Iron incorporated Ia3d mesostructured silicate prepared at room temperature: Excellent Friedel–Crafts benzylation catalyst

Abstract

The incorporation of Fe3+ ions in the framework of FDU-5, a cubic Ia3d silicate, with different Si/Fe ratio have been synthesized for the first time in room temperature under acidic condition employing solvent drying method without the necessity of pH adjustments. The synthesized samples, Fe-FDU-5, were investigated using different characterization techniques including XRD, N2 sorption, TEM, UV–vis, ESR, NH3-TPD, H2-TPR and pyridine-absorbed FT-IR techniques. The presence of isolated Fe3+ species and extraframework Fe2O3 particles were confirmed at all loadings (1.2–4.5 wt% Fe). The N2 sorption studies of Fe-FDU-5 materials evidenced a specific surface area of 340–394 m2/g, total pore volume of 0.41–0.44 cm3/g and a narrow pore distribution of 4.4–4.9 nm. Fe-FDU-5 are excellent catalysts for benzylation of benzene and is independent of acid sites. A near complete conversion of benzyl chloride (BnCl) was achieved in 20 min over Fe-FDU-5 where as other metal ions including Al3+, Sn4+ and Mn2+or Mn3+ supported on various silica supports yielded only 3–8% BnCl conversion. Moreover, both framework Fe3+ and extraframework octahedral Fe species are found beneficial for this reaction, however, bulk Fe2O3 species are inactive.