Investigation of alkali metals addition on the catalytic activity of CuFe2O4 for soot oxidation.

• The enhanced soot oxidation activity is ascribed to the formation of surface oxygen vacancies. • The low initial temperature (T ig = 308 °C) and the low temperature of maximum CO 2 emission (T max = 389 °C) were achieved. • DFT calculations were performed to correlate with the activity test results. Soot particle exhausted from diesel engines are causing severe health and environmental problems. Alkali metals (Li, Na, K, Cs) doped CuFe 2 O 4 catalysts were synthesized to eliminate soot residue. XRD, Raman, SEM, H 2 -TPR and temperature-programmed oxidation (TPO) were employed to investigate the effect of alkali metals addition on CuFe 2 O 4. Density functional theory (DFT) calculations were used to explore the inner reaction mechanism. The results revealed that the doping of all alkali metals facilitated the formation of oxygen vacancies which are the main active sites for soot oxidation. The CuFe 2 O 4 doped by K showed smallest crystal size and the most oxygen vacancies. Therefore, Cu 0.9 K 0.1 Fe 2 O 4 catalyst performed best catalytic activity in soot oxidation with the T ig of 308 °C and T max of 389 °C. [ABSTRACT FROM AUTHOR]