Dissolution of polycyclic aromatic hydrocarbons in subcritical and supercritical Water: A molecular dynamics simulation study. (23rd February 2019)

• Record Type: Journal Article
• Authors: Qu, Hao; Gong, Jian-Hong; Tan, Xue-Cai; Yuan, Pei-Qing; Cheng, Zhen-Min; Yuan, Wei-Kang
• Is Part Of: Chemical engineering science. Volume 195(2019)
• Page Start: 958
• Page End: 967
• Publication Date: 2019-02-23
• Subjects: Supercritical water -- Polycyclic aromatic hydrocarbons -- Molecular dynamics simulation -- Phase structure -- Pyrolysis; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2018.10.042
• Languages: English
• ISSNs: 0009-2509

Abstract

Graphical abstract: By the differences in heavy oil composition and thermodynamic state of water applied, the oil-in-water emulsion structure of heavy oil/SCW systems may transit to the condensed emulsion or pseudo single-phase structure, determining their feasible application in upgrading of heavy oil. Highlights: MD simulation on dissolution of PAHs or PAH mixtures in sub-CW/SCW was applied. Dissolution of heavy PAHs in sub-CW/SCW is sensitive to thermodynamic state of water. Preferential dissolution of light PAHs occurs during dissolution of PAH mixtures. Electrostatic interaction promotes the dissolution of PAHs in sub-CW/SCW. Heavy oil/SCW could exist in condensed emulsion or pseudo single-phase structure. Abstract: To get a better understanding of the upgrading of heavy oil under severe hydrothermal environment, a molecular dynamics simulation on the dissolution of oil droplets containing polycyclic aromatic hydrocarbons (PAHs) or PAH mixtures in subcritical or supercritical water (sub-CW/SCW) was applied. Being the representative of light PAHs, naphthalene dissolves readily into sub-CW/SCW. The dissolution of heavy PAHs, like benzo[α]pyrene and benzo[ghi]perylene however is sensitive to the thermodynamic state of water. During the dissolution of PAH mixtures, a preferential dissolution of light PAHs into the water phase occurs, leaving heavy PAHs concentrated in the oil droplets. With the simultaneous increase in water density and temperature, the miscibility of PAHs with sub-CW/SCW is improved by the enhanced attractive electrostatic interaction between PAHs and hydrothermal environment and the weakened interaction between PAHs. By the differences in heavy oil composition and the thermodynamic state of water, the upgrading of heavy oil in sub-CW/SCW could be run in the condensed emulsion or pseudo single-phase structure.