Photoelectro-synergistic catalysis combined with a FIA system application on determination of chemical oxygen demand

In this paper, photoelectro-synergistic catalysis oxidation of organics in the water on Ti/TiO₂/PbO₂ electrode was investigated. The prepared TiO₂ film was investigated with Atomic force micrograph (AFM). Furthermore, the results were compared with those obtained from electrocatalysis (EC) and electro-assisted photocatalysis (PC). The method proposed employed photoelectro-synergistic catalysis (PEC), together with flow injection analysis, to determine the chemical oxygen demand (COD) values. It was shown that the method of photoelectro-synergistic catalysis had lower detection limit (15.0 mg l⁻¹) and wider linear range (30.0–2500.0 mg l⁻¹) than the methods of electro-assisted photocatalysis and electrocatalysis. The results obtained by the proposed method and conventional one were compared by carrying out the experiment on 20 wastewater samples and also agreed well by high correlation (R = 0.9912).     

Epoxidation of cyclohexene with tert-butyl hydroperoxide catalyzed by polymer anchored molybdenum complexes

Catalytic activity of molybdenum hexacarbonyl anchored on various polymers was investigated for the epoxidation of cyclohexene with tert-butyl hydroperoxide. The activity was increased by anchoring on the polymer. The catalyst on polystyrene showed much higher activity than Mo(CO)₆ used under homogeneous conditions.

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Oxidative desulfurization of dibenzothiophene with molecular oxygen using emulsion catalysis

Dibenzothiophene (DBT) is oxidized to the corresponding sulfoxide and sulfone in an emulsion system (W/O) composed of polyoxometalate anion [C(18)H(37)N(CH(3))3](5)[PV(2)Mo(10)O(40)] as both the surfactant and catalyst, using molecular oxygen as the oxidant and aldehyde as the sacrificial agent under mild conditions.     

Epoxidation of cyclohexene on modified Ti-containing mesoporous MCM-41

Ti-MCM-41, B-Ti-MCM-41 and Ti-grafted MCM-41 were synthesized, characterized and studied in the epoxidation of cyclohexene. The synthetic methods and the effect of water in the oxidant are discussed.     

Mechanism of the catalysis by aliphatic amines of the oxidation of anthrone with molecular oxygen

Using anthrone as an example, the oxidation of aromatic ketones with molecular oxygen catalyzed by aliphatic amines of various structures has been studied. Analysis of kinetic and spectroscopic data permits the prediction of the mechanism of the reaction, the establishment of the equilibrium constants, and the rate constants for the separate stages.     

Silica-metalloporphyrins hybrid materials: preparation and catalysis to hydroxylate cyclohexane with molecular oxygen

Three types of novel silica-metalloporphyrins hybrid materials, Si-S-APTCPPFe, Si-S-APTCPPMn and Si-S-APTCPPCo, were prepared at room temperature by sol–gel method involving a thiol-ene polymerization reaction of 5-(4-allyloxy)phenyl-10,15,20-tri(4-chlorophenyl)porphyrin (APTCPP) with 3-mercaptopropyltrimethoxysilane (MPS). The hybrid materials were characterized by XRD, SEM, FT–IR, UV–Vis and TG, and were investigated as catalysts for the aerobic oxidation of cyclohexane. It is found that these hybrid materials are more efficient catalysts than the analogous non-supported metalloporphyrins for cyclohexane hydroxylation in metalloporphyrin–O₂–ascrobate system and the metal ion in the porphyrins significantly affected the catalytic efficiencies of these hybrid materials.     

Epoxidation of alkenes with molecular oxygen and isobutyraldehyde catalyzed by immobilized vitamin B12 within Al-MCM-41

Vit-B₁₂/ Al-MCM-41 catalyzed successfully the epoxidation either of cis or trans — stilbene with O₂ as oxidant and isobutyraldehyde as co-reductant with 86–98% reactivity and 97–100% selectivity. Other olefins such as norbornene and styrene undergo epoxidation reaction under similar conditions with good to fair selectivity. Details of the reactions will be presented in this article.     

