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

In the present study, LaCoO(3) perovskite was used as an active filter to suppress the sensitivity of a Pt/SnO(2) sensor to CO and C(2)H(5)OH. A sol-gel procedure was used for the preparation of SnO(2) fine powder, which was impregnated with hexachloroplatinic acid to obtain 1.0 wt% Pt on SnO(2). The LaCoO(3) perovskite fine powder was prepared by citrate method, using nitrate precursors of La and Co. LaCoO(3) is an effective oxidation catalyst for oxidation of both carbon monoxide and ethanol at temperatures lower than 250 degrees C. However, the catalyst does not convert methane at temperatures as high as 400 degrees C. The Pt/SnO(2) is highly sensitive to ethanol and shows a significant sensitivity to CO. The perovskite filter eliminates the sensitivity of the sensor to CO and C(2)H(5)OH, making the sensor highly selective to methane in the presence of CO and ethanol in air. (c) 2006 Published by Elsevier B.V.