(92f) From Pore to Process: Ultra-Efficient SF6/N2 Continuous Separation Using Inexpensive Robust MOF Composites

Physisorption presents a promising alternative to cryogenic distillation for capturing the most potent greenhouse gas, SF₆, but existing adsorbents face challenges in meeting diverse chemical and engineering concerns. Herein, with insights into in-pore chemistry and industrial process design, we report a systematic investigation that constructed two novel low-cost composites pellets (Al(fum)@2%HPC and Al(fum)@5%Kaolin) coupled with an innovative two-stage Vacuum Temperature Swing Adsorption (VTSA) process for the ultra-efficient recovery of low-concentration SF₆ from N₂. Record-high selectivities (>10⁴) and SF₆ dynamic capacities (2.68~2.76 mmol/g) were achieved, while the exceptional SF₆ productivities (58.46~60.79 L/kg), yields (97.39~98.32%), and recyclability (~1000 cycles) were demonstrated in real fixed-bed adsorption-desorption experiments under mild regeneration conditions. 2D ssNMR/in-situ FTIR, DFT-D binding/diffusion simulation analyses revealed the multi-site binding mode and the ultra-fast diffusion of SF₆ within the channels. The proposed VTSA processes successfully met the dual stringent requirements of both environmental protection and electricity equipment operation: the SF₆ recovery 99.91% (the SF₆ content of emission is 900 ppm) accompanied with a cyclic average SF₆ purity of 99.91% and a working capacity of 2.10 mmol/g, which significantly ouperformed the industrial employed adsorbent Zeolite 13X and showed only 1/5 the energy consumption of the cryogenic distillation process.