Filtration and regeneration performances of SiC fiber potentially applied to gasoline particulates

In this study, for filtration of gasoline particulates, we tested SiC fibers potentially applied for a gasoline particulate filter (GPF). Carbon particles were used as model soot. Focusing on the porosity and the fiber diameter, the filtration efficiency and the pressure drop were examined. To promote the carbon oxidation, the fiber was coated with the Pt-catalyst. Results show that, by reducing the porosity, the filtration efficiency increases, but the pressure drop across the filter (filter backpressure) becomes larger. When the porosity is lower than 0.94, the improvement of filtration efficiency is not enough. Secondary, when the fiber with smaller diameter is adopted by keeping the porosity constant, the filtration efficiency is found to increase. Especially, the combination of 18, 14, 10 mu m fiber sheets exhibits more efficient filtration performance without increasing the pressure drop. As for the continuous regenerating trap (CRT), the oxidation of carbon particles starts around 420 degrees C, and more carbon particles are oxidized at higher temperature. At 600 degrees C, the pressure drop can be kept smaller, because a part of deposited particles is continuously oxidized. At 800 degrees C, the filtration efficiency is worsened with the larger pressure drop. From the above experimental data, the CRT at 600 degrees C is suitable. When the fiber surface is coated with Pt catalyst, the oxidation of carbon particles starts at 250 degrees C. When the temperature is higher than 330 degrees C, the pressure drop of the catalyzed filter is even smaller than that of the non-catalyzed filter. It is concluded that the coating of catalysts is effective for reducing the pressure drop as well as the oxidation temperature.