Synergistic Claisen rearrangement and crosslinking for hollow fiber membranes toward helium recovery from natural gas

Thermally rearranged (TR) polymers are promising membrane materials due to their excellent gas permeability and thermal stability. Nevertheless, the harsh thermal rearrangement conditions (typically >400 °C) and limited intrinsic selectivity severely hinder their application for helium (He) recovery. Herein, we propose a synergistic Claisen rearrangement-crosslinking (CRX) strategy to address this issue. The He/CH 4 selectivity of the CRX hollow fibers increased from 59.47 in precursors to 120.51, corresponding to an enhancement of 102.6%. Moreover, SEM images revealed that 2D shrinkage mode effectively alleviated thermal densification, resulting in a ∼ 15% thinner skin layer. Consequently, the CRX-240-1 h-2D membranes achieved a higher He permeance of 281.66 GPU while maintaining excellent He/CH 4 selectivity. Importantly, under operating conditions of 70 °C and 0.5 MPa, CRX-240-1 h-2D membranes still maintained outstanding performance. Overall, this work provides an energy-efficient and reliable approach for the fabrication of TR hollow fiber membranes, showing great potential for helium recovery from natural gas.