Mechanism of catalytic decomposition of pentachlorophenol by a highly recyclable heterogeneous SiO2-[Fe-porphyrin] catalyst

被引:42
作者
Christoforidis, Konstantinos C. [1 ]
Louloudi, Maria [2 ]
Milaeva, Elena R. [3 ]
Deligiannakis, Yiannis [1 ]
机构
[1] Univ Ioannina, Dept Environm & Nat Resources Management, Phys Chem Lab, Agrinion 230100, Greece
[2] Univ Ioannina, Dept Chem, Inorgan Chem Lab, Ioannina 45100, Greece
[3] Moscow MV Lomonosov State Univ, Dept Organ Chem, Moscow 119992, Russia
关键词
Heterogeneous catalyst; EPR; DR-UV-Vis; Ferryl; Compound I; High-valent iron; Fe-porphyrin; Immobilized; PCP; CATION RADICAL COMPLEXES; ELECTRON-PARAMAGNETIC-RESONANCE; HORSERADISH-PEROXIDASE COMPOUND; WATER-SOLUBLE IRON(III); HYDROGEN-PEROXIDE; IRON-PORPHYRIN; OXIDATIVE-DEGRADATION; CHLORINATED PHENOLS; HUMIC SUBSTANCES; FENTONS REAGENT;
D O I
10.1016/j.jcat.2009.12.016
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
A novel heterogenized FeR4P-SiO2 shows enhanced catalytic efficiency for PCP conversion vs. the homogeneous FeR4P catalyst. The heterogenized FeR4P-SiO2 catalyst is highly recyclable in the presence of imidazole in solution. EPR and DR-UV-Vis data provide direct evidence that high-valent iron species [(R4P+center dot FeIV)=O] are formed in the heterogenized FeR4P-SiO2 system. The electron spin density of the al, cation radical (Por(+center dot)) is mainly localised on the tetrapyrole frame, and this results in the observed weak magnetic coupling between the S = 1 oxo-ferryl moiety (Fe-IV=O) and the S = 1/2 porphyrin cation radical (Por(+center dot)). A catalytic cycle mechanism is suggested. Accordingly, the reduction in [(R4P+center dot FeIV)=O] can proceed via a substrate molecule, in a one electron-transfer, thus producing [R4PFeIV] plus a radical entity derived from the substrate. Then, a second electron-transfer to [R4PFeIV] leads to the regeneration of the initial R4PFeIII state. This second electron can originate from either a substrate molecule or a radical substrate species. (C) 2009 Elsevier Inc. All rights reserved.
引用
收藏
页码:153 / 162
页数:10
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