Difference in Extraction Yields between CS<sub>2</sub>/NMP and NMP for Upper Freeport Coal

Takanohashi, Toshimasa; Xiao, Fang; Yoshida, Takahiro; Saito, Ikuo

doi:10.1021/ef020141h

Cited by 17 publications

(10 citation statements)

References 11 publications

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“…However, these extractions are often conducted for much shorter periods of time and involve ultrasonic irradiation. Takanohashi et al found that soaking APCS 1 coal in NMP for 2 weeks increased the extraction yield in NMP to ∼28%, which is a result that is comparable to ours.…”

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confidence: 90%

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Concerning the Nature of Coal Solutions and Suspensions

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Sobkowiak

Mathews³

et al. 2004

Energy Fuels

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Coal extract and suspensions of coal particles are capable of forming viscoelastic gels. The nature of the connections or interactions in these systems is not clear. Simple experiments reported in this article indicate that NMP/CS2 extracts from Upper Freeport coal are predominantly solutions of molecular species that nevertheless form gels at certain concentrations. The physical gels formed in these mixtures must therefore involve some specific association that, in turn, can lead to aggregation, such as π-cation interactions, or a phase separation. This latter mechanism must involve bicontinuous domains where one of the phases is glassy, to provide the cohesive properties necessary for elastic properties. In contrast, gels formed from insoluble coal particles most probably associate through forces common to many colloidal suspensions. In such systems, it is not the local pairwise interactions between molecules alone that is important, but the sum of all interactions between the molecules in each particle. This results in a large interaction energy that is proportional to particle size and the association of these particles to form a space filling network and a gel with viscolelastic properties.

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confidence: 90%

“…Gels can be classified into two broad types: chemical gels, where the crosslinks are chemical bonds; and physical gels, where the junction zones can form as a result of entanglements (in high-molecular-weight polymers), some specific association, or a phase transformation . The latter possibilities are summarized in Figure , following Keller .…”

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confidence: 99%

Concerning the Nature of Coal Solutions and Suspensions

Painter

Sobkowiak

Mathews³

et al. 2004

Energy Fuels

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“…The extraction of coal is mainly controlled by two factors: one is the solubility of the solvent to coal, and another is the penetration ability of the solvent into the coal cross-link structure . A number of studies have been carried out to examine the existence of synergic effects between two solvents. − ,,, The viscosities of high-boiling-point solvents, such as NMP, are too high to enter the cross-link structure of coals. Shui et al reviewed the speculations about the reasons for extraction enhancement in the CS 2 /NMP mixed solvent, and they pointed out that CS 2 may disrupt the dipole-based association of NMP and, thus, decrease the viscosity of the CS 2 /NMP mixed solvent, resulting in NMP penetrating more quickly into the macromolecular network structure of coal and breaking the stronger coal–coal interaction.…”

Section: Resultsmentioning

confidence: 99%

“…Extraction and thermal dissolution (TD) have attracted more and more attention as effective approaches for identifying the structural characteristics of coals and to using coals in a clean and ecofriendly manner. − Takanohashi et al , pointed out that some strongly polar solvents and binary solvents, such as pyridine, tetrahydrofuran (THF), and carbon disulfide/ N -methyl-2-pyrrolidinone (CS 2 /NMP), are excellent solvents to dissolve the organic species of bituminous coals. Additionally, a small amount of additives, such as tetracyanoethylene and halogenide salt, are beneficial for increasing the extract yield of bituminous coals in CS 2 /NMP. , Ashida et al , fractionated two bituminous coals and a lignite into six fractions by tetralin and 1-methylnaphthalene (1-MN) using a sequential TD method and examined the difference in the chemical structure and thermal properties of the fractions.…”

Section: Introductionmentioning

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Sequential Extraction and Thermal Dissolution of Baiyinhua Lignite in Isometric CS₂/Acetone and Toluene/Methanol Binary Solvents

et al. 2015

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Baiyinhua lignite (BL) was sequentially extracted and thermally dissolved in isometric CS2/acetone and toluene/methanol binary solvents to obtain an extract in isometric CS2/acetone (EICA) and a soluble portion (SP) in isometric toluene/methanol (SPITM). The yields of EICA and SPITM are notably higher than the total extract yield from sequential extraction with CS2 and acetone (or acetone and CS2) and the total SP yield from sequential thermal dissolution in toluene and methanol (or methanol and toluene), indicating that there exists an obvious synergic effect between CS2 and acetone during the extraction and between toluene and methanol during the thermal dissolution. EICA and SPITM mainly consist of hydrocarbons and oxygen-containing organic species, respectively. Little difference in Fourier transform infrared spectroscopy spectra of BL and its extraction residue was observed, while the intensities of absorbances assigned to the phenolic OH, CO, and C–O/C–O–C groups of the thermal dissolution residue are obviously lower than those of BL and its extraction residue. X-ray photoelectron spectroscopy analysis shows that C–O/C–O–C groups in BL remarkably decreased after thermal dissolution, corresponding to the abundant phenols dissolved in SPITM. The difference in weight loss between BL and its extraction residue is close to the yield of EICA, while the difference in weight loss between extraction and thermal dissolution residues is significantly lower than the yield of SPITM.

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“…Previous studies found that the coal extraction yield acquired by mixed-solvent extraction was often higher than that acquired by as ingle-solvent extraction. [8][9][10][11] Mixed solvents composed of carbon disulfide (CS 2 )a nd polar aprotic solvents [such as N-methyl-2-pyrrolidinone( NMP), N, N-dimethylformamide (DMF), etc.] have significant advantages for coal extraction.…”

Section: Introductionmentioning

confidence: 99%

Physicochemical Properties and Slurry Ability of Lignite Upgraded by a Solvent‐Extraction Approach

et al. 2015

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Supercritical carbon dioxide (scCO2)/coal tar/N‐methyl‐2‐pyrrolidinone (NMP) mixed solvent was used to upgrade lignite by extraction in a semicontinuous supercritical extraction device. The upgraded lignite has potential applications in coal–water slurry (CWS) gasification. The effects of the process conditions (operating temperature, pressure, solvent ratio, and particle size) on the physical and chemical properties of the upgraded lignite were studied. The Brunauer–Emmett–Teller specific surface area and the Barrett–Joyner–Halenda absorption pore volume of the upgraded coal increased to approximately twice those of the raw lignite. The BJH adsorption average pore diameter of the upgraded coal was smaller than that of raw lignite. The heavy constituents in coal tar were absorbed into the coal pore structure, and the low‐molecular‐weight compounds in lignite and coal tar could be extracted. The results showed that upgraded lignite with a better slurry ability was achieved by extraction with the scCO2/coal tar/NMP mixed solvent. The upgraded CWS concentration increased by 6–10 %. The flowability of the upgraded CWS improved slightly. After upgrade through the scCO2/tar/NMP process, the pseudoplastic‐fluid trend of the upgraded CWS improved, and the lignite gasification reactivity improved.

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Difference in Extraction Yields between CS₂/NMP and NMP for Upper Freeport Coal

Cited by 17 publications

References 11 publications

Concerning the Nature of Coal Solutions and Suspensions

Concerning the Nature of Coal Solutions and Suspensions

Sequential Extraction and Thermal Dissolution of Baiyinhua Lignite in Isometric CS₂/Acetone and Toluene/Methanol Binary Solvents

Physicochemical Properties and Slurry Ability of Lignite Upgraded by a Solvent‐Extraction Approach

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Difference in Extraction Yields between CS2/NMP and NMP for Upper Freeport Coal

Cited by 17 publications

References 11 publications

Concerning the Nature of Coal Solutions and Suspensions

Concerning the Nature of Coal Solutions and Suspensions

Sequential Extraction and Thermal Dissolution of Baiyinhua Lignite in Isometric CS2/Acetone and Toluene/Methanol Binary Solvents

Physicochemical Properties and Slurry Ability of Lignite Upgraded by a Solvent‐Extraction Approach

Contact Info

Product

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Difference in Extraction Yields between CS₂/NMP and NMP for Upper Freeport Coal

Sequential Extraction and Thermal Dissolution of Baiyinhua Lignite in Isometric CS₂/Acetone and Toluene/Methanol Binary Solvents