Transitional metal oxides

Massidda S, Continenza A, Posternak M and Baldereschi A 1997 Quasiparticle energy bands of transition-metal oxides within a model GW scheme Phys. Rev. B 55 13 494-502... 

Svane A and Gunnarsson Q 1990 Transition-metal oxides in the self-interaction-corrected density-functional formalism Phys. Rev. Lett. 65 1148... 

Szotek Z, Temmerman W M and Winter H 1993 Application of the self-interaction correction to transition-metal oxides Phys. Rev. B 47 4029... 

Wang L S 2000 Photodetachment photoelectron spectroscopy of transition metal oxide species Photoionization and Photodetaohment Advanced Series in Physical Chemistry 10, ed C Y Ng (Singapore World Scientific)... 

The mechanisms by which transition metal oxidizing agents convert alcohols to aldehydes and ketones are complicated with respect to their inorganic chemistry The organic chemistry is clearer and one possible mechanism is outlined m Figure 15 4 The... 

Several kinds of conduction mechanisms are operative in ceramic thermistors, resistors, varistors, and chemical sensors. Negative temperature coefficient (NTC) thermistors make use of the semiconducting properties of heavily doped transition metal oxides such as n-ty e Ti O andp-ty e... 

NL Li O. Thick film resistors are also made from transition-metal oxide soHd solutions. Glass-bonded Bi... 

Reaction with Meta/ Oxides. The reaction of hydrogen chloride with the transition-metal oxides at elevated temperatures has been studied extensively. Fe202 reacts readily at temperatures as low as 300°C to produce FeCl and water. The heavier transition-metal oxides require a higher reaction temperature, and the primary reaction product is usually the corresponding oxychlorides. Similar reactions are reported for many other metal oxides, such as Sb202, BeO, AI2O2, andTi02, which lead to the formation of relatively volatile chlorides or oxychlorides. 

Alcohol autoxidation is carried out in the range of 70—160°C and 1000—2000 kPa (10—20 atm). These conditions maintain the product and reactants as Hquids and are near optimum for practical hydrogen peroxide production rates. Several additives including acids, nitriles, stabHizers, and sequestered transition-metal oxides reportedly improve process economics. The product mixture, containing hydrogen peroxide, water, acetone, and residual isopropyl alcohol, is separated in a wiped film evaporator. The organics and water are taken overhead and further refined to recover by-product acetone and the... 

Alkali metal haHdes can be volatile at incineration temperatures. Rapid quenching of volatile salts results in the formation of a submicrometer aerosol which must be removed or else exhaust stack opacity is likely to exceed allowed limits. Sulfates have low volatiHty and should end up in the ash. Alkaline earths also form basic oxides. Calcium is the most common and sulfates are formed ahead of haHdes. Calcium carbonate is not stable at incineration temperatures (see Calcium compounds). Transition metals are more likely to form an oxide ash. Iron (qv), for example, forms ferric oxide in preference to haHdes, sulfates, or carbonates. SiHca and alumina form complexes with the basic oxides, eg, alkaH metals, alkaline earths, and some transition-metal oxidation states, in the ash. 

N. Singh, "VOC Destmetion at Low Temperatures Using a Novel Thermally Stable Transition-Metal Oxide-Based Catalyst," presented at the First North American Conference on Emerging Clean Air Technologies and Business Opportunities, Toronto, Canada, Sept. 1994. 

P. A. Cox, Transition Metal Oxides, Oxford University Press, New York, 1995. 

MetaUic conduction occurs in transition-metal oxides such as ReO, vanadium(II) oxide [12035-98-2] VO, titanium(II) oxide [12137-20-17,... 

Oxidation catalysts are either metals that chemisorb oxygen readily, such as platinum or silver, or transition metal oxides that are able to give and take oxygen by reason of their having several possible oxidation states. Ethylene oxide is formed with silver, ammonia is oxidized with platinum, and silver or copper in the form of metal screens catalyze the oxidation of methanol to formaldehyde. Cobalt catalysis is used in the following oxidations butane to acetic acid and to butyl-hydroperoxide, cyclohexane to cyclohexylperoxide, acetaldehyde to acetic acid and toluene to benzoic acid. PdCh-CuCb is used for many liquid-phase oxidations and V9O5 combinations for many vapor-phase oxidations. 

Volume 45 Transition Metal Oxides. Surface Chemistry and Catalysis by H.H. Kung... 

This process has many similarities to the Phillips process and is based on the use of a supported transition metal oxide in combination with a promoter. Reaction temperatures are of the order of 230-270°C and pressures are 40-80 atm. Molybdenum oxide is a catalyst that figures in the literature and promoters include sodium and calcium as either metals or as hydrides. The reaction is carried out in a hydrocarbon solvent. 

The use of supported transition metal oxide and Ziegler-Natta-type catalysts for polymerising aliphatic olefins (alkenes) was extended in the 1960s and 1970s to the ring-opening polymerisation of cyclo-olefins. 

Raman spectroscopy has provided information on catalytically active transition metal oxide species (e. g. V, Nb, Cr, Mo, W, and Re) present on the surface of different oxide supports (e.g. alumina, titania, zirconia, niobia, and silica). The structures of the surface metal oxide species were reflected in the terminal M=0 and bridging M-O-M vibrations. The location of the surface metal oxide species on the oxide supports was determined by monitoring the specific surface hydroxyls of the support that were being titrated. The surface coverage of the metal oxide species on the oxide supports could be quantitatively obtained, because at monolayer coverage all the reactive surface hydroxyls were titrated and additional metal oxide resulted in the formation of crystalline metal oxide particles. The nature of surface Lewis and Bronsted acid sites in supported metal oxide catalysts has been determined by adsorbing probe mole-... 

Transition metal oxides or their combinations with metal oxides from the lower row 5 a elements were found to be effective catalysts for the oxidation of propene to acrolein. Examples of commercially used catalysts are supported CuO (used in the Shell process) and Bi203/Mo03 (used in the Sohio process). In both processes, the reaction is carried out at temperature and pressure ranges of 300-360°C and 1-2 atmospheres. In the Sohio process, a mixture of propylene, air, and steam is introduced to the reactor. The hot effluent is quenched to cool the product mixture and to remove the gases. Acrylic acid, a by-product from the oxidation reaction, is separated in a stripping tower where the acrolein-acetaldehyde mixture enters as an overhead stream. Acrolein is then separated from acetaldehyde in a solvent extraction tower. Finally, acrolein is distilled and the solvent recycled. 

A thin layer deposited between the electrode and the charge transport material can be used to modify the injection process. Some of these arc (relatively poor) conductors and should be viewed as electrode materials in their own right, for example the polymers polyaniline (PAni) [81-83] and polyethylenedioxythiophene (PEDT or PEDOT) [83, 841 heavily doped with anions to be intrinsically conducting. They have work functions of approximately 5.0 cV [75] and therefore are used as anode materials, typically on top of 1TO, which is present to provide lateral conductivity. Thin layers of transition metal oxide on ITO have also been shown [74J to have better injection properties than ITO itself. Again these materials (oxides of ruthenium, molybdenum or vanadium) have high work functions, but because of their low conductivity cannot be used alone as the electrode. 

The Structural Stability of Transition Metal Oxide Insertion Electrodes for Lithium Batteries... 

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