich Mg M0.99Oy catalysts also resulted in drastic activity increases. The act ivity increases followed non-effective loadings of MoO3 in the range 0 -2 wt%, because it is necessary to neutralize the surface magnesium wi th MoO3 before the formation of molybdenum-rich surface. The pH of the aqueous (NH4)(6)Mo7O24 solution for the MoO3 loading apparently influ enced the activity. Under the acidic conditions the MoO3 loading resul ted in the drastic activity increase but under the basic conditions th e effect of the MoO3 loading was poor, suggesting that a cluster-type MoO3 on MgMoO4 surface is responsible for the activity of propane oxid ative dehydrogenation. (C) 1998 Elsevier Science B.V. All rights reser ved.