Oxides of Fe, Co, Ni

Usually Fe203 is regarded to be weakly acidic and basic. It catalyzes the dehydrogenation of ethanol, but only dehydration has been reported for 2-butanoP and isopropanol.It has been reported that 7-Fe203 which had been partially reduced was very active for the isomerization of 1-butene via a cationic allyl intermediate. IR study of adsorption and desorption of NH3 showed the presence of strong Lewis acid sites, but formation of nitrogen oxides from adsorbed NH3 was observed at higher temperatures. Interaction of the surface with acetic acid produced acetone.  

Catalyst Surface area (m g ) Phase byXRD SO,2- content (wt%) Amounts of NH3 irrevenibly adsorbed at 303 K Isomerization of 1-butene at 373 K Dehydration of 2-butanol at 473 K 

CoO and C03O4 are the ordinary oxides of cobalt, the latter being more stable at low temperatures and under high partial pressures of oxygen. C03O4 is one of the most active single metal oxides for oxidation reactions. 

The relationship between the degree of coordinative unsaturation and the catalytic activity has been discussed by Siegel and Tanaka. Dimerization of olefin has been reported for C03O4 supported on carbon.  

NiO mixed with solid acids such as Si02, SiOz—AI2O3 and NiS04 are active for dimerization of olefins. The active site has been suggested to be a combination of a low valent nickel and an acid site. In the case of NiO — Si02 — AI2O3, the ac- 

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Binary oxide catalysts are of major industrial importance. Such compounds are combinations of the oxides of Fe, Co, Ni, Cu, and Zn with those of Cr, Mo, and W. 

Another difference between the MMD and EDS wastes may be the presence of higher levels of metal ions and metal oxides of Fe, Co, Ni, Pb, Al, Zn, Sn, and Cu in some EDS neutralents. The fragmentation of the munition bodies in the EDS, as well as the hours of rocking back and forth during the neutralization process, may expose more metal surface to the MEA reagent, which is a fairly good extractant for these metal ions. In addition, heavy metal constituents of the munition fuze (e.g., mercury from mercury fulminate) will... 

A catalyst library of 112 catalysts was screened. Seven metal oxides, A1203, Si02, Ti02, ZnO, Ga203, Zr02 and La203 were selected as supports and 16 metal or metal oxides, Mn, Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt, Cu, Zn, Ag, Au, Ga, In and Sn, were selected as additive to support oxides. An additive metal or metal oxide was... 

This chapter is largely concerned with the structural chemistry of Fe, Co, Ni, Pd, and Pt, for the most part in finite complexes. The structures of the simpler compounds of these and other transition metals have been described under Halides, Oxides, etc. in the appropriate chapters. Other groups of compounds described in earlier chapters include hydrido compounds, oxo-, peroxo-, and superoxo-compounds, carbonyls, and nitrosyls, in Chapters 11, 12, and 18, respectively. We note here a few general points. 

The ease of reduction increases, therefore, from Cr3+ to Ni3+ in the series of LaM03 perovskites. The same trend has been found for the simple oxides of Fe, Co, and Ni (115). On the other hand, the mixed oxides LaM03 (M = Fe, Co, Ni) were found to be more stable in a H2 atmosphere than the simple oxides NiO, Fe203, and Co304 (92) this shows the increased stability of transition-metal cations in a perovskite structure. The TPR experiments also show that the stability of perovskite oxides increases with increasing size of the A ion. 

PO can be made degradable by means of additives. The types of additives include aromatic ketones (benzo-phenone and substituted benzophenones [47], qui-none), aromatic amines (trisphenylamine), polycyclic aromatic hydrocarbons (anthracene, certain dyes such as xanthene dyes), or transition metal organic compounds. The transition metal compounds of Fe, Co, Ni, Cr, Mn are widely used. Organo-soluble acetyl acetonates of many transition metals are photooxidants and transition metal carboxylates are also thermal pro-oxidants. Co acetylacetonate appears to be an effective catalyst for chemical degradation of PP in the marine environment. The preferred photoactivator system is ferric dibutyldithiocarbamate with a concentration range of 0.01. 1%. Scott has patented the use of organometallic compounds hke iron (ferric) dibutyldithiocarbamate or Ni-dibutyl-dithiocarbamate [48]. Cerium carboxylate [49] and carbon black are also used in such materials [50]. 

Putile Ceramic Pigments. StmcturaHy, aH mtile pigments are derived from the most stable titanium dioxide stmcture, ie, mtile. The crystal stmcture of mtile is very common for AX2-type compounds such as the oxides of four valent metals, eg, Ti, V, Nb, Mo, W, Mn, Ru, Ge, Sn, Pb, and Te as weH as haHdes of divalent elements, eg, fluorides of Mg, Mn, Fe, Co, Ni, and Zn. 

Thorium metal alloys readily with a large number of metals, including Fe, Co, Ni, Cu, Au, Ag, B, Pt, Mo, W, Ta, Zn, Bi, Pb, Hg, Na, Be, Mg, Si, Se, and Al. Like many electropositive metals, finely divided thorium metal is pyrophoric in air, and bums to give the oxide. Massive metal, chips, and turnings... 

Meta/ Oxides. The metal oxides aie defined as oxides of the metals occurring in Groups 3—12 (IIIB to IIB) of the Periodic Table. These oxides, characterized by high electron mobiUty and the positive oxidation state of the metal, ate generally less active as catalysts than are the supported nobel metals, but the oxides are somewhat more resistant to poisoning. The most active single-metal oxide catalysts for complete oxidation of a variety of oxidation reactions are usually found to be the oxides of the first-tow transition metals, V, Cr, Mn, Fe, Co, Ni, and Cu. 

At the other end of the conduction spectrum, many oxides have conductivities dominated by electron and positive hole contributions to the extent that some, such as Re03, SnOa and tire perovskite LaCrOs have conductivities at the level of metallic conduction. High levels of p-type semiconduction are found in some transition metal perovskites especially those containing alio-valent ions. Thus the lanthairum-based perovskites containing transition metal ions, e.g. LaMOs (M-Cr, Mn, Fe, Co, Ni) have eirlranced p-type semiconduction due to the dependence of the transition metal ion valencies on the ambient... 

A similar situation with changing oxidation state of Ru within a series of compounds was observed for the ordered perovskites BaLaMRuOe (M = Mg, Fe, Co, Ni, Zn) [115]. The measured isomer shifts in the range +0.06 to +0.13 mm s ... 

Quinoxaline 1-oxide gave complexes with the chlorides of Cr, Mn, Fe, Co, Ni, Cu, and Zn 919 also with the perchlorates of the same metals.921 Quinoxaline 1,4-dioxide gave complexes with the chlorides of Cr, Mn, Fe, Co, Ni, Cu, and Zn 312,886 also with the perchlorates of the same metals.312,922... 

Iron and Stainless Steel. The purpose of XPS investigations on typical corrosion systems like iron or stainless steel, is the determination of the composition of the passive surface layer, if possible, as a function of depth. As a consequence of the technical and economic relevance of corrosion reactions, XPS investigations on corrosion systems are numerous. With respect to the application of XPS, there is no difference between corrosion systems and any other electrochemical surface reaction like oxide formation on noble metals. Therefore, in this paragraph only a few recent typical results of such studies, using XPS, will be mentioned. For a detailed collection of XPS corrosion studies the reader is referred to references [43,104], A review of aqueous corrosion studies, using XPS, was given by McIntyre for the elements O, Cr, Mn, Fe, Co, Ni, Cu and Mo [105], The book edited by M. Froment [111] gives an impression of the research achieved on passivity of metals up to 1983. 

The new silazane 5 may be reacted with activated metals, organometallic compounds or simple metal amides, or may first be transformed to its lithium salt and then reacted with metal(II) chlorides [11]. In all these cases, metal derivatives of 5 are obtained with the general formula j [Mc (/BuO)Si 9N(9M, which have no further base coordinated to the metal. So far we have synthesized amides with M = Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Ba, all elements in oxidation state +2. X-ray structure determinations have been performed on the calcium, manganese, iron, zinc, and barium derivatives. 

Of the two models, homogeneous accretion is generally favoured. H. Wancke from the Max Planck Institute in Mainz (1986) described a variant of this model, in which the terrestrial planets were formed from two different components. Component A was highly reduced, containing elements with metallic character (such as Fe, Co, Ni, W) but poor in volatile and partially volatile elements. Component B was completely oxidized and contained elements with metallic character as their oxides, as well as a relatively high proportion of volatile elements and water. For the Earth, the ratio A B is calculated to be 85 15, while for Mars it is 60 40. According to this model, component B (and thus water) only arrived on Earth towards the end of the accretion phase, i.e., after the formation of the core. This means that only some of the water was able to react with the metallic fraction. 

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