Insight into catalytic activity of K-Ce catalysts and K-Ce based mixed catalysts on diesel soot combustion

A series of K-Ce catalysts with different K/(K+Ce) molar ratios are successfully prepared by hydrothermal method, to optimize catalyst diesel particlate filter (CDPF) regeneration efficiency of soot elimination. The K-Ce catalyst is an excellent promoter for soot combustion by thermogravimetric analysis (TGA), and the KC-0.2 catalyst has the best catalytic activity because proper K ions lead to more oxygen vacancies and improve contact efficiency with soot. This result corresponds well to characterization analysis, such as XRD, SEM and XPS. In a 10%O2/90%N2 atmosphere, the KC-0.2 has the highest average mass loss rate (Wmean), maximum mass loss rate (Wmax) and combustion stability index (Rw). The weight ratios of the soot/KC-0.2 mixture are less than 1:10, making catalytic oxidation easier for the soot. Thermal aging in static air at 600 °C is used to investigate the catalytic stability of KC-0.2, and the TGA results show that KC-0.2 has good stability at temperatures lower than 600 °C. Compare to KC-0.2, the KC-0.2 based mixed catalyst with ZrO2 participation is further prepared by mechanical method and has better catalytic activity because the presence of Zr enhances redox surface sites of catalyst. This facilitates the exploration of novel catalysts through combinatorial catalysis.