Highly selective sensor to CH4 in presence of CO and ethanol using LaCoO3 perovskite filter with Pt/SnO2

In the present study, LaCoO3 perovskite was used as an active filter to suppress the sensitivity of a Pt/SnO2 sensor to CO and C2H5OH. A sol-gel procedure was used for the preparation of SnO2 fine powder, which was impregnated with hexachloroplatinic acid to obtain 1.0 wt% Pt on SnO2. The LaCoO3 perovskite fine powder was prepared by citrate method, using nitrate precursors of La and Co. LaCoO3 is an effective oxidation catalyst for oxidation of both carbon monoxide and ethanol at temperatures lower than 250 °C. However, the catalyst does not convert methane at temperatures as high as 400 °C. The Pt/SnO2 is highly sensitive to ethanol and shows a significant sensitivity to CO. The perovskite filter eliminates the sensitivity of the sensor to CO and C2H5OH, making the sensor highly selective to methane in the presence of CO and ethanol in air.