A highly stable asymmetric hollow fiber catalytic membrane reactor for selective oxidation of ethane to ethylene

Abstract

The oxidative dehydrogenation of ethane (ODHE) offers a promising alternative to energy-intensive steam cracking but is hindered by ethylene over-oxidation when using gaseous oxygen. This work presents a highly stable catalytic membrane reactor for the selective oxidation of ethane to ethylene, based on an asymmetric hollow fiber oxygen-permeable membrane (Ce₀.₈Sm₀.₂O₂₋δ/Ce₀.₈₅Sm₀.₁₅O₂₋δ-Sm₀.₆Sr₀.₄Fe₀.₇Al₀.₃O₃₋δ, CSO/CSO-SSAF) integrated with a porous Ce₀.₉Gd₀.₁O₂₋δ (CGO) catalytic layer. This design enables the controlled delivery of active lattice oxygen (O²⁻) to the reaction site. The seamless integration of the catalytic layer with the ceramic membrane results in low ionic resistance and thereby promotes effective synergy between reaction and diffusion processes. The CGO layer selectively combusts the hydrogen by-product, driving the dehydrogenation equilibrium toward ethylene. High C2H4 selectivity of 92%-99% with C2H6 conversions of 18%-51% at 625-700 °C were achieved via the CGO@CSO/CSO-SSAF catalytic membrane. It demonstrates exceptional operational stability, maintaining 18% conversion and 99% selectivity over 500 hours. This stability originates from the synergistic coupling between the selective CGO catalyst and the oxygen-ion-transporting membrane, and the dense CSO protective layer which ensures structural integrity against corrosive atmospheres. The study demonstrates a viable and intensified process for selective alkane conversion with long-term stability.