Development of Oxygen Sensor for Gas Analyser

Abstract

Simple and small size oxygen sensor with fast response was designed on the base of oxygen concentration cell with solid electrolyte. The sensor can be used as a detector for various gas analysers independently or with combination of other gas detectors such as thermal conductivity detector.
The sensor consists of two elements, a furnace and a thermocouple. The element is a stabilized zirconia pipe (4φ X 2-3φ X 150 mm) coated with porous platinum electrodes on both sides of the pipe (Fig.2). Two elements (reference and measurment cell) are located in the furnace (40 mm long) and heated to 800-1OOO C. The carrier gas is divided into two streams; one runs through the reference cell and the other is led into the measurment cell via the reactor containing a sample. The differential motive force between two electrodes is measured continuously (Fig.3).
The sensitivity of the sensor increases with the decrease of oxygen pressureof a carrier gas and 1X10-4 ml-O2 at Po2=10-3 atm (Fig.4) can be detected.
Though the sensor is not sensible to inert gases, gases, such as nitrogen oxides, affect the response through the dissociation and evolution of oxygen at high temperatures. The combustible gases, such as H2 and CO, react with oxygen at high temperature and reduce the oxygen concentration in a carrier gas (Fig.7).
This report describes the applications of the sensor for the study of oxidation andreduction reaction of cobalt oxide (Fig.5) and thermal decomposition of caluciumoxalate monohydrate (Fig.7).