Extraction of lignite with water in sub- and supercritical states

Hu, Haoquan; Guo, Shang; Hedden, Kurt

doi:10.1016/s0378-3820(97)00057-x

Cited by 40 publications

(24 citation statements)

References 3 publications

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“…The polycyclic aromatic nature of coals is a key consideration in making coals an attractive feedstock for pitch-like products. In addition to conventional transportation fuels use, the non-volatile aromatic liquid residues could be used as a feedstock for non-fuel applications, for pitch production in particular (Hu et al, 1998;Cheng et al, 2012;Rahman et al, 2013). The problems which limit the efficiency of current coal conversion processes are not necessary amenable to a solution using conventional solvents, or other established chemical conversion concepts.…”

Section: Introductionmentioning

confidence: 99%

“…Water is a unique solvent in terms of abundance and environmental and technological safety (Tc = 374°C, Pc = 21.8 MPa and ρ c = 0.322 g/cm 3 ) (Kashimura et al, 2004;Han et al, 2015;Wu et al, 2009). It has been shown to stimulate the cleavage of ester bonds (Hu et al, 1998;Bermejo et al, 2004) and thus provide a deep conversion of organic matter from coal. Toluene is of particular interest to technology because it is an abundant component of low-boiling fractions obtained in various coal conversion processes and has an easily attainable critical temperature (318.6°C), pressure (4.11 MPa) and density (0.292 g/cm 3 ) (Torrente and Galán, 2010;Park et al, 2007;Owczarek and Blazej, 2003;Hourcade et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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Study of Supercritical Coal Extraction in Toluene Containing Fluids

Kuznetsov¹,

Kolesnikova²,

Кузнецова³

et al. 2016

American Journal of Applied Sciences

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Abstract:The conversion of brown coals and sapropelic coal in toluene containing mixtures with co-solvents (water, ethanol and tetralin) was studied under sub-and supercritical conditions within the temperature range of 375-550°C and at pressures from 7 to 40 MPa. It was found that the extent of coal extraction in the toluene solvent medium, at 400°C, was significantly increased by the addition of small amounts of hydrogen-donor tetralin or ethanol co-solvents. The extract yield from sapropelic coal reached 79-83%, with the gas yield being small. The effect of process variables on extract yields under sub-and supercritical conditions was monitored. Coal extraction in the toluene-tetralin mixtures was found to depend mainly on the hydrogen donor ability of the tetralin co-solvent irrespective of sub-or supercritical toluene states. According to the composition, the bitumen extracted from coals can be used as a feedstock for pitch production. In the water containing mediums, aside from coal liquefaction, coal methanation, hydrolysis and oxidation reactions occurred resulting in the generation of large amounts of methane, hydrogen and carbon dioxide.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study of Supercritical Coal Extraction in Toluene Containing Fluids

Kuznetsov¹,

Kolesnikova²,

Кузнецова³

et al. 2016

American Journal of Applied Sciences

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“…Supercritical water at 673-698 K and 14-24.5 MPa was applied to Western Canadian lignite and high-volatile bituminous coals, with 50% and 35% maximal conversion (on a dry, ash-free basis) to liquid and gaseous products [33]. Supercritical, but also subcritical, water was applied to lignite coal for the extraction of liquid products, applied to Turkish [34] and Dayan lignite coals [35]. Their yield increased with increasing pressure and temperatures of 673 to 723 K were effective, but with increasing temperatures mainly gas and light oil production was enhanced.…”

Section: Supercritical Extraction Applied To Fuelsmentioning

confidence: 99%

Extraction by Subcritical and Supercritical Water, Methanol, Ethanol and Their Mixtures

Marcus

2018

Separations

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Hot, subcritical and supercritical water, methanol, ethanol and their binary mixtures have been employed to treat fuels (desulfurize coal and recover liquid fuels from coal and oil shales) and to extract valuable solutes from biomass. The properties of these solvents that are relevant to their extraction abilities are presented. Various extraction methods: accelerated solvent extraction (ASE), pressurized liquid extraction (PLE), supercritical fluid extraction (SFE, but excluding supercritical carbon dioxide) with these solvents, including microwave-and ultrasound-assisted extraction, are dealt with. The extraction systems are extensively illustrated and discussed.

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“…There have been many studies applying extraction methods to recover useful components from brown coal, such as supercritical gas extraction [2], supercritical fluid extraction [3,4], alkali extraction [5], solvent extraction [6][7][8], and hydrothermal extraction [9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%