Pyrolysis behavior and kinetics of the trapped small molecular phase in a lignite

Tian, Bin; Qiao, Yingyun; Bai, Lei; Feng, Wen; Jiang, Yuan; Tian, Yuanyu

doi:10.1016/j.enconman.2017.02.077

Cited by 91 publications

(25 citation statements)

References 58 publications

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“…The average E value of EX was 146.63 kJ/mol, which was higher than E (98.1 kJ/mol) [36] obtained via the DAEM method in the thermal process of the mobile fractions from a lignite by using NMP/CS 2 mixed solvent extraction. This might be due to the heavier components extracted by THF.…”

Section: Kinetic Analysiscontrasting

confidence: 54%

“…This might be due to the heavier components extracted by THF. However, the average value of E for different coals were 180 [36] and 192 kJ/mol [37], respectively, which were higher than the average E of EX in this study, suggesting EX was more easily pyrolyzed than raw coal during the thermal process. With the separate addition of Fe(N) and Fe(C), the average value of EX-Fe(N) and EX-Fe(C) was obviously decreased to 122.17 and 102.39 kJ/mol, respectively, indicating that Fe-based catalysts facilitate the cracking of EX, leading to an increase in EX reactivity, and making the pyrolysis reactions more available.…”

Section: Kinetic Analysismentioning

confidence: 68%

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Study on the Catalytic Pyrolysis Mechanism of Lignite by Using Extracts as Model Compounds

et al. 2019

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Understanding the catalytic pyrolysis mechanism of lignite is of great significance for obtaining a high yield of the target products or designing high-efficiency catalysts, which are generally derived by using simple model compounds, while the ordinary model compounds cannot represent the real atmosphere of lignite pyrolysis owing to the simple structures and single reactions. Based on the coal two-phase model, the extractable compounds are the important compositions of coal, which can reflect the partial characteristics of raw coal while obtaining a high extraction yield. Hence, a better understanding of the interaction between the coal structure and catalyst can be inferred by using a mobile phase in coal as model compounds instead of conventional simple compounds. In this work, tetrahydrofuran extracts of lignite were chosen as model compounds to study the catalytic pyrolysis mechanism with separate addition of Fe(NO3)3 and FeCl3 by using a thermogravimetric combined with mass spectrometry. It was found that about 77.88% of the extracts were vaporized before 700 °C, and the residual yield was 22.12%. With the separate addition of 5 wt % of Fe(NO3)3 and FeCl3, the conversion of the extracts increased to 84.38% and 89.66%. Meanwhile, the final temperature decreased to 650 and 550 °C, respectively. The addition of Fe(NO3)3 and FeCl3 promoted the breakage of aliphatic chains at approximately 150 °C, leading to the generation of CH4 and H2 in the temperature range 100–200 °C, which were nearly invisible for that without catalyst. The addition of iron-based catalysts allowed more CO2 formation at approximately 200 °C since they enabled efficient promotion of the cleavage of carboxyl functionals at lower temperatures. The enlarged peak of H2O and CH4 at approximately 500 °C means that iron-based catalysts are significant for the cleavage of methoxy groups in the catalytic respect. Aromatic side chains facilitated cracking at approximately 500 °C, leading to more light aliphatics and aromatics generation in this temperature range.

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Section: Kinetic Analysiscontrasting

confidence: 54%

Section: Kinetic Analysismentioning

confidence: 68%

Study on the Catalytic Pyrolysis Mechanism of Lignite by Using Extracts as Model Compounds

et al. 2019

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“…The study of dynamic processes can increase our understanding of the phenomenon of coal spontaneous combustion, control the characteristics of coal spontaneous combustion, and develop new prevention and control technology. 29 The activation energies have been obtained by methods such as Coats-Redfern (model tting), Friedman (FR), Flynn-Wall-Ozawa (FWO), and Kissinger-Akahira-Sunose (KAS). [30][31][32] In summary, the current research on lignite spontaneous combustion mainly focuses on the evolution process of coal oxidative spontaneous combustion and the changes in various indices in the coal oxidation process; however, little research on secondary oxidation of coal is included.…”

Section: Introductionmentioning

confidence: 99%

Thermogravimetric and infrared spectroscopic studies of the spontaneous combustion characteristics of different pre-oxidized lignites

Chen

Zhai

et al. 2019

RSC Adv.

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“…Gasification is an important route for efficient and clean utilization of the coal resources. It is not only the foundation for synthesizing chemical products and developing poly-generation technologies, such as the Integrated Gasification Combined Cycle (IGCC), but also the key to the development of other high-tech energy technologies (Xu et al 2015a, b;Tian et al 2017a, b). Nitrogen-containing compounds found in gasified product gas include NH 3 , HCN, etc.…”

Section: Introductionmentioning

confidence: 99%

“…Alkali and alkaline earth metals considerably change the characteristics of gasification of coal char and volatiles reforming behavior over the char (Bai et al 2014). Specifically, alkali and alkaline earth metals change the kinetics of coal gasification, enhance the gasification reactivity of char, increase the rate of gaseous products formation and change the composition of the produced tar (Kitsuka et al 2007;Zhang et al 2017;Zubek et al 2018;Tian et al 2017a, b;. Meanwhile, the nitrogen transformation is affected by the reactivity of coal char and the composition of tar (Park et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite

Zheng

Wang

Liu

et al. 2019

Int J Coal Sci Technol

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This work evaluated the effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite at the temperature of 873-1173 K in a fluidized-bed/fixed-bed quartz reactor. The results indicated that the alkali metal Na and alkaline earth metals Ca, Mg in coal have different effects on inherent nitrogen transformation to NH 3 , HCN and char-N during the lignite steam gasification. Specifically during the steam gasification of Shengli lignite, Na and Ca, Mg not only catalyze the inherent nitrogen conversions to NH 3 , but also promote the secondary reactions of the nascent char-N as well as the generation of NH 3 from the generated HCN, meanwhile they also inhibited the inherent nitrogen conversion to HCN and char-N. The presence of Na, Ca and Mg hindered the formation of oxidized nitrogen (N-X) functional groups, but enhanced pyridinic nitrogen (N-6) and quaternary nitrogen's (N-Q) formation in char.

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Pyrolysis behavior and kinetics of the trapped small molecular phase in a lignite

Cited by 91 publications

References 58 publications

Study on the Catalytic Pyrolysis Mechanism of Lignite by Using Extracts as Model Compounds

Study on the Catalytic Pyrolysis Mechanism of Lignite by Using Extracts as Model Compounds

Thermogravimetric and infrared spectroscopic studies of the spontaneous combustion characteristics of different pre-oxidized lignites

Effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite

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