Fe-MCM-41 nanoparticles as versatile catalysts for phenol hydroxylation and for Friedel–Crafts alkylation

Abstract

Iron-containing MCM-41 nanoparticles (Fe-MCM-41 NPs) were successfully prepared using cetyltrimethylammonium bromide (CTAB) in sodium hydroxide medium at ambient temperature from both direct-hydrothermal and post-synthesis methods. The materials were characterized by X-ray diffraction, nitrogen adsorption/desorption isotherms, SEM, TEM, and UV–vis spectroscopy. The characterization results show the existence of highly ordered hexagonal mesopores in the nanoparticles and tetrahedral Fe species in the framework. In phenol hydroxylation with aqueous H2O2, Fe-MCM-41 nanoparticles displayed higher initial reaction rate than Fe-MCM-41 with larger particle size. It is proposed that the diffusion of the reactants is accelerated and the accessibility to the catalytic Fe species is enhanced in the shorter mesopore channels in Fe-MCM-41 nanoparticles. The recyclability potential of the nanoparticles was evaluated in the regeneration by room-temperature washing approach. Fe-MCM-41 NPs also appear to be suitable catalysts for the Friedel–Crafts alkylation of benzene with benzyl chloride.