(214b) Design Principles for High-Selectivity Chemical Looping Oxidative Dehydrogenation of Ethane

Ethylene is one of the largest-volume commodity chemicals worldwide, with a correspondingly high carbon footprint. We have previously demonstrated that replacing conventional steam cracking with chemical looping oxidative dehydrogenation (CL-ODH) of ethane holds significant potential to reduce energy consumption and CO₂ emissions in ethylene production. CL-ODH is a two-step process. In the first step, ethane is selectively oxidized to ethylene and water by contacting it with a mixed metal oxide oxygen carrier that donates its lattice oxygen to the reaction. In the subsequent step, the oxygen carrier is regenerated by contact with air, replenishing its lattice oxygen while also providing heat that can be utilized to achieve isothermal operation. Because thermodynamics favor the deep oxidation of both ethane and ethylene to CO₂, it is critical for the oxygen carrier to be catalytically modified to suppress over-oxidation of the products while enabling selective oxidation of hydrogen. In our system, this is achieved by impregnating the carrier surface with salts that melt and spread during calcination. In this work, we describe our recent advancements in the salt coating of CL-ODH oxygen carriers. These developments provide further insight into the mechanism by which the salts suppress deep oxidation while allowing selective hydrogen combustion. The potential to enable autothermal operation through tailored oxygen carrier design is also discussed.