Rafael Eustaquio-Rincón

Extraction of Hydrocarbons from Crude Oil Tank Bottom Sludges using Supercritical Ethane

Abstract A custom‐built, solvent recirculating, supercritical fluid extraction (SFE) apparatus was used to study the extraction of hydrocarbons from a crude oil tank bottom sludge (COTBS) with supercritical ethane. The SFE experiments were carried out varying the pressure (10 MPa and 17.20 MPa) and temperature (35°C and 65°C). The yield of the extracted hydrocarbon fraction increased with increase in extraction pressure at constant temperature, and decreased with increase in extraction temperature at constant pressure. The maximum extraction yield was obtained at the pressure and temperature conditions that lead to the highest solvent density. The extracted hydrocarbon fraction was a significantly upgraded liquid relative to the original untreated COTBS.

Liquid-liquid miscibility for biliary systems: N-methylpyrrolidone + n-alkane and propanenitrile + n-alkane

Abstract Eustaquio-Rincon, R., Molnar, R. and Trejo., A. 1991. Liquid-liquid miscibility for binary systems: N -methylpyrrolidone + n -alkane and propanenitrile + n -alkane. Fluid Phase Equilibria 68: 187-195. Liquid-liquid miscibility data have been determined experimentally for binary systems of N -methylpyrrolidone with n -butane n -hexane and n -dodecane and propanenitrile with n -octane, n -decane, n -dodecane, n -tetradecane and n -hexadecane. All the systems present upper critical solution temperature (UCST) and those for the propanenitrile + alkane binaries vary linearly with the alkane chain length. The UCST for the N -methylpyrrolidone+alkane binaries indicate that the alkane-rich phase in the system with n -butane is close to a gas-liquid critical end point. The Weimer-Prausnitz version of the Regular Solutions Theory is used to describe the behaviour of the UCSTs.

Experimental liquid-liquid miscibility curves for binary systems: ethanenitrile and butanenitrile with n-alkanes

Liquid-liquid miscibility temperatures, as a function of composition, have been determined experimentally for the binary systems formed by ethanenitrile (acetonitrile) with octane, nonane, decane, undecane and dodecane and butanenitrile with octane, decane, dodecane, tetradecane and pentadecane. This study was also extended to include binary systems of pentanenitrile with long-chain alkanes, however, no liquid-liquid phase separation was observed from room temperature down to 270 K. All the measured systems present solubility curves characterized by asymmetry with respect to equimolar composition and the presence of an upper critical solution temperature (UCST). The experimental results show that for a given set of binary mixtures with a common nitrile the solubility diminishes with increasing alkane chain length, which is a clear manifestation of increasing non-ideality, and for mixtures with a common alkane the solubility increases with increasing nitrile chain length, which in turn is evidence of the decreasing effective polarity of the nitriles as their chain length increases. The Weimer-Prausnitz modification for polar components of Hildebrands Regular Solution Theory incorporating a Flory-Huggins entropy of mixing has been used to calculate the UCST for the ten systems measured and these values compare very well with those obtained experimentally considering that no adjustable parameter is included in the theory. The theory was also used to calculate the critical composition and qualitative agreement is observed with experimental data.

Thermodynamics of liquid binary (alkanenitrile–alkane) mixtures. Part1.—Experimental excess molar volume at 298.15 K and its interpretation with the Prigogine–Flory–Patterson theory

Density measurements have been made by means of a vibrating tube densitometer, at 298.15 K, over the whole composition range for 25 binary liquid mixtures of propanenitrile, butanenitrile, pentanenitrile and hexanenitrile with several different hydrocarbons. Values of the molar excess volume, VE, were derived and the results show a regular pattern of behaviour for each of the four sets of binary system. For a given alkanenitrile, the magnitude of VE increases with the hydrocarbon chain length and also for a given hydrocarbon, VE decreases with the chain length of the nitrile. The Prigogine–Flory–Patterson theory was applied to analyse the experimental behaviour by calculating three different contributions to VE, i.e. interactional, free volume and internal pressure. The theory is capable of reproducing the main features of the experimental VE results by using a fitted binary interaction parameter.

Liquid-liquid miscibility curves for binary systems: N-methylpyrrolidone with several hydrocarbon isomers

Abstract Eustaquio-Rincon, R., Romero-Martinez, A. and Trejo, A., 1993. Liquid-liquid miscibility curves for binary systems: N-methylpyrrolidone with several hydrocarbon isomers. Fluid Phase Equilibria, 91: 187-201. Experimental liquid-liquid miscibility data have been obtained for 14 binary systems formed by N-methylpyrrolidone with isobutane, cis-butene-2, trans-butene-2, 2,2-dimethylbutane, 2,3-dimethylbutane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, 1-hexene, 1-heptene and 1-octene. The temperatures studied range from 240 K for 1-hexene up to 374 K for isobutane. All the systems present miscibility curves with upper critical solution temperatures (UCSTs). The system with 1,3-butadiene presents complete miscibility. The values of UCST are correlated using pure component property data.

Experimental liquid–liquid phase equilibria for binary systems: ethanenitrile with several hydrocarbon isomers

Abstract Liquid–liquid miscibility temperatures, as a function of composition, for the nine binary systems formed by ethanenitrile (acetonitrile), as common component, with 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane and cyclooctane, have been determined by the sealed-tube technique. All the studied systems show an upper critical solution temperature (UCST). We have used the Weimer–Prausnitz modification for polar components of Hildebrands regular solution theory (RST) to calculate UCSTs and the results compare very well with those obtained experimentally for the systems studied. We have established that the value for the induction energy density parameter included in the modified RST, which arises from induction forces between the polar component and the nonpolar component, originally proposed only for linear and cyclic saturated hydrocarbons in polar solvents, is also valid for binary systems of the type polar component+branched paraffin. The RST with the Flory–Huggins entropy gives values of the critical composition which are systematically higher than the experimental values.

Thermodynamics of liquid binary (alkanenitrile–alkane) mixtures. Part 2.—Experimental excess molar heat capacity at 298.15 K and structure in solution

Excess molar heat capacities at constant pressure (CEp) have been determined at 298.15 K, as a function of mole fraction, for 17 binary liquid mixtures of propanenitrile, butanenitrile, pentanenitrile and hexanenitrile mixed individually with some of the following alkanes: hexane, heptane, octane, decane, dodecane and tetradecane. CEp is positive and extremely large for propanenitrile with hexane and heptane, increasing in magnitude with the alkane chain length, 6 and 8 J mol–1 K–1 equimolar composition, respectively, whereas for the systems with butanenitrile, pentanenitrile and hexanenitrile as the common component, CEp, varies from small positive values for the systems with lower alkanes to negative values for the systems with the larger alkanes. For some of these systems the curve CEp(x) presents a ‘W shape’, i.e. it exhibits two minima separated by a maximum, that is, two changes of sign of the curvature. The observed behaviour is discussed in terms of structure in the solutions due to non-randomness or local concentration fluctuations and randomness balance. In this way, the concentration–concentration correlation function, Scc, is calculated using a molecular groups contribution model for the excess Gibbs energy of the systems studied in order to correlate these effects.