Catalytic Oxidation Of Methylene In Hydrocarbons

The selective oxidation of hydrocarbons is of great importance and status in petroleum and chemistry industry. The oxidation of methylene is an important part. It is interesting and challenging, according to biomimetic catalytic principles, to simulate the active center of enzyme, design biomimetic homogeneous and heterogeneous catalysts, and realize the direct oxidation of hydrocarbons with molecular oxygen under mild conditions.We developed a homogeneous biomimetic catalytic system consisting of hemin and N-hydroxyphthalimide (NHPI). The biomimetic catalytic cycle was completed without stoichiometric reductants under mild conditions. This system showed high activity and selectivity for the selective oxidation of ethylbenzene with dioxygen. 90.3% conversion of ethylbenzene with 94.3% selectivity for acetophenone (AcPO) can be obtained at 373 K under 0.3 MPa O2 for 9 h.Another high efficient [Fe(phen)₃](ClO₄)₂/NHPI system showed excellent results, which was comparable to the best reported result. 90.2% conversion of ethylbenzene with 98.8% selectivity for AcPO can be obtained at 333 K under 0.3 MPa O2 for 9 h.Co/SBA-15 was synthesed with tetrahedral coordinated Co(II) highly dispersed in the mesopores. No bulk Co₃O₄, octahedral Co(II), or Co(III) were detected. Co/SBA-15 showed much higher activity than Co(OAc)₂ or Co₃O₄ in the liquid-phase aerobic oxidation of ethylbenzene under solvent-free condition. Thetetrahedral cobalt(II) can efficiently decompose alkyl peroxides, and thus facilitate the reaction.Metalloporphyrin and quasiporphyrin complexes were introduced into SBA-15 to simulate the micro-environment in active centers of enzyme. The activity of metal complexes/SBA-15 is low active but enhanced by combined it with NHPI. The modification of N-(β-aminoethyl)-γ-aminopropyl trimethoxy-silane can inhibit the reaction. The coordination may affect the redox property of metal centers.