Chlorophenols in water are resistant to biological oxidation and they have to be destroyed by chemical oxidation. In the present work, Fe(III), Co(II) and Ni(II) incorporated MCM41 mesoporous solids were used as catalysts for oxidation of 2,4,6-trichlorophenol in water with or without the oxidant, H(2)O(2). The catalysts were prepared by impregnation and were characterized by XRD and FTIR measurements. The parent MCM41, Fe(III), Co(II) and Ni(II) impregnated MCM41 had cation exchange capacity of 20.5, 25.5, 24.2, 26.0 mequiv./100g, respectively. The catalysts were used after calcination at 773-873 K for 5 h. The reactions were carried out in a high pressure stirred reactor at 0.2 MPa (autogenous) and 353 K under various reaction conditions. The conversion achieved with Fe(III), Co(II) and Ni(II) incorporated MCM41 in 5h is respectively 59.4, 50.0 and 65.6% with 2,4,6-TCP:H(2)O(2) molar ratio of 1:1, and 60.2, 60.9 and 68.8% in absence of H(2)O(2). The oxidation has a first order rate coefficient of (1.2-4.8)x10(-3)min(-1). The results show that introduction of Fe(III), Co(II) and Ni(II) into MCM-41 through impregnation produces very effective catalysts for wet oxidation of 2,4,6-trichlorophenol.
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http://dx.doi.org/10.1016/j.jhazmat.2007.05.039 | DOI Listing |
Chem Sci
December 2024
Jagiellonian University, Faculty of Chemistry Gronostajowa 2 30-387 Kraków Poland +48 12 686 24 89.
Chem Biodivers
November 2024
Department of Chemistry, Faculty of Science, Sohag University, Sohag, Egypt.
Int J Health Sci (Qassim)
January 2024
Department of Clinical Laboratory Sciences, College of Applied Medical Science, Jouf University, Aljouf, Saudi Arabia.
Chempluschem
January 2025
Institut de Ciència Molecular (ICMol), Universitat de València, Catedrático José Beltrán 2, 46980, Paterna, Spain.
The synthesis and characterization of a Co/Fe mixed-metal banana-shaped polyoxometalate with the formula [(CoFe(HO)PWO)(PWO)] (CoFe) is reported. This transition-metal-substituted polyoxometalate readily assembles from its components in a one-pot reaction and crystallizes in the monoclinic space group P2/c. The structure of CoFe can be considered a double sandwich composed by two B-α-{CoFePWO} Keggin units, in which one coordinatively saturated octahedral metal position is equally occupied by Co(II) and Fe(III) ions with a 50 % of site occupancy.
View Article and Find Full Text PDFPhys Chem Chem Phys
October 2024
State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Why does binding of dioxygen (O) to metal centers, the initial step of O storage, transportation, and activation, almost inevitably induce metal-to-O single-electron transfer and generate superoxo (O˙) species, instead of genuine O02 adducts? To address this question, this study describes highly correlated wavefunction-based calculations using CASSCF/NEVPT2 (CASSCF = complete active space self-consistent field, and NEVPT2 = -electron valence state second-order perturbation theory) approaches to explore the electronic-structure evolution of O association on Fe(II)(BDPP) (HBDPP = 2,6-bis((2-()-diphenylhydroxylmethyl-1-pyrrolidinyl)methyl)pyridine) and Co(II)(BDPP) to produce = 3 Fe(III)(BDPP)(O˙) (1) and Co(III)(BDPP)(O˙) (2). CASSCF/NEVPT2 calculations suggest that the processes furnishing 1 and 2 feature an avoided crossing resulting from interactions of two diabatic curves, of which one is characterized as Co(II) and Fe(II) centers interacting with a triplet O ligand and the other as Co(III) and Fe(III) centers bound to a superoxo ligand. In both cases, the avoided crossing induces a one-electron transfer from the divalent metal center to the incoming O ligand and leads to formation of trivalent metal-O˙ complexes.
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