Solvent treatment of coals 1. Effects on microporosity at ambient temperature

Klotzkin, Myrna P.

doi:10.1016/0016-2361(85)90112-7

Cited by 23 publications

(8 citation statements)

References 11 publications

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“…The medium rank coking coal showed maximum extraction yield. Work on Soxhlet extractions by Klotzkin reported 25% extraction yields with NMP as the solvent. Pande and Sharma have used polar solvents such as NMP and EDA to study the swelling behavior as well as dissolution of coal in individual solvent as well as in their mixture.…”

Section: Solvent Extraction Of Coal Under Reflux Conditions At Atmosp...mentioning

confidence: 99%

Separative Refining of Coals through Solvolytic Extraction under Milder Conditions: A Review

Sharma

Dhawan

2018

Ind. Eng. Chem. Res.

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Not only cleaning but refining of coal has become an area of utmost importance both industrially and academically because of stringent environmental norms being imposed globally for arresting the climate change. However, coal is a polluting fuel, therefore, there is a grave need of deep refining of coal to obtain ashless coal for increasing its efficiency of utilization in order to minimize its impact on environment. The presence of ash in coal also greatly reduces the coal utility because of its deleterious effect on the boiler parts and gasification equipment. Solvent extraction (organo-refining) techniques produce Super Clean Coal (SCC) or Ultra Clean Coal (UCC) with almost zero ash content. The utilization of the SCC in the Integrated Gasification Combined Cycle (IGCC) Power Generation would increase the availability of this otherwise efficient and cleaner coal technology. Research work on different processes of solvent extraction of coal under varying conditions of temperature, pressure, and the nature of the solvent used and other parameters, their effect on the extraction yield have been discussed presently. Extraction of coal under milder ambient pressure conditions is desirable as this affords the recovery of coal without its fractionation, structural dislocations, or changes. The effect of the use of single solvent, mixture of two solvents (of solvent and cosolvent), i.e., synergism in enhancing the extraction yield under milder atmospheric pressure conditions have been reviewed. Utilization of high boiling solvents and coal derived solvents along with successive sequential solvent extractions for obtaining the enhanced extraction yields mainly under ambient pressure conditions have been discussed in the present paper. Hypercoal production under high pressure conditions, its characteristics, and utilization have also been described. Use of ionic liquids as potential solvents for coal extraction (especially of lignites) has also been discussed. Physical and chemical pretreatments greatly enhance the coal solvent extraction yield. Different potential uses of SCC such as in production of carbon nanotubes as a super clean fuel dust for car engines, synthesis of chemicals, etc. have been discussed. Separate discussion on nanotechnology of coals as related to solvent extraction of coal has also been included presently.

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Section: Solvent Extraction Of Coal Under Reflux Conditions At Atmosp...mentioning

confidence: 99%

Separative Refining of Coals through Solvolytic Extraction under Milder Conditions: A Review

Sharma

Dhawan

2018

Ind. Eng. Chem. Res.

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“…Ge et al found the increase of pore volume and surface area, as well as generation of micropores, when three brown coals were dealt with microwave irradiation (MWI), resulting in easy diffusion of solvent into the coal matrix. With the assistance of MAE using different solvents, considerable amounts of alkane hydrocarbons, alkylated aromatic compounds, and even polycyclic aromatic hydrocarbons were successfully separated from coal and detected. , Various organic solvents, such as tetrahydrofuran (THF), acetone, pyridine, organic amines, N -methyl-2-pyrrolidinone, , dimethyl sulphoxide, dimethylformamide, and ionic liquids, , were used to extract the organic matters from coals. Notably, although some of them demonstrate an excellent extraction performance for bituminous coals, most of the solvents have low extract yield for low-rank coals, because they are not applicable to these coals and the extraction system employed is not efficient enough .…”

Section: Introductionmentioning

confidence: 99%

Structural Features and Pyrolysis Behaviors of Extracts from Microwave-Assisted Extraction of a Low-Rank Coal with Different Solvents

et al. 2018

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Microwave-assisted extraction (MAE) of a low-rank Naomaohu (NMH) coal was conducted with two solvents, cyclohexanone (CYC) and tetrahydrofuran (THF), to obtain extracts (ECYC and ETHF) and residues (RCYC and RTHF). The parent coal, extract, and residue were characterized by ultimate analysis, TG, FTIR, GPC, 1H NMR, and solid-state 13C NMR. The results showed that MAE process is more efficient than Soxhlet extraction. The solvent CYC exhibits a higher total extract yield of 8.3 wt % than THF, being 4.7 wt %, during MAE and more efficiency in extracting organic components of NMH coal, especially condensed arenes and macromolecular compounds. The average molecular weight of ECYC is higher than that of average aromatic cluster of NMH coal. Online pyrolysis–vacuum ultraviolet photoionization mass spectrometry was taken to determine the initial pyrolysis products of parent coal, RCYC, and ECYC. The distribution of initial pyrolysis products suggested that NMH coal and ECYC possess similar basic arene structures and ECYC is rich in macromolecular clusters with lots of side chains and bridge bonds. The chemical structure of ECYC could reflect the macromolecular network structure of NMH coal to some extent. This could be an effective method to understand the organic structure of coal.

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“…Various organic solvents were used as solvent for an effective extraction of different rank coals. − Among these solvents, N -methyl-2-pyrrolidinone (NMP) has been found to be a strong solvent for extraction due to its comparatively higher soluble fraction yield than others no matter for single − or cosolvents. − The high extraction yield promoted the understanding of coal structure, Iino et al extracted Zaozhuang bituminous coal (the carbon content is 86.9 wt %) with CS 2 –NMP (1:1 by volume) mixed solvent giving an ultrahigh yield up to 77.9 wt %. The fact of a large quantity of extractable substance existing in coal has challenged the concept of the two-phase model of coal structure, which believes that coal consists of a mobile phase and a rigid phase; the mobile phase occupies a small quantity and contains soluble molecules, while the rigid phase dominates and is insoluble. , …”

Section: Introductionmentioning

confidence: 99%

Molecular Composition of Soxhlet N-Methyl-2-pyrrolidinone Extracts from a Lignite

Yan

et al. 2016

Energy Fuels

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N-Methyl-2-pyrrolidinone (NMP) is a capable solvent which could extract more substance from coals than any other solvents. However, the molecular composition of the extract was still unclear. In this study, a lignite was subjected to Soxhlet extraction using pyridine followed by NMP. The NMP extract and its hydrolyzed product were characterized by negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. The results showed that the NMP extract and its hydrolyzed product had very high nitrogen contents and N x O y class species with multiple nitrogen and oxygen atoms dominant in the detected species. Relative abundance of 15N isotope and the molecular composition of extracts obtained from different extraction conditions indicated that the NMP involved into the extracts. Both self-polymerization of NMP and chemical reactions between NMP and coals occurred in the thermal extraction.

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Solvent treatment of coals 1. Effects on microporosity at ambient temperature

Cited by 23 publications

References 11 publications

Separative Refining of Coals through Solvolytic Extraction under Milder Conditions: A Review

Separative Refining of Coals through Solvolytic Extraction under Milder Conditions: A Review

Structural Features and Pyrolysis Behaviors of Extracts from Microwave-Assisted Extraction of a Low-Rank Coal with Different Solvents

Molecular Composition of Soxhlet N-Methyl-2-pyrrolidinone Extracts from a Lignite

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