Analysis on the Feasibility of Oxidative Dehydrogenation of Ethane with Electrochemical Means

The combination of horizontal drilling with hydraulic fracturing has transformed the outlook of the U.S. chemical industry sector, as domestic shale offer plentiful low-cost alkane feedstock. Steam cracking of alkanes for the production of olefins is an energy intensive thermodynamically limited process, requiring approximately 180 MJ/ton ethylene produced and emits large quantities of criteria pollutants (such as NO_X and SO_X). The capital intensity of current steam cracking technology, along with non-attainment status in many current locations limits the expansion of the U.S. chemical industry sector. Process intensification approaches, which increase reaction efficiency and better integrate reaction latent heat are attractive, as such concepts could significantly improve chemical manufacturing energy efficiency. An attractive alternative being considered is oxidative dehydrogenation (ODH) of ethane, as the process is exothermic without thermodynamic limitation. Several ODH process concepts are under development, include fixed/fluidized bed and chemical looping concepts. However, the lack of modularity, cryogenic air separation, and oxygen carrier deactivation/costs associated with these ODH concepts still need to be overcome.

An attractive alternative being considered by Ohio University (OHIO), is an electrogenerative oxidative ODH (e-ODH) process, which utilizes solid oxide fuel cell (SOFC) technology with oligomerization and CO₂ capture, to convert ethane into a transportation fuel product. The e-ODH process potentially offers significant advantages over current ODH concepts, including co-production of chemicals and electrical power and process intensification through inherent oxygen separation/modularity provided by the SOFC platform. To assess e-ODH process potential, OHIO has developed an Aspen Plus^® simulation for a 500 bbl/day system, to evaluate process efficiency and support a preliminary techno-economic study. For this simulation, pure ethane and air both enter the system separately. Ethane reacts with oxygen from air across an SOFC to form ethylene, which is then oligomerized utilizing a zeolite catalyst into transportation fuel product. This presentation will study results including estimates of process efficiency, product costs ($/GGE), and environmental emissions potential.