A process for extracting high molecular weight hydrocarbons from a solid phase in equilibrium with a liquid hydrocarbon phase: Solubility‐selectivity behavior of certain organic groups

Abstract

In a recent paper (Cordeiro et al., 1972), the authors demonstrated that methane pressurization of solutions of n-decane and n-dotriacontane in equilibrium with a solid phase of n-dotriacontane will enhance the solubility of the high-molecular-weight paraffin n-dotriacontane. The experimental method and data correlation using the FloryHuggins model were presented in detail. The significance of this work lies in its potential application to petroleum recovery, specifically recovery of those high-molecularweight materials left behind after primary and secondary recovery techniques have been employed. Salient features of this methane pressurization process are enhanced solubilities of high-molecular-weight materials due to methane swelling of the liquid phase, increased fluidity of the liquid phase caused by the presence of the methane, and subsequent ease of methane by outgassing.This note reports the effect of methane pressurization on a second prototype ternary three-phase system in which the role of paraffin n-dotriacontane is played by the aromatic phenanthrene. Included is an assessment of the process in terms of its selectivity in solubilizing aromatics versus paraffins in a liquid phase containing n-decane.Thermodynamically speaking, in addition to liquid phase composition, the process derivatives The experimental plan of attack pursued before (Cordeiro et al.) was again followed. For the prototype system with phenanthrene (denoted by subscript 14), the temperature range studied was broader, since the freezing point depression of the phenanthrene was greater due to the addition of n-decane. Furthermore, to expedite the Flory-Huggins correlation for the phenanthrene system, a less suitable candidate for that model, it was found necessary to include composition dependence, by no means insignificant in this case, into vi. We found T / T , as our earlier work with n-dotriacontane. Table 1 maps out methane pressurization of the new system at 369.15"K ( T / T , = 0.9930) while Table 2, via a sample calculation, demonstrates in moles the same isothermal pressurization process.Similarities between the two processes studied (that is, aromatic and paraffinic solid phases) are that (1 > 0 always and (2 is a strong function of T/T,, demonstrating that solids near their melting points are preferentially dissolved.At T / T , = 0.9930, both phenanthrene and n-dotriacontane exhibit a limiting pressure, at which point one can simply dissolve solid with methane indefinitely. This behavior is indicated in Figure 1