The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Graphite vaporization induced by long pulses of near infrared laser to produce fullerenes is reported. Results of iodine photodissociation laser-driven (λ = 1.315 μm, pulse length 150 μs) formation of C 60 fullerenes at various experimental conditions (number of laser shots, helium pressure, target surface shape) are summarized. In addition, laser production methods, as well as UV...
The copper-catalysed reduction of NO with carbon has been studied over copper-loaded carbon materials (graphites and activated carbon). Characterization of the different preparations has been carried out by X-ray diffraction, temperature-programmed reduction in hydrogen and surface reaction of NO. The copper loading, the nature of the copper phase, the presence of functional groups on the surface...
Amounts between 2.5 and 5.9% of HBr, HCl and Cl 2 were added to fullerene forming benzene/oxygen/argon flat-flames burning at 75 mbar in an attempt to affect halogen substitutions in the carbon framework. The inhibition effect of HBr dramatically reduced the yield of fullerene, while it stayed in the same order of magnitude after addition of HCl or Cl 2 . No formation of halogenated...
Coconut charcoals of different grades were studied for assessing the removal efficiency of chemical warfare (CW) agents from aqueous solutions. Oxygen analogue of sulphur mustard and phenol were used as model compounds for CW agents for adsorption studies. Freundlich and Langmuir adsorption isotherms were plotted. Equilibrium constant and maximum adsorption capacity for carbons were computed from...
Two-dimensional carbon/carbon composites were densified with carbon by pyrolysis of propane using the pulse chemical vapor infiltration (CVI) process which repeats the cycle of evacuation and introduction of gas. The experimental parameters were deposition temperature, reactant gas concentration, flow rate, gas introduction time, evacuation time, and pulse number. The most effective parameters of...
A stage 2 FeCl 3 -graphite intercalation compound (GIC) was chemically reduced with a lithium-naphthalene complex in THF and 1-MB. The GIC was also reduced electrochemically in THF, PC and EC+DEC, containing 1 mol/dm 3 of LiClO 4 . When the reduction was performed in THF chemically or electrochemically, fine iron particles were obtained in the graphite matrix. The mean diameter...
This work presents the different effects of steam and carbon dioxide activation of a char in both the development of microporosity and the micropore size distribution using immersion microcalorimetry of liquids with different molecular size (benzene, 2,2 dimethylbutane, iso-octaine and α-pinene). The study has been carried out with three series of carbons, two of them prepared by steam activation...
The influence of surface functional groups on activated carbons on the adsorption and desorption of lithium ions, present in trace amounts in aqueous solution, has been studied in the absence and presence of an applied electric field.Application of an electric current during the experiments dramatically increased the sorption of the ions. Moreover, lithium could be released into the solution by reversing...
A series of activated carbons was prepared from bituminous coal by chemical activation with potassium hydroxide and zinc chloride and also by physical activation with carbon dioxide. The effect of process variables such as carbonization time, temperature, particle size, chemical agents, method of mixing and impregnation ratio in the chemical activation process was studied in order to optimize those...
Electrocatalytic electrodes were prepared by coating amphiphilic carbonaceous material containing platinum acetylacetonate from N,N-dimethylformamide on a glassy carbon surface. The electrocatalytic activity of the electrodes was evaluated for hydrogen generation in 1 M hydrogen perchloride by means of voltammetry. The current densities for proton reduction increased at the potential of -0.2 V vs...
Five activated carbons with different porosity, prepared by chemical activation of peach stones with phosphoric acid, have been further activated in a carbon dioxide gas flow at 825°C for different periods of time to cover a wide range of burn-off. The porosity of all activated carbons was determined by adsorption of N 2 (77 K), CO 2 (273 K) and n-C 4 H 10 (273...
This paper describes an investigation of the adsorption of CH 3 I on a KI-impregnated carbon and the influence of competitive adsorption on the process. A gravimetric method was used to study the equilibrium capacity and kinetics for the adsorption of CO 2 and CH 3 I in the presence of He, and CH 3 I in the presence of CO 2 on the carbon. The results of these...
The effect of the coal carbonization step heating rate on the reactivity of the chars obtained, as well as on their porous structure development in the subsequent activation step, was analyzed. Different types of carbonization process were investigated, combining a low heating rate (5 K/min) and high heating rate (hundreds of K per second) in this step. Chars obtained in these processes were activated...
Exposure of jet fuel to high temperatures in aircraft fuel lines triggers pyrolysis reactions which eventually lead to deposition of carbonaceous solids on metal surfaces. This is a particularly important problem for advanced future aircraft which may expose fuel to very high temperatures. Different optical textures were observed in samples of deposits formed in different sections of aircraft fuel...
A small angle X-ray scattering study of carbons made from pyrolyzed sugar is presented. An analysis of the micropore size and surface area was performed as a function of the heat-treatment temperature between 600 and 2100°C. The observed X-ray data were analyzed using the model of Kalliatet al. , corrected for the experimental smearing function of the slits. The surface areas of the macro and micropores...
The surface chemistry and the porous texture of activated carbons prepared from a charred product (C Jex -600), which was obtained from rockrose (Cistus ladaniferus, L.) extracted previously into petroleum ether, were studied. Activated carbons were prepared by heating C Jex -600 between 350 and 850°C in air to 40% burnoff. Methods of chemical analysis and FTIR...
A new procedure for regenerating activated carbon based on thermal desorption with liquid water under subcritical conditions (300°C and 120 atm) is proposed. The method was assayed with three types of activated carbons exhausted with phenols (phenol and 4-nitrophenol), textile dyes (sirius red C.I.: 29080 and orange II C.I.: 15510) and pesticides (carbofuran and atrazine). In all cases, total recovery...
This study is devoted to the comparison of the oxidizing ability of graphite and fullerite towards the three heavy alkali metals. These elements are able to intercalate very easily into graphite and fullerite, leading to various binary compounds. In the case of graphite, that is 2D host material, the alkali metal atoms intercalate in the bidimensional van der Waals's gap. These latter can be systematically...
This paper presents the general results of an investigation of the friction and wear of a carbon-carbon (C/C) composite material in dry nitrogen and ambient air using a constant speed type of test apparatus. With brake applications in mind, much of the work has been carried out at experimental conditions that allow the temperature of the specimen to reach 700°C by frictional heating. The steady-state...
The release of nitrogen oxides during the combustion of coal chars is a major environmental problem. In this study, the effect of iron catalysts on the release of NO during the combustion of a suite of carbons was investigated using a thermogravimetric analyser-mass spectrometer. The anisotropic carbons were prepared from acenaphthylene while the isotropic carbons were prepared from polyvinylidene...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.