Oxidative Dehydrogenation of Ethane: Common Principles and Mechanistic Aspects

The increasing demand for light olefins and the changing nature of basic feedstock has stimulated substantial research activity into the development of new process routes. Steam cracking remains the most industrially relevant pathway, but other routes for light-olefin production have emerged. Fluid catalytic cracking only produces ethene in minor concentrations. Challenged by marked catalyst deactivation, in contrast, catalytic dehydrogenation ethane up opens a more selective route to ethene. The oxidative dehydrogenation (ODH) of ethane, which couples the endothermic dehydration of ethane with the strongly exothermic oxidation of hydrogen, would potentially be the most attractive alternative route because it avoids the need for excessive internal heat input, but also consumes valuable hydrogen. In this Review, the current state of the ODH of ethane is compared with other routes for light-olefin production, with a focus on the catalyst and reactor system variants. New catalyst systems and reactor designs have been developed to improve the industrial competitiveness of the ODH reaction of ethane. The current state of our fundamental understanding of the ODH of light alkanes, in particular in terms of catalyst and reactor development, is critically reviewed. The proposed mechanisms and the nature of the active site for the ODH reaction are described and discussed in detail for selected promising catalysts. The reported catalytic performance and the possible limitations of these ODH catalysts will be examined and the performance of the emerging approaches is compared to the currently practiced methods.