Showing papers in "Fuel in 1976"

TL;DR: In this article, coal was converted to benzene-soluble, liquid products through a reaction path which appears to involve thermal cleavage of chemical bonds in the coal (so-called depolymerization), and free radicals formed pyrolytically were stabilized in the early stages by autogenous hydrogen transfer, and in later stages by abstraction of hydrogen from the hydrogen-donating tetralin.

TL;DR: The molecular weights of asphaltenes, as determined by vapour-pressure osmometry, vary considerably and are dependent upon the nature of the solvent as well as the temperature.

TL;DR: In this paper, a coal conversion model was developed that accounts for thermal decomposition of the coal, secondary char-forming reactions of volatiles, and homogeneous and heterogeneous reactions involving hydrogen.

TL;DR: In this paper, the role played by the oxygen functions in hydrogen-bonding interactions which occur between the asphaltene and resin entities of Athabasca bitumen is investigated. But the results show that hydrogen bonding occurs readily between these fractions and allows feasible representation of the manner by which the asphtenes are peptized by the resins.

TL;DR: In this paper, a cross-polarization technique was applied to obtain high-resolution carbon-13 spectra of vitrains from two coals, which overcomes the problem of dipolar line broadening by protons, permits estimates of the carbon aromaticities of solid coals.

TL;DR: In this paper, radiofrequency low-temperature ashing of subbituminous and bituminous coals was used to determine the mineral phases present at each temperature interval by X-ray diffraction analyses.

TL;DR: In this paper, the catalytic effect of coal mineral matter constituents on hydrogenation has been investigated in the ash samples of a North Assam coal sample, and it was shown that both iron and titanium present in coal have a catalytically active form of iron sulphide.

TL;DR: In this article, a high-volatile bituminous coal (HVab) was examined by means of transmis sion electron microscopy in a highvoltage electron microscope (1 MeV).

TL;DR: In this paper, the kinetics and catalysis of the reaction between steam and two different coal chars were investigated in a small fixed-bed reactor, where various possible catalysts were tested, and the effect of catalyst concentration was examined.

TL;DR: This article showed that 40% to 60% of the oxygen present in asphaltenes is accessible to acetylation and that a considerable portion of these groups may occur as collections of two or more functions on the same aromatic ring or on adjacent peripheral sites, or sites adjacent to a carbonyl function, in a condensed aromatic system.

TL;DR: In this paper, a central horizontal section covering the temperature range 300-650 °C was prepared for microscopic examination, quantitative data being obtained along isothermal traverses parallel to the hot wall, and the carbonization of those coals producing a fused structure was characterized by a highly porous zone the structure of which was related broadly to the dilatation of coal as measured in the Ruhr dilatometer.

TL;DR: In this article, thermal changes involved during pyrolysis of twelve US coals of various ranks in a helium atmosphere at 5.6 MPa (gauge) and temperatures up to 580 °C are reported.

TL;DR: In this article, the US Bureau of Mines (USBP) method for the separation of heavy petroleum hydrocarbons into structural types ( saturates, monoaromatics, diaromatic and polyaromatic-polar material) has been modified.

TL;DR: In this paper, the mechanism of high-pressure hydrogenolysis is discussed for Hokkaido coals of different ranks, and it is established that this mechanism can be applied generally to the same coal types.

TL;DR: In this article, the results were converted to weight loss by a correlation developed from subsidiary fixed-bed experiments and mass balances on the fluidized bed of sand in an atmosphere of nitrogen at temperatures up to 400 °C.

TL;DR: In this paper, the feasibility and efficiency of direct conversion of coal into acetylene depend on such factors as coal feed rate, size range of coal particles, volatile matter in the coal, and the plasma operating conditions.

TL;DR: In this paper, infrared and chemical studies of the resin fraction isolated from Athabasca bitumen indicate that oxygen in these fractions exists predominantly as ester functions, and evidence for this was obtained from hydrolysis, acetylation and methylation reactions.

TL;DR: In this paper, preliminary experiments have been made by pace-heating three coals from about −40 °C to 120 °C at a rate of 0.5 °C/min in various concentrations of oxygen and analysing the effluent gases.

TL;DR: Two petrographic types of Tertiary brown coals, xylitic and earthy, were carbonized, and activated with carbon dioxide between 1123 and 1273 K.

TL;DR: In this article, a laboratory reactor system was developed for the determination of products obtainable from the flash heating of raw coal in flowing hydrogen at pressures up to 100 atm. The system provided for control of heating rate, solids-contact time and vapour-product residence time.

TL;DR: In this paper, the chemical structure of coal-hydrogenolysis was investigated and the mechanism further discussed in detail on the basis of the chemical structures of each corresponding product in the mechanism discussed in our previous report, and it was concluded that oil (S 1 ) and oil(S 2 ) whose production processes differ from each other have corresponding differences in their respective chemical structures.

TL;DR: In this paper, a mathematical model of the drying process that occurs in a power station mill is developed and tested, and modifications to a simple model are proposed to account more realistically for gas-particle interactions.

TL;DR: In this paper, the influence of reac tion temperature was explored from 620 to 980 °C with a vapour-product residence time of 0.6 s. The effect of increasing residence time was explored at 700 °C.

TL;DR: In this article, the acidity of five low-rank coals from various parts of the world have been determined by aqueous ion exchange and non-aqueous titration procedures.

TL;DR: In this paper, high-performance liquid chromatography via gel permeation separates tetrahydrofuran-soluble SRC into several size fractions and Nuclearmagnetic-resonance data strongly suggest that hexamethylphosphoramide-solubile SRC is approximately 95% aromatic in character.

TL;DR: In this article, it was suggested that the maceral resinite was comprised of two contrasting chemical-structural groups: one confined to peats, brown coals, lignites and sub-bituminous coals and the other to low and medium-rank bituminous coal.

TL;DR: In this paper, bituminous coal, lignite, peat and more recent biogenic materials were reacted as water slurries at 380 °C for short periods with hydrogen, directly and from the water gas shift reaction, without organic solvents or catalysts.

TL;DR: In this article, carbonized vitrinite samples from a weakly caking and a strongly coking coal have been carbonized both fresh and after preoxidation for 14 days at 105 °C to points within the temperature range 300-800 °C.