Modelling and sensing characteristics of an amperometric hydrocarbon sensor

Abstract

An amperometric hydrocarbon sensor was fabricated by mounting a thin layer of 7CuO·10ZnO·3Al 2O 3 catalyst on top of the platinum cathode of an oxygen sensor with 9% yttria-stabilised zirconia as the electrolyte. A one-dimensional theoretical model was developed to relate the sensor response to the rate processes occurring in the mixed metal oxides catalyst and in the oxygen cell. The response was shown theoretically to follow a mixed first- and half-order concentration dependency. Sensing response towards methane, ethane, propane, isobutane and ethylene was obtained at various temperatures from 1023 to 1093 K and at an applied voltage of 0.8 V to the oxygen cell. The voltage applied was sufficiently high to maintain the oxygen cell under diffusion-controlled or limiting current operating conditions. The response for each of the five hydrocarbons was adequately described by the model with an absolute error of 2.4–5.7%. The rate parameters of the models obtained from the correlation were comparable with the values reported for similar media.