Oxidation catalytic metal-generated

Of particular note we found improved selectivity with certain extiuded carbon supports versus granular carbons, graphitic carbons, metal oxides (titaiua and zircoitia), and carbon treated with zircoiua. Data shown in Figures 34.6 and 34.7 were generated in batch experiments using Ni/Re as catalytic metals. In Figure 34.6a,... 

Variation of the content of impurities in the different CNT preparations [21] offers additional challenges in the accurate and consistent assessment of CNT toxicity. As-produced CNTs generally contain high amounts of catalytic metal particles, such as iron and nickel, used as precursors in their synthesis. The cytotoxicity of high concentrations of these metals is well known [35, 36], mainly due to oxidative stress and induction of inflammatory processes generated by catalytic reactions at the metal particle surface [37]. Another very important contaminant is amorphous carbon, which exhibits comparable biological effects to carbon black or relevant ambient air particles. 

The photoelectrochemical kinetic scheme involves a photochemical reaction that is followed by an electrochemical reaction. The photochemical reaction is used to produce or deactivate the reducing agent. Catalytic metallic nuclei are formed in the subsequent electrochemical reaction. For example, the Fe reducing agent (Red) needed for reaction (8.24) is generated in the photochemical reduction of complexed Fe ions. This redox photolysis is the ligand-to-metal charge transfer with the overall reaction of oxidation of [ 204] ... 

Recently, the preparation of metallosilicates with MFI structure, which are composed of silicone oxide and metal oxide substituted isomorphously to aluminium oxide, has been studied actively [1,2]. It is expected that acid sites of different strength from those of aluminosilicate are generated when some tri-valent elements other than aluminium are introduced into the framework of silicalite. The Bronsted acid sites of metallosilicates must be Si(0H)Me, so the facility of heterogeneous rupture of the OH bond should be due to the properties of the metal element. Therefore, the acidity of metallosilicate could be controlled by choosing the metal element. Moreover, the transition-metal elements introduced into the zeolite framework play specific catalytic roles. For example, Ti-silicate with MFI structure has the high activity and selectivity for the hydroxylation of phenol to produce catechol and hydroquinon [3],... 

Both stoichiometric and catalytic reactions of allylic compounds via 7r-allyl complexes are known. Reactions of nucleophilic 71-allyl complexes with electrophiles involve oxidation of metals and hence constitutes stoichiometric reactions. 7i-Allyl complexes of Ni, Fe, Mo, Co and others are nucleophilic and undergo the stoichiometric reaction with electrophiles. However, electrophilic 71-allyl complexes react with nucleophiles, accompanying reduction of metals. For example, 71-allylnickel chloride (2) reacts with electrophiles such as aldehydes, generating Ni(II), and hence the reaction is stoichiometric. In contrast, electrophilic 7i-allylpalladium chloride (3) reacts with nucleophiles such as malonate and Pd(0) is generated. Thus repeated oxidative addition of allylic compounds to Pd(0) constitutes a catalytic reaction. 

The third way to prepare CNT-ceramic composite powders is via the synthesis of CNT by a CCVD process, in situ in the ceramic powder. A ceramic powder which contains catalytic metal particles at a nanometric size, appropriate to the formation of CNTs, is treated at a high temperature (600-1100°C), in an atmosphere containing a hydrocarbon or CO. In the method reported in 1997 by the present authors,27 iron nanoparticles are generated in the reactor itself, at a high temperature (>800°C), by the selective reduction in H2/CH4 (18% CH4) of an a-Al203 based oxide solid solution ... 

Milk and milk products contain a wide variety of metal ions, including the pro-oxidant transition metal ions, Cu2+ and Fe3+. Metal ions capable of undergoing reversible one-electron reductions are important pro-oxidants, which function primarily by decomposing hydroperoxides to generate new reaction chains (Labuza, 1971 Pokorny, 1987). Either the oxidized or reduced metal ion can decompose hydroperoxides to allow the following catalytic cycle to increase the rate of lipid oxidation ... 

A number of low-grade transition metal ores (for example, minerals containing nickel oxides) can be used as catalysts. Smuda has demonstrated that microwave or radiofrequency irradiation of a mixture of such ores with a carbon source initiates reduction of the oxide to metal. With this approach, poisoning the active sites of the catalyst will not be critical for the process since there will be a constant supply and generation of active catalyst with the feed material. In addition to well-known catalytic properties of nickel in organic reactions, it was also shown that Ni on carbon and other supports, catalyzes hydrodechlorination and dehydrochlorination of chlorinated organic waste streams [22-24],... 

The synthesis of unsymmetrical biaryls 8 from two monoaryl species involves the coupling of a metallated aromatic molecule 6 with an aryl halide or triflate 4 under the action of palladium(O) catalysis. The reaction involves a catalytic cycle in which palladium(O) inserts into the C-halogen bond via an oxidative addition to generate an arylpalladium(II) species 5 (Scheme 10.18). This undergoes a trans-metallation with the metallated component, producing a biarylpalladi-um(II) complex 7. The biaryl product is formed by reductive elimination. In the process, Pd(0) is regenerated and this can then react with a second molecule of aryl halide. Pd(0) is therefore a catalyst for the reaction. 

---