Ordered carbon

Alkali moderation of supported precious metal catalysts reduces secondary amine formation and generation of ammonia (18). Ammonia in the reaction medium inhibits Rh, but not Ru precious metal catalyst. More secondary amine results from use of more polar protic solvents, CH OH > C2H5OH > Lithium hydroxide is the most effective alkah promoter (19), reducing secondary amine formation and hydrogenolysis. The general order of catalyst procUvity toward secondary amine formation is Pt > Pd Ru > Rh (20). Rhodium s catalyst support contribution to secondary amine formation decreases ia the order carbon > alumina > barium carbonate > barium sulfate > calcium carbonate. 

In this paper, we review progress in the experimental detection and theoretical modeling of the normal modes of vibration of carbon nanotubes. Insofar as the theoretical calculations are concerned, a carbon nanotube is assumed to be an infinitely long cylinder with a mono-layer of hexagonally ordered carbon atoms in the tube wall. A carbon nanotube is, therefore, a one-dimensional system in which the cyclic boundary condition around the tube wall, as well as the periodic structure along the tube axis, determine the degeneracies and symmetry classes of the one-dimensional vibrational branches [1-3] and the electronic energy bands[4-12]. 

In a study on the influence of supports on rhodium, the amount of dicyclohexylamine was found to decrease in the order carbon > barium carbonate > alumina > barium sulfate > calcium carbonate. Plain carbon added to rhodium-on-alumina-catalyzed reactions was found to cause an increase in the amount of dicyclohexylamine, suggesting that carbon catalyzes the formation of the intermediate addition product (59). 

The basic building block of carbon is a planar sheet of carbon atoms arranged in a honeycomb structure (called graphene or basal plane). These carbon sheets are stacked in an ordered or disordered manner to form crystallites. Each crystallite has two different edge sites (Fig. 2) the armchair and zig-zag sites. In graphite and other ordered carbons, these edge sites are actually the crystallite planes, while in disordered soft and hard carbons these sites, as a result of turbostratic disorder, may not... 

J. Li, C. Papadopoulos, and J. Xu, Highly-ordered carbon nanotube arrays for electronics applications. 

In the intercalation reactions, ions (anions X or cations M+) penetrate into the van der Waals gaps between the ordered carbon layers resulting in the enlargement of their inter-layer distance [23,24]. The corresponding charges are conducted by carbon and accepted into the carbon host lattice. 

Carbon nanotubes, as graphene and graphite, are highly ordered carbon phases. However, a separate line can be drawn for historical development of disordered carbon phases among them is an amorphous carbon (am-C). In it, strong bonding between carbons did not allow for completely chaotic distribution of carbon atoms in solid-state phase. Instead, amorphous carbon exhibits random distribution of three possible coordinations of carbon atoms in a planar sp, tetrahedral sp and... 

Xia, Z., Curtin, W.A., Sheldon, B.W., Fracture toughness of highly ordered carbon nanotube/alumina nanocomposites, J. Eng. Mater. Tech., 2004, 126(3) 238. 

Pyrolytic graphite. Pyrolytic graphite is produced by pyrolysis of hydrocarbons under reduced pressure to give a deposit of highly ordered carbon crys-... 

Ryoo, R., Joo, S.H., and Jun, S. Synthesis of highly ordered carbon molecular sieves via template-mediated structural transformation. J. Phys. Chem. B 103, 1999 7743-7746. 

Li, X, Papadopoulos, C., Xu, J. M., and Moskovits, M., Highly ordered carbon nanotube arrays for electronic applications. Appl. Phys. Lett. 75, 367 (1999). 

Writing half-reaction for the oxidation of oxalic acid. Balancing (i) the atoms in the order carbon-oxygen-hydrogen and in (ii) Equalising the charge ... 

Abstract. The model for describing the electrical conductivity of nanocarbon material, consisting of the particles of disordered carbon, carbon nanotubes and the ordered carbon phase is proposed. 

Nanocarbon material (NCM), containing both the ordered carbon structures (carbon nanotubes (CNT), the particles of nanographite) and the particles of the disordered carbon phase, is known to be promising for using as elements of the nanodimensional devices and as fillers, for example, of lithium batteries. Structure and phase composition of NCM depend essentially on the methods of their obtaining and the regimes of the subsequent temperature and chemical treatment. Therefore, finding the correlation between the structural and phase composition and transport properties of NCM as well the description of the mechanisms of their conductivity are the important problems. 

As it was shown recently [1-3], NCM is the complex heterogeneous system, which contains the disordered and ordered carbon phases, as well as the particles of metal-catalyst. The disordered carbon phase is the particles of amorphous carbon, and also so-called of nanoonions. The ordered carbon phase includes single- or... 

For the ordered carbon phase, i.e., for nanographite and multi-walled CNT, we consider the mechanism of conductivity similar to that existing in the highly oriented pyrolytic graphite... 

FORMATION OF ORDERED CARBON NANOSTRUCTURES AT PYROLYSIS OF HYDRATED CELLULOSE CONTAINING THE METALS OF FERROUS SUBGROUP... 

Abstract. The influence of the additions of the metal salts of the ferrous subgroup on the process of carbonisation of hydrated cellulose fibers has been investigated and the structure of obtained Me-carbon fibers has been studied. It is established that the presence in the hydrated cellulose fibers such salts as nickel chloride and nickel, cobalt and ferric nitrates promote the formation of structure ordered carbon phases at the process of carbonisation. 

Keywords carbon fibers, carbonisation, metallic catalysts, ordered carbon, x-ray diffraction. 

The metals of ferrous subgroup and their alloys are usually used as the catalysts in processes of formation ordered carbon nanostructures [1], There is a clear correlation between the sizes of catalyst particles and the tipe of carbonic deposits on their surface. 

It is established, that during the carbonization of systems HC- salt of metal of ferrous subgroup the reducing of the salts to the free metals take place. These highly disperse metals catalyze (at definite THT) the processes of carbon structuring with formation of different phases of ordered carbon. On literary data... 

The appearance of new phases of structure ordered carbon is accompanied by the fall of Me-CF strength (Table 2) and by the development of a porosity. The sorbate volume of pores in the samples of Me-CF with THT above 800 °C, which was determined by the sorption of benzene, makes 0.13-0.16 CM3-g 1 for chlorides and 0.11-0.26 cM3 g 1 for nitrates. 

Destruction of preliminary structured PAN films under intense IR radiation in inert atmosphere during very short time (10 s - 2 min) leads to the intensification of carbonization processes with the formation of ordered carbon structures. Figure 1 shows Raman spectra of PAN films carbonized by IR radiation. 

The rise in intensity of IR radiation does not change the placement of bands in Raman spectrum, only their intensities (Fig. 1). The intensity of the 1355 cm 1 band decreases, which attests to the formation of more ordered carbon structures. 

Chemical reactions proceeding in the system under the conditions of IR pyrolysis result in the changes of PAN crystalline structure. X-ray phase analysis (XRPA) has shown that at T>200°C in the course of formation of ordered carbon structures crystalline and amorphous phases of initial PAN disappear, while another amorphous carbon phases appear [12] ... 

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