A Universal Porous Adsorbent for the Selective Capture of Carbon Dioxide

Efficient and sustainable methods for carbon dioxide (CO₂) capture are essential. Its atmospheric concentration must be reduced to meet climate change targets, and its removal from sources such as chemical feedstocks is vital. While mature technologies involving chemical reactions that absorb CO₂ exist, they have many drawbacks. Porous materials with void spaces that are complementary in size and electrostatic potential to CO₂ offer an alternative. In these materials, the molecular CO₂ guests are trapped by noncovalent interactions, hence they can be recycled by releasing the CO₂ with a low energy penalty. Capacity and selectivity are the twin challenges for such porous adsorbents. Here, we show how a metal-organic framework, termed MUF-16 (MUF = Massey University Framework), is a universal adsorbent for CO₂ that sequesters large quantities of CO₂ from a broad palette of gas streams with record selectivities over competing gases. The crystallographically-determined position of the CO₂ molecules captured in the framework pores illustrate how complementary noncovalent interactions envelop CO₂ while repelling other guest molecules. The low affinity of the pore environment for other gases underpins the strikingly high selectivity of MUF-16 for CO₂ over methane, nitrogen, hydrogen, acetylene, ethylene, ethane, propylene and propane. Breakthrough gas separations under dynamic conditions benefit from short time lags in the elution of the weakly-adsorbed component to deliver a repertoire of high-purity products. MUF-16 is an inexpensive, robust, recyclable adsorbent that is universally applicable to the removal of CO₂ from sources such as natural gas, syngas, flue gas and chemical feedstocks.