Estudo do Comportamento de Fase e Volumétrico do Sistema Dióxido de Carbono + n-Hexadecano + n-Butil Ciclohexano a Altas Temperaturas e Pressões

Abstract

This work reports carbon dioxide (CO2) + n-hexadecane (C16) + n-butyl cyclohexane (butyl) phase and volumetric behavior at pressure up to P = 13.30 MPa (for vapor-liquid equilibria - VLE) and P = 100.00 MPa (for volumetric analysis) and for temperature up to T = 403.15 K. VLE measurements were carried out using a variable volume cell to bubble pressure determination. Three different compositions were studied: i) alkane-rich phase; ii) equimolar; and, iii) butyl-rich phase, covering a molar fraction range of 0.15 – 0.57, 0.15 – 0.61, and 0.15 – 0.56, respectively. Bubble point pressure prediction capability of two different equations of state were tested, as follows: Peng-Robinson (PR), Soave-Redlich-Kwong (SRK) and their predictive forms (PSRK - predictive Soave-Redlich-Kwong and VTPR - volume translated Peng-Robinson). Best results were obtained for SRK equation of state for regressed binary interaction parameter (kij), with a total average absolute relative deviation (AARD) of 16.15% of for all phases. Density measurements were obtained by intermediate of a U-tube vibrating densimeter, for a gas mole fraction of 0.0, 0.40 and 0.62; 0.0, 0.46 and 0.59; and, 0.0, 0.45 and 0.60 for: i) alkane-rich phase; ii) equimolar; and, iii) butyl-rich phase, respectively. These data were correlated by using Tamman-Tait equation and the capacity of the four state equations (SRK, PSRK, PR and VTPR) were tested for liquid phase prediction. PR and its predictive form, VTPR, presented the best results of AARD.