Alumina as Solid‐State Ligand in Enhancing the Redox Catalytic Property of Iron Oxide Grafted AlSBA‐15 towards Arylation of Arene

Abstract

Abstract2–8 wt % iron has been grafted over SBA‐15 and 10 wt % alumina grafted SBA‐15 (AlSBA‐15) through selective extraction deposition technique using LaFeO3 as iron precursor in acidic solution. DRS‐UV spectra confirmed the presence of iron as isolated Fe(III), Fe(III)‐clusters and amorphous FeOx oligomers. SEM‐EDX mapping, FT‐IR, XPS, HR‐TEM and 27Al MAS NMR characterisation results confirmed that iron grafted over AlSBA‐15 preferentially reside on the alumina. The donor‐acceptor interaction of grafted iron ions with alumina atoms displaying Lewis acid properties stabilized iron at higher oxidation state Fe(III+δ). This increased the BE of Fe2p electrons (XPS) and shifted the temperature of iron reduction in 2–8 wt %Fe/AlSBA‐15 materials to higher value (600 °C) compared with Fe/SBA‐15 (H2‐TPR). In arylation of benzene, 8 wt %Fe/AlSBA‐15 demonstrated excellent redox catalytic activity with TOF close to homogeneous catalyst and 82 % biphenyl yield. The catalyst demonstrated consistent catalytic performance for 7 cycles.