Efficient separation of long-chain alpha-olefins via NaX zeolite in simulated moving bed adsorption process

Abstract

Long-chain α-olefins are key intermediates in organic synthesis, commonly comprising 40 % to 80 % of the products derived from processes including dehydration of long-chain alcohols, CO₂ hydrogenation, and Fischer–Tropsch synthesis. The separation of α-olefins from alkanes and endo-olefins, with boiling points and molecular structural properties, is a challenging task that requires low energy consumption. Adsorption separation offers a promising alternative to the traditional, energy-intensive distillation process. In this study, a simulated moving bed (SMB) system equipped with a configurable multi-way solenoid valve setup was developed for the separation of C₈, C₁₀, and C₁₂ α-olefins from paraffins. NaX zeolites were used as adsorbents, and cyclohexane served as the desorption agent. Initial SMB parameters were determined rationally and efficiently through micro packed-bed chromatography pulse experiments and the application of a safety factor method. At a temperature of 60 °C and a pressure of 0.9 MPa, the purity of C8, C10, and C12 α-olefins was refined to 99.5 %, 99.2 %, and 97.3 %, respectively, on a simulated moving bed chromatography system with optimized parameters. A novel single-column simulation approach was established to determine valve switching times, zone configurations, and flow rates for complicated systems. This approach has the potential to be integrated with genetic algorithms for rapid screening and optimization of SMB configurations in the future. The SMB system was operated continuously for 72 h, during which the purity of the α-olefin in the extracted liquid remained stable. The design and optimization of SMB parameters provide an important foundation for the industrial application of adsorption separation processes for long-chain α-olefins and paraffins.