Upgrading of Tsingtao Vacuum Residuum in Supercritical Water (I): A Preliminary Phase Structure Study by Molecular Dynamics Simulations

Zhang, Tingting; Chen, Xuefeng; Haiping, Shen; Zhang, Da

doi:10.1021/acs.energyfuels.8b04326

Cited by 14 publications

(8 citation statements)

References 38 publications

(62 reference statements)

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“…The visbreaking products shown in Table 2 were characterized using elemental analysis, VPO measurement, and NMR characterization. The average molecular structure of the visbreaking products was then calculated according to the modified Brown−Ladner formula, with the results listed in Table 4 [25][26][27]. The average molecular structure of the visbreaking products obtained in the SC C 6 H 12 and SC C 6 H 6 evolved with a similar trend.…”

Section: Effect Of H-donation Of Scc6h12 On Visbreakingmentioning

confidence: 93%

The Visbreaking of Heavy Oil in Supercritical Cyclohexane: The Effect of H-Donation

et al. 2022

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The performance of heavy oil visbreaking in supercritical cyclohexane (SCC6H12) was evaluated, followed by a comparison with its reaction in supercritical benzene (SCC6H6). The dealkylation-based viscosity reduction in the SCC6H12 was accelerated by improving the diffusivity, through which a product viscosity (80 °C) as low as 0.5 Pa.s was readily obtained by visbreaking at 380 °C for 5 min. A competition between dealkylation and condensation took place throughout the visbreaking process. As the reaction proceeded or the temperature increased, condensation played an increasingly dominant role in the visbreaking. Unlike the inert SCC6H6, the SCC6H12 participated in the visbreaking by saturating the alkyl carbon radicals essential for dealkylation and the aromatic carbon radicals essential for condensation. The viscosity reduction efficiency of the visbreaking in the SCC6H12 was initially suppressed by the H-donation of the solvent, but recovered rapidly due to the improved diffusion environment. Benefiting from the saturation of the aromatic carbon radicals, the asphaltene content of the product obtained in the SCC6H12 was lower than the corresponding value of the product obtained in the SCC6H6.

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Section: Effect Of H-donation Of Scc6h12 On Visbreakingmentioning

confidence: 93%

The Visbreaking of Heavy Oil in Supercritical Cyclohexane: The Effect of H-Donation

et al. 2022

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“…According to the molecular dynamics simulation by Zhang et al, under the SCW environment applied here, only an emulsion structure can be formed for the mixture of Tsingtao VR and SCW. 43 Since Tsingtao VR and Tahe AR are much similar in apparent properties, it is suggested that the same phase structure could be applied to the mixture of Tahe AR and SCW. The accelerated coking shown in Figure 1, thus, could be ascribed to the concentration of heavy fractions in the oil droplets.…”

Section: Elemental Composition Of Heavy Fractions Table 2 Lists the E...mentioning

confidence: 99%

Demetallization of Heavy Oils of High Metal Content through Pyrolysis under Supercritical Water Environment

Tang

Zheng

et al. 2020

Energy Fuels

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Through pyrolysis under a supercritical water (SCW) environment, the demetallization of Tsingtao vacuum residuum (VR) and Tahe atmospheric residuum (AR) with a total vanadium and nickel content above 300 ppm was studied. By introducing SCW, pyrolysis of heavy oil can be carried out in an emulsion structure in which heavy fractions rich in metals are concentrated in oil droplets. A metal removal rate higher than 90% could be obtained in 2 h, which is faster than the pyrolysis under the nitrogen environment. Although the two heavy oils have similar apparent properties, Tsingtao VR is characterized by the metal enrichment in the heaviest asphaltenes and the higher condensation activity of asphaltenes. Because of the preferential condensation of heavy fractions rich in metals, the liquid product yield of Tsingtao VR could be 15 wt % higher than that of Tahe AR at the metal removal rate of 70% to 90%.

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“…Therefore, visbreaking in SCW is usually carried out at a pressure approaching 30 MPa, which exceeds the industrially acceptable operating range. For some ultrainferior heavy oil, even under severe hydrothermal conditions, the heavy oil/SCW system still maintains the two-phase or emulsion structure suitable for deep pyrolysis …”

Section: Introductionmentioning

confidence: 99%

“…For some ultrainferior heavy oil, even under severe hydrothermal conditions, the heavy oil/ SCW system still maintains the two-phase or emulsion structure suitable for deep pyrolysis. 17 In contrast, only a few studies have tried subcritical water (sub-CW) for heavy oil processing. Cuijpers et al found that, below the thermal cracking threshold temperature, viscosity reduction can still be obtained during the visbreaking of heavy oil in the presence of sub-CW.…”

Section: Introductionmentioning

confidence: 99%

Visbreaking of Heavy Oil in a Mixed Solvent of Subcritical Water and Light Aromatics

Ling

Zhu

et al. 2021

Ind. Eng. Chem. Res.

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To achieve high-efficiency viscosity reduction in a mild hydrothermal environment, the visbreaking of heavy oil in a mixed solvent of subcritical water (sub-CW) and light aromatics was investigated. By solubilizing sub-CW in heavy oil, the dealkylation involved in visbreaking follows not only a free radical mechanism but also an ionic mechanism. The further introduction of light cycle oil rich in light aromatics but containing olefin groups has a complicated influence on visbreaking. Because of the presence of olefin groups, the viscosity reduction efficiency is initially reduced. In addition, the condensation to asphaltenes is promoted in the late visbreaking stage. However, these adverse effects are offset by the promotion of the solubilization of sub-CW in heavy oil by light aromatics. With enhanced dealkylation in both free radical and ionic mechanisms, a viscosity reduction rate of over 90% and reduced asphaltene formation can be obtained in the middle stage of visbreaking.

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Upgrading of Tsingtao Vacuum Residuum in Supercritical Water (I): A Preliminary Phase Structure Study by Molecular Dynamics Simulations

Cited by 14 publications

References 38 publications

The Visbreaking of Heavy Oil in Supercritical Cyclohexane: The Effect of H-Donation

The Visbreaking of Heavy Oil in Supercritical Cyclohexane: The Effect of H-Donation

Demetallization of Heavy Oils of High Metal Content through Pyrolysis under Supercritical Water Environment

Visbreaking of Heavy Oil in a Mixed Solvent of Subcritical Water and Light Aromatics

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