In-situ variable-temperature single-point NMR imaging study of coals

Saito, Koji; Komaki, Ikuo; Hasegawa, K.; Tsuno, Hisayuki

doi:10.1016/s0016-2361(99)00176-3

Cited by 24 publications

(14 citation statements)

References 21 publications

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“…Compared to single pulse excitation experiments (Bloch Decay), techniques based on the cross polarization (CP) [1] allow short repetition times and have a gain in sensitivity, due to the polarization transfer from abundant ( 1 H) to dilute ( 13 C) spins, which is of great importance for the structural analysis of heterogeneous mixtures of soil as well as of coal organic material (OM) [2][3][4][5][6][7][8][9]. Although valuable information concerning the chemical composition of such materials were already obtained, more knowledge of their physicochemical properties is needed.…”

Section: Introductionmentioning

confidence: 99%

CP dynamics of heterogeneous organic material: characterization of molecular domains in coals

Abelmann

Totsche

Knicker

et al. 2004

Solid State Nuclear Magnetic Resonance

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Simplified equations are used in common approaches to describe cross polarization (CP) dynamics of solids. The CP behavior may be modulated by several nuclei interactions and physicochemical sample properties. At high magnetic fields and spinning speeds, these modulations can obscure the results. To elucidate their impact on the CP behavior of natural organic materials variable contact time (VCT) experiments were acquired with a high temporal resolution for two coal samples. The measurements were distinctly influenced by interfering fluctuations. Conventional approaches showed insufficient flexibility in terms of degrees of freedom to calculate the CP dynamics. The use of an original fundamental equation as model resulted in sufficient flexibility for such heterogeneous systems. The best results were obtained assuming a two component system. On these conditions a differentiation between amorphous and crystalline domains within the coal samples was enabled.

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Section: Introductionmentioning

confidence: 99%

CP dynamics of heterogeneous organic material: characterization of molecular domains in coals

Abelmann

Totsche

Knicker

et al. 2004

Solid State Nuclear Magnetic Resonance

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“…31) The occurrence of coal softening can be explained on the basis of the solution of high molecular components in low molecular weight components. 31) Saito et al 33) observed a change in mobility of coal by using the in situ NMR imaging technique, and reported that as the temperature was increased in the range 300-425°C, the mobile components gradually Fig. 9.…”

Section: Thermal Decomposition Characteristicsmentioning

confidence: 99%

“…increased around the initial mobile components present at 25°C. Saito et al 33) reported that the mobile components of hard coking coal are larger than that of semi-soft coking coal. With the addition of pyrene, some of the molecules of coal likely melt into molten pyrene during heating, increasing mobile component.…”

Section: Thermal Decomposition Characteristicsmentioning

confidence: 99%

Effects of Hydrocarbon Addition on Increase in Dilatation of Coal

et al. 2019

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The addition of coal tar pitch mainly composed of polycyclic aromatic hydrocarbons (PAHs), increases the dilatation of coal. We investigated the effect of PAHs on the maximum dilatation (MD) of hard coking coals and semi-soft coking coals. Twenty-six kinds of PAHs and aliphatic hydrocarbon were used as additive agents. The use of a PAH with a molecular weight in the range 152.19-178.23 as an additive agent almost unchanged the MD. When a PAH with a molecular weight in the range 178.23-378.47 was added to the coal, the MD of the coal increased. The increase in MD achieved with the addition of 9,10-dihydrophenanthrene was larger than that obtained with the addition of phenanthrene. This is likely because the hydrogen atoms in the ninth and tenth positions in 9,10-dihydrophenanthrene inhibit the polymerization of the coal structure. The MD was hardly affected by the addition of a linear aliphatic hydrocarbon (C 28 H 58) but MD decreased due to the addition of anthraquinone with carbonyl carbon. When a PAH with nonplanar structure was added to the coal, the increase in MD was smaller than when a PAH with planar structure was added.

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“…Most of the studies have focused on determining the pore information of OS particles using gas adsorption/desorption, SEM, mercury intrusion, and drawn some conclusions [15][16][17]. Similar techniques have been applied to coal [18,19] and char [20][21][22]. There are few reports about the surface characteristic of SC particle from microwave pyrolysis of OS and its change during pyrolysis.…”

Section: Introductionmentioning

confidence: 99%

Electron Microscopy Analysis of Semi-Coke From the Microwave Pyrolysis of Oil Shale With Its Fractal Description

Wang¹,

Tong²,

Liu³

et al. 2010

Oil Shale

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This paper discusses the potential use of microwave technology as an energyefficient alternative to current heating technologies employed for treatment of Jilin Huadian oil shale and analyzes the surface pore structure of its semicoke particle by a scanning electron microscope (SEM). The fractal theory was introduced into Scanning Electron Microscopy image analysis, and the particle surface fractal dimension (D) was used to describe quantitatively the surface character of oil shale/semi-coke particles. The SEM image was transformed into fractal one and the fractal dimensions were figured out with the box-counting approach. According to adsorption isotherm data, FHH model approach was also used to calculate the surface fractal dimension. Then, the box-counting approach was corroborated by using FHH model approach. It means that the fractal pore structure characteristics of samples could be described by a box-counting approach. Meanwhile, the results also showed that the microwave pyrolysis technology had a notable impact on the pore structure of samples.

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In-situ variable-temperature single-point NMR imaging study of coals

Cited by 24 publications

References 21 publications

CP dynamics of heterogeneous organic material: characterization of molecular domains in coals

CP dynamics of heterogeneous organic material: characterization of molecular domains in coals

Effects of Hydrocarbon Addition on Increase in Dilatation of Coal

Electron Microscopy Analysis of Semi-Coke From the Microwave Pyrolysis of Oil Shale With Its Fractal Description

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