Pyrolysis of a typical low-rank coal: application and modification of the chemical percolation devolatilization model

Lv, Tong; Li, Huaixiang; Yan, Jiqing; Cen, Jianmeng; Xia, Zhixiang; Tian, Jianglei; Wang, Qinhui

doi:10.1039/d1ra01981c

Cited by 10 publications

(2 citation statements)

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“…Coal is an essential fossil fuel and a chemical resource with a high carbon content and heterogeneous structures. With increasing requirements for carbon neutrality, coal utilization is gradually changing from traditional combustion for power generation to clean and efficient multilevel development. − The chemical structure of coal determines its reactivity during the conversion process; in particular, the carbon skeletal structure dominates the evolution of the main organic products. − Solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy is a powerful nondestructive approach for determining the structural characteristics of various carbonaceous materials. The development of cross-polarization (CP) and magic angle spinning (MAS) technologies in the 1970s , enabled the convenient and effective application of 13 C NMR spectroscopy in solid fuels with complex components, such as coal.…”

Section: Introductionmentioning

confidence: 99%

Carbon Structure of Coal from the CP/MAS ¹³C NMR Spectra: Effect of Contact Time and Potential Quantitative Modification

Lv,

Fang,

Zeng

et al. 2024

Energy Fuels

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Carbon structures are important for converting coal into chemical products and carbon materials. Solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy is a powerful approach for determining the structural characteristics of carbon in coal. However, there is much controversy regarding the quantitative reliability of typical cross-polarization magic angle spinning (CP/MAS) 13 C NMR experiments of coal. This study systematically investigated the effect of one of the important factors, CP contact time, using six different coal types with V daf values ranging from 6% to 44%. A series of experimental results at variable contact times from 0.01 to 10 ms indicated that aromatic and aliphatic carbons undergo polarization transfer at different rates, and the nonprotonated carbon of aromatic groups polarized 2−3 times more slowly than that of aliphatic groups. It is challenging for a single CP/MAS 13 C NMR experiment with coal to ensure that each type of carbon is sufficiently polarized before the signal decay of the proton spin−lattice relaxation. As a potential quantitative indicator, the initial magnetization intensity independent of contact time was obtained using a classical five-parameter model for CP dynamics, and the initial aromaticity was further calculated. A linear correlation between the apparent and initial aromaticity was introduced into a calibration method of model compounds to refine the effect of contact time. The modified carbon structural parameters of the coal samples showed better agreement in terms of the H/C atomic ratio, Fourier transform infrared spectroscopy, and empirical aromaticity formulas. These results will help to provide a convenient reference for the quantitative analysis of the carbon structure in coal.

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Section: Introductionmentioning

confidence: 99%

Carbon Structure of Coal from the CP/MAS ¹³C NMR Spectra: Effect of Contact Time and Potential Quantitative Modification

Lv,

Fang,

Zeng

et al. 2024

Energy Fuels

Self Cite

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“…The poly-generation technology based on coal pyrolysis can produce pyrolysis gas with high heat value, upgraded coal tar, clean solid fuel coke and other high-value products to realize multi-level and efficient utilization of coal resources. 4 In recent years, high CO 2 emissions have caused many environmental problems. CO 2 capture, utilization, and storage (CCUS) technology is the best option to reduce global warming while addressing the energy crisis.…”

Section: Introductionmentioning

confidence: 99%

Effects of CO₂ atmosphere on low-rank coal pyrolysis based on ReaxFF molecular dynamics

Jin

et al. 2023

RSC Adv.

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Comparison of structural characteristics and combustibility analysis about hydrochar and pyrochar

Huang

Wang

et al. 2022

J Therm Anal Calorim

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The structure characteristics and combustibility of pyrochar and hydrochar were compared using scanning electron microscopy, nitrogen adsorption, Fourier transform infrared spectrum, Raman spectrum and thermogravimetry. The random pore model was applied to analyze the combustion process of chars. With the temperature increasing, analysis of physical structure revealed that the pore structure of hydrochar was more developed than that of pyrochar. Meanwhile, the hydrothermal process had an advantage over pyrolysis in terms of removing oxygen-containing functional groups and improving the coal rank, mainly attributed to the existence of subcritical water. In addition, the high determination coefficient of random pore model indicated that the model could accurately obtain the kinetic parameters. The activation energies calculated of hydrochars were higher than that of pyrochars, indicating that carbon in hydrochar had a more structural stability. The pyrochar obtained after 220 °C was less combustible than hydrochar due to its severe pore collapse during the combustion process.

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Pyrolysis of a typical low-rank coal: application and modification of the chemical percolation devolatilization model

Abstract: The modified CPD model with tar consumption and a gas correlation expression improved the prediction accuracy of coal pyrolysis products and provides a reference for their application over a wider range of conditions.

Cited by 10 publications

References 29 publications

Carbon Structure of Coal from the CP/MAS ¹³C NMR Spectra: Effect of Contact Time and Potential Quantitative Modification

Carbon Structure of Coal from the CP/MAS ¹³C NMR Spectra: Effect of Contact Time and Potential Quantitative Modification

Effects of CO₂ atmosphere on low-rank coal pyrolysis based on ReaxFF molecular dynamics

Comparison of structural characteristics and combustibility analysis about hydrochar and pyrochar

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Pyrolysis of a typical low-rank coal: application and modification of the chemical percolation devolatilization model

Abstract: The modified CPD model with tar consumption and a gas correlation expression improved the prediction accuracy of coal pyrolysis products and provides a reference for their application over a wider range of conditions.

Cited by 10 publications

References 29 publications

Carbon Structure of Coal from the CP/MAS 13C NMR Spectra: Effect of Contact Time and Potential Quantitative Modification

Carbon Structure of Coal from the CP/MAS 13C NMR Spectra: Effect of Contact Time and Potential Quantitative Modification

Effects of CO2 atmosphere on low-rank coal pyrolysis based on ReaxFF molecular dynamics

Comparison of structural characteristics and combustibility analysis about hydrochar and pyrochar

Contact Info

Product

Resources

About

Carbon Structure of Coal from the CP/MAS ¹³C NMR Spectra: Effect of Contact Time and Potential Quantitative Modification

Carbon Structure of Coal from the CP/MAS ¹³C NMR Spectra: Effect of Contact Time and Potential Quantitative Modification

Effects of CO₂ atmosphere on low-rank coal pyrolysis based on ReaxFF molecular dynamics