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• The mesoporous iron oxide was successfully synthesized by using the waste wood powder as a template. • The alkali concentration had an effect on the physicochemical properties and performance of the synthesized iron oxides. • The iron oxide catalyst with larger surface area and pore volume exhibited higher yield of gasoline and diesel distillates. • The perfect performance of mesoporous iron oxide catalyst is ascribed to the presence of more exposure Fe active sites. In order to develop a high-efficiency iron oxide catalyst for the slurry-phase hydrocracking of poor heavy oil, the mesoporous iron oxide was successfully synthesized by using the waste wood powder as a template, and the influence of alkali concentration in the resulting solution on crystal phase, morphology and pore structure of the synthesized samples was investigated. The crystal phase of the synthesized iron oxide transfers from α-Fe 2 O 3 to γ-Fe 2 O 3 , and their crystal sizes gradually decrease with an increase of alkali concentration based on the XRD and HRTEM results. Additionally, the iron oxide with mesoporous structure, larger surface area and pore volume is obtained at the higher concentration of alkali in solution confirmed by N 2 adsorption-desorption analysis. The assessment result of the iron oxide catalyst employed in the slurry-phase hydrocracking of vacuum residue (VR) illustrates that the yields of gasoline and diesel distillates obtained over Fe-O-B 20 , Fe-O-B 24 and Fe-O-B 30 catalysts are higher compared with those over Fe-O-B 2 and Fe-O-B 14 catalysts, it can be attributed that more exposure Fe active sites derived from their larger surface area and pore volume availably improve the catalyst hydrogenation activity, which can inhibit the over-cracking reaction of intermediate products and the condensation of polycyclic aromatic hydrocarbon in VR to enhance the yields of gasoline and diesel distillates. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations were applied to characterize the dissolution of subcritical water (Sub-CW) in polycyclic aromatic hydrocarbons (PAHs). The phase equilibria of Sub-CW/PAHs are characterized by the dissolution of Sub-CW in PAHs. The solubility of Sub-CW increases with temperature but is relatively insensitive to pressure changes. Furthermore, an increase in PAH scale leads to a decrease in Sub-CW solubility. The PAH-rich phase can be divided into an interface region and a bulk region, and the water concentrations in the two regions differ greatly. The Hansen solubility parameters of PAHs and Sub-CW exhibit opposite distributions, hindering the mutual solubility between the two. The dissolution of Sub-CW is promoted by the destruction of intermolecular hydrogen bonds of water at increasing temperature, but is ultimately inhibited by the difference in dispersion properties between PAHs and Sub-CW. According to the Gibbs solvation free energy, the electrostatic interaction between PAHs and Sub-CW favors the dissolution of Sub-CW. Meanwhile, the van der Waals interaction shows different effects. • Phase equilibria of PAHs and Sub-CW were studied by MD simulation. • Phase equilibria of PAHs and Sub-CW feature dissolution of Sub-CW in PAHs. • Solubility of Sub-CW in PAHs is sensitive to temperature change. • Opposite distributions of Hansen HSP hinder dissolution of Sub-CW in PAHs. • Electrostatic interaction promotes dissolution of Sub-CW in PAHs. [ABSTRACT FROM AUTHOR]

The phase equilibria of subcritical water (Sub-CW) and four-ring N-, S-containing heterocyclic aromatic hydrocarbons (hetero-PAHs) were investigated by molecular dynamics simulation. In a temperature range of 250–350 °C and a pressure range of 4.2–21 MPa, the mixture of hetero-PAHs and Sub-CW shows an equilibrium between water-rich and oil-rich liquid phases, characterized by a significant dissolution of water in the oil phase. The solubility of Sub-CW is 1.9–3.8 wt% in N-containing hetero-PAHs and 1.0 to 2.7 wt% in S-containing hetero-PAHs. Compared with polycyclic aromatic hydrocarbons (PAHs) with the same ring number, the presence of the thiophenic ring in hetero-PAHs leads to a decrease in the solubility of Sub-CW. The particularity of N-containing hetero-PAHs lies in the hydrogen bond between the pyridinic ring and water molecules, which increases the solubility of Sub-CW at temperatures below 300 °C. The solubility of Sub-CW in hetero-PAHs/PAHs can be correlated with the Gibbs solvation free energy of water dissolved in the oil phase and the cohesive energy density of the oil phase as parameters. • Phase equilibria of hetero-PAHs and Sub-CW were studied by MD simulation. • Phase equilibria feature dissolution of Sub-CW in hetero-PAHs rich phase. • The presence of thiophenic rings in hetero-PAHs decreases Sub-CW solubility. • The presence of pyridinic rings in hetero-PAHs increases Sub-CW solubility. • Hydrogen bonds play vital roles in Sub-CW solubility in N-containing hetero-PAHs. [ABSTRACT FROM AUTHOR]

The difficulty of the H-abstraction of alkyl radicals from PAHs or hetero-PAHs follows the order: S-containing heterocycles > PAHs > N-containing heterocycles. • H-abstraction of CH 3 or C 2 H 5 from PAHs or hetero-PAHs was investigated. • CH 3 instead of C 2 H 5 is responsible for aromatic C radical formation on PAHs. • Activation entropy determines the difference in k T S T of H-abstraction on PAHs. • H-abstraction difficulty: S-containing heterocycles > PAHs > N-containing heterocycles. To understand the condensation during heavy oil thermal processing, the formation of aromatic carbon radicals by H-abstraction of methyl radicals (CH 3) or ethyl radicals (C 2 H 5) from polycyclic aromatic hydrocarbons (PAHs) or heterocyclic aromatic hydrocarbons (hetero-PAHs) was studied by density functional calculation. The H-abstraction from different PAHs all has a positive standard state Gibbs free energy change, while increasing reaction temperature or radical concentration promotes the reaction to proceed spontaneously. CH 3 mainly contributes to the formation of aromatic carbon radicals on PAHs, and the activation entropy of H-abstraction determines the difference in reaction rate constants. The particularity of H-abstraction from hetero-PAHs is reflected at the α-site of heterocycles. The H-abstraction from N-containing hetero-PAHs occurs preferentially at the α-site of heterocycles, and both CH 3 and C 2 H 5 could participate in abstracting the α-H. The H-abstraction from S-containing hetero-PAHs occurs preferentially on coupled aromatic rings, showing reaction behavior similar to the H-abstraction on PAHs. [ABSTRACT FROM AUTHOR]