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Role of CO₂ in Catalytic Ethane-to-Ethylene Conversion Using a High-Temperature CO₂ Transport Membrane Reactor

Zhang, Peng, Tong, Jingjing, Huang, Kevin
ACS sustainable chemistry & engineering 2019 v.7 no.7 pp. 6889-6897
carbon dioxide, catalysts, cracking, ethane, ethylene, ethylene production, hydrogen, production technology, steam
The noncatalytic, thermo-dehydrogenation-based steam cracking is a benchmark technology for ethylene production from ethane or naphtha. However, this technology is energy-and emission-intensive. Aiming to develop low-energy and low-emission ethylene production technology, this work explores a new way to make ethylene with CO₂ directly captured by a membrane reactor operated on bi-ionic CO₃²–/O²– chemistry. The performance of such a combined CO₂ capture and ethane conversion membrane reactor incorporated with a Cr₂O₃-ZSM-5 catalyst is promising. Through conversion studies under different conditions, we also unveil that the mechanisms of this membrane-based catalytic ethane-to-ethylene conversion are dominated by thermo-dehydrogenation of ethane, accompanied by concurrent reverse water gas shift (RWGS) and reverse Bouduoard (RB) reactions. With the catalyst, the active role of CO₂ is to promote H₂ removal via RWGS, thus the production of ethylene and suppress coking via RB.