Efficient SO2 Removal Using a Microporous Metal–Organic Framework with Molecular Sieving Effect

Removal of trace SO2 contaminants from gas mixtures by the molecular sieving effect is highly desired. Herein, a microporous metal–organic framework Cu2(pzdc)2(pyz) [CPL-1, pzdc = 2,3-pyrazinedicarboxylate; pyz = pyrazine] with a dumbbell-shaped 1D channel and specific binding sites is explored for deep desulfurization. The proper size of 4.1 × 6.2 Å and strong SO2 trapping sites on CPL-1 render a high adsorption uptake of SO2 (44.8 cm3 g–1) with a record-high selectivity for SO2/N2 (368) and SO2/CH4 (74.3) separation under ambient conditions. Moreover, the dispersion-corrected density functional theory calculations have identified the dual specific adsorption sites of SO2, such as Sδ+···Oδ− electrostatic interactions and Oδ−···Hδ+ hydrogen bonds. The feasibility of CPL-1 for SO2/N2, SO2/CH4, CO2/CH4, CO2/N2, and mimicked flue gas mixture separations was validated by dynamic breakthrough experiments. Water vapor and CO2 impurity were introduced to the gas feed streams to confirm the excellent separation performance of CPL-1. Moreover, a scale-up production of CPL-1 via a facile and green method was conducted, and a reproducible CPL-1 adsorbent with undamaged adsorption and separation performances was successfully manufactured in kilogram quantity. These unique features render CPL-1 a very promising adsorbent for practical desulfurization processes.