Removal of NO_x with Porous Cell Stacks with La_0.85Sr0.15Co_xMn_1-xO_3+δ-Ce_0.9Gd_0.1O_1.95 Electrodes Infiltrated with BaO

Porous cell stacks with composite electrodes of La_0.85Sr_0.15Co_xMn_1-xO₃-Ce_0.9Gd_0.1O_1.95 were tested for activity toward selective electrochemical reduction of NO_x to N₂ in the presence of 10% O₂. The cell stacks were produced by tape casting, laminating and sintering the backbone structure followed by infiltration with BaO or La_0.85Sr_0.15MnO_3+δ. The cell stacks were tested in an atmosphere of 1000 ppm NO or NO₂ + 10% O₂ in Ar with 10% O₂ in Ar as reference, and in the temperature range of 250 to 500 °C. The cell stacks were investigated electrochemically with cyclic voltammetry and polarization, and the outlet gas composition was monitored. Doping with Co increases the electrodes activity for reducing NO_x, and up to 93% conversion in the presence of 10% O₂ at 400 °C was measured. Infiltration with BaO was necessary to achieve any formation of N₂. Square wave polarization increased the activity of the electrodes achieving a current efficiency as high as 20% at 350 °C, and this indicates a problem with mass transfer. An atmosphere containing NO₂ also increased the activity of the electrodes, which points to a mechanism with a NO₂ related intermediate. © 2014 The Electrochemical Society. All rights reserved.