RT Journal Article
T1 Thermodynamic properties and phase equilibria of branched chain fluids using first- and second-order Wertheim’s thermodynamic perturbation theory
A1 Jiménez Blas, Felipe
A1 Vega, Lourdes F.
AB We present an extension of the statistical associating fluid theory (SAFT) for branched chain molecules using Wertheim’s first- and second-order thermodynamic perturbation theory with a hard-sphere reference fluid (SAFT-B). Molecules are formed by hard spherical sites which are tangentially bonded. Linear chains are described as freely jointed monomeric units, whereas branched molecules are modeled as chains with a different number of articulation points, each of them formed by three arms. In order to calculate the vapor–liquid equilibria of the system, we have considered attractive interactions between the segments forming the chain at the mean-field level of van der Waals. The Helmholtz free energy due to the formation of the chain is explicitly separated into two contributions, one accounting for the formation of the articulation tetramer, and a second one due to the formation of the chain arms. The first term is described by the second-order perturbation theory of Phan et al. [J. Chem. Phys. 99, 5326 (1993)], which has been proven to predict the thermodynamic properties of linear chain fluids in a similar manner to Wertheim’s approach. The formation of the chain arms is calculated at Wertheim’s first-order perturbation level. The theory is used to study the effect of the chain architecture on the thermodynamic properties and phase equilibria of chain molecules. The equation predicts the general trends of the compressibility factor and vapor–liquid coexistence curve of the system with the branching degree, in qualitative agreement with molecular simulation results for similar models. Finally, SAFT-B is applied to predict the critical properties of selected light alkanes in order to assess the accuracy of the theory. Experimental trends of the critical temperature of branched alkanes are qualitatively captured by this simple theory.
PB AIP Publishing
SN 0021-9606
SN 1089-7690 (electronico)
YR 2001
FD 2001
LK http://hdl.handle.net/10272/17333
UL http://hdl.handle.net/10272/17333
LA eng
NO Blas, F. J., Vega, L. F.: "Thermodynamic properties and phase equilibria of branched chain fluids using first- and second-order Wertheim’s thermodynamic perturbation theory",  Journal of Chemical Physics. Vol. 115, n. 8, págs. 3906-3915, (2001). DOI: 10.1063/1.1388544
NO This work was supported by the Spanish Government under Project No. PB96-1025 and VI Plan Propio de Investigación de la Universidad de Huelva. One of the authors (F.J.B.) acknowledges a doctoral fellowship from Comisionat per a Universitats i Recerca from the Generalitat de Catalunya during the course of this work
DS Repositorio Institucional de la Universidad de Huelva
RD 15 jun 2026