Anion Pillared Metal–Organic Framework Embedded with Molecular Rotors for Size-Selective Capture of CO₂ from CH₄ and N₂

Abstract

The CO2 sequestration is extremely urgent due to the growing greenhouse effect and the subsequent serious environmental crisis. The development of porous materials with a size-selective effect for CO2 from other molecules still remains a challenge, due to the difficulties to control pore size within 3–4 Å. Here, we proposed and designed a novel anion-pillared material (termed as ZU-66, ZU = Zhejiang University) embedded with “molecular rotors” toward the industrially relevant CO2/CH4 and CO2/N2 separation. Interestingly, the temporarily fixed molecular rotors under the ambient condition afforded a size-selective channel for CO2 from CH4 and N2. To our best knowledge, there were only a handful of examples achieving the molecular sieving between CO2 and CH4. Such a behavior endowed ZU-66 with high separation selectivity for both CO2/CH4 (136) and CO2/N2 (355) and high CO2 capacity (4.56 mmol g–1, 298 K, 1 bar). The actual breakthrough experiment further verified its great potential in both CO2/CH4 and CO2/N2 separation. The specific adsorption behavior within ZU-66 was further revealed through the modeling calculation.