Highly selective Pt/SnO2 sensor to propane or methane in presence of CO and ethanol, using gold nanoparticles on Fe2O3 catalytic filter

Gold nanoparticles on Fe2O3 are used as a catalytic filter for Pt/SnO2 sensor to make it highly selective to propane or methane in presence of CO and ethanol. Gold nanoparticles with an average size of 2.5 nm on Fe2O3 were prepared by co-precipitation method and characterized by TEM, XRD and BET. SnO2 was prepared by a sol–gel method and impregnated with aqueous solution of H2PtCl6 to get 1 wt% Pt/SnO2. A flow system was used to measure the sensor response in absence or presence of the interfering gases and the filter.Without using the filter, the Pt/SnO2 sensor shows comparable sensitivity to propane, methane and CO and much higher sensitivity to ethanol. The filter converts CO to insensitive CO2 at room temperature. Ethanol is strongly adsorbed on the catalytic filter at room temperature and is completely oxidized to CO2 at temperatures higher than 200 °C. No significant adsorption or oxidation of propane and methane occurs at temperatures lower than 200 °C. The filter-sensor combination becomes highly selective to propane or methane in presence of CO and ethanol.