A highly selective sensor to acetylene and ethylene based on LaFeO3

Abstract

Gas sensing using metal oxides can be a highly cost effective and reliable technology in a variety of medical and industrial applications. However, selectively sensing a specific gas in a complex gas mixture continues to be a significant challenge. Here, we focus on acetylene and ethylene sensing with LaFeO3 (LFO) based sensors with novel applications, such as online monitoring and maintenance of electrical power transformers, in mind. We prepared LFO’s via sol gel method at five different calcined temperatures (500–900 °C). X-ray diffraction (XRD) patterns showed that all five materials were single phased with a perovskite crystal structure. We then used these materials as active sensing layers during exposure to various test gases, including C2H2, C2H4, CH4, C2H6, CO, CO2 and H2 at different operating temperatures (150 °C, 200 °C, 250 °C and 300 °C). All of our sensors showed a significant response to unsaturated hydrocarbons, namely acetylene and ethylene, but not to the other gases. We further improved this high selectivity of our sensors, to only detect acetylene and not ethylene, by controlling the operating temperature. We then tested the effects of different backgrounds, such as humidity, and CO2 levels, on our LFO sensors. The sensors were saturated faster in humid than dry conditions, in particular at lower operating temperatures, and there was no influence of CO2. Therefore, our results demonstrate novel oxide-based sensors capable of distinguishing between acetylene and ethylene, enabling interesting new industrial applications.