Chemistry of solvents in brown coal liquefaction: Estimation of steady state recycle solvent quality

Aiura, M.; Masunaga, Toshio; Kageyama, Yoichi; Kawai, Shinya

doi:10.1016/0378-3820(86)90004-4

Cited by 7 publications

(3 citation statements)

References 8 publications

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“…It is well recognized that the effective hydrogen-donor species are hydroaromatics in liquefaction solvents for traditional liquefaction processes. 17 As shown in Table 1, the BDEs of C−H at the α-carbon position (C α −H) for typical H-donors in coal liquefaction are in the range of 310−365 kJ/mol.…”

Section: Resultsmentioning

confidence: 99%

“…To gain better understanding of which mechanism is more plausible under coal liquefaction conditions, some common H-donors and free radicals produced from coal pyrolysis were chosen as model compounds. It is well recognized that the effective hydrogen-donor species are hydroaromatics in liquefaction solvents for traditional liquefaction processes . As shown in Table , the BDEs of C–H at the α-carbon position (C α –H) for typical H-donors in coal liquefaction are in the range of 310–365 kJ/mol.…”

Section: Resultsmentioning

confidence: 99%

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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%

Section: Resultsmentioning

confidence: 99%

Rational Design of Hydrogen-Donor Solvents for Direct Coal Liquefaction

Hou

Zhou

Guo³

et al. 2018

Energy Fuels

View full text Add to dashboard Cite

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“…Several attempts to measure the ability to donate hydrogen during coal liquefaction of a chemical compound have been performed. A hydrogen donor parameter is defined based on one or several of the next parameters: solubility, polarity, chemical reaction tests, mass spectrometry, structural parameters, and spectroscopic features obtained from 1 H and 13 C NMR. − …”

Section: Fundamentalsmentioning

confidence: 99%

Use of Hydrogen Donors for Partial Upgrading of Heavy Petroleum

et al. 2016

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The huge energy required to overcome the high-pressure drop in pipelines due to the high viscosity of heavy crude oils has motivated the development of technologies to improve the flow properties of these heavy hydrocarbons, such as friction reduction, viscosity reduction, and in situ upgrading. It has been reported that a series of H-donors has been used to upgrade heavy oil for their transportation (low viscosity and high API gravity). Virtually any organic compound with a low oxidation potential can serve as a useful hydrogen donor. The low oxidation potential enables the transfer of hydrogen(s) from the donor to the substrate under mild reaction conditions. The choice of donor is based on the nature of the reaction, its availability, and solubility in the reaction medium.

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