Enhanced soot oxidation by oxygen vacancies via K + doped CuFe 2 O 4 spinel catalysts

Soot particulate emitting from diesel engines are serious to both human health and environment. Efficient catalyst is vital in diesel particulate filter technology to decrease soot oxidation temperature. Cu1−xKxFe2O4 (x = 0, 0.05, 0.1, and 0.15) catalysts are synthesized and analyzed with XRD, Raman, BET, SEM, TEM, TG, EDS, XPS, catalytic activity tests, and kinetic analysis. The results suggests that many factors affect the catalytic activity, and the contents of oxygen vacancies are dominant. A large amount of oxygen vacancies which facilitate to the soot oxidation are created with the assistance of K+, and they increase with the increasing doping contents. Excessive surface concentration of K+ may lead to the partially covering of active sites of the catalysts. Therefore, Cu0.9K0.1Fe2O4 catalyst exhibits the best catalytic activity in soot oxidation, which decreases the Tmax of soot by 279°C. This decrease makes it highly promising for application in diesel particulate filter.