Chemical Properties of Superfine Pulverized Coal Particles. 3. Nuclear Magnetic Resonance Analysis of Carbon Structural Features

Liu, Jiaxun; Luo, Lei; Ma, Junfang; Zhang, Hai; Jiang, Xiumin

doi:10.1021/acs.energyfuels.6b01029

Cited by 40 publications

(15 citation statements)

References 49 publications

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“…CO is because of the bond breakages of C=O and C–O–C at stage I . The generation of CO 2 is mainly contributed to the breakages of aliphatic bonds, oxygen‐containing –COOH groups and partial weak aromatic bonds at stage II . The release amount of CO 2 is increased when the heating rate is elevated.…”

Section: Resultsmentioning

confidence: 99%

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Mass loss evolution of bituminous fractions at different heating rates and constituent conformation of emitted volatiles

Xia

Wang

et al. 2019

Energy Science & Engineering

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Bitumen is frequently used as energy source. To further understand bituminous combustion and emitted volatiles during its energy generation and conversion at the fraction level including saturates, aromatics, resins, and asphaltenes (SARA), an elemental analyzer, thermogravimetry coupled with mass spectrometer and Fourier‐transform infrared spectroscopy (TG‐MS‐FTIR) were utilized to monitor the mass loss evolution, and confirm molecular structures of emitted volatiles, and track the whereabouts of main elements during each SARA fraction combustion. Results indicate that TG, DTG, and Gram‐Schmidt (G‐S) curves show two‐stage characteristics, while the total ion chromatogram (TIC) curves present one‐stage characteristic during each SARA fraction combustion. Also, as the heating rate is raised, TG, DTG, TIC, and G‐S curves are shifted to higher temperature and the total emitted volatile amount is increased from saturates to asphaltenes. Molecular weights of main volatiles are distributed in the range of 12‐64. The elemental species of volatiles are consistent with those of SARA fractions. Finally, the typical volatiles of saturates and aromatics are similar, and the release amount of CO and CO2 at stage II is larger than those at stage I. SO2 is released during the combustion of resins. SO2 and NO2 are identified in volatiles of asphaltenes.

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Section: Resultsmentioning

confidence: 99%

“…CO 2 is released at below 450°C at stage I due to the presence of aliphatic and aromatic –COOH groups. As the temperature further rises at stage II, more stable ether structures and oxygen‐bearing heterocycles are decomposed into CO 2 . The bands at 3500‐4000 cm −1 are owing to the stretching of O–H bond.…”

Section: Resultsmentioning

confidence: 99%

Mass loss evolution of bituminous fractions at different heating rates and constituent conformation of emitted volatiles

Xia

Wang

et al. 2019

Energy Science & Engineering

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“…The O/C ratio was also found to be increased by 1.5-2.5 times for all the modified samples. For the anthracite samples, the O/C ratio was higher than for the semi-coke samples due to the removal of oxygen-containing species during the pyrolysis [29,30]. According to the data in Table 2, for the modified samples, an increase in the H/C ratio could be observed.…”

Section: Introduction Of the Activating Additivesmentioning

confidence: 93%

Effect of Cu(NO3)2 and Cu(CH3COO)2 Activating Additives on Combustion Characteristics of Anthracite and Its Semi-Coke

et al. 2020

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The process of anthracite and its semi-coke combustion in the presence of 5 wt.% (in terms of dry salt) additives of copper salts Cu(NO3)2 and Cu(CH3COO)2 was studied. The activating additives were introduced by an incipient wetness procedure. The ignition and combustion parameters for coal samples were examined in the combustion chamber at the heating medium temperatures (Tg) of 600–800 °C. The composition of the gaseous combustion products was controlled using an on-line gas analyzer. The fuel modification with copper salts was found to reduce the ignition delay time on average, along with a drop in the minimum ignition temperature Tmin by 138–277 °C. With an increase in Tg temperature, a significant reduction in the ignition delay time for the anthracite and semi-coke samples (by a factor of 6.7) was observed. The maximum difference in the ignition delay time between the original and modified samples of anthracite (ΔTi = 5.5 s) and semi-coke (ΔTi = 5.4 s) was recorded at a Tg temperature of 600 °C in the case of Cu(CH3COO)2. The emergence of micro-explosions was detected at an early stage of combustion via high-speed video imaging for samples modified by copper acetate. According to the on-line gas analysis data, the addition of copper salts permits one to reduce the volume of CO formed by 40% on average, providing complete oxidation of the fuel to CO2. It was shown that the introduction of additives promoted the reduction in the NOx emissions during the combustion of the anthracite and semi-coke samples.

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“…The molecular structure of brown coal is characterized by array of lateral and bridging bonds prone to fracture at sufficiently low temperatures. It is especially important for the active oxygen-containing functional groups: -OCH 2 , -OH, -COOH, -C=O (Zhang et al 2017;Liu et al 2016;Wang et al 2016). With the surface increasing, the concentration of functional groups decreases and additives affect the oxidation during heating.…”

Section: Effect Of Additives On Coal Oxidation Characteristicsmentioning

confidence: 99%

Non-isothermal oxidation of coal with Ce(NO3)3 and Cu(NO3)2 additives

Ларионов

Gromov

2019

Int J Coal Sci Technol

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Non-isothermal oxidation of brown coal with 5 wt% of Cu(NO 3) 2 , 5 wt% of Ce(NO 3) 3 and {2.5 wt% Cu(NO 3) 2 ? 2.5 wt% Ce(NO 3) 3 } additives was studied. The introduction of additives was carried out by an incipient wet impregnation method to ensure uniform distribution of cerium and copper nitrates within the structure of coal powdery samples (according to SEM and EDX mapping). The samples reactivity was studied in an isothermal oxidation regime at 200°C (1 h) and by DSC/TGA at 2.5°C/min heating rate. The additives implementation was found to reduce significantly the oxidation onset temperature (DT i = 20-55°C), the samples oxidation delay time (Dt i = 2-22 min) and overall duration of the oxidation process (Dt c = 8-16 min). The additives efficiency could be graded in accordance with the activation on the coal oxidation in the following row: Cu(NO 3) 2 [ {Cu(NO 3) 2 ? Ce(NO 3) 3 } [ Ce(NO 3) 3. According to the mass spectroscopy, the obtained row of activation correlates well with the initial temperature of the studied nitrate's decomposition (from 190 to 223°C). A presence of nitrates was found to change significantly the trend of heat release taking place during the oxidation of coal samples (according to DSC/TGA data). The influence of coal morphology and volatiles content in initial sample on the parameters of the oxidation process was studied as well. Activation energy (E a) of the coal oxidation was calculated using Coats-Redfern method. Maximum decrease in E a from 69 to 58 kJ/mol was observed for the samples with Cu(NO 3) 2 .

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Chemical Properties of Superfine Pulverized Coal Particles. 3. Nuclear Magnetic Resonance Analysis of Carbon Structural Features

Cited by 40 publications

References 49 publications

Mass loss evolution of bituminous fractions at different heating rates and constituent conformation of emitted volatiles

Mass loss evolution of bituminous fractions at different heating rates and constituent conformation of emitted volatiles

Effect of Cu(NO3)2 and Cu(CH3COO)2 Activating Additives on Combustion Characteristics of Anthracite and Its Semi-Coke

Non-isothermal oxidation of coal with Ce(NO3)3 and Cu(NO3)2 additives

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