Epoxidation of styrene with molecular oxygen catalyzed by a novel oxovanadium(IV) catalyst containing two different kinds of ligands

A novel type of oxovanadium(IV) 8‐hydroxyquinoline (8‐Q) complex and oxovanadium(IV) acetylacetonate (acac) complex were synchronously anchored on to amino‐modified SBA‐15 (named VO(acac:8‐Q)‐SBA‐15) and examined as a catalyst for styrene oxidation. The structure of the synthesized catalyst was characterized by means of X‐ray diffraction (XRD), FT‐IR, diffusion reflection UV–visible, inductively coupled plasma atomic emission spectroscopy (ICP‐AES), scanning electron microscopy (SEM), and thermogravimetric analysis (TG). Characterizations with FT‐IR, diffusion reflection UV‐visible, ICP‐AES and TG suggested the incorporation of oxovanadium(IV) complex in amino‐modified SBA‐15. XRD and SEM results indicated that SBA‐15 remained intact throughout the grafting procedure. It was found that VO(acac:8‐Q)‐SBA‐15 catalyst was more active than single‐ligand catalysts VO(acac)₂‐SBA‐15 and VO(8‐Q)₂‐SBA‐15 and that the product selectivity varied in cases of different oxidants. The catalyst VO(acac:8‐Q)‐SBA‐15 with two different ligands showed high yield of styrene oxide (45.8%) and good recoverability when using air as oxidant. Copyright © 2012 John Wiley & Sons, Ltd.     

Energy-efficient chlorine production by gas-phase HCl electrolysis with oxygen depolarized cathode

For the first time, gas-phase electrolysis of HCl to chlorine was conducted in a fuel cell type reactor with an oxygen depolarized cathode. Very low cell voltages below − 1 V at industrially relevant current densities of 4 kA m^− 2 were obtained. Compared to technical HCl electrolysis processes, this leads to a reduction in electrical energy demand of approximately 30%. The temperature and the relative humidity (rH) of the cathode inlet gas were identified as key parameters controlling the overall performance of the system.     

Molecular oxygen and oxidation catalysis by phosphovanadomolybdates

The history of aerobic catalytic oxidation mediated by a subclass of polyoxometalates, the phosphovanadomolybdates of the Keggin structure, [PV(x)Mo(12-x)O40](3+x)-, is described. In the earlier research it was shown that phosphovanadomolybdates catalyze oxydehydrogenation reactions through an electron-transfer oxidation of a substrate by the polyoxometalate that is then reoxidized by oxygen. These aerobic oxidations are selective and synthetically useful in various transformations, notably diene aromatization, phenol dimerization and alcohol oxidation. Oxygen transfer from the polyoxometalate to arenes and alkylarenes was also discussed as a homogeneous analog of a Mars-van Krevelen oxidation. "Second generation" catalysts include binary complexes of the polyoxometalate and a organometallic compound useful, for example, for methane oxidation and nanoparticles stabilized by polyoxometalates effective for aerobic alkene epoxidation.     

Epoxidation of trans-stilbene with molecular oxygen over an eco-friendly heterogeneous cobalt oxide/reduced graphene oxide composite material

Research on Chemical Intermediates - We report the synthesis of 1, 5, 10 wt% cobalt oxide/reduced graphene oxide (CoO–RGO) composite materials by a simple solvothermal method. We assessed...     

Crown ether-appended Fe (III) porphyrin: Synthesis, characterization and catalytic oxidation of cyclohexene with molecular oxygen

A new crown ether appended Fe(Ⅲ) porphyrin complex was prepared by sulfuryl chloride appended benzo-15-crown-5 to the meso position of meso-5,10,15,20-tetra(4-hydrophenyl)porphyrin,and it was applied to catalytic oxidation of cyclohexene with molecular oxygen without reductant,showing a remarkable catalytic activity(conversion is up to 94%) and selectivity for 2-cyclohexen-1-ol(73%).     

Epoxidation of α-pinene with molecular oxygen catalyzed by poly(vinylbenzyl)acetylacetonate complexes of some metal ions

Poly(vinylbenzyl)acetylacetonate complex of cobalt is a very effective catalyst for the epoxidation of α-pinene under an atmospheric pressure of molecular oxygen at 25°C. With isobutyraldehyde as a reductant, the yield of the epoxidation of α-pinene amounts to 94.3% within 6 hr. The catalyst can be recycled at least eight times without apparent loss of activity.     

Oxygen transfer catalysis by chemical analogs of monooxygenases

New chemical analogs of monooxygenases and new reactions of alkane oxidation mediated by metal complexes are reviewed. Mechanisms of dioxygen and alkane activation and those of oxygen transfer from O₂ and active oxygen donors to C-H bonds via ferryl and other intermediates are discussed.Submitted as an invited lecture at the VIIIth International Symposium on Homogeneous Catalysis held on August 2–7, 1992 (Amsterdam, the Netherlands).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 272–279, February, 1993.