A Universal Porous Adsorbent for the Selective Capture of Carbon Dioxide

2020-04-13T10:26:06Z (GMT) by Omid Taheri Qazvini Shane G. Telfer

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.