Photocatalytic degradation of methylene blue with spent FCC catalyst loaded with ferric oxide and titanium dioxide

The spent fluid catalytic cracking (FCC) catalyst has been loaded with ferric oxide (Fe2O3) and titanium dioxide (TiO2). Fe-Ti/SF composite (loaded with 5 wt% TiO2 and 5 wt% Fe2O3), Fe/SF composite (loaded with10 wt% Fe2O3) and Ti/SF composite (loaded with 10 wt% TiO2) have been fabricated via a modified-impregnation method. The band gaps of the Fe-Ti/SF, Fe/SF and Ti/SF composites (evaluated by the energy versus [F(R infinity)hv](n)) are 2.23, 1.98 and 3.0 eV, respectively. Electrochemical impedance spectroscopy shows that the Fe-Ti/SF has lower electron transfer resistance, it has the small charge transfer resistance and fast charge transfer rate. The interparticle electrons transfer between the Fe2O3 and TiO2, which can improve the separation of the photo-electrons and holes. The holes transfer from valence band of TiO2 to the valence band of Fe2O3, which can provide more active sites around the adsorbed molecules. The methylene blue degradation efficiencies (with the Fe-Ti/SF, Fe/SF and Ti/SF composites) are similar to 94.2%, similar to 22.3% and similar to 54.0% in 120 min, respectively. This work reveals that the spent FCC catalyst as supporter can be loaded with Fe2O3 and TiO2. This composite is highly suitable for degradation of methylene blue, which can provide a potential method to dispose the spent FCC catalyst in industry.