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Coal resonance study

The design temperature of 600°C. was chosen by considering coal as a free radical source. Electron spin resonance studies of coals (I) indicate that a rather sharp maximum in nonspin-paired electron content occurs in coals when processed in this temperature zone—i.e., 500°-550°C. Chlorine moreover can be converted to atomic chlorine by several energy sources—corona discharge, silent electric discharge, ca. 4700 A. light, etc. [Pg.671]

Davidson, R. M. ] 986. Nuclear Magnetic Resonance Studies of Coal. Report ICTIS/TR32. International Energy Agency, London. [Pg.179]

MHz Proton Magnetic Resonance Study of Coal-Derived Liquids... [Pg.285]

Hatcher P. G. and Breger I. A. (1981) Nuclear magnetic resonance studies of ancient buried wood I. Observations on the origins of coal to the brown coal stage. Org. Geochem. 3, 49-55. [Pg.3682]

Magnetic Resonance Study of Labeled Guest Molecules in Coal... [Pg.23]

Retcofsky, H. L. Hough, M. R. Electron Spin Resonance Studies of Coals... [Pg.57]

Steelink, C. A. (1966). Electron paramagnetic resonance studies of humic acid and related model compounds. Coal Sci. (Adv. Chem. Ser.) 55, 80-90. [Pg.631]

Hatcher P.G., Lerch H.E. Ill, Bates A. L.,VerheyenT.V. (1989a) Solid-state 13C nuclear magnetic resonance studies of coalified gymnosperm xylem tissue from Australian brown coals. Org. Geochem. 14, 145—55. [Pg.338]

Structural parameters derived by nuclear magnetic resonance studies were employed to calculate the conformation and size of the hypothetical aromatic systems (Figure 10.2) (Bartle et al., 1975). And it is interesting to note the small size of the systems coincide with the natural product origins of coal but offer an attractive alternative to the graphite-type layers that were (even still are) perceived to exist in coal. Such products could arise from the former, but not from the latter. [Pg.290]

Other evidence from carbon-13 magnetic resonance studies of the carbon disulfide extract of coal also favors the occurrence of small-ring systems. The mean structural unit appears to consist of two-to-three ring condensed aromatic systems with 40% of the available aromatic carbons bearing alkyl, phenolic, and/or naphthenic groups. Indeed, the mass spectrum of the extract indicated the presence of alkyl aromatic compounds having from 1 to 10 or more alkyl carbons per molecule. [Pg.299]

BurchiU, R, Howarth, O.W., Richards, D.G., and Sword, B.J. Solid-state nuclear magnetic resonance studies of phosphorus and boron in coals and combustion residues. e/1990 69 421-128. [Pg.165]

Electron spin resonance (esr) (6,44) has had more limited use in coal studies. A rough estimate of the free-radical concentration or unsatisfied chemical bonds in the coal stmcture has been obtained as a function of coal rank and heat treatment. For example, the concentration increases from 2 X 10 radicals/g at 80 wt % carbon to a sharp peak of about 50 x 10 radicals/g at 95 wt % carbon content and drops almost to zero at 97 wt % carbon. The concentration of these radicals is less than that of the common functional groups such as hydroxyl. However, radical existence seems to be intrinsic to the coal molecule and may affect the reactivity of the coal as well as its absorption of ultraviolet radiation. Measurements from room... [Pg.220]

The O-methylated extract was derivatized with 99 percent C-enriched methyl iodide. The NMR spectrum of the extract showed a strong absorption at 56 ppm (relative to TMS), which can be attributed to unhindered aryl methyl ethers (67%), a smaller absorption at 60 ppm, attributable to hindered aryl methyl ethers (23%), and a resonance at 51 ppm, assignable to methyl esters derived from carboxylic acids (10%).(16) TTiese results are consistant with those of Liotta l al, who studied the alkylation of whole Illinois No. 6 coal.(12)... [Pg.143]

P21 Persistent electron paramagnetic resonance (EPR) signals have been reported in coals, chars, and soots (26-29), but PMj 5 has not been studied by EPR. (Prom Dellinger et ah, 2001)... [Pg.221]

This volume covers a wide range of fundamental topics in coal maceral science that varies from the biological origin of macerals to their chemical reactivity. Several chapters report novel applications of instrumental techniques for maceral characterization. These new approaches include solid l3C NMR, electron spin resonance, IR spectroscopy, fluorescence microscopy, and mass spectrometry. A recently developed method for maceral separation is also presented many of the new instrumental approaches have been applied to macerals separated by this new method. The contributions in this volume present a sampling of the new directions being taken in the study of coal macerals to further our knowledge of coal petrology and coal chemistry. [Pg.7]

Free Radicals in Macerals. Electron spin resonance (ESR) has been used to study carbon free radicals in coals, and to some extent, separated macerals. The technique provides information on radical density and the environment of the radicals. The resonance position, termed the g-value, is dependent on the structure of the molecule which contains the free electron. The line width is also sensitive to the environment of the unpaired electron. In an early study, Kroger (71) reported that the spin concentration varied between maceral groups with liptinite < vitrinite inertinite. For this limited set of samples the spin concentration increases with rank for liptinites and vitrinites and decreases for the micrinite samples. On the other hand, van Krevelen (72) found the same general results except... [Pg.18]

There have been a large number of electron spin resonance (ESR) studies of coal and coal products,(1J but a microscopic interpretation of the resulting data has been hampered by the chemical heterogeneity of the coal samples examined. While several surveys of specially selected macerals have appeared, 3), the recent evolution of maceral separation techniques - now allows detailed ESR observations to be made on coals systematically fractionated in which coal rank, maceral type, and maceral density are simultaneously distinguished. The present report surveys the behavior of a variety of ESR properties of carbon radicals in exinite, vitrinite, and inertinite macerals in a variety of coals of different rank. These data... [Pg.124]

Bartuska VJ, Maciel GE, Bolkers HI, Fleming Bl (1980) Structural studies of lignin isolation procedures by nC NMR Holzforschung 34 214-217 Dixon WT, Schaefer J, Sefcik MD, Stejskal EO, McKay RA (1981) Quantitative chemical composition of materials such as humic soils, lignins, and coals by high-resolution carbon 13 NMR J Magn Reson 45 173-176... [Pg.160]

Hatcher P. G., Wilson M. A., Vassallo A. M., and Lerch H. E. (1989b) Studies of angiospermous wood in Australian brown coal by nuclear magnetic resonance and analytical pyrolysis new insights into the early coalification process. Int. J. Coal Geol. 13, 99-126. [Pg.3683]


See other pages where Coal resonance study is mentioned: [Pg.345]    [Pg.472]    [Pg.173]    [Pg.174]    [Pg.138]    [Pg.506]    [Pg.62]    [Pg.63]    [Pg.426]    [Pg.302]    [Pg.226]    [Pg.499]    [Pg.171]    [Pg.399]    [Pg.9]    [Pg.308]    [Pg.175]    [Pg.221]    [Pg.286]    [Pg.66]    [Pg.319]    [Pg.3660]    [Pg.183]   


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