Preparation method effect of La0.9K0.1Co0.9Ni0.1O3 perovskite on catalytic soot oxidation

Abstract

In order to evaluate the effect of preparation method of La0.9K0.1Co0.9Ni0.1O3 perovskite on the catalytic activity towards soot oxidation, three synthetic routes, self-combustion (SC), sol–gel (SG) and microwaves-assisted (MW) were used. After characterizing the samples using different analytical techniques (SEM, TEM, DRX, XPS, H2-TPR and O2-TPD), the results suggested that the synthesis method influenced not only the textural and physicochemical properties of the catalyst, but also the availability of active sites such as oxygen vacancies (α-O/Ototal), and reducible sites (Co3+/Co2+ ratio). The above results along with the small particle sizes obtained for solids, favored the catalytic activity toward soot oxidation in the following order: SG (T50 435 °C) > MW (T50 455 °C) > SC (T50 491 °C). However, although the material synthesized by SG was the most active, the material synthesized by MW presented greater thermal stability and better selectivity toward CO2 than the other synthesis methods after 6 catalytic cycles. DRIFT analysis indicated that the evolution of molecular CO2 comes along with the bidentate carbonate species decomposition, although the presence of thermally stable carbonates species was also seen.