Is true ethane oxydehydrogenation feasible?

Oxydehydrogenation of ethane as a route to ethylene has the attractive feature of removing the thermodynamic equilibrium conversion limitation of the simple dehydrogenation. For example, in the dehydrogenation of ethane to ethylene, the maximum conversion possible at 1000degreesC is 51%, while essentially complete (100%) conversion is possible even at ambient conditions. The best catalysts discovered to date are those from Union Carbide's work ( in the late 1970s and early 1980s), which operate at 300-400degreesC. These reducible Mo-V-Nb oxide catalysts are thought to react via a surface ethoxide intermediate on a Mo or V site that can then undergo a beta-elimination process to form ethylene. On the other hand, the surface ethoxide can be oxidized further to form surface acetate, which leads to acetic acid on hydrolysis with water. Aside from these low-temperature reducible catalysts, many catalysts containing reducible metal oxides and non-reducible metals are known to convert ethane to ethylene at 500-800degreesC. It is proposed that these catalysts are essentially dehydrogenation catalysts where the H-2 formed from straight dehydrogenation or during a surface intermediate stage after H-abstraction is converted to H2O, thereby shifting the dehydrogenation equilibrium. Therefore, the big question, the challenge, and the opportunity remains as to whether true oxydehydrogenation is possible at relative low-to-moderate temperatures? This challenge/opportunity will be discussed in the backdrop of some of the recent advances in alkane activation.