The pyridine vapor adsorption behavior and its influence on suppressing low-temperature cross-linking reactions during slow pyrolysis of lignite

Wang, Zhiqing; Bai, Zongqing; Li, Wen; Chen, Haokan; Li, Baoqing

doi:10.1016/j.jaap.2009.10.001

Cited by 16 publications

(7 citation statements)

References 27 publications

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“…This may be due to a change in chemical structure, the cleavage of hydrogen bonds caused by the pyridine treatment (reaction of O-functional groups and pyridine) as described above. 21) The fluidity property of the physically mixed coal with the soluble components was about the same as that of the pyridine-treated coal; however, the MF value (0.95 log(ddpm)) was slightly larger. On the other hand, the chemically modified coal showed the lowest initial softening temperature (IST) (400°C) among the tested samples, the MF was observed at 450°C and resolidification took place at 470-480°C.…”

Section: Fluidity Of Chemically Modified Coalmentioning

confidence: 83%

Production of High-Strength Coke from Low-Quality Coals Chemically Modified with Thermoplastic Components

et al. 2019

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In order to produce high-strength coke from low-quality coals, noncovalent bonds between O-functional groups in coal were cleaved by pyridine containing HPC pyridine soluble and HPC-derived thermoplastic components were introduced into the pores formed by swelling; thus, the synergistic effect during carbonization of the suppression of cross-linking reactions and the fluidity amplification due to close placement of coal and thermoplastic components was investigated. When HPC was extracted with pyridine, a decrease in O-functional groups was observed in the pyridine-soluble and pyridine-insoluble components. When HPC was extracted with MeOH, on the other hand, O-functional groups in HPC selectively moved into the soluble components. When non-or slightly-caking coal was chemically-modified with the prepared HPC pyridine-soluble components by utilizing the solvent-swelling effect of pyridine, the fluidity improved compared with the coals physically mixed with the soluble components or HPC. On the other hand, the fluidity of the chemically-modified sample with the MeOH-soluble components hardly changed from that of the original sample, and no effect of the modification with the thermoplastic component was observed. Furthermore, it was clarified that higher-strength coke can be produced from the chemically-modified sample with the HPC pyridine-soluble components than from the original coal or the physically mixed coal with the soluble components. The contraction behavior during carbonization of the chemically-modified sample with the soluble components and that of the original coal was investigated; as a result, a large difference was not observed between these two. Thus, it was found that high-strength coke can be produced from low-quality coals by the present method.

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Section: Fluidity Of Chemically Modified Coalmentioning

confidence: 83%

Production of High-Strength Coke from Low-Quality Coals Chemically Modified with Thermoplastic Components

et al. 2019

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“…This indicated that methanol swelling could affect the releasing behavior of the gas and tar during pyrolysis. When exposed to solvent, the noncovalent interactions between functional groups of the coal could be broken by the solvent such as a hydrogen bond. , The noncovalent interactions between functional groups were closely related to the cross-link reactions. Thus, the solvent rearranged the structure of the coal and behaved differently during pyrolysis.…”

Section: Resultsmentioning

confidence: 99%

“…Solvent swelling can affect the structure of the coal, 15−18 which can make the coal structure loosen, changes the mobility of small molecules of the coal, and is related to the cross-link reactions of the coal, resulting in an increase in coal pyrolysis conversion. 19,20 Usually the coals with a similar pyrolysis process have the same T p , which is at the maximum weight loss rate −(dW/dt) Max . 28 As shown in Table 2, all T p values of SD, SD-DE, and SD-DE-ME were at 466 °C, which indicated that the procedure of demineralization and methanol swelling did not change the pyrolysis process very much.…”

Section: Resultsmentioning

confidence: 99%

“…In the presence of swelling solvents, coal molecules dissociate, rearrange, and reassociate in lower free energy conformations, probably in a different molecular structure . Swelling solvents can break weaker bonds and combine the effect of creating macropores in coal structure, which decreases diffusional limitations, with the formation of active sites as the result of breaking some bonds. , Coal swelling can also reduce cross-linking reactions in the process of pyrolysis, inhibit the formation of CO 2 and H 2 O, , increase the yield of the pyrolysis tar, and change the composition of the products. , In order to control the pyrolysis process and the composition and distribution of the products, catalysts also attract much attention from coal researchers.…”

Section: Introductionmentioning

confidence: 99%

“…15,16 Coal swelling can also reduce cross-linking reactions in the process of pyrolysis, inhibit the formation of CO 2 and H 2 O, 17,18 increase the yield of the pyrolysis tar, and change the composition of the products. 19,20 In order to control the pyrolysis process and the composition and distribution of the products, catalysts also attract much attention from coal researchers.…”

Section: Introductionmentioning

confidence: 99%

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Study on the Volatiles and Kinetic of in-Situ Catalytic Pyrolysis of Swelling Low-Rank Coal

Min

Zheng

et al. 2017

Energy Fuels

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A new method combined solvent swelling with an in-situ catalytic effect of metal ions was developed and introduced in coal pyrolysis to increase the coal conversion and the tar yield as well as to improve the quality of the tar products. Low-rank coal of Shendong coal from China was used to investigate the effect of demineralization, swelling, and in-situ catalysis on pyrolysis reactivity and kinetic characteristics, yield distribution of products, and the tar composition. The experiments were performed using a thermogravimetric analyzer/Fourier transform infrared spectrometer (TG-FTIR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and a fixed-bed reactor to examine the pyrolysis behavior of raw coal, demineralized coal, methanol swelling demineralized coal, and methanol swelling with metal ions (Ca2+, Cu2+, and Co2+) in-situ-impregnated coal, respectively. The results showed that coal conversion could be promoted by pretreatment of solvent swelling and in-situ-impregnated Cu2+ and Co2+ ions, respectively. The gas evolution results of FTIR indicated that the in-situ loading of Cu2+ and Co2+ ions had a catalytic effect on the evolution of CO2, CH4, and aromatics of the swollen coal. The tar yield of demineralized coal was improved by the methanol-swelling pretreatment. With the in-situ loading of Cu2+ and Co2+ ions, the tar yield of swelling coal further increased by 16.80% and 28.75%. The composition of tar analyzed by Py-GC/MS indicated that methanol swelling increased the relative content of the acidic compounds and also had a positive effect on the yields of PCX (phenol, cresol, xylenol). The in-situ loading of metal ions increased the relative content of the aromatic compounds but had a different effect on the formation of BTXN (benzene, toluene, xylene, and naphthalene). The Cu2+ and Co2+ ions had a catalytic effect on phenols decomposition during coal pyrolysis, resulting in a decrease of the relative content of the acidic compounds dramatically. The kinetic results showed that the in-situ impregnation of Ca2+, Cu2+, and Co2+ ions into the swollen coal could result in a decrease of the activation energy and pre-exponential factor at the corresponding temperature range of the first and the second prolysis stage. In addition, a possible mechanism on in-situ catalytic pyrolysis of swelling coal was discussed and proposed based on the evolution and composition of the evolved species investigated during pyrolysis. The impregnation of the metal ions may catalyze the primary reactions and secondary reactions during coal pyrolysis.

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Effects of temperature and solvents on structure variation of Yunnan lignite in preheating stage of direct liquefaction

Hou

Bai

Pan

et al. 2019

Fuel

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The pyridine vapor adsorption behavior and its influence on suppressing low-temperature cross-linking reactions during slow pyrolysis of lignite

Cited by 16 publications

References 27 publications

Production of High-Strength Coke from Low-Quality Coals Chemically Modified with Thermoplastic Components

Production of High-Strength Coke from Low-Quality Coals Chemically Modified with Thermoplastic Components

Study on the Volatiles and Kinetic of in-Situ Catalytic Pyrolysis of Swelling Low-Rank Coal

Effects of temperature and solvents on structure variation of Yunnan lignite in preheating stage of direct liquefaction

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