Kinetic behaviors of high concentration NOx removal from simulated lean-burn engine exhaust via electrochemical-catalytic cells

The electrochemical-catalytic cell (ECC) is a simplified solid oxide fuel cell (SOFC) by deleting the current-collecting parts. Either the ECCs or the SOFCs of this work were anode-supported and constructed with yttria-stabilized zirconia (YSZ) as the electrolyte, Ni–YSZ as the anode, and the composite of Mn- or Co-based LaSr perovskite and gadolinia-doped ceria as the cathode. The results show that the kinetics and the associated mechanism of NO reaction during high concentration NOx removal from simulated lean-burn engine exhaust are the same in the ECCs and the SOFCs. This indicates that the underlying chemical changes and the electrocatalytic processes taking place in the ECCs are the same as those in the SOFCs operating at open circuit. The reaction is direct NO decomposition and, in general, both the rate constant and the reaction order decrease with increasing temperature from 400 to 500 °C; second order reaction dominates. However, the cathode materials can have strong effects on the kinetic behaviors.

► Electrochemical-catalytic cell (ECC) is simplified solid oxide fuel cell (SOFC).
► The reaction is direct NO decomposition.
► The kinetic behaviors are the same in the ECCs and the SOFCs at open circuit.
► The rate constant and the reaction order decrease with increasing temperature.
► The cathode materials can have strong effects on the kinetic behaviors.