Synthesis of highly dispersed iron species within mesoporous (Al-) SBA-15 silica as efficient heterogeneous Fenton-type catalysts

Iron and iron-aluminium containing ordered SBA-15 silica catalysts were synthesized for the first time at relatively high iron content (Si/Fe molar ratio down to similar to 21) using an adapted two-step pH-adjustment approach needed for the incorporation of heteroatom species in the mesostructure. The pH applied for the second step of synthesis significantly affected (i) the content of inserted iron and (ii) the state of iron species. Thus, under acidic conditions, the iron heteroatoms were partly incorporated within the mesoporous SBA-15 structure. The solids displayed a moderate activity in the Fenton-type peroxidation of Reactive Red 120 azo dye owing to the low density of active sites for H2O2 activation. Nearly complete iron incorporation was achieved at slightly basic pH with iron mostly presented as isolated and/or highly dispersed species. Furthermore, it was observed that the co-addition of aluminium to iron significantly promoted stabilization of iron species in isolated and/or highly dispersed state, which exhibited improved catalytic properties for the dye degradation with fast cleavage of azo-chromophore into intermediates and high mineralization level. (C) 2016 Elsevier Inc. All rights reserved.