Improving the Performance of Catalytic Combustion Type Methane Gas Sensors Using Nanostructure Elements Doped with Rare Earth Cocatalysts

Abstract: Conventional methane gas sensors based on catalytic combustion have the drawbacks of high working temperature, low thermal stability and small measurement range. To improve their performance, cerium, which possesses high oxygen storage and release ability, was introduced via nanotechnology to prepare Ce-contained nanostructure elements. Three kinds of elements with different carriers: Al₂O₃, n-Al₂O₃ and n-Ce-Al₂O₃ were prepared and separately fabricated (Pt-Pd/Al, Pt-Pd/n-Al, Pt-Pd/n-Ce-Al). The performances of Wheatstone Bridges with three different catalytic elements were tested and compared. The results indicated that the cerium-containing element exhibited better performance than other elements regarding activity, anti-sulfur ability and thermal stability. Moreover, a constant temperature circuit was also applied in this system. The measurement range was extended from 4% to 10% by automatically decreasing the working current in a reasonable range. The maximum error for 0%–10% CH₄ was controlled below 5%, which fully meets the measurement requirements.