Pyrolysis of Asphaltenes in Subcritical and Supercritical Water: Influence of H-Donation from Hydrocarbon Surroundings

Liu, Qing-Kun; Xu, Yan; Tan, Xue-Cai; Yuan, Pei‐Qing; Cheng, Zhenmin; Wang, Yuan

doi:10.1021/acs.energyfuels.6b03135

Cited by 28 publications

(14 citation statements)

References 50 publications

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“…They can cause a reduction in the net rate of the thermal cracking free radical chain reaction pathway by terminating the free radicals through H donation. This influence of the presence of natural H‐donors in VR feeds on the cracking rate was shown in References 40,41. This effect was further verified in those studies by observing experimentally that the addition of an external H‐donor like tetralin significantly reduced the cracking rates of VR maltenes and asphaltenes.…”

Section: Results: Inference Of Lr Kinetics Parameterssupporting

confidence: 56%

Inference of reaction kinetics for supercritical water heavy oil upgrading with a two‐phase stirred reactor model

Raghavan

Ghoniem

2021

AIChE Journal

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We present the development and application of a two‐phase stirred reactor model for heavy oil upgrading in the presence of supercritical water (SCW), with coupled phase‐specific thermolysis reaction kinetics and multicomponent hydrocarbon–water phase equilibrium. We demonstrate the inference of oil and water phase kinetics parameters for a compact lumped reaction kinetics scheme through the application of this model to two different sets of batch reactor experiments reported in the literature. We infer that, although SCW can suppress the formation of newer polynuclear aromatics (PNA) from distillate range species, it is broadly ineffective in deterring the combination of pre‐existing PNA fragments in the oil feed. Quantification of the conversion to distillate liquids before the onset of coke formation helps arrive at a clear conclusion on whether the use of SCW in the batch reactor leads to better product outcomes for different oil feeds and operating conditions.

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Section: Results: Inference Of Lr Kinetics Parameterssupporting

confidence: 56%

Inference of reaction kinetics for supercritical water heavy oil upgrading with a two‐phase stirred reactor model

Raghavan

Ghoniem

2021

AIChE Journal

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“…In contrast, the substituents decomposed from asphaltenes have good solubility in sub-CW. The H β atom contained in the decomposed substituents becomes an effective hydrogen donor for saturating the aromatic carbon radicals in asphaltenes, thereby inhibiting the condensation of asphaltene to coke. − The more effective the dealkylation, the lower the yield of coke formation. Therefore, it is proposed that the pyrolysis of asphaltenes in sub-CW follows both the free radical mechanism and the ionic mechanism, in accordance with the results of Cuijpers .…”

Section: Results and Discussionmentioning

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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“…37 The activation energies listed in Table 3 fall within the range reported in the literature. [21][22][23]44,45 It is generally accepted that the condensation behavior of oil components depends on their group composition. The heavier the oil component, the higher the activation energy for condensation.…”

Section: Reaction Kinetic Parameters Of Pyrolysismentioning

confidence: 99%

Demetallization of heavy oil through pyrolysis: A reaction kinetics analysis

et al. 2020

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By tracking the transfer of vanadium and nickel in pyrolysis products, a seven‐lump reaction kinetic model for pyrolysis‐based demetallization of heavy oil was established. During pyrolysis, the demetallization of heavy oil is achieved by condensing metal‐rich resins and asphaltenes to coke. The condensation of oil components originally contained in heavy oil differs greatly in reaction behavior, having the activation energy between 167 and 361 kJ/mol. As the pyrolysis progresses, the newly formed heavy components show a condensation behavior close to that of the light components. Limited by high activation energy and low initial fraction, the condensation of asphaltenes to coke and the resulting removal of metals contained in asphaltenes are hindered. Meanwhile, the condensation of light components has a major contribution to coke formation. An increase in reaction temperature accelerates the demetallization, but hardly changes the yield and component distribution of liquid products at the same metal removal rate.

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Pyrolysis of Asphaltenes in Subcritical and Supercritical Water: Influence of H-Donation from Hydrocarbon Surroundings

Cited by 28 publications

References 50 publications

Inference of reaction kinetics for supercritical water heavy oil upgrading with a two‐phase stirred reactor model

Inference of reaction kinetics for supercritical water heavy oil upgrading with a two‐phase stirred reactor model

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

Demetallization of heavy oil through pyrolysis: A reaction kinetics analysis

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