Dual selective Pt/SnO2 sensor to CO and propane in exhaust gases of gasoline engines using Pt/LaFeO3 filter

In this study, a novel dual selective Pt/SnO2 sensor to carbon monoxide and propane in exhaust gases of a gasoline engine, using a Pt/LaFeO3 perovskite catalytic filter, is presented. SnO2 was prepared by a sol–gel method and LaFeO3 by a combustion synthesis method. The samples were impregnated with aqueous solutions of H2PtCl6 to get 1.0 wt% Pt/SnO2 and 1.0 wt% Pt/LaFeO3. BET surface area measurement, XRD, EDS, TEM, HR-TEM, temperature programmed methods of reduction (TPR) and O2-desorption (TPD) analyses were carried out to investigate surface and bulk properties of the samples. In a mixture of 10,000 ppm carbon monoxide, 1000 ppm nitric oxide and 1000 ppm propane in 1.0% oxygen, Pt/LaFeO3 catalytic filter-Pt/SnO2 sensor combination is selective to CO and C3H8 at the temperature ranges of 150–250 and 350–400 °C, respectively. In the temperature range of 150–250 °C, the filter-sensor combination has a significant response to CO, whereas negligible response to C3H8 and NO is observed. On the other hand, at temperatures higher than 350 °C, CO and NO in the mixture are completely converted to almost inert products on the filter and the sensor shows a response only to C3H8.