Magnetic catalysis

Materials with hollow sphere structures have attracted much attention due to their excellent physical and chemical properties, and they are technologically important for a variety of application such as optics, electrics, magnetics, catalysis, acoustics, catalyst support, etc. 

Most lanthanide ions are paramagnetic, a property first exploited in the mid-1950s when it was found that the dysprosium(III) ion accelerated the rate of decarboxylation of phenylmalonic acid (Pitzer and Gelles, 1953). This magnetic catalysis was considered a minor effect (Gelles and Pitzer, 1955), and not until 1960 was this phenomenon applied to the resolution of the inadvertent overlap of NMR spectral resonances (Jackson et al., 1960). 

Rare earths have been used either as neutron absorbers (Eu, Dy) or as burnable poisons (Gd, Er) either as oxides or titanates (see Section 15.3.4.1). Their main drawback (excepted for Dy) is a very high specific activity after neutron irradiation, leading to complicated management after use. Moreover, rare earths are presentiy in high demand for magnets, catalysis, technical ceramics, or electronic applications, etc. [20] with the demand increasing [21]. The main reserves are located in the USA, Australia, China, and Russia. Due to lower processing costs, rare earths are now mainly extracted and refined in China [22] (Fig. 15.2). Extraction and separation... 

Size reduction-induced polarization happens in compounds containing N, O, and F and metals with the outermost s-orbit filled with unpaired electrons like Ag, Au, Rh, while happens not to metals with such s-orbit that is empty or filled with paired electrons, such as Pt and Co. Such polarization of substance at the nanoscale creates properties that the bulk counterpart never demonstrates such as the dilute magnetism, catalysis, superhydrophobicity, fluidity, lubricity, as will be addressed in later section. 

Polarization of the non-bonding electrons is responsible for the size emergence of defect and nanostructures with properties that the bulk material does not demonstrate. This kind properties include dilute magnetism, catalysis, Dirac-Fermi polaron, magnetoresistance, etc. 

Small metal clusters are also of interest because of their importance in catalysis. Despite the fact that small clusters should consist of mostly surface atoms, measurement of the photon ionization threshold for Hg clusters suggest that a transition from van der Waals to metallic properties occurs in the range of 20-70 atoms per cluster [88] and near-bulk magnetic properties are expected for Ni, Pd, and Pt clusters of only 13 atoms [89] Theoretical calculations on Sin and other semiconductors predict that the stmcture reflects the bulk lattice for 1000 atoms but the bulk electronic wave functions are not obtained [90]. Bartell and co-workers [91] study beams of molecular clusters with electron dirfraction and molecular dynamics simulations and find new phases not observed in the bulk. Bulk models appear to be valid for their clusters of several thousand atoms (see Section IX-3). 

Brey W S 1983 Applications of magnetic resonance in catalytic research Heterogeneous Catalysis Selected American Stories ed B FI Davis and W P Flettinger Jr (Washington American Chemical Society)... 

Karge FI G, Flunger M and Beyer FI K 1999 Characterization of zeolites—infrared and nuclear magnetic resonance spectroscopy and x-ray diffraction Catalysis and Zeolites, Fundamentals and Applications ed J Weitkamp and L... 

XPS has been used in almost every area in which the properties of surfaces are important. The most prominent areas can be deduced from conferences on surface analysis, especially from ECASIA, which is held every two years. These areas are adhesion, biomaterials, catalysis, ceramics and glasses, corrosion, environmental problems, magnetic materials, metals, micro- and optoelectronics, nanomaterials, polymers and composite materials, superconductors, thin films and coatings, and tribology and wear. The contributions to these conferences are also representative of actual surface-analytical problems and studies [2.33 a,b]. A few examples from the areas mentioned above are given below more comprehensive discussions of the applications of XPS are given elsewhere [1.1,1.3-1.9, 2.34—2.39]. 

In this chapter shock modification of powders (their specific area, x-ray diffraction lines, and point defects) measurements via analytical electron microscopy, magnetization and Mossbauer spectroscopy shock activation of catalysis, solution, solid-state chemical reactions, sintering, and structural transformations enhanced solid-state reactivity. 

Nonstoichiometric oxide phases are of great importance in semiconductor devices, in heterogeneous catalysis and in understanding photoelectric, thermoelectric, magnetic and diffusional properties of solids. They have been used in thermistors, photoelectric cells, rectifiers, transistors, phosphors, luminescent materials and computer components (ferrites, etc.). They are cmcially implicated in reactions at electrode surfaces, the performance of batteries, the tarnishing and corrosion of metals, and many other reactions of significance in catalysis. ... 

Mossbauer spectroscopy is a specialist characterization tool in catalysis. Nevertheless, it has yielded essential information on a number of important catalysts, such as the iron catalyst for ammonia and Fischer-Tropsch synthesis, as well as the CoMoS hydrotreating catalyst. Mossbauer spectroscopy provides the oxidation state, the internal magnetic field, and the lattice symmetry of a limited number of elements such as iron, cobalt, tin, iridium, ruthenium, antimony, platinum and gold, and can be applied in situ. 

Late transition metal or 3d-transition metal irons, such as cobalt, nickel, and copper, are important for catalysis, magnetism, and optics. Reduction of 3d-transition metal ions to zero-valent metals is quite difficult because of their lower redox potentials than those of noble metal ions. A production of bimetallic nanoparticles between 3d-transi-tion metal and noble metal, however, is not so difficult. In 1993, we successfully established a new preparation method of PVP-protected CuPd bimetallic nanoparticles [71-73]. In this method, bimetallic hydroxide colloid forms in the first step by adjusting the pH value with a sodium hydroxide solution before the reduction process, which is designed to overcome the problems caused by the difference in redox potentials. Then, the bimetallic species... 

Part II Macromolecules Catalysis Colloid Science Electrochemistry Electron Spin Resonance Environmental Chemistry Genetal and Synthetic Methods Mass Spectrometry Nuclear Magnetic Reson n e Organometallic Chemistry Organophosphorus Chemistry Photochemistry... 

The application of magnetic resonance techniques to biological systems is a relatively new approach for the study of macromolecules. In this review we have presented the different approaches which have been made to study Bi2-enzymes. Clearly some progress has been made particularly from the application of ESR to a study of the enzymes ethanolamine ammonia-lyase and ribonucleotide reductase. Although 13C NMR is well in its developmental stages it is obvious that this technique will prove to be very useful for the examination of coenzyme-enzyme interactions. Studies of how corrinoids bind in enzymes and how sulfhydryl containing proteins are involved in enzyme catalysis comprise two major problems which must be overcome before realistic mechanisms can be presented for this group of enzymes. 

In the bulk form, vanadium oxides display different oxidation states and V—O coordination spheres and exhibit a broad variety of electronic, magnetic, and structural properties [96, 97], which make these materials attractive for many industrial applications. Prominent examples range from the area of catalysis, where V-oxides are used as components of important industrial catalysts for oxidation reactions [98] and environment pollution control [99], to optoelectronics, for the construction of light-induced electrical switching devices [100] and smart thermo-chromic windows. In view of the importance of vanadium oxides in different technological applications, the fabrication of this material in nanostructured form is a particularly attractive goal. 

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