Performance and mechanism of the separation of C8 α‐olefin from F‐T synthesis products using novel Ag‐DES

Abstract

As an attractive alternative technology for the separation of long chain olefin and paraffin, a novel silver‐based deep eutectic solvent (Ag‐DES) was prepared and utilized for 1‐octene/n‐octane separations. Comprehensive reactive extraction separation experiments were performed to highlight the Ag‐DES concentration and operating temperature discriminations using compounds with different ratio of 1‐octene/n‐octane. The novel Ag‐DES showed optimal separation performance regarding 1‐octene/n‐octane and possessed the highest levels separation selectivity in the range 3.57–16.11 with excellent circulation stability in our best knowledge. Furthermore, FT‐Raman measurements and quantum chemistry calculation were performed to elucidate the interaction mechanism of Ag‐DES in the separation of 1‐octene and n‐octane, which revealed that both chemical complexation and strong physical attraction existed in the complex of Ag‐DES and 1‐octene rather than n‐octane. A practical process was proposed for the separation of olefin and paraffin, which indicates that an advanced separation technology could largely reduce the energy consumption. This study lends important insight for the development of Ag‐DES reactive extraction separation process for the energy‐efficient long chain α‐olefins purification from F‐T synthesis products.

Application of silver ionic liquid in the separation of olefin and alkane

“…After the extraction process, the resulting organic phase/aqueous phase/IL system was readily separated. The recovery process utilized the thermal instability of the complex, allowing the olefins to be recovered via its decomposition 13 . The complex was rotated while evaporating for 12 h at a constant temperature of 50 °C and depressurized at a low pressure to obtain Ag[NTf 2 ] as a white solid.…”

“…The Ag + IL in the bottom layer was washed with deionized water to ensure that all salt residues were removed. The product structure was characterized by 13 C, 1 H nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) (Figs S1 and S2). The viscosity of the IL was determined to be 19.3 cP at atmospheric pressure and room temperature, using a LVDV-II+PRO viscometer (Brookfield engineering, Middleboro, MA, USA).…”

“…The recovery process utilized the thermal instability of the complex, allowing the olefins to be recovered via its decomposition. 13 The complex was rotated while evaporating for 12 h at a constant temperature of 50 °C and depressurized at a low pressure to obtain Ag[NTf 2 ] as a white solid. The recovered silver salt could be reused in the aqueous phase to avoid waste.…”

“…It is known that the olefin double bond is able to undergo reversible interactions with σ and π bonds of metal ions 13 . Specifically, a reversible complexation strategy based on silver (Ag + ) ions was developed for olefin/alkane separation.…”

“…It is known that the olefin double bond is able to undergo reversible interactions with ⊞ and π bonds of metal ions. 13 Specifically, a reversible complexation strategy based on silver (Ag + ) ions was developed for olefin/alkane separation. Salts comprising Ag + ions with various anions (including NO 3 − , BF ) were dissolved in ILs to improve the olefin separation performance.…”