Noble metal oxidation catalysts have been shown to convert gasoline sulfur to automotive particulate sulfate emissions. A study was carried out in a laboratory bench scale reactor to evaluate the effect of vehicle operating conditions and catalyst type on the conversion of SO2 to SO3. The factors studied included catalyst temperature, exhaust gas O2 content and space velocity. The results are compared with data from a vehicular study designed to assess total sulfur emissions from catalyst-equipped cars.
This study indicates that control of exhaust sulfate emissions may be achieved through close control of the oxygen content of exhaust gas and that the choice of catalyst affects the degree of conversion of SO2 to SO3 and the amount of oxidized sulfur retained in the catalyst system.