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.