Analysis of coal-derived liquid obtained by mild hydrogenation

Katoh, Takashi; Ōuchi, Koji

doi:10.1016/0016-2361(85)90185-1

Cited by 23 publications

(4 citation statements)

References 46 publications

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“…Although there are plenty of aromatics with alkyl side-chains in coal liquefaction solvents, , alkyl substituents are excluded for their inefficiency in reducing C–H BDE, as compared with alkenyl or methylene groups. Phenyl is another common group appearing in structures of coal liquefaction solvents. , Besides, several moieties in different size containing alkene groups are included in our library for bidentate substitution, as coal liquefaction solvents are mainly composed of aromatics with different number rings and arrangement …”

Section: Resultsmentioning

confidence: 99%

Rational Design of Hydrogen-Donor Solvents for Direct Coal Liquefaction

Hou

Zhou

Guo³

et al. 2018

Energy Fuels

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Facing the challenge of processes in direct coal liquefaction (DCL), it is vital to develop optimal hydrogen-donor solvent (H-donor) to dramatically moderate coal liquefaction conditions. Here, we propose an approach for rational design of optimal H-donor candidates based on density functional theory (DFT) calculations combining reverse searching algorithm. First, the mechanism of hydrogen transfer from H-donor to coal radical was investigated by using common model compounds. DFT calculations show that the concerted hydrogen transfer route promoted by coal radicals is the dominant pathway. The C−H bond dissociation enthalpies (BDEs) show strong correlation with intrinsic reaction barriers and rate constants (in log scale), which allow us to define a cheap metric for comparing the hydrogen-donation ability of different H-donors. Then the framework for rational design of H-donor candidates is established to seek molecules with low C−H BDEs based on inverse molecular design strategy. In the searching procedure, the chemical structure of parent molecule is varied by appropriate substituent from a predefined library (15 substituents). To reduce searching space, four empirical rules are proposed to guide the structural modifications. Finally, the H-donor candidates designed are validated by transition state calculations. It is confirmed that the inverse molecular design approach is effective for seeking candidate H-donors with lower reaction barriers and potentially higher rate of hydrogenation, which open a window for the rational design of optimal H-donors to improve the yields of the liquid products from coal under mild conditions.

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Section: Resultsmentioning

confidence: 99%

Rational Design of Hydrogen-Donor Solvents for Direct Coal Liquefaction

Hou

Zhou

Guo³

et al. 2018

Energy Fuels

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“…In flow systems, for example, the tar yields differ from 2 to 20 wt %. ,,− This difference, however, may also be attributed to the ambiguous definition of tar, as it often refers to all the materials condensed from the volatiles generated. It is often found that the tars contain not only oil, such as those defined frequently as the hexane-soluble matters, , but also water, asphaltene, preasphaltene, and even organic and inorganic solid matters. These nonoil fractions may constitute 50–80 wt % of the tars. − Most of the tars, therefore, are usually of high viscosity and turn into solids shortly at ambient conditions. ,, This indicates a need to distinguish the yields of various tar fractions for better understanding and evaluation of pyrolysis techniques.…”

Section: Introductionmentioning

confidence: 99%

“…1,2,10−15 This difference, however, may also be attributed to the ambiguous definition of tar, as it often refers to all the materials condensed from the volatiles generated. It is often found that the tars contain not only oil, such as those defined frequently as the hexane-soluble matters, 16,17 but also water, asphaltene, preasphaltene, and even organic and inorganic solid matters. These nonoil fractions may constitute 50−80 wt % of the tars.…”

Section: Introductionmentioning

confidence: 99%

Oils and Phenols-and-Water-Free Tars Produced in Pyrolysis of 23 Chinese Coals in Consecutive Temperature Ranges

Shi

Liu

et al. 2013

Energy Fuels

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Coal pyrolysis has been widely studied, and the overall tar yield has been reported frequently in the literatures. It is recognized that the yield and composition of the tar vary with the coal rank and pyrolysis temperature, but detailed information is limited, especially for the oil fraction defined as the hexane-soluble matter. In this work, 23 Chinese coals of different rank with carbon content of 73.7–89.1% are pyrolized in a fixed-bed reactor, and the liquid products collected in the temperature ranges of 110–300, 300–400, 400–500, 500–600, and 600–800 °C are extracted by n-hexane. The yields of phenols-and-water-free tars and oils are estimated, and the oil fractions are analyzed by HPLC. It is found that the total yields of the phenols-and-water-free tar are generally greater than 10 wt % of the coals (dry and ash-free), and 30–60 wt % of the tars are soluble in n-hexane. Generally, about 50 wt % of the phenols-and-water-free tars and oils are produced in the temperature range of 400–500 °C. The HPLC analysis indicates that the oils from the coals with carbon contents of less than 80 wt % are dominated by aliphatic hydrocarbons, whereas those from the coals with carbon contents of greater than 80 wt % are dominated by one- and two-ring aromatics. Aliphatic hydrocarbons appear in all the oil fractions regardless of the pyrolysis temperature and coal rank, whereas the one-ring aromatics are found only in oils produced at 400–500 °C.

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“…Various instrumental methods have been used to examine the structural characterization of char and the soluble products; that is, functional group changes (Akrami et al, 1997;Brodzki et al, 1995;Collin et al, 1983;Desando and Ripmeester, 2002;Katoh and Ouchi, 1987;Masuda et al, 1996;Poirier and Das, 1984;Schweighardt et al, 1976). In this study, changes in functional groups with oxygen have been examined by FT-I.R.…”

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confidence: 99%

Effects of Coal Liquefaction Parameters on the Removal of Oxygen and the Higher Heating Value of the Soluble Products

Karaca

2005

Energy Sources

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Analysis of coal-derived liquid obtained by mild hydrogenation

Cited by 23 publications

References 46 publications

Rational Design of Hydrogen-Donor Solvents for Direct Coal Liquefaction

Rational Design of Hydrogen-Donor Solvents for Direct Coal Liquefaction

Oils and Phenols-and-Water-Free Tars Produced in Pyrolysis of 23 Chinese Coals in Consecutive Temperature Ranges

Effects of Coal Liquefaction Parameters on the Removal of Oxygen and the Higher Heating Value of the Soluble Products

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