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 remediation from chemical feedstocks and natural gas is vital. While mature technologies involving chemical reactions that trap the CO2 do 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. Porous materials that are selective towards CO2 when it is present with an array of competing gases are challenging to produce. Here, we show how a metal-organic framework, termed MUF-16 (MUF = Massey University Framework), is a ‘universal’ adