Solid state 13C and 1H NMR studies of the evolution of the chemical structure of coal char and tar during devolatilization

Fletcher, Thomas H.; Solum, Mark S.; Grant, David M.; Critchfield, Scott; Pugmire, Ronald J.

doi:10.1016/s0082-0784(06)80385-1

Cited by 34 publications

(32 citation statements)

References 24 publications

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“…6(b). This is in agreement with Fletcher's work, 23,24) in which the authors measured the chemical structure of chars prepared from different coals using a different technique-13 C-NMR spectroscopy. …”

supporting

confidence: 90%

“…By using 13 C-NMR (Nuclear Magnetic Resonance) spectroscopy and FTIR (Fourier Transform Infrared) spectroscopy, the chemical structure of fresh chars was investigated. [22][23][24][25] Fletcher et al 24) also compared the chemical structure of chars from five coals of different ranks. However little systematic investigation has been reported on the influence of pyrolysis conditions on char chemical structure.…”

Section: Introductionmentioning

confidence: 99%

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Chemical Structure of Chars Prepared under Conditions Prevailing in the Blast Furnace PCI Operation.

et al. 2002

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Using a drop tube furnace, char samples were prepared from coals of different ranks, under conditions similar to those prevailing during pulverized coal injection into the blast furnace. The chemical structure of resultant chars was determined by quantitative X-ray diffraction analysis (QXRDA) and high-resolution transmission electron microscopy (HRTEM), and investigated as a function of pyrolysis temperature, heating rate and coal type. Among the parameters examined, pyrolysis temperature was the key factor influencing char chemical structure. Char obtained at higher temperature is generally more ordered, with the distinctive peaks becoming sharper and the background intensity becoming lower. Heating rate is another important factor affecting char chemical structure. Char is more ordered at lower heating rate due to the longer residence time. Although considerable differences were still observed in the chemical structure of chars prepared from coals of different ranks, it is clear that such differences are reduced after coal pyrolysis. Char structural evolution during post-pyrolysis and combustion was also investigated. The importance and potential applications of this work to the blast furnace PCI operation have been outlined. KEY WORDS: pulverized coal injection; coal pyrolysis; char combustion; char reactivity; char chemical structure. different ranks. However little systematic investigation has been reported on the influence of pyrolysis conditions on char chemical structure. As part of an overall study on char structure and char reactivity, this paper is focused on the effect of pyrolysis conditions on char chemical structure. A subsequent paper will discuss char physical structure. Char structure formed as a result of pyrolysis serves as the starting point of combustion during PCI operation. These wellcharacterized chars have been subsequently used to establish an understanding of the effect of char structure on char combustion reactivity. Experimental Char PreparationA drop tube furnace (DTF) was used in this investigation to prepare chars under conditions similar to those prevailing in the raceway region of a blast furnace. Details regarding the drop tube furnace can be found elsewhere, 8) and only a brief account is given here. It consists of a coal feeding system, a sampling probe, a gas distribution system and an electrically heated furnace. The composition of gaseous reactants, position of the sampling probe as well as feeding rate of coal particles are adjustable depending on experimental conditions. To prepare char, a metered stream of coal particles was entrained into the iso-thermal zone of the furnace by a preheated gas flow (99 vol% N 2 ϩ1 vol% O 2 ), and a char sample was collected using a water-cooled probe after a residence time of about 1 second. A slightly oxidizing atmosphere was used to burn off the volatiles released during coal pyrolysis. This was considered necessary to avoid contamination of char samples with soot and condensed tar. Three size-graded Australian black coals of differ...

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confidence: 90%

Section: Introductionmentioning

confidence: 99%

Chemical Structure of Chars Prepared under Conditions Prevailing in the Blast Furnace PCI Operation.

et al. 2002

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“…These char data are consistent with those of Watt 5,7 . However, these char data differ slightly from other previous work 2,[8][9][10] that indicated that the number of aromatic carbons per cluster in the char does not increase substantially during pyrolysis. The previous data showed values of C Cl generally staying in the range of 12 to 16, whereas the current data show slight increases in range (13 to 18), but these data are within experimental error.…”

Section: Solid-state 13 C Nmr Analysis Of Hpcp Pyrolysis Samplescontrasting

confidence: 99%

Determination of the Forms of Nitrogen Released in Coal Tar During Rapid Devolatilization

Fletcher¹

1998

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“…OWADAYS, emission from industrial processes as well as the number of cars, air traffic and shipping boats with combustion engines, is steadily increasing [1][2][3][4][5][6]. Despite the fact that a huge effort is being devoted to develop electromobility, combustion engines fueled by either diesel or gasoline is still prevailing.…”

Section: Introductionmentioning

confidence: 99%

Polycyclic Aromatic Hydrocarbons Generated by the Incomplete Combustion: Case of Fluoranthene

2017

IJACEBS

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Abstract-Incipient soot nanoparticles represent a real threat, due to the fatal and irreversible damages they can cause on health and environment. The incomplete combustion of engine's fuel leads to the creation of these nanoparticles. It has been shown that they are formed by some extremely carcinogenic Polycyclic Aromatic Hydrocarbons (PAH), precisely, the aggregation of dimers and trimers and so on of PAH. Understanding the structural parameters of these aggregations is crucial to clarify the real composition of soot which remains not completely understood. This present paper is devoted to the study of the dimerization of fluoranthene. Different structural building ways have been suggested, with full and partial covering between the monomer entities. The number of the interacting six membered rings varies between one and three cycles, from each monomer. The impact of structure on both binding energy and equilibrium distance has been analyzed. Binding energies vary between -5.88 and -8.41 kcal/mol. The structural parameters seem to play a key role in the dispersion-type interactions for the fluoranthene dimers.

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Solid state 13C and 1H NMR studies of the evolution of the chemical structure of coal char and tar during devolatilization

Cited by 34 publications

References 24 publications

Chemical Structure of Chars Prepared under Conditions Prevailing in the Blast Furnace PCI Operation.

Chemical Structure of Chars Prepared under Conditions Prevailing in the Blast Furnace PCI Operation.

Determination of the Forms of Nitrogen Released in Coal Tar During Rapid Devolatilization

Polycyclic Aromatic Hydrocarbons Generated by the Incomplete Combustion: Case of Fluoranthene

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