Journal of Molecular Catalysis A: Chemical
MCM41 was synthesized and Fe(III)protoporphyrin(IX) (Hemin, Fe(III)PPIX) was directly encapsulated into MCM41 pores through the self-assembly formation mechanism using micelles of quaternary alkylammonium salt (cetyl trimethyl ammonium bromide) as the solvent for Fe(III)PPIX and template for formation of MCM41 spontaneously. The catalysts obtained were characterized by XRD, BET N2 adsorption isotherm, diffuse reflectance UV–vis and FT-IR techniques. Fe(III)PPIX/MCM41 was used in some typical test reactions, such as oxidation of phenol, ortho-methoxyphenol (guaiacol) and synthesis of indophenol. Kinetic parameters including initial reaction rates, rate constants, Vmax, turnover number, Michaelis constant and catalytic efficiency were obtained and compared to those of Fe(III)/MCM41(as a blank) and horseradish peroxidase (HRP) enzyme (consisting of Fe(III)PPIX as the prosthetic group). Results showed that Fe(III)PPIX/MCM41 catalyst was able to mimic horseradish peroxidase with a Km value of 183 μM with respect to guaiacol (as the reducing substrate of HRP). Fe(III)PPIX/MCM41 catalyzes the oxidation reactions (in the presence of hydrogen peroxide) at higher rates than the homogeneous Fe(III)PPIX system and Fe(III)/MCM41 heterogeneous catalyst, but at lower rates than the enzyme as a homogeneous catalytic system.

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