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Four series of activated carbon have been prepared from carbonized olive stones. One of them, series D, was prepared using carbon dioxide as activating agent, and the other three, series AV, W, and H, with water vapor under different experimental conditions. Two of the series, D and H, were prepared in such a way that the gasification rate for both reactants was identical, in an attempt to reduce...
The combustion behavior of a suite of isotropic carbons has been investigated using a thermo-gravimetric analyser mass spectrometer. The carbons were prepared from polyvinylidene chloride (PVDC) and a phenolic resin by carbonisation under argon to 873 K in the pressure range 0.1-7.5 MPa. Nitrogen was introduced into the carbons (HTT 873 K) by both ammonia treatment at the final heat-treatment temperature...
Three furnace carbon blacks, a thermal black, and an electrically conductive sample were submitted as received to chlorination, at 450°C, with a mix of chlorine and carbon tetrachloride vapors. The treated samples were examined using chemical and spectroscopic (XPS) methods. The interpretation of the XPS spectra is facilitated by comparison with spectra of reference materials. XPS detects various...
The adsorption behaviour of anionic naphthalene derivatives at the graphite-aqueous solution interface has been studied at 25°C at pH 7 and an ionic strength of 0.05 M. The orientation and packing of the adsorbates is strongly dependent upon the number and type of functional groups attached to the aromatic rings. A thermodynamic analysis has been used to evaluate quantitatively the adsorbate-adsorbent...
Carbon deposit morphology during catalytic disproportionation of CO is dependent on a number of variables. Hydrogen has a significant effect on the form of carbon deposited. It is proposed that the effect of hydrogen is to cause (or allow) open forms of carbon such as filaments to be produced. Hydrogen atoms serve to satisfy valences at the free edges of graphite planes. Without hydrogen, carbon...
Evidence for the formation of an archetypal hemi-toroidal link structure between adjacent concentric walls in pyrolytic carbon nanotubes is presented. The observed and simulated TEM images for such structures are in excellent agreement. This study suggests that double-walled carbon nanotubes, in which the inner and outer tubes are linked by such hemi-toroidal seals, may be one viable way of overcoming...
A microscopic cross-linking model has been applied to calculate the Young's modulus as a function of heat-treatment temperature (HTT) of petroleum coke (a graphitizable carbon) and Akabira coal (a non-graphitizable carbon). This model is an extension of a previous model for non-graphitizable carbons, where not only the coalescence of crystallites along the c axis, but also the coalescence along thea...
The present study compares low energy tribological behavior among five different carbon-carbon composites designated E (2D PAN/CVI), A (2D pitch/resin/CVI), TH (high density 2D PAN/pitch), TL (low density 2D PAN/pitch), and T3D (3D PAN/pitch). Results indicate that all composites had steady-state friction coefficients close to 0.2, except for TL which had a much larger initial...
The influence of support surface chemistry and metal precursor species on the properties of Pt/C catalysts has been analyzed. The char of a phenolformaldehyde polymer is the carbon source for obtaining four different supports: three with different degree of surface oxidation and another one modified by ion-exchanged calcium. These supports have been impregnated with aqueous solutions of two platinum...
The novel bonding of an additional carbon layer over a C/C composite substrate surface was studied. Furan resin was selected for the additional carbon layer precursor. Molding was performed using a hot press apparatus. Polyvinyl chloride resin (PVC) was used as the bonding agent. The bonding mechanisms were studied with thermal gravity analysis, thermal gravity-mass spectroscopy, and high-temperature...
We have studied the formation of coke during the thermal coupling of an equimolecular methanehydrogen mixture at 1230°C and under a one-atmosphere pressure. Coke samples are recovered in rectangular boats placed along the pyrolysis reactor. The deposits show a non-homogeneousness of coke along the reactor in terms of deposition rate and in terms of structure. We observed at least two kinds of coke...
The geometrical conditions pertaining to closure, helicity, and interlayer distance between successive layers with circular cross-sections in carbon tubules (nanotubes) have been examined. Both the intralayer length of the C-C bonds and the interlayer distance between successive layers must vary with the radius of the layers. The division into groups of the sheets in nanotubes is found to be due...
Carbonization of petroleum and coal tar pitches to toluene insoluble fraction (TI) was investigated under air and nitrogen gas blowing systems. The TI yield was evaluated on the basis of the weight of pitch loaded. Changes of the yield with the reaction time were analyzed by a kinetic model of carbonization. The model assumes that pitch as a reactant contains a reactive component, P 1 , which...
During the electrochemical intercalation and deintercalation processes of sulfuric acid into graphite, the electrical resistivity along the graphene layers was followed with a contactless method. At 20°C, the intercalation process is associated with a large decrease of resistivity; the lowest values are observed for stages 8 to 5 formation, and remain nearly constant until stage 1. However, the...
The relationship between the structure and mechanical properties of both polyacrylonitrile (PAN)-and pitch-based carbon fibres has been studied in detail. Raman spectroscopic studies on the deformation of carbon fibres have shown that the rates of Raman band shift per unit strain, for both PAN- and mesophase pitch-based fibres, increase linearly with Young's modulus of the fibres. The shift rate...
The possibilities for preparative separation of fullerene (C 60 /C 70 ) mixture by flash chromatography on activated carbon or activated carbon fibres as a stationary phase are shown. The effect of the nature of the activated carbon and of its specific surface area on the elution time, chromatographic peak width, amount, and purity of the recovered product (C 60...
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