Electrochemical Oxidative Dehydrogenation of Ethane to Ethylene in a Solid Oxide Electrolyzer

Abstract

Oxidative dehydrogenation of ethane to ethylene is an important process in light olefin industry; however, the over‐oxidation of ethane leads to low ethylene selectivity. Here, we report a novel approach to electrochemical oxidative dehydrogenation of ethane in anode in conjunction with CO2 reduction at cathode in a solid oxide electrolyser using a porous single‐crystalline CeO2 electrode at 600 °C. We identify and engineer the flux and chemical states of active oxygen species that evolve from the lattice at anode surface to activate and dehydrogenate ethane to ethylene via the reaction of epoxy species. Active oxygen species (O2−, O22− and O2−) at the anode surface effectively dehydrogenate ethane to ethylene, but O− species tend to induce deep oxidation. We demonstrate exceptionally high ethylene selectivity of 95 % and an ethane conversion of 10 % with a durable operation of 300 h.

Light olefin synthesis from a diversity of renewable and fossil feedstocks: state-of the-art and outlook

“…115 CO 2 -Assisted CL-ODH was also realized using an electrochemical approach at 600 °C: porous single-crystal CeO 2 electrodes were designed and used with solid single-crystal Y 2 O 3 /ZrO 2 electrolyte and an ethylene selectivity of ∼95% at a conversion of 10% was observed. 177 During the process, ethylene is generated on the anode while, in parallel, the CO 2 reduction to CO on the cathode gave oxygen ions transferred to the anode.…”

Advancements in Environmentally Sustainable Technologies for Ethylene Production

“…Examples of solid electrolytes with high conductivity to O 2− at elevated temperatures would be composite oxides of yttrium, zirconium, and cerium. 96,100 For the H + charge carrier, the solid electrolyte has high conductivity to H + at high temperatures, and the protons generated by the dehydrogenation of ethane at the anode migrate to the cathode for further reaction, as shown in Figure 10b. A few examples of proton charge carriers would be oxides of barium, cerium, and zirconium.…”

“…101 The presence of oxygen in the process also ensures that coke formation at the electrodes stays minimum. 96,100 However, the presence of O 2 at high temperatures can have impacts such as (a) degraded performance of the electrolyte charge carriers, 101 (b) the possibility of the over oxidation of the products of ethylene to CO or CO 2 , 97,102,103 and (c) safety hazards around mixing of ethane and oxygen. 97,104 The ENDH process (overall reaction: C 2 H 6 ↔ C 2 H 4 + H 2 ) can also be carried out in an electrolyzer or fuel cell mode with the respective charge carrier.…”

“…This approach had the advantage of fixing greenhouse gases in tandem with producing organic chemicals. Ye et al 100 reported oxidative dehydrogenation of ethane to ethylene in a solid oxide electrolyzer operated in tandem with CO 2 reduction to CO on the cathode. The catalyst was a single crystal operating CeO 2 at 600 °C, which could reach ethane conversion up to 10% and ethylene selectivity of 95%.…”

“…For the O 2– electrolyte charge carrier, O 2 needs to reduce to O 2– ions at the cathode, and then ions migrate to the anode for further reaction, as shown in Figure a. Examples of solid electrolytes with high conductivity to O 2– at elevated temperatures would be composite oxides of yttrium, zirconium, and cerium. , For the H + charge carrier, the solid electrolyte has high conductivity to H + at high temperatures, and the protons generated by the dehydrogenation of ethane at the anode migrate to the cathode for further reaction, as shown in Figure b. A few examples of proton charge carriers would be oxides of barium, cerium, and zirconium. − A simplified graphical representation of the cell operation mode and associated reactions is provided in Figure .…”