Phase Behavior for the System Carbon Dioxide + p-Nitrobenzaldehyde: Experimental and Modeling

Abstract

The experimental study and thermodynamic modeling of the phase behavior of pressurized reactional systems allows the optimization of several unit operations involved in the process of product formation. In this work, experimental data of phase equilibria for the CO 2 + p-nitrobenzaldheyde binary system were obtained through the static synthetic method. The range of temperature, pressure, and p-nitrobenzaldehyde molar fraction investigated were 281−353 K, 6.5−25.0 MPa, and 2.638 × 10 −3 to 5.903 × 10 −3 , respectively. A model previously developed to describe asymmetric mixtures presenting fluid and solid phases was applied to describe the phase behavior of the system. This model uses the Peng−Robinson equation of state (PR-EoS) to describe the properties of the fluid phases and an expression for the fugacity of p-nitrobenzaldehyde as a pure solid for the solid phase. Different model parametrization strategies were studied, and complete isopleths were calculated considering the fluid−fluid, solid−fluid, and solid−fluid−fluid phase equilibria over wide ranges of temperature and pressure. The experimental results showed nonmonotonic (local minimum) solid−fluid phase behavior for all mixture compositions investigated. The model employed and the parametrization strategies were able to describe the experimentally observed phase behavior.

Equilibria Data for the CO2 + Ethanol + Ketoprofen Systems – Experimental and Modeling

“…Nevertheless, the existing understanding appears inadequate to solely anticipate whether solid solutions or solid precipitation would predominantly occur in a (practically) pure state, or vice versa, without supplementary experimental solid-state data for the system under investigation [24]. The present study has adopted the most straightforward approach, assuming that the solid phase consists solely of pure ketoprofen.…”

“…In other words, it has assumed a complete lack of miscibility in the solid state, which appears reasonable given the significant molecular size and shape disparities between ketoprofen and CO2. Furthermore, when considering the two extreme assumptions for the solid state, namely complete miscibility versus complete immiscibility, it is generally more realistic to assume complete immiscibility in most cases [24]. Although it has chosen to model precipitation in a pure state for this study, do not possess sufficient evidence to completely dismiss the possibility of some CO2 coexisting with ketoprofen in the solid phase at equilibrium under sufficiently high pressure.…”

“…The extent of solid phase miscibility is deemed insignificant for nonpolar compounds characterized by significant variations in molecular size and shape [22,23]. Based on practical experience, various empirical guidelines have been employed to forecast the likelihood of solubility in the solid state [24].…”