Enhanced discrimination of 1‐octene over 2‐octene for high‐selectivity separation by bimetallic Ag ⁺ /Cu ²⁺ ionic liquid

Abstract

The separation of 1‐octene from 2‐octene is a key bottleneck in the purification of Fischer–Tropsch (F–T) C8 α‐olefins because of their similar physicochemical properties and competitive metal–olefin complexation. To address the limited discrimination between terminal and internal olefins, this study systematically screened metal‐based ionic‐liquid extractants and introduced Cu ²⁺ into Ag ⁺ ‐based ionic liquid (IL) system. The resulting bimetallic Ag ⁺ /Cu ²⁺ ‐IL increased the 1‐octene/2‐octene selectivity by up to 74.6% relative to the corresponding single‐Ag ⁺ reference system. Quantum chemical calculations, molecular dynamics simulations, multistage extraction experiments, and process modeling indicate that Cu ²⁺ is associated with altered Ag‐centered local binding and accessibility, consistent with reduced 2‐octene co‐extraction. The bimetallic system maintained its selectivity advantage under multistage operation with 99.97% cumulative 1‐octene recovery and achieved an 80.7% reduction in energy demand relative to conventional distillation. This work offers a new mechanistic strategy and a process‐feasible route for separating terminal olefins from internal olefins.