In-situ pyrrole polymerization modified Pebax membrane with enriched selective adsorption sites for aromatic/aliphatic hydrocarbon separation

Pebax-PPy membranes are constructed for aromatic/aliphatic hydrocarbon separation. • The separation mechanism of the Pebax-PPy membrane is explored. • Pebax-PPy membrane achieves a good separation factor for toluene/ n -heptane mixture. Separation of low-cracking-activity aromatics from naphtha prior to steam cracking is critical for boosting olefin yields. Pervaporation technology utilizing aromatic-selective membranes enables efficient separation of aromatic/aliphatic hydrocarbon mixtures. In this work, an in-situ oxidative polymerization strategy is proposed to directly polymerize pyrrole monomers within a polyether block amide (Pebax) solution, followed by spin-coating to fabricate Pebax-Polypyrrole (PPy) membranes. The in-situ formed PPy is uniformly dispersed in the Pebax matrix, effectively avoiding filler agglomeration and interfacial defects generated in conventional mixed matrix membranes. Theoretical simulations reveal that π-π interactions and N-H···π hydrogen bonding between PPy and aromatics significantly improve the membrane's selectivity toward aromatics. The Pebax-PPy membrane achieves a separation factor of 7.16 and a permeation flux of 662 g m −2  h −1 for a 50 wt% toluene/ n -heptane mixture. Furthermore, the Pebax-PPy membrane enriches toluene from 15.0 wt% to 90.2 wt% in simulated naphtha via a two-stage membrane cascade process, demonstrating enormous application potential for the pre-separation of aromatics from naphtha. Download: Download high-res image (398KB) Download: Download full-size image