Effectiveness of non-noble metal based diesel oxidation catalysts on particle number emissions from diesel and biodiesel exhaust

摘要

Two new formulations of non-noble metal based diesel oxidation catalysts based on Co-Ce based mixed oxide (DOC_2) and perovskite catalysts (DOC_3) were prepared and retrofitted in a 4-cylinder diesel engine fueled by diesel and Karanja biodiesel blend (KB20). In this study, their effectiveness in reducing raw exhaust particulate emissions vis-a-vis a commercial diesel oxidation catalyst (DOC_1) was evaluated. Emission characteristics such as particle number-size distribution, mass-size distribution, and surface area-size distribution, total particle number concentration and count mean diameter as a function of engine load at constant engine speed were evaluated. Variations in total particle number concentration as a function of engine speed were also determined. The prepared DOCs and the commercial DOC showed varying degrees of performance as a function of engine operating conditions. Overall, effectiveness of the prepared DOCs appeared to be more fuel specific. For diesel exhaust overall performance of DOC] was more effective compared to both prepared DOCs, with DOC2 being superior to DOC_3. In case of KB20 exhaust, the overall performance of DOC_2 was either more effective or nearly comparable to DOC_1 while DOC_3 being not so effective. This showed that the DOCs based on Co-Ce based mixed oxide catalysts have potential to replace commercial noble metal based DOCs, especially in engines fueled by biodiesel.