A review of upgrading heavy oils with supercritical fluids

Abstract

Due to the decrease in light crude oil and the ever-increasing demand for the upgrading of heavy oils, the development of new heavy oil processing technology has been attracting wide attention.

Hydrothermal upgrading of heavy oil in the presence of water at sub-critical, near-critical and supercritical conditions

“…This is the consequence of the intensification of cracking reactions. As is indicated that the HTU process is dominated by free-radical reactions [36]. With the increase of temperature and pressure in NC and SC conditions, a large amount of C−N and C−S bonds were cleaved, which is partly evidenced by the significant reduction in nitrogen and sulphur content (Section 3.3.2).…”

An experimental and modeling study of vacuum residue upgrading in supercritical water

“…Furthermore, water itself can act either as a catalyst or reactant, reducing the hydrogen requirement of downstream processes. 13 Previous studies 5,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] have established the potential of SCW treatment to upgrade model compounds and fractions of crude oil. When it comes to crude oil, most literature studies report the effects of SCW treatment on the bulk properties 14,15,18 and only a few studies describe changes at the molecular level.…”

“…Previous studies have established the potential of SCW treatment to upgrade model compounds and fractions of crude oil. When it comes to crude oil, most literature studies report the effects of SCW treatment on the bulk properties and only a few studies describe changes at the molecular level .…”

Solvation of Esters and Ketones in Supercritical CO2

“…Supercritical fluid (SCF) has attracted considerable attention as a density-tunable medium that enables the control of physicochemical properties such as permittivity, viscosity, and thermal conductivity. − Supercritical carbon dioxide (scCO 2 ) has been most extensively utilized as a solvent for chemical and physical processes because of its low critical point ( T c = 304.1 K, P c = 7.4 MPa), nontoxicity, and its cost-effectiveness as a fluid. − High solubility of the solute in scCO 2 is important for the efficient use of scCO 2 in chemical and physical processes. , For example, carbonyl compounds exhibit high solubility in scCO 2 . − In particular, esters and ketones have served as the most popular carbonyl compounds utilized in scCO 2 . − To understand the mechanism of both their high solubility and the intermolecular interactions in scCO 2 , several experimental and theoretical investigations have been reported. − Fink et al observed a 5-fold increase in solubility by attachment of a carbonyl group onto a solute molecule . Kazarian et al used infrared spectroscopy to observe large interaction between CO 2 and the carbonyl group .…”