Spinel AFe2O4 Catalysts: Preparation and Catalytic Combustion of Toluene

Abstract

Nanocrystalline AFe2O4(A=Cu, Co, Ni, Mg, Zn) ferrite spinel catalysts were prepared by Sol-Gel auto-combustion method. In order to investigate the influence of A sites in AFe2O4 spinel catalysts, the catalytic combustion of toluene was investigated, and the catalysts were characterized by XRD, N2 adsorption-desorption, SEM, TEM, H2-TPR, and XPS. It was found that AFe2O4 catalysts have excellent catalytic activity. Among the catalysts, the CuFe2O4 catalyst obtains the highest catalytic activity, and its light-off temperature (T50) and the complete combustion temperature (T90) of toluene were 188℃ and 239℃, respectively. And AFe2O4 catalysts have obviously lamellar spinel crystal structure and the multilevel pore structures with prevalence to mesoporous, which will improve the catalytic activity of the catalysts. It is concluded that the elements of A site on AFe2O4 have great influence on catalytic combustion activity. The H2 reduction temperature is only 289℃, when A site was occupied by Cu. CuFe2O4 has crystal lattice volume of 0.294 nm3 with CuO and α-Fe2O3 formed in the crystal. The concentration of electrophilic oxygen and oxygen vacancy in all oxygens (Oele/O1S) is 36%. Lamellar trans spinel crystal lattice, the synergies of trans spinel CuFe2O4 with CuO and α-Fe2O3, and the multilevel pore structures with prevalence to mesoporous are the main reasons for the catalytic activity improvement of CuFe2O4.