Mechanism of K-catalyzed transformation of solid carbon structure into carbon nanotubes in coal

Zhang, Tiankai; Zhang, Yongfa; Wang, Qi; Lv, Xuemei; Luo, Yunhuan

doi:10.1016/j.fuproc.2020.106409

Cited by 11 publications

(2 citation statements)

References 58 publications

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“…As the concentration of the carbon matrix inside the catalyst gradually increases and reaches saturation, these carbon matrixes grow as carbon nanotubes on the catalyst particle surface. The surface of Fe 3 C catalyst particles with a moderate size produces carbon nanotubes, while smaller or larger particles are eventually coated with carbon shells. − …”

Section: Resultsmentioning

confidence: 99%

Fe₃C@C/CNT Hybrids Derived from Catalytic Pyrolysis of Lignite: Electrocatalysts for OER

Liu

et al. 2023

Energy Fuels

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Using lignite as the raw material to prepare a new OER catalyst, and thus to make high-value use of lignite and to meet the research and development needs for new energy materials at the same time, a novel Fe/Fe 3 C active species has been reported as a promising catalyst to replace precious metals. In this study, we developed a facile method for the preparation of Fe 3 C@C/CNT hybrid materials by catalytic pyrolysis of lignite using KOH and FeCO 3 . The structural characteristic of Fe 3 C@C/CNT hybrid materials is that Fe 3 C nanoparticles are encapsulated in carbon layers and carbon nanotubes, forming a special core−shell structure. The prepared materials have good graphitization and a large specific surface area (957 m 2 g −1 ). We discussed the effects of KOH, FeCO 3 , and melamine in the catalytic pyrolysis of lignite to produce Fe 3 C@C/CNT materials:(1) Lignite can be catalyzed by KOH to generate carbon nanotubes and porous structures. (2) The transformation of carbon matrix to graphitic carbon is catalyzed and the Fe source for Fe 3 C is provided by FeCO 3 . (3) The aggregation of Fe into large and irregular Fe nanoparticles is inhibited by melamine, which facilitates the generation of Fe 3 C. When the Fe 3 C@C/CNT hybrid is used as an OER catalyst, the OER overpotential is only 407 mV at a current density of 10 mA cm −2 in an alkaline electrolyte, which has great application potential. This work is conducive to improving the economic benefits of lignite and provides a new idea for the high value-added utilization of lignite.

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Section: Resultsmentioning

confidence: 99%

Fe₃C@C/CNT Hybrids Derived from Catalytic Pyrolysis of Lignite: Electrocatalysts for OER

Liu

et al. 2023

Energy Fuels

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“…Furthermore, the C–O/C=O content increased after hydromodification ( Table 3 ), indicating that hydromodification promotes the conversion of carboxyl and carbonyl groups to the ether bond. Zhang et al 41 have believed that the carbon source required for CNT growth mainly comes from the aromatic carbon C–C, C–H, and ether carbon C–O–C structures, which would accumulate pure carbon atoms or carbon clusters for the growth of CNTs. In this study, hydromodification promoted the increase in the aromatic carbon and ether bond structures in lignite, increasing a large amount of carbon source precursors for CNT growth.…”

Section: Resultsmentioning

confidence: 99%

Tuning Lignite Structure via Hydromodification To Promote the Formation of Coal-Based CNTs: Exploration for the Carbon Source of CNTs

et al. 2023

Self Cite

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Although the preparation of coal-based carbon nanotubes (CNTs) has been realized in many studies, the relationship between carbon source structure of coal and CNT growth has not been studied in depth. In this study, we used lignite and KOH as raw material and catalyst and tuned lignite structure via hydrothermal modification to promote the formation of CNTs during catalytic pyrolysis. The main carbon source of CNTs was explored from the change of coal structure and pyrolysis characteristics. The results indicate that the CNT yield of lignite pyrolysis products is only 2.39%, but the CNT yield increases significantly after lignite was hydrothermally modified in a subcritical water–CO system. The graphitization degree, the order degree, and CNT content increase continuously with the increase in modification temperature, and C-M340 has the highest CNT content of 9.41%. Hydromodification promotes the rearrangement of aromatic carbon structures to generate more condensed aromatic rings linked by short aliphatic chains and aromatic ether bonds. The variation of these structures correlates well with the formation of CNTs and leads to the change in the carbon source components released during coal pyrolysis. Compared to lignite, modified coal releases more aromatic compounds, especially polycyclic aromatic hydrocarbons with ≥3 rings and phenols during catalytic pyrolysis, which is conducive to the transformation into carbon clusters and provides carbon sources for CNT growth. In addition, modified coal releases a slightly more carbon-containing gas (CH4 and CO) than lignite, which has a limited effect on the growth of CNTs. This study provides a novel and efficient method for enhancing the growth of CNTs by a molecular tailoring strategy of coal.

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Carbon nanotubes growth in modified bluecoke powders: Preparation and characterization, formation mechanism of CNTs, and potential application

Wu,

Shi,

Yang

et al. 2024

Advanced Powder Technology

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Mechanism of K-catalyzed transformation of solid carbon structure into carbon nanotubes in coal

Cited by 11 publications

References 58 publications

Fe₃C@C/CNT Hybrids Derived from Catalytic Pyrolysis of Lignite: Electrocatalysts for OER

Fe₃C@C/CNT Hybrids Derived from Catalytic Pyrolysis of Lignite: Electrocatalysts for OER

Tuning Lignite Structure via Hydromodification To Promote the Formation of Coal-Based CNTs: Exploration for the Carbon Source of CNTs

Carbon nanotubes growth in modified bluecoke powders: Preparation and characterization, formation mechanism of CNTs, and potential application

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Mechanism of K-catalyzed transformation of solid carbon structure into carbon nanotubes in coal

Cited by 11 publications

References 58 publications

Fe3C@C/CNT Hybrids Derived from Catalytic Pyrolysis of Lignite: Electrocatalysts for OER

Fe3C@C/CNT Hybrids Derived from Catalytic Pyrolysis of Lignite: Electrocatalysts for OER

Tuning Lignite Structure via Hydromodification To Promote the Formation of Coal-Based CNTs: Exploration for the Carbon Source of CNTs

Carbon nanotubes growth in modified bluecoke powders: Preparation and characterization, formation mechanism of CNTs, and potential application

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Fe₃C@C/CNT Hybrids Derived from Catalytic Pyrolysis of Lignite: Electrocatalysts for OER

Fe₃C@C/CNT Hybrids Derived from Catalytic Pyrolysis of Lignite: Electrocatalysts for OER