Showing papers in "Carbon in 1998"

TL;DR: In this paper, the increasing importance of carbon materials in catalytic processes is analyzed in terms of the most important characteristics of these materials when acting as catalysts or catalyst supports, such as surface area, porosity, chemical inertness and oxygen surface groups.

TL;DR: In this article, the authors show that the viscosity of dispersions as a function of their concentration shows a dramatic increase in gradient above a critical concentration, leading to the formation of viscoelastic gels.

TL;DR: In this article, a discussion is presented on the possible mechanisms of phosphoric acid activation, drawing upon extensive research on the use of phosphorous compounds as fire retardants for wood and cellulose, and it is considered that activation of amorphous polymers produces mostly micropores, while activation of crystalline cellulose produces a mixture of pore sizes.

TL;DR: In this paper, the same three process steps (fiber formation, stabilization, and carbonization) are used to produce both polyacrylonitrile-based (PAN-based) and pitch-based carbon fibers, their final properties differ significantly.

TL;DR: In this paper, an activated carbon obtained from olive stones and with very low ash content (0.10%) was treated with either HCl, HF or HNO3, and the changes in surface chemistry were studied by temperature-programmed desorption and Fourier transformed infrared spectroscopy.

TL;DR: In this article, a high surface area activated carbon, graphitized carbon fibers and synthetic diamond powder were characterized by X-ray diffraction, temperature-programmed desorption and diffuse reflectance infrared (IR) spectroscopy (DRIFTS).

TL;DR: In this article, the micropore size distributions determined from experimental isotherms using such models usually show minima near two and three molecular diameters effective pore width, regardless of the simulation method used.

TL;DR: In this article, the results reveal that the surface area and pore volume of the resulting carbons increase with the chemical ratio, H3PO4/coal, and the results suggest that the combined activation is suitable for producing high porosity carbons with a high proportion of mesoporosity.

TL;DR: In this article, the effects of micropore structure of activated carbons on the high resolution αsplot for nitrogen adsorption isotherms were examined with the grand canonical Monte Carlo simulation.

TL;DR: In this article, an overview of the observed phase transformations and structures of metastable polymeric phases, both crystalline and disordered, as analyzed under ambient conditions, and a pressure-temperature diagram showing which synthesis conditions result in which final phases in the pressure range up to 20 GPa (200 kbar) and at temperatures up to 2300 K.

TL;DR: Ozone treatment of isotropic pitch-based carbon fiber was found to increase the surface oxygen concentration and change surface oxygen from C −O to CO, thereby causing the contact angle between fiber and water to be decreased to zero as mentioned in this paper.

TL;DR: In this paper, a specific Raman spectrum of carbon spherical shells (onions) synthesized by annealing induced (T = 1800 K) chipping off the outer carbon layers from 5-nm size diamond particles has been observed.

TL;DR: In this article, the infusible softwood acetic acid lignin (SAL) was converted to a fusible one as a raw material for carbon fibers by removing the high molecular mass fraction.

TL;DR: In this paper, a molecular simulation study of the adsorption of methane/water vapor mixtures on porous activated carbons, which are doped by placing associating oxygenated sites on the pore surfaces, is presented.

TL;DR: In this paper, the use of diamond-like carbon films in infra red optical, mechanical, electronic and biomedical applications is discussed, and some of these thin film requirements can be met already using existing diamondlike carbon coatings.

TL;DR: Theoretical Young's moduli have been estimated for carbon fibers composed of single-walled fullerene nanotubules aligned in the direction of the tubule axis as discussed by the authors.

TL;DR: In this paper, an ab initio molecular orbital study is performed on a single layer of graphite and the results on bond length, bond angle, bond order, and Raman frequency and activity are compared with experimental data on graphite.

TL;DR: In this paper, the mesopore radius of carbon aerogels was found to range from 2.0 to 6.1 nm by changing the amount of resorcinol, formaldehyde, distilled water, and sodium carbonate used in polycondensation.

TL;DR: In this paper, the same experimental set-up as for the solar production of fullerenes, was used to produce carbon nanotubes by direct vaporization of a mixture of powdered carbon and catalyst (Co, Ni, Y).

TL;DR: In this paper, the carbon adsorbent used in this study selectively removed the anions of hexavalent chromium from the solution, whereas, depending upon the solution pH, no or very small uptake of metal cations was observed.

TL;DR: In this paper, high resolution electron microscopy (HREM) observations reveal that this route leads to the formation of highly crystalline tubes with reduced numbers of layers, including tubes with only one or two layers.

TL;DR: In this paper, an experimental and theoretical study of carbon oxidation in the presence of substitutionally doped boron has been carried out for a range of carbon materials, where both inhibiting and catalytic effects were observed.

TL;DR: In this article, the surface area and pore volume of the activated carbon supports are generally enhanced upon acid treatment due to the removal of impurities present in the carbon, and the adsorption capacity of Ni2+ on the carbon supports is also increased.

TL;DR: In this article, high strength, PAN-based carbon fibers were treated with oxygen plasmas and isobutylene plaasmas, and the effects of exposure time, plasma power and gas pressure on the quantity of acidic functional groups introduced onto the fiber surfaces were examined.

TL;DR: In this paper, pyrocarbon deposition from ethylene, acetylene and 1,3-butadiene was studied with a vertical hot-wall reactor at ambient pressure and 1000 °C; initial partial pressures of the hydrocarbons and residence time were varied.

TL;DR: In this paper, pyrocarbon deposition from methane was studied at ambient pressure and 1100 °C using a vertical hot-wall deposition reactor; the methane initial partial pressure was varied up to 75 kPa and the residence time up to 1 second.

TL;DR: In this paper, the role of N 2, O 2, CO 2 and H 2 O gases in the activation of wood by phosphoric acid was analyzed. But the authors did not consider the effect of other gases.

TL;DR: In this article, the feasibility of preparing activated carbons from extracted oil palm fibre, an abundant oil palm waste, was studied, and 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 pyrolysed chars.

TL;DR: In this paper, the graphite and activated carbon have been ball milled under vacuum for up to 1000 hours and shown that the reactivity of both carbons during combustion increased with milling time, the greatest increase was concomitant with a decrease in graphite crystallinity.

TL;DR: In this article, a semi-empirical model was developed that can be used to correlate with the thermal conductivity of graphite matrix on the basis of solid conductivity, bulk density and porosity.