High-Performance Co-production of Electricity and Light Olefins Enabled by Exsolved NiFe Alloy Nanoparticles from a Double-Perovskite Oxide Anode in Solid Oxide-Ion-Conducting Fuel Cells
Ting Tan, Ziming Wang, Kevin Huang, Chenghao Yang
Abstract
Light olefins (LOs) such as ethylene and propylene are critical feedstocks for many vital chemicals that support our economy and daily life. LOs are currently mass produced via steam cracking of hydrocarbons, which is highly energy intensive and carbon polluting. Efficient, low-emission, and LO-selective conversion technologies are highly desirable. Electrochemical oxidative dehydrogenation of alkanes in oxide-ion-conducting solid oxide fuel cell (SOFC) reactors has been reported in recent years as a promising approach to produce LOs with high efficiency and yield while generating electricity. We report here an electrocatalyst that excels in the co-production. The efficient catalyst is NiFe alloy nanoparticles (NPs) exsolved from a Pr- and Ni-doped double perovskite Sr 2 Fe 1.5 Mo 0.5 O 6 (Pr 0.8 Sr 1.2 Ni 0.2 Fe 1.3 Mo 0.5 O 6-δ, PSNFM) matrix during SOFC operation. We show evidence that Ni is first exsolved, which triggers the following Fe-exsolution, forming the NiFe NP alloy. At the same time as the NiFe exsolution, abundant oxygen vacancies are created at the NiFe/PSNFM interface, which promotes the oxygen mobility for oxidative dehydrogenation of propane (ODHP), coking resistance, and power generation. At 750 °C, the SOFC reactor with the PSNFM catalyst reaches a propane conversion of 71.40% and LO yield of 70.91% under a current density of 0.3 A cm –2 without coking. This level of performance is unmatchable by the current thermal catalytic reactors, demonstrating the great potential of electrochemical reactors for direct hydrocarbon conversion into value-added products.