Enhancement on Sensitivity and Stability of Methane Sensor by Increasing Pd Amount and Acid-Assisted Loading

Abstract

Al2O3 was loaded with different amounts (5 wt%, 10 wt%, and 15 wt%) of Pd via isometric-impregnation. Transmission electron microscopy (TEM) demonstrated that the 15 wt% Pd/Al2O3 has numerous Pd nanoparticles formed on Al2O3. To decrease the hydrolysis rate of Pd(NO3)(2), which could cause the formation of Pd aggregates on Al2O3, determinate concentrations of HNO3 were mixed with the impregnation solution. The measuring results of TEM and Brunauer-Emmett-Teller-specific surface areas revealed that 15 wt% Pd loaded with 10 vol% HNO3 has high dispersion on Al2O3. The influences of the loading amounts of Pd and the acidity of the impregnated solution on the sensitivity and stability of gas sensors were investigated. Catalytic combustion gas sensors based on 15 wt% Pd/Al2O3 prepared from a 10 vol% HNO3-90 vork Pd(NO3)(2) impregnating solution exhibited high responses to methane and strong ability to resist organic silicon.