Fe =O oxidant

A number of commercial oxidation catalysts are based on V and Mo oxides. They are multicomponent materials, such as the mixed oxides Mo-Fe-O (oxidation of methanol to formaldehyde), V-P-O (oxidation of butane to maleic anhydride), Bi-Mo-O (propylene to acrylonitrile), Bi-Fe-Mo-O... 

The reaction of nonheme Fe complexes that are analogues of Rieske dioxygenase enzymes have been studied by the group of Que [234,235] (see Chapter 18). A possible mechanism has been suggested [241] (Fig. 1.31) for a bispidme ligand. An [Fe oOH] intermediate is formed initially, which undergoes 0-0 bond homolysis to form a ferryl [Fe =O] oxidant and HO. The oxidant was formed independently by reaction of the complex with lodosylbenzene as indicated by the appearance of an expected electronic transition in the near infrared of e = 400 M cm . This was able to epoxidize czs-cyclooctene in an Ar atmosphere. 

The detection of redox potential of a solution is important in environmental analysis to judge the redox state of the system so that one can predict the possible direction of oxidation-reduction reactions. Electron acceptors such as oxygen, nitrate and sulfate are consumed by the biological oxygen demand of organic carbon. Chemical reduction can occur indirectly by the chemical reduction of oxidized pollutants via formation of hydrogen. Direct chemical oxidation of organics are possible via Fe (O) oxidation/reduction reactions. ... 

This experiment describes the use of FIA for determining the stoichiometry of the Fe +-o-phenanthroline complex using the method of continuous variations and the mole-ratio method. Directions are also provided for determining the stoichiometry of the oxidation of ascorbic acid by dichromate and for determining the rate constant for the reaction at different pH levels and different concentration ratios of the reactants. 

The reduction of iron ore is accompHshed by a series of reactions that are the same as those occurring in the blast furnace stack. These include reduction by CO, H2, and, in some cases soHd carbon, through successive oxidation states to metallic iron, ie, hematite [1309-37-17, Fe202, is reduced to magnetite [1309-38-2], Fe O, which is in turn reduced to wustite [17125-56-3], FeO, and then to metallic iron, Fe. The typical reactions foUow. 

The Stock Oxidation-Number System. Stock sought to correct many nomenclature difficulties by introducing Roman numerals in parentheses to indicate the state(s) of oxidation, eg, titanium(II) chloride for TiCl2, iron(II) oxide for FeO, titanium(III) chloride for TiCl, iron(III) oxide for Fe203, titanium(IV) chloride for TiCl, and iron(II,III) oxide for Fe O. In this system, only the termination -ate is used for anions, followed by Roman numerals in parentheses. Examples are potassium manganate(IV) for K2Mn02, potassium tetrachloroplatinate(II) for K PtCl, and sodium hexacyanoferrate(III) for Na3Fe(CN)3. Thus a set of prefixes and terminations becomes uimecessary. 

Iron Oxide Reds. From a chemical point of view, red iron oxides are based on the stmcture of hematite, a-Fe202, and can be prepared in various shades, from orange through pure red to violet. Different shades are controlled primarily by the oxide s particle si2e, shape, and surface properties. Production. Four methods are commercially used in the preparation of iron oxide reds two-stage calcination of FeS047H2 O precipitation from an aqueous solution thermal dehydration of yellow goethite, a-FeO(OH) and oxidation of synthetic black oxide, Fe O. ... 

Because the surface tension of oxides such as Fe O, AI2O2, etc, is much lower than that of the majority of metals and alloys, the presence of... 

Over the years, HteraHy thousands of catalyst formulations have been evaluated and those available today are significantly more active, which has allowed considerable improvement in productivity and plant operation. Today, a typical catalyst contains approximately 93 wt % Fe O, and about 1 wt % potassium oxide, 3 wt % alumina, 3 wt % calcium oxide, and 0.5 wt % siHca, which is actually an unnecessary impurity. 

Brown oxides are manufactured either by blending mixtures of the red, yellow, and black oxides or by precipitation of an iron salt with alkaU followed by partial oxidation of the precipitate. The result is a mixture of red Fe202 [1309-37-1] and black Fe O [1309-38-2] FeO Fe202-... 

The black oxides are prepared by the controlled precipitation of Fe O (treat FeSO -7H2 O with NaOH and O2) to form a mixture of ferrous and ferric oxides. 

When it is desirable to use a weak black, bone black may be substituted for carbon. It is manufactured by calcining animal bones and contains approximately 85% calcium phosphate and calcium carbonate. Black iron oxide (Fe O is stable up to 150°C. Copper chromite black (Cu(Cr02)2) is iuert to all but mbberlike compositions and has been calcined to 600°C. 

Over the years, Pourbaix and his co-workers in the CEBELCOR Institute, founded under his direction, extended these diagrams by including lines for metastable compounds. Figure 7.66 illustrates such a presentation for the Fe-O system over the temperature range 830-2200 K. Pourbaix used these diagrams as a basis for a discussion of the stability of metallic iron (solid, liquid and vapour phases), the oxides of iron as a function of oxygen pressure and temperature from which he explained the protection of iron at high temperature by immunity and passivation. He also pointed out the... 

Hydroxyl radicals. The acid ionization constant of the short-lived HO transient is difficult to determine by conventional methods but an estimate can be made because HO, but not its conjugate base, O -, oxidizes ferrocyanide ions HO + Fe(CN) — OH- + Fe(CN)g . Use the following kinetic data26 for the apparent second-order rate constant as a function of pH to estimate Ka for the acid dissociation equilibrium HO + H20 =... 

The Fe—O distances in hematite are 1.99 and 2.06 A. The (Mn,Fe)—O distances in bixbyite are expected to be the same in case that (Mn, Fe) has the coordination number 6, and slightly smaller, perhaps 1.90 A, for coordination number 4. The radius of 0= is 1.40 A, and the average O—O distance in oxide crystals has about twice this value. When coordinated polyhedra share edges the O—O distance is decreased to a minimum value of 2.50 A, shown by shared edges in rutile, anatase, brookite, corundum, hydrargillite, mica, chlorite, and other crystals. Our experience with complex ionic crystals leads us to believe that we may... 

Ifon(III) oxide Iron(III) is Fe, and oxide is O. To be a neutral compound, there must be two... 

The stoichiometry of transition metal oxides is more variable. Iron, for example, forms three binary oxides. In FeO the iron atoms have lost two electrons each (Fe, O ), and in Fc2 O3 they have lost three electrons each... 

Fe -, O" ). The third oxide, Fc3 O4, contains one Fe cation for every two Fe" cations. Other transition metals lose anywhere from one to eight electrons in forming oxides. There is no simple pattern that determines which oxide is most stable, but we can tell how many electrons the metal has lost by assigning a gain of tw o... 

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