Selective detection of unburned-hydrocarbon in the exhaust gas using catalytic filter

Pd/LaMnO₃ was used as a catalytic filter for Pt/SnO₂ sensor to selectively detect propane, as a representative of unburned-hydrocarbons, in the presence of CO and NO for exhaust gas application. SnO₂ was synthesized by a sol-gel method and LaMnO₃ was prepared through a combustion synthesis recipie. The samples were impregnated with aqueous solutions of H₂PtCl₆ and Pd(NO₃)₂.2H₂O to prepare 1.0 wt% Pt/SnO₂ and 1.0 wt% Pd/LaMnO₃. By using Pd/LaMnO₃ filter, the fabricated sensor responded to propane similar to a mixture of CO, NO and C₃H₈. Thus, the combination of Pd/LaMnO₃ filter and Pt/SnO₂ sensor becomes highly selective to propane in presence of CO and NO in the exhaust stream of a gasoline engine.