(544gq) Effect of Lanthanum and Chlorine Doping on Strontium Titanates for the Electrocatalytically-Assisted Oxidative Dehydrogenation of Ethane

Ethylene, a basic building block of many polymeric materials, is industrially produced by steam cracking of naphtha which is a highly energy-intensive process [1]. An alternate technology of ethylene production is oxidative dehydrogenation (ODH) of ethane, however this technology leads to oxidation of ethylene to CO and/or CO₂, thus reducing the overall selectivity towards ethylene. Literature suggests that oxygen ions provides higher ethylene selectivity than gas phase oxygen during oxidative dehydrogenation of ethane [2]. Therefore, in this study, ODH is carried out in a solid oxide fuel cell (SOFC)-type reactor in which external electrical energy is provided to enhance the flux of oxide ions to the anode side. The electrolyte used is yttria-stabilized zirconia (YSZ) sandwiched between two electrodes. Commercially available La_0.8Sr_0.2MnO₃-YSZ is used as the cathode, while an inhouse developed lanthanum doped strontium titanate perovskite oxide is used as the anode material.

Strontium titanate-type perovskites were synthesized using a modified Pechini method. Synthesized materials were characterized using XRD, XPS, Four probe DC van der Pauw conductivity, RAMAN, DRIFTS and temperature-programmed oxidation with CO₂ techniques to study their bulk and surface structural properties and electrical/ionic mobility.

Electrochemical activity experiments were performed at 600°C in the current density range 0-3.5 mAcm^-2. The activity results showed that lanthanum doping of strontium titanate improves ethane conversion, and additional chlorine incorporation into the perovskite structure enhances both ethane conversion as well as selectivity towards ethylene [3].

References:

[1] T. Ren, M. Patel, K. Blok, Olefins from conventional and heavy feedstocks: energy use in steam cracking and alternative processes, Energy 31 (4) (2006) 425–451.

[2] M.P. Woods, B. Mirkelamoglu, U.S. Ozkan, Oxygen and nitrous oxide as oxidants: implications for ethane oxidative dehydrogenation over silica-titania-supported molybdenum, J. Phys. Chem. C 113 (23) (2009) 10112–10119.

[3] D. Dogu, K.E. Meyer, A. Fuller, S. Gunduz, D.J. Deka, N. Kramer, A. Co, U.S. Ozkan, Effect of lanthanum and chlorine doping on strontium titanates for the electrocatalytically-assisted oxidative dehydrogenation of ethane, Applied Catalysis B: Environmental 227 (2018) 90-101.