The size of polyaromatic layer of coal char estimated from elemental analysis data

Matsuoka, Koichi; Akahane, Takeshi; Aso, Hiromi; Sharma, Atul; Tomita, Akira

doi:10.1016/j.fuel.2007.03.001

Cited by 28 publications

(10 citation statements)

References 20 publications

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“…Furthermore, a similar H/C ratio (∼0.26) was obtained for lower and higher porosity models. The H/C ratio of char molecular models obtained here is smaller than experimental data from demineralized char of Upper Freeport coal (∼0.24) . No cross-linking or oxygenic functional groups involved in the present atomistic models of coal chars have contribution to the H/C difference.…”

Section: Resultscontrasting

confidence: 66%

“…The H/C ratio of char molecular models obtained here is smaller than experimental data from demineralized char of Upper Freeport coal (∼0.24). 72 No cross-linking or oxygenic functional groups involved in the present atomistic models of coal chars have contribution to the H/C difference. The deviations between two models at the aspect of the number of each molecule, the number of carbon and hydrogen atoms, and the molecular mass are <4%.…”

Section: Energy and Fuelsmentioning

confidence: 79%

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Construction Strategy for Atomistic Models of Coal Chars Capturing Stacking Diversity and Pore Size Distribution

Wang

Watson²,

Louw³

et al. 2015

Energy Fuels

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While there are efficient construction strategies for crystalline, amorphous, and polymeric structures, there are few that enable construction where there are distributions of properties within structures of various order/disorder. Coal chars are one example and are particularly challenging. Chemical and physical properties that vary over length scales along with the distributions of the stacking extent impact the local domain size and orientation. These properties influence char reactivity. Similarly, the pore size distribution imparts access to the reactive surface. Thus, relatively large-scale structures (50 000s of atoms) are needed with control of the distributions of structural features and to allow for incorporation of mesoporosity. These challenges limit the size and availability of coal char models limiting the effectiveness of atomistic simulations. Here, a highly

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Section: Resultscontrasting

confidence: 66%

Section: Energy and Fuelsmentioning

confidence: 79%

Construction Strategy for Atomistic Models of Coal Chars Capturing Stacking Diversity and Pore Size Distribution

Wang

Watson²,

Louw³

et al. 2015

Energy Fuels

View full text Add to dashboard Cite

show abstract

“…During gasification, the organic and inorganic matter undergoes various chemical and physical transformations [14]. In order to maximise the gasification efficiency, there is a need to understand the mechanism of the chemical and physical transformation, as this will assist in the reduction of carbon emissions in the process especially when gasifying low rank coal [15][16][17]. Several options are used to control the feed rate of coal during gasification: fixed bed, fluidised bed, and entrained flow gasifiers [18].…”

Section: Introductionmentioning

confidence: 99%

Pyrolysis: Pathway to Coal Clean Technologies

Odeh¹

2017

Pyrolysis

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Pyrolysis remains key to all coal utilisation processes such as combustion, gasification and liquefaction. Understanding the thermochemical changes accompanying these processes through pyrolysis would help in defining the technical performance of the processes. With the recent concern for the environment and renewed interest in research on clean coal technology (CCT), hydrogen from coal through the integrated gasification combined cycle has been considered for the proposed hydrogen economy.

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“…Although some findings have demonstrated similarity in the results obtained from nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) of low-rank coals, the outcome for high-rank coals has always been different. Other investigators have found it difficult to obtain the aromaticity of some types of coal using the X-ray diffraction (XRD), because they find the analytical technique challenging. − They concluded that XRD is good for the determination of the structural sizes (interlayer spacing, crystallite diameter, crystallite height, etc.) and not for the determination of aromaticity. ,− The NMR technique is not available to all research laboratories because the cost of operation is high.…”

Section: Introductionmentioning

confidence: 99%

“…and not for the determination of aromaticity. ,− The NMR technique is not available to all research laboratories because the cost of operation is high. Coupled with the cost implications is the fact that there are inconsistencies in the aromaticity obtained from this technique. ,− …”

Section: Introductionmentioning

confidence: 99%

Comparative Study of the Aromaticity of the Coal Structure during the Char Formation Process under Both Conventional and Advanced Analytical Techniques

Odeh

2015

Energy Fuels

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Six coal samples of different rank, five southern hemisphere and one northern hemisphere, were studied using both conventional and advanced analytical techniques: scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), carbon nuclear magnetic resonance (C NMR), and X-ray diffraction (XRD). Apart from SEM that was used to study the coal to char morphology, the other analytical techniques were used to determine the molecular structural parameter of coal, specifically, the aromaticity, f a. The application of these techniques to the simulation of coal formation revealed the aromaticity to be between 0.86 and 1.03 for lignite, between 0.86 and 1.03 for sub-bituminous, between 0.87 and 1.03 for bituminous, between 0.88 and 1.03 for semi-anthracite, and between 0.94 and 1.03 for anthracite. This reported value for the aromaticity was obtained from the conventional method of analyses. Similar values showing the same consistencies in coal rank were obtained using the FTIR (between 0.66 and 0.79 for lignite, between 0.58 and 0.90 for sub-bituminous, between 0.84 and 1.00 for bituminous, between 0.94 and 1.00 for semi-anthracite, and between 0.97 and 1.00 for anthracite). The values obtained using both C NMR and XRD were at variance from those obtained using both the conventional and FTIR, which call into question the reliability, authenticity, and dependability of these sophisticated and expensive analytical techniques. It is therefore proposed for researchers and coal scientist to rely on the conventional analysis technique of determining aromaticity, which serves as a predictive index for char reactivity, to understand the data obtained from these advanced analytical techniques.

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The size of polyaromatic layer of coal char estimated from elemental analysis data

Cited by 28 publications

References 20 publications

Construction Strategy for Atomistic Models of Coal Chars Capturing Stacking Diversity and Pore Size Distribution

Construction Strategy for Atomistic Models of Coal Chars Capturing Stacking Diversity and Pore Size Distribution

Pyrolysis: Pathway to Coal Clean Technologies

Comparative Study of the Aromaticity of the Coal Structure during the Char Formation Process under Both Conventional and Advanced Analytical Techniques

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