ABSTRACT Adsorption‐based processes offer an efficient approach for the treatment of ventilation air methane (VAM). However, existing separation mechanisms typically distinguish CH 4 and N 2 based on their insignificant differences in polarizability and size, and remain largely ineffective for VAM with extremely low CH 4 concentrations. Here, we reported a clathrate‐like methane trap featuring dense arrays of electronegative O/N atoms as in methane hydrate, which exhibited electrostatic potential and shape complementarity toward CH 4 , realizing precise CH 4 recognition. The clathrate‐like methane trap exhibited a high isosteric heat of adsorption ( Q st ) of 36.0 kJ mol −1 for CH 4 , a benchmark Q st difference between CH 4 and N 2 (19.6 kJ mol −1 ), and the highest reported equilibrium‐kinetic combined selectivity (19.0). Breakthrough experiments confirmed that this trap efficiently captured CH 4 from a CH 4 /N 2 (1/99) mixture, providing a record‐high breakthrough selectivity (3.8). Its practical potential was validated by conducting a two‐bed, six‐step, variable‐pressure swing adsorption process, and 25% purity CH 4 could be obtained from a CH 4 /N 2 (1/99) mixture. In situ infrared spectroscopy and computational modelling studies revealed that the rational arrangement of dense N/O binding sites imparted a synergy between optimal pore shape and surface electrostatic potential that boosted CH 4 affinity.
Zhang et al. (Thu,) studied this question.