Influence Of Preparation Methods On Property Of Methane Catalytic Pellistors

Catalytic gas sensor is the key device to monitor the methane in coalmine. Theperformance improvement has important significance in the construction andproduction of coalmine. The key to enhance the performance of catalytic gas sensor isthe preparation technology of supporter and catalyst of pellistors. On high temperaturecatalytic condition, the Al₂O₃supporter and Pd active component in the pellistors ofgas sensors are easy to sinter and decrease the surface area of Pd/Al₂O₃. In themeantime, the pellistors are also easy to be poisoned by sulfurous gas in methane. Theoutputs of pellistors are influenced by high concertration water vapor as well. Thethermal stability and sensitivity of pellistors are decreased consequently. Thus, thestability, lifetime and calibration cycle of gas sensors are decreased as well.In order to improve the process of gas sensors, microcosmic material science isapplied to improve the preparation technology and doping technology of pellistors. Aseries of material methods are utilized to analyze the surface of catalyst. The pellistorsprepared by improved catalyst are tested in gas-contained atmosphere at hightemperature via electrology method. Activity, thermal stability, sulfur tolerance andoutput in high humility are tested and analyzed.To improve the supporter of pellistors, nano meter Al₂O₃is prepared by sol-gelmethod. Since the surface area of supporter is highly increased by nanometer effort,the dispersion of active component is enhanced significantly. In the meantime, all theinfluencing factors are tested and analyzed. The best preparing condition is obtainedconsequently. The improvement of pellistors modified by glow discharge cold plasmais also preliminary discussed. Via ‘cold outside, hot inside’effect from cold plasma,the surface of pellistors is processed at low temperature. The noble metal on thesurface of pellistors is reduced&calcined without the change of monolithicconstruction. This method promotes the dispersibility of surface active component andthus reduces the reaction temperature in catalytic combustion.Noble metal Pt is doped with active component Pd. By alloy effect of Pd-Pt, thedistribution of metal on the surface of pellistors is improved and the sintering betweenPd and Pt is avoided. In this way, activity and sulfur resistance ability is enhanced.The stability is also improved to a certain extent. In the meantime, optimal ratio Pd: Ptis obtained by testing pellistors with different ratios of Pd: Pt. Ce/Zr and Solidsolution Ce-Zr-O are utilized to improve the performance of pellistors. Since rare earth elements have stronge OSC（oxygen storage capability）, the requirement ofcatalytic combustion reaction is decreasd. Consequently, the reaction is promoted. Theperformance of pellistors with rare earth elements are improved significantly. Thepellistors with Ce display perfect sulfur resistance performance and the pellistors withZr displays better anti-ageing performance in high humility atmosphere.