Electrochemical removal of NO and CH4 in the presence of excess O2, H2O and CO2 using Sm2O3-doped CeO2 as a solid electrolyte

Abstract

Electrochemical removal of NO and CH₄ from a gas stream containing excess O₂, H₂O and CO₂ has been carried out between 400 and 800 °C using a single-compartment reactor, which is constructed from CeO₂-based solid electrolyte with two palladium electrodes. At all temperatures studied, both NO and CH₄ were decomposed by applying a direct current to the reactor. NO was decomposed to N₂ in two different ways depending on the applied current. At low currents, NO was electrolysed together with O₂ at the palladium cathode; and, at high currents, NO was catalytically reduced over the palladium surface free from adsorbed oxygen. By investigating the influences of the concentration of NO, H₂O, CO₂, CH₄ or C₃H₈ contained in the reactant gas to these two decompositions, their mechanisms are discussed in detail.