Extension of the Cubic-plus-Association (CPA) Equation of State to Amines

Abstract

The cubic-plus-association (CPA) equation of state has been extended to modeling mixtures containing amines. Special focus was given to primary and secondary amines, which are known to self-associate, thus forming hydrogen bonds in mixtures with alkanes. Pure-compound parameters have been determined from vapor pressure and liquid density data, but phase equilibrium data were also used as guidance for selecting the optimum sets among those which best represent the pure-compound properties. Diethylamine was modeled as a two-site molecule, whereas the two primary amines considered (methylamine, ethylamine) were modeled using both the two-site and three-site schemes. Both schemes perform overall equally well, when care is exercised in the parameter estimation, by giving more weight on the vapor pressures rather than the liquid densities. Thus, only results using the two-site scheme are shown. Excellent binary vapor-liquid equilibria have been obtained for amine + aliphatic hydrocarbons with a low value of the binary interaction parameter. Satisfactory results are obtained also for crossassociating systems with alcohols but less so with water, using, moreover, a rather high value of the interaction parameter.

Solvation Phenomena in Association Theories with Applications to Oil & Gas and Chemical Industries

“…-Mixtures of organic acids or amines and alcohols are also successfully modeled using CPA with ECR Kaarsholm et al, 2005), as shown for some typical systems in Figures 5-7, while aqueous mixtures of acids and amines require large negative interaction parameters and the representation is not always entirely satisfactory.…”

Comparison of SRK and CPA equations of state for phase equilibrium of binary and ternary systems containing aromatics

“…Among the different proposed equations of state (EoS) cubic-plus-association (CPA) model is one of the most new EoS models is able to well correlates the phase equilibria of aqueous systems comprises of aliphatic, olefinic and aromatic hydrocarbons [2][3][4][5][6][7][8][9][10][11][12]. This equation of state first proposed by Kontogeorgis et al [13] is an extension of the SRK EoS [14] that consists of two separate terms.…”

“…Moreover, Folas et al [8] extended the CPA EoS to model the phase equilibria of industrially important binary mixtures of alcoholhydrocarbon. Furthermore, Kaarsholm et al [7] utilized the CPA EoS to model the phase behavior amines. Their obtained results revealed that CPA EoS is a strong model to calculate the binary vapor-liquid equilibria data for amine-aliphatic hydrocarbons with a low value of the binary interaction parameter.…”

Thermodynamic properties and vapor–liquid equilibria of associating fluids, Peng–Robinson equation of state coupled with shield-sticky model

“…The CPA-EOS uses the Soave-Redlich-Kwong (SRK) EOS for the physical part and Chapman's association term [22] as many SAFT models used for the association contribution. Remarkably, although the CPA EOS has simpler form than complex SAFT, the obtained results of some complicated associating systems are comparable to that from SAFT [34], and it has been widely adopted in the traditional and emerging field including the phase behaviors of associating fluids such as alkanols [35,36], carboxylic acids [37], amines [38], petroleum reservoir fluids [39], biodiesel [40], and drug-like molecules [41]. It is worth mentioning that there are also other CPA-type EOSs such as ESD (Elliott-Suresh-Donohue) proposed by Elliott et al [42] and the Peng-Robinson (PR) CPA EOS by Wu and Prausnitz [43].…”