Abstract: Apparatus for the reduction of nitrogen oxides in gas streams are disclosed comprising an oxygen ion-conducting substrate, an anode disposed on the substrate, a cathode disposed on the substrate, and a voltage source connected to the anode and the cathode in which the cathode is comprised of gold so that the nitrogen oxides are adsorbed and dissociated on the cathode, nitrogen may recombine into nitrogen gas on the cathode, and oxygen ions are transported through the substrate from the cathode to the anode. Methods for the reduction of nitrogen oxides in gas streams are also disclosed.

Abstract: Exhaust gas analyzers are disclosed for analyzing the exhaust gases from a combustion process including a sensor unit mounted for direct contact with the exhaust gases in which the sensor unit includes a number of sensors such as lambda sensors, NOx sensors, oxygen sensors, and residual heat sensors, mounted on a common substrate for detecting specific gases and temperatures in the exhaust gases and generating signals based thereon, the substrate being an oxygen-ion-conductive ceramic material and the sensors elements including conductive patterns applied to the common substrate, and a common analyzer connected to the sensor units for analyzing the signals generated by the sensor elements.