Methane Combustion Using Pd Deposited on CeO_x-MnO_x/La-Al₂O₃ Pellistors

Pd deposited on CeO_x-MnO_x/La-Al₂O₃ has been prepared as a sensitive material for methane (CH₄) detection. The effect of different amounts (1.25%, 2.5% and 5%) of Pd loading has been investigated. The as prepared materials were deposited on Pt microcoils using a drop-coating method, as a way of developing pellistors operated using a Wheatstone bridge configuration. By spanning the operating temperature range between 300 °C and 550 °C, we established the linearity region as well as the maximum sensitivity towards 4900 ppm of CH₄. By making use of the sigmoid dependence of the output voltage signal from the Wheatstone bridge, the gas surface reaction and diffusion phenomena have been decoupled. The pellistor with 5% Pd deposited on CeO_x-MnO_x/La-Al₂O₃ exhibited the highest selective-sensitivity in the benefit of CH₄ detection against threshold limits of carbon monoxide (CO), sulfur dioxide (SO₂) and hydrogen sulfide (H₂S). Accordingly, adjusting the percent of Pd makes the preparation strategies of pellistors good candidates towards CH₄ detection.