Te-doped MoV-Oxide (M1 phase) for ethane ODH. The role of tellurium on morphology, thermal stability and catalytic behaviour

Undoped and Te-doped MoV-Oxide (M1 phase) catalysts have been prepared hydrothermally (Te/Mo ratio in the synthesis gel from 0 to 0.17; and heat-treated at 400 or 600°C in N2 atmosphere), characterized by several physicochemical techniques and tested in the oxidative dehydrogenation (ODH) of ethane. The morphology and microporosity of the catalysts, the nature of V-species on the catalyst surface and the catalytic performance strongly depend on the composition and the heat-treatment temperature. When calcined at 400°C, the selectivity to ethylene decreases when the amount of tellurium increases, whereas when heat treated at 600°C, the selectivity to ethylene increases when the Te-loading increases. These trends have been explained on the basis of the good correlation between selectivity to ethylene and the concentration of V4+ species on the surface of catalysts, in which the most selective catalyst is that prepared with a Te/Mo ratio of 0.17 and heat-treated at 600°C.