Reduction of nitrogen oxide by steam electrolysis cell using a protonic conductor SrZr0.9Yb0.1O3-alpha and the catalyst Sr/Al2O3

A steam electrolysis cell was constructed with a high-temperature type prot onic conductor, SrZr0.9Yb0.1O3-alpha. The reduction of nitrogen oxide (NO) by hydrogen, which was produced by a steam electrolysis cell, was examined. Helium gas with 8% O-2 and 1000 ppm NO was used as a model gas for the exh aust gas from automotive engines operating under lean-burn condition. The r emoval efficiency of NO was measured, using steam electrolysis cells with d ifferent catalysts on the cathodes. A mixture of Pt-sponge and Sr/Al2O3 cat alyst was found to be most effective for the preferred reduction of NO in t he presence of excess O-2. It was suggested that the preferred reduction of NO occurred via the electrochemical reduction of NO absorbed into Sr/Al2O3 , not via the chemical reduction of NO by H-2 gas. (C) 2000 Elsevier Scienc e B.V. All rights reserved.