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Flow injection combined with thermal analysis-mass spectrometry is a useful technique for studying gasification reactions. It provides a rapid, powerful method of separating the variables of a particular reaction, such as reactant concentration, reactant composition and temperature, studying their influence on the reaction products and differential thermal analysis. The present work illustrates the...
The authors investigated carbonization and graphitization behavior of coal tar pitch (CTP) treated with iodine. The behavior of weight decrease and the microstructural development with increase of heat treatment temperature were different between non-treated and iodine-treated CTP. The carbon yield of CTP increased from 40 to 70% by the iodine treatment. Flow type texture was obtained from non-treated...
Because of the high production rate of gaseous reaction products in critical temperature ranges where out-diffusion is relatively slow, glassy carbon ware is difficult to make in thick section by pyrolysis of phenolic resin, without causing kilning faults. Using wedge shapes of cured phenolic resin we found the greatest thickness possible for a fixed heating rate during postcuring (400-500 K) and...
Transient temperature and thermal stress distributions of a cylindrical rod which is locally heated eccentrically at an end surface are analyzed on the basis of thermoelastic theories. These results give a theoretical background of the fracture of graphite electrodes used in steel-making arc furnaces, which is occasionally found when electrodes are operated under high-power conditions. An experimental...
The potential for damage during the pyrolysis of phenolic/carbon composite material in the processing of carbon/carbon components is high. Accurately modeling the kinetics of the pyrolysis reaction could lead to improvements in processing. A mechanism for the pyrolysis of phenolic/carbon composite describing the reaction as occurring in three major regions is the foundation of a kinetic model. ...
Copper- and chromium-impregnated and non-impregnated charcoals have been characterized by X-ray photoelectron spectroscopy and scanning electron microscopy, showing the composition and distribution of elements in the charcoal substrate. Water (as D 2 O) was reacted with dried charcoals and its gradual thermal desorption was studied by mass spectrometry. The impregnated charcoal retains substantially...
Flow adsorption experiments have been carried out on CH 4 , O 2 , N 2 and H 2 O with active carbons at a range of pressures and temperatures.The equipment used was a new model Microscal Flow Adsorption Microcalorimeter in which the adsorption and the associated heat evolution could be measured simultaneously with the aid of appropriate down stream detectors. The flow...
Mesoporous carbon xerogels were prepared from the sol-gel polymerization of resorcinol with formaldehyde (RF) followed by carbonization. The effect of the initial pH of the RF solution on the surface area, pore volume, pore size distribution and nanostructure was studied. A brief mechanism of polymerization is discussed. Typically, a lower initial pH yielded carbon xerogels with a higher surface...
Activated carbons impregnated with a mixture of copper(ii), iron(ii), iron(iii) and chromium(iii) oxide catalysts were prepared in order to facilitate catalytic regeneration of AC saturated with phenols. The temperature ranges of phenol oxidation (T p ), carbon oxidation (T c ) and carbon burn-off were determined from DTA/TGA investigations in oxidizing and inert atmospheres. The...
Surface structures and reactivities of carbons gasified in N 2 O and in O 2 are compared in this study. The carbon employed was derived from pyrolysis of phenol-formaldehyde resins. It was found that greater surface area and pore volume are created for the carbon gasified in O 2 than that in N 2 O. At high extents of burn-off the carbon gasified in N 2 O shows...
Physical and chemical properties of carbons previously used for air purification in sewage plants are investigated. The chosen samples are characterized by pH values (estimated according to ASTM D 3838) between 2 and 10. Their H 2 S breakthrough capacities are less than 0.01 g of H 2 S/cm 3 of carbon. The surface chemistry and porous structure are determined using sorption...
Four ash-free cellulose chars were obtained at temperatures of 400, 500, 600 and 700°C, respectively, at which the thermogravimetric plots approach a final constant mass, avoiding further high-temperature vapour activations to prevent micropore formation. Stable thermal behaviour was obtained, however, under further heat treatment at temperatures equal to or lower than those of the respective preparations...
The gas desorption properties of mixed graphite and water glass (K 2 SiO 3 + H 2 O) were investigated by thermal desorption spectroscopy. It was observed that mainly H 2 O and CO 2 were desorbed from the materials after a baking treatment in the atmosphere. The surface morphology became rough or smooth as the graphite content or the water glass increased,...
The deintercalation process of fluorine species from fluorine-graphite intercalation compounds (F-GICs) has been investigated by evolved gas analysis. The controlled transformation rate thermal analysis method was used. In this way, the rate of production of the gaseous phase is permanently controlled at low pressure, so that both temperature and pressure gradients can be lowered at will, avoiding...
Activated carbons can be impregnated with metal oxides (Cr, Cu, Ag, Mo, Zn, Cc) and/or organic compounds (triethylenediamine (TEDA)) to help capture high vapor pressure substances. However, this process lowers the temperatures of initial oxidation and spontaneous ignition and affects both the CO and CO 2 effluent concentrations upon heating. This study quantifies the depression of the point...
The feasibility of preparing activated carbons from extracted oil palm fibre, an abundant oil palm waste, was studied. Preliminary tests were conducted to investigate the influences of different operating parameters, such as initial material size, inert gas flow rate, heating rate, pyrolysis temperature and hold time, on the properties of the pyrolysed chars. The pyrolysed chars were characterized...
The factors that influence oxidation resistance of B 4 C/C composites with self-healing properties during oxidation are discussed in this paper. Isothermal oxidation behavior of B 4 C/C composites with different B 4 C content is examined from 600 to 900°C. Analysis of oxidation kinetics of B 4 C/C composites at the temperature range of 600–900°C showed that nominal...
C–SiC–B 4 C composite materials were fabricated from pitch based needle coke, SiC and B 4 C with or without SiC nanoparticulate additive by grinding and then pressureless sintering. Anisothermal and isothermal oxidation tests of the composites obtained were carried out in oxygen flow at temperature increasing continuously from 773 to 1573K. Self-protection behavior of the composites...
An experimental and theoretical study of carbon oxidation in the presence of substitutionally doped boron has been carried out. The effects of boron loading, reaction temperature and degree of burnoff were analyzed for a range of carbon materials. Both inhibiting and catalytic effects were observed. Several semiempirical molecular orbital modeling approaches were used in an attempt to rationalize...
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