Metalloporphyrins immobilized in Fe3O4@SiO2 mesoporous submicrospheres: Reusable biomimetic catalysts for hydrocarbon oxidation

SEM-a-d-and-TEM-b-c-e-f-images-of-a-c-Fe3O4-NM-MeP-and-d-f-Fe3O4-AM-MeP-samples — SEM (a, d) and TEM (b, c, e, f) images of (a-c) Fe3O4-NM-MeP and (d-f) Fe3O4-AM-MeP samples. Insets in (c) and (f) correspond to spatially resolved Fe (red) Si (blue) EDX intensities along an arbitrary axis (orange lines). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Writers: Isaltino A. Barbosa and Paulo C. de Sousa Filho and Douglas L. da Silva and Fabrício B. Zanardi and Lucas D. Zanatta and Adilson J.A. de Oliveira and Osvaldo A. Serra and Yassuko Iamamoto

Keywords: Mesoporous structures; Core@shell structures; Magnetite particles; Porphyrins; Biomimetic catalysis

Abstract: We successfully immobilized metalloporphyrins (MeP) in mesoporous silica coating magnetite spheres. In this sense, we prepared two different classes of core@shell supports, which comprise aligned (Fe₃O₄-AM-MeP, MeP = FeP or MnP) and non-aligned (Fe₃O₄-NM-MeP, MeP = FeP or MnP) mesoporous magnetic structures. X-ray diffractometry and energy dispersive X-ray spectroscopy confirmed the mesoporous nature of the silica shell of the materials. Magnetization measurements, scanning and transmission electron microscopies (SEM/TEM), electrophoretic mobility (ζ-potential), and infrared spectroscopy (FTIR) also confirm the composition and structure of the materials. The catalysts maintained their catalytic activity during nine reaction cycles toward hydrocarbon oxidation processes without detectable catalyst leaching. The catalysis results revealed a biomimetic pattern of cytochrome P450-type enzymes, thus confirming that the prepared materials are can effectively mimic the activity of such groups.