Liquid–liquid equilibrium and mechanism study on separation of short carbon chain hydrocarbon mixtures by Cyrene

Abstract

The separation of short‐chain hydrocarbon mixtures is of great significance for the efficient utilization of fossil energy. Liquid–liquid extraction, as one of the commonly used treatment methods, has significant advantages in terms of operation conditions and energy consumption. As a new dipolar aprotic solvent developed in recent years, dihydrolevoglucosenone (Cyrene) has a wide range of sources and a green composition. In this paper, the liquid–liquid equilibrium and extraction mechanism of Cyrene and five hydrocarbon mixtures with short carbon chains, including toluene/n‐heptane, toluene/cyclohexane, n‐hexane/cyclohexane, n‐pentane/pentene, and n‐hexane/hexene, have been studied by combining experiments and quantum chemical calculations, and the extraction effects under different conditions have been investigated. The results showed that the forces between Cyrene and the different solutes are mainly van der Waals (VDW) forces dominated by dispersion forces, with some weak hydrogen bonds present. Due to the difference in interaction energy, the order of extraction selectivity was toluene‐n‐heptane > toluene‐cyclohexane > n‐hexane‐hexene > n‐hexane‐cyclohexane > n‐pentane‐pentene, and the order of distribution coefficients of the extracted components (aromatics, olefins, and cycloalkanes) was toluene > pentene > hexene > cyclohexane. The dissolution processes of all systems were heat‐absorbing, and they all reached the extraction equilibrium within 60 s. The reliability of the experimental data was verified using the Othmer–Tobias equation and the Hand equation, and the binary interaction parameters of all systems were obtained by the non‐random two liquid (NRTL) model, providing basic data and references for the subsequent studies on the separation of Cyrene and short‐chain hydrocarbons.

Effects of Soaking Solvents by an Isothermal Crystallization Process on Physical Properties and Structures in One-Step-Drawing Films of Biodegradable P(3HB) Copolymers

“…49 At this point, the promoting effect of water on the crystallization of P(3HB) copolymer films is greatly weakened, and slow crystallization with the formation of microcrystalline nuclei occurs. Moreover, hexane is a nonpolar solvent that can only promote crystallization through van der Waals forces between molecules, 50 and its inducing effect on crystallization is relatively poor. In the IC process, it can provide an atmosphere for the P(3HB) copolymer film to slow crystallization.…”