Converting lignite to caking coal via hydro-modification in a subcritical water–CO system

Zhao, Yuqiong; Zhang, Mo; Cui, Xintao; Dong, Dongliu; Wang, Qi; Zhang, Yongfa

doi:10.1016/j.fuel.2015.11.028

Cited by 21 publications

(27 citation statements)

References 28 publications

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“…Wang et al 14 observed that the hydromodification of Shenhua coal in the tetralin-H 2 system promoted the generation of some active components with medium molecular structures and increased the degree of order in the coal, which improved the G RI from 0 to 60 at a temperature of 350 °C. Our previous work 3 involved the hydromodification of lignite in a subcritical water−CO system and exhibited better results than those of Wang et al When FeS was used as a catalyst, the G RI of modified coal could reach or exceed the value of 90 (the G RI of lignite is 0). However, the role of FeS in hydromodification is not well understood.…”

Section: Introductionmentioning

confidence: 81%

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Role of FeS Catalyst in the Hydromodification of Lignite in a Subcritical Water–CO System

Zhao

Guo

et al. 2021

ACS Omega

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The impacts of FeS catalysts on the hydromodification and structural evolution of lignite were investigated using Fourier transform infrared spectroscopy, nuclear magnetic resonance, and X-ray photoelectron spectroscopy. The results indicate that the caking property of lignite can be significantly improved in the presence of the FeS catalyst. When 6.0 wt % FeS was added, the maximum caking index (G RI ) of modified coal reached 95. During the hydromodification, FeS has little effect on the intrinsic water gas shift reaction, but it can increase the CO conversion by promoting the decomposition and hydrogenation of coal so that more active hydrogen is generated and introduced into modified coal. FeS is conducive to the rupture of distal aliphatic groups in the extractible solutes, which promotes the entrance of hydrogen into the aromatic nucleus (H ar ) and α positions (H α ) of asphaltenes and β positions (H β ) of preasphaltenes. After the catalytic hydromodification, the longer side chains or bridge bonds break and are hydrogenated to form the aliphatic structures with a shorter chain or a higher branched degree. Meanwhile, more oxygen-containing functional groups were removed along with the reduction of volatiles in the modified coal. The synergistic effect of FeS on these factors is favorable for the generation of plastic materials, which contributes to the development of the caking property of lignite.

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Section: Introductionmentioning

confidence: 81%

“…Coal hydromodification was carried out in a 300 mL autoclave with a magnetic stirrer. 3 First, 30 g of lignite, 30 g of water, and 0.0− 8.0 wt % (i.e., 0.0, 1.0, 2.0, 4.0, 6.0, 8.0, 10.0 wt %) FeS of lignite were added to the autoclave. Carbon monoxide was used to flush out the residual air in the reactor.…”

Section: Methodsmentioning

confidence: 99%

Role of FeS Catalyst in the Hydromodification of Lignite in a Subcritical Water–CO System

Zhao

Guo

et al. 2021

ACS Omega

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“…Relevant literature showed that in high-temperature atmospheres of CH 4 -CO 2 and CO-H 2 O, more •H free radicals could be provided under the effect of the catalyst and the reforming reaction was coupled with the pyrolysis reaction. Also, the •H free radicals had strong attack ability, which made the pyrolysis oil underwent hydrogenation reaction and more heavy 6 Geofluids oil cracked into light oil [34,35]. Therefore, the water vapor and CO 2 atmospheres made the pyrolysis oil lighter and improved its quality and the effect of water vapor was better than that of CO 2 .…”

Section: Carbon Number Distributionmentioning

confidence: 99%

Investigation on the Effect of Atmosphere on the Pyrolysis Behavior and Oil Quality of Jimusar Oil Shale

Kang

Wang

et al. 2022

Geofluids

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High-temperature H2O and CO2 can improve the pyrolysis behavior of oil shale. Therefore, in this paper, Jimusar oil shale was selected as the research object and the effect of the reaction atmosphere (H2O, CO2, and N2) on its pyrolysis behavior, pyrolysate distribution, and pyrolysis oil quality was fully compared and studied. The results showed that compared with the N2 atmosphere, the presence of H2O and CO2 both increased the weight loss and weight loss rate during pyrolysis of oil shale and the existence of H2O advanced the initial precipitation temperature of volatiles by 17°C. The comprehensive release characteristic indices of volatiles during pyrolysis of oil shale in the CO2 and H2O atmospheres increased by 49.34% and 114.35%, respectively, which significantly improved its pyrolysis reactivity. Both H2O and CO2 atmospheres improved the pyrolysis oil yield of oil shale, and the pyrolysis oil yield in the H2O atmosphere performed better than that in the CO2 atmosphere. Especially, the H2O atmosphere could increase the pyrolysis oil yield by 41.42%. The existence of CO2 prevented methyl radicals from accepting hydrogen radicals during pyrolysis and reduced the alkane yield, while CO2 participated in the addition reaction of alkane, which increased the alkene yield. High-temperature H2O provided more hydrogen source, which increased the alkane yield and inhibited the alkene formation. Both H2O and CO2 atmospheres promoted the cracking of polycyclic aromatics and increased the yield of small-molecular aromatics in the pyrolysis oil. During the pyrolysis process of oil shale, CO2 and H2O underwent reforming reaction with the heavy oil, which increased the light component fraction, thereby increasing the H/C ratio of pyrolysis oil. Thus, the existence of H2O and CO2 atmospheres improved the quality of pyrolysis oil and the effect of H2O was better than CO2. The H2O and CO2 atmosphere promoted the formation of a well-developed pore structure, which was conducive to mass and heat transfer during pyrolysis of oil shale.

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“…Converting noncoking coal into coking coal is an important process for the efficient use of low‐rank coal and has attracted the interest of researchers . Hydro‐plasticization involves the catalytic hydrogenation of low‐rank coal at high temperatures and pressures using molecular hydrogen and a hydrogen donor solvent to simultaneously supply hydrogen .…”

Section: Introductionmentioning

confidence: 99%

“…Shui et al performed a hydrothermal treatment of Shenfu (SF) subbituminous coal and found that the caking properties of hydrothermally treated coal were positively correlated with the solvent extraction . Zhang et al performed the hydro‐plasticization of lignite in a CO‐subcritical water system and found that the caking properties of the modified coal depended on the extraction yield of preasphaltene (PS) . Gao et al carbonized the coal liquefaction liquid–solid mixture and found that the obtained solid semi‐coke has good caking property.…”

Section: Introductionmentioning

confidence: 99%

Significantly enhances caking index of long‐flame coal under tetralin‐glycerol/H₂ system

Liu

Wang

Yang

et al. 2019

Asia-Pacific J Chem Eng

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For alleviating of the shortage of coking coal resource and efficient cleaning and utilization of low-rank coal, hydro-plasticization of low-rank coal was carried out. However, the caking property of low-rank coal cannot be obviously improved under mild conditions in the traditional tetralin-H 2 system. This study is to investigate the feasibility of mixed tetralin-glycerol as a solvent in the process of low-rank coal hydro-plasticization. The solvent ratios of tetralin-glycerol, reaction pressure, and atmosphere were varied to evaluate their effects on hydro-plasticization. The results show that the caking index (G RI ) of long-flame coal increases from 0 to 78 at mild conditions, and the hydrogen transfer mechanism might be directly from H 2 to coal rather than through hydrogen-donor solvents in the mixed solvent case. The solvent extraction and the G RI of modified coals were measured and found that the G RI of modified coal has a good linear relationship with PAA yield, and its R 2 is .985.

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Converting lignite to caking coal via hydro-modification in a subcritical water–CO system

Cited by 21 publications

References 28 publications

Role of FeS Catalyst in the Hydromodification of Lignite in a Subcritical Water–CO System

Role of FeS Catalyst in the Hydromodification of Lignite in a Subcritical Water–CO System

Investigation on the Effect of Atmosphere on the Pyrolysis Behavior and Oil Quality of Jimusar Oil Shale

Significantly enhances caking index of long‐flame coal under tetralin‐glycerol/H₂ system

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Converting lignite to caking coal via hydro-modification in a subcritical water–CO system

Cited by 21 publications

References 28 publications

Role of FeS Catalyst in the Hydromodification of Lignite in a Subcritical Water–CO System

Role of FeS Catalyst in the Hydromodification of Lignite in a Subcritical Water–CO System

Investigation on the Effect of Atmosphere on the Pyrolysis Behavior and Oil Quality of Jimusar Oil Shale

Significantly enhances caking index of long‐flame coal under tetralin‐glycerol/H2 system

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Significantly enhances caking index of long‐flame coal under tetralin‐glycerol/H₂ system