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Oligomeric pitch syntheses from quinoline and isoquinoline were studied using AlCl 3 as a Friedel Craft type catalyst at 280 C and 300 C to obtain N-enrichcd pitch substances. The yield and analyses of pitch product suggest very different reactivities of the substrates, much lower reactivity and pitch yield, more loss of nitrogen and hydrogen at preparation of isoquinoline pitch (IQP) being...
XPS is used to study the binding energy of the Cls, Nls and Ols photoelectrons of surface groups on several nitrogen-containing activated carbons. Specific binding energies are assigned to amide (399.9 eV). lactam and imidc (399.7 eV). pyridine (398.7 eV), pyrrole (400.7 eV), alkylamine. secondary amide and N-alkylimide (399.9 eV) and trialkylaminc (399.7 cV) functional groups on activated carbon...
A review is given on the gasification of carbonaceous materials by oxygen-containing reactant molecules, with the emphasis on the attempt to unify the mechanistic description of the gasification process. This seems to hold for both the uncatalyzed and the alkali catalyzed reaction at elevated temperatures, although clear exceptions exist. In particular transient kinetic experiments, employing labelled...
Microporous carbons characterized by different structural properties were prepared by carbonization of poly(sodium-4-styrenesulfonate) in a nitrogen flow at temperatures in the range of 500-850°C. The carbonization process and the microstructural characteristics of the carbonaceous materials obtained have been studied by differential thermal analysis (DTA), diffuse reflectance FT-IR spectroscopy,...
The adsorption experiments of l.l.2-trichloro-2.2.l-trifluoroethane on dry activated carbon pellet were carried out at 298 K. For low concentrations of l.l.2-trichloro-2.2.1-trifluoroethane. the Langmuir equation was well correlated by experimental dataIn this study the effects of presorbed water upon the adsorption capacity of l.l,2-trichloro-2.2.l-trifluoroethane by a pellet-type carbon adsorbent...
Structural and spectroscopic studies of a new graphite uranyl sulfate phase are performed. By using X-ray diffraction, an electron distribution pattern along the graphite c-axis for stages 1-4 is calculated, based on [001] analysis; [hk0] and [hkl] reflection analysis allows the determination of the parameters of the planar primitive cell and demonstrates the existence of a three-dimensional order...
The electrochemical properties of carbon fibres (CFs) differentiated by heat treatment at temperatures up to 2400°C and oxidation in concentrated nitric acid were studied.Changes in the shapes of cyclic voltammetric curves for working electrodes prepared from carbon fibres (CFs) were analysed in aqueous and nonaqueous electrolytes. Possible ranges of the sweep potential were estimated for the electrochemical...
A high resolution transmission electron microscopy study of fluorine-intercalated carbon fibers has been carried out on two types of host materials: high-temperature treated pitch-based and PAN-based fibers. TEM images and corresponding Fourier transforms have shown that only stage-1 compounds and graphitic-type domains are detected in the experiment conditions. In particular, no interlayer spacing...
Plasma-assisted Chemical Vapor Deposition (PACVD) B 4 C coating and a hybrid PACVDB 4 C Si 3 N 4 coating were deposited on a two-dimensional C-C substrate. Oxidation behavior of coated and uncoated C-C composites was studied using a thermogravimetric analyzer (TGA) in both the isothermal and kinetic mode. The PACVD coating provided an excellent oxidation protection...
Different preparation methods of Pt(IV) chloride-graphite intercalation compounds from micrometer sized graphite powder and their subsequent chemical reduction are described. The reaction products were investigated by XRD, SEM, EDX and neutron activation analysis. Pt(IV) chloride-GIC was obtained by the isothermal vapour transport method of PtCl 4 between 350 and 500°C under a pressure of...
Active carbons of different origins (ex-coconut shell, ex-coal, ex-peat and ex-wood) have been used as adsorbents of potassium aurocyanide. Various treatments were applied to the active carbons: heat treatment at 800°C, heat treatment at 800°C followed by HCl (1) washing, heat treatment at 650°C, washing with HCl 10%, esterification with methanol, oxidation with nitric acid and extraction with toluene...
Carbon/carbon composites with porosities as low as 7% were fabricated within 8-12 hours using the forced flow-thermal gradient chemical vapor infiltration (FCVI) process. Preforms consisting of 40 layers of T-300 plain weave carbon cloth were infiltrated with a feed containing a carbon source and a diluent. The carbon sources studied in the present work included propylene, propane, and methane and...
Chemical vapor deposition (CVD) coatings used for the oxidation protection of carbon-carbon (C-C) composites provide inadequate oxidation protection due to extensive thermal cracking. One method to reduce the thermal cracking is to use plasma-assisted chemical vapor deposition (PACVD). In this study a PACVD SiC coating and a hybrid PACVD SiC Si 3 N 4 multilayer coating were deposited...
The synthesis of electrochemical carbyne from perfluorinated hydrocarbons was optimized. The relative yield of carbyne was monitored by Raman spectroscopy using the C C stretching mode. The position and relative intensity of this band depend on the type of fluorocarbon and reducing agent used. Optimum conditions were attained for electrochemical reduction of poly(tetrafluoroethylene) with K- or...
1 3 C NMR and FTIR analyses have been employed to follow the evolution of chemical structure in relation to porosity development, as a function of heat treatment temperature (HTT), for activated carbons produced from white oak by phosphoric acid activation. The chemical changes affected by acid treatment at low HTT are: by 50°C there is significant alteration of the lignin structure; by 100°C...
To improve the performance of adsorption machines using the activated carbon-methanol pair, a new procedure for shaping adsorbent materials as bricks was developed. In this paper, research activity on the preparation of composite carbon samples is described together with the results on methanol adsorption capacity and on thermal conductivity measurements. Carbon bricks of a pre-defined form were...
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