Investigation of Vapor−Liquid Equilibria for Supercritical Carbon Dioxide and Hydrocarbon Mixtures by Perturbed-Chain Statistical Associating Fluid Theory

Abstract

The perturbed-chain statistical associating fluid theory (PC-SAFT) is used to investigate the vapor-liquid equilibria for binary supercritical carbon dioxide (CO 2 ) and hydrocarbon mixtures. The molecular parameters m, σ, and /k for pure CO 2 and hydrocarbons with carbon number n e 20 are taken from the work of Gross and Sadowski. m, σ, and /k for n-alkanes with n > 20 are obtained by extrapolation from the linear relationships between molecular parameters and molecular weight M w . The binary interaction parameters (k ij ) are regressed by using the experimental data. Investigation shows PC-SAFT is able to accurately describe the vaporliquid-phase equilibria for both CO 2 -light hydrocarbon and CO 2 -heavy n-alkane (up to C 44 ) binary mixtures. When the carbon number n in each hydrocarbon ranges from 1 to 20, the regressed k ij increases monotonically with the increase of n. However, when n is greater than 20, there is a unique binary interaction parameter (k ij ) 0.16) that can well describe the vapor-liquid-phase equilibria for CO 2 -eicosane, CO 2 -octacosane, CO 2hexatriacontane, and CO 2 -tetratetracontane binary mixtures.

Measurement and Correlation of High Pressure Phase Equilibria for CO2 + Alkanes and CO2 + Crude Oil Systems

“…In fact, large amounts of such data and models have existed in the literature, covering the binary systems of CO 2 and hydrocarbons. A large majority of pertinent works are primarily based on the binary system of CO 2 –alkane, CO 2 –bitumen, and the rest are chiefly related to ternary mixtures of alkanes–CO 2 –water. − The available phase equilibrium data for mixtures of CO 2 with multicomponent hydrocarbons is very limited in view of the diversity of the hydrocarbons and the ranges of temperature and pressure investigated . Thus, more reliable experimental methods and precise high-pressure high-temperature phase behavior data are required, particularly in the range of operating conditions suitable for CO 2 -EOR.…”

Prediction of the Binary Interaction Parameter of Carbon Dioxide/Alkanes Mixtures in the Pseudocritical Region

“…For a given reduced temperature, it is shown how k ij varies for the CO 2 /alkane systems when the CN varies between 1 and 10 (in Figure 4a). Fu et al 12 investigated the VLE for supercritical CO 2 and HC (CN ≤ 20) mixtures by PC-SAFT. For CO 2 / n -alkane mixtures, the k ij can be expressed as k ij = 0.030128 log( n ) + 0.0726141.…”

“…Therefore, obtaining an accurate BIP for the system is key to ensure the accuracy of the physical property prediction. The BIPs can be obtained by regression according to the experimental data of the mixture properties and the EoS − or VLE. − However, it is complicated to obtain the experimental data for BIPs. Therefore, several attempts have been made to establish equations to estimate the BIPs based on the combination of cubic EoS with appropriate mixing rules.…”

Thermodynamics for the Separation of CO₂</b>-N₂ Mixtures by Zeolite MFI

“…的吸附选择性的影响，应用 PC-SAFT 状态方程 [17,18] 确定脱吸之后气体混合物中液化分离 [17] 系的汽液相平衡图。本文结合 PC-SAFT [17,18] 状态方程 [17] 。以 270 K 时 的实验数据 [20] 拟合所得的交叉作用参数 k ij = -0.01。 以…”