Detection of methane in oxygen-poor atmospheres using a catalytic asymmetric sensor design

By Seman, Michael & Wolden, Colin A.
Published in Sensors and Actuators B: Chemical NULL 2001

Abstract

A catalytic sensor for the detection of methane in oxygen-poor atmospheres has been tested. This sensor is based on the difference in catalytic activity of a ruthenium and a platinum electrode for the reaction of methane and CO2 to hydrogen. The electrolyte used is SrCe0.95Yb0.05O3-α (SCYb5), a high-temperature proton conductor. The sensor shows a good response to methane at 500°C in a concentration range of 1–90 kPa with a small dependence on the CO2 concentration, especially, at low methane partial pressures (<10 kPa). At temperatures higher than 500°C, a maximum in the potential difference of the sensor is detected. This maximum can be attributed to a change in the electrode selectivity. It is shown that the sensor can be used to detect methane if the CO2 concentration is kept high enough, to ensure that there is no reaction change. The potential difference of the sensor decreases with increasing temperature, which can be attributed to either the increasing electronic conductivity of the electrolyte, or a decreasing catalytic activity difference between the electrodes.

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