Effect of heat reflux extraction on the structure and composition of a high-volatile bituminous coal

Tian, Bin; Qiao, Yingyun; Tian, Yuanyu; Xie, Kui; Li, Dawei

doi:10.1016/j.applthermaleng.2016.08.104

Cited by 18 publications

(9 citation statements)

References 49 publications

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“…The significant weight loss of extraction residues at the temperature slightly higher than 200 °C in DTG may be ascribed to the release of these extracts during thermal degradation. Furthermore, a similar phenomenon was also found in the literature . Different from raw coal and the residues, both extracts obtained by THF and CYC solvents have an extra peak at about 300 °C in DTG curves.…”

Section: Resultssupporting

confidence: 86%

“…Furthermore, a similar phenomenon was also found in the literature. 45 Different from raw coal and the residues, both extracts obtained by THF and CYC solvents have an extra peak at about 300 °C in DTG curves. The temperature with the maximum mass loss rate of two extracts is at about 300 °C, remarkably lower than those of parent coal and residues.…”

Section: Tg/dtg Analysis Of Nmh Coal and Extractionmentioning

confidence: 98%

“…The absorbances near 807 and 725 cm −1 (assigned to the bending vibration of aromatic bonds) in coal and residues are not obvious compared with extracts, owing to the interference of mineral matters. 45 3.2.4. Structural Features of NMH Coal and Extract from 13 C NMR.…”

Section: Tg/dtg Analysis Of Nmh Coal and Extractionmentioning

confidence: 99%

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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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Section: Resultssupporting

confidence: 86%

Section: Tg/dtg Analysis Of Nmh Coal and Extractionmentioning

confidence: 98%

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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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“…The technology involves heating the matrix for a particular time, leading to a complex chemical reaction. As the process uses reflux extractor as the main reactor, better mass transfer and contact efficiency are achieved between solvent and treated matrix (Tian et al 2016 ). The vapor trickles down to the flask, thus controlling the temperature of the reaction.…”

Section: Extraction Methods Of Polyphenolsmentioning

confidence: 99%

Techniques and modeling of polyphenol extraction from food: a review

et al. 2021

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There is a growing demand for vegetal food having health benefits such as improving the immune system. This is due in particular to the presence of polyphenols present in small amounts in many fruits, vegetables and functional foods. Extracting polyphenols is challenging because extraction techniques should not alter food quality. Here, we review technologies for extracting polyphenolic compounds from foods. Conventional techniques include percolation, decoction, heat reflux extraction, Soxhlet extraction and maceration, whereas advanced techniques are ultrasound-assisted extraction, microwave-assisted extraction, supercritical fluid extraction, high-voltage electric discharge, pulse electric field extraction and enzyme-assisted extraction. Advanced techniques are 32-36% more efficient with approximately 15 times less energy consumption and producing higher-quality extracts. Membrane separation and encapsulation appear promising to improve the sustainability of separating polyphenolic compounds. We present kinetic models and their influence on process parameters such as solvent type, solid and solvent ratio, temperature and particle size.

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“…On the other hand, previous works reported that AFCs originating from various ranks of coal exhibit similar gasification reactivities when extracted using 1-methylnaphthalene. This indicates that the properties of AFCs are determined not only by the raw material but also by the type of solvent used. , Polar solvents tended to produce AFCs with higher hydrogen-to-carbon (H/C) and oxygen-to-carbon (O/C) ratios than nonpolar solvents, resulting in higher gasification rates. ,, …”

Section: Introductionmentioning

confidence: 99%

Steam Gasification of Thermally Extracted Ash-Free Coals: Reactivity Effects Due to Parent Raw Coals and Extraction Solvents

et al. 2017

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Utilization of coal is currently limited to coal-fired power plants and iron smelting, partly because of the incombustible ash in coal and the inability of existing technologies to modify its properties. This work investigates whether the gasification behavior of ash-free coals (AFCs) can be modified. Sixteen different AFCs were prepared using variously ranked coals (Eco, Cyprus, Drayton, and Hail Creek) and extraction solvents with different polarities (N-methyl-2-pyrrolidone, ethylenediamine, 1-methylnaphthalene, and tetralin). Next, the reactivities of the AFCs in steam gasification at 800 °C were tested, and the results are discussed taking into consideration their compositional differences. A combination of low-rank coals and polar solvents produces reactive AFCs that can be catalytically gasified under mild conditions. In contrast, AFCs extracted using nonpolar solvents are less reactive and possibly applicable as a carbon electrode precursor. In short, the properties of AFCs can be changed to some extent using the appropriate combination of coals and extraction solvents.

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Effect of heat reflux extraction on the structure and composition of a high-volatile bituminous coal

Cited by 18 publications

References 49 publications

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

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

Techniques and modeling of polyphenol extraction from food: a review

Steam Gasification of Thermally Extracted Ash-Free Coals: Reactivity Effects Due to Parent Raw Coals and Extraction Solvents

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