(455d) Thermodynamically Tuned Redox Catalyst for Ethane to Liquid Fuels Via Chemical Looping in Simple, Distributed Reactors

Ethane in shale gas is difficult to transport challenges for geographically isolated natural gas producers as it is not easily liquefied, and dedicated ethane pipeline capacity is limited. This leads to frequent ethane rejection, where ethane is either injected into the natural gas pipelines or flared on-site. We proposed a modular ethane-to-liquids (M-ETL) technology enabled by chemical looping oxidative dehydrogenation of ethane (CL-ODH) to ethylene followed by oligomerization to transportable liquid fuels. In a CL-ODH scheme, a redox catalyst selectively donates its lattice oxygen to selectively convert ethane to ethylene and water. Air, or steam, is then introduced in a subsequent regeneration step to replenish the oxygen depleted catalyst. The controlled feeding of reducing, purging, and oxidizing gasses is enabled by automated valve switching.

By eliminating complex feed preheating and expensive furnaces, the net exothermicity of the oxidative dehydrogenation (ODH) of ethane facilitates a simple autothermal operation. However, many previously studied mixed metal oxide materials active to CL-ODH display an endothermic ethane ODH step with a highly exothermic regeneration step. Here, we show reactor performance results of a redox material that is exothermic on both sides of the reaction. This is achieved by selecting materials with properties tuned for thermodynamically favorable oxygen donation. Perovskites, which have an ABO₃, structure consisting of one or more A-site site and B-site metal cations, can be further doped to match the thermodynamics of the CL-ODH reactions. Such material design allows for engineering of simpler reactor schemes, with internal heat transfer, similar to the Catofin process.

We present long-term, large laboratory-scale performance results of a perovskite-based catalyst that exhibits this desirable thermodynamic behavior including 1000+ hr. of reaction testing. ASPEN-based chemical process modeling further validates the ability to eliminate heat exchange, enabled by the novel materials. Additionally, updated techno-economics informed by sensitivity analysis from the process modeling of the modular reactor system will also be presented