Iron(II) phthalocyanine immobilized SBA-15 catalysts: Preparation, characterization and application for toluene selective aerobic oxidation

Iron(II) tetracarboxyl phthalocyanine (tcFePc) grafted onto amino-functionalized SBA-15 catalysts for selective oxidation of toluene by oxygen and N-hydroxyphthalimide (NHPI) were studied under mild conditions. The catalysts were characterized by nitrogen adsorption measurements, X-ray diffraction, element analyses, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Their catalytic performance depended on the isolated amino group and tcFePc contents, which induced the surface composition and porosity of the catalysts. Less isolated amino groups (2.4 μmol/m²) and more grafted tcFePc (20 wt%) facilitate the oxidation efficiency of toluene to benzoic acid. Meanwhile, more isolated amino groups (3.8 μmol/m²) and less grafted tcFePc (11 wt%) weaken the oxidation activity of toluene and tend to form benzaldehyde. Reaction parameters, reaction scope and catalyst reusability were also investigated over 20 wt% tcFePc@NH₂-SBA-15-3. Moreover, a plausible pathway for this catalytic process was proposed to involve a radical mechanism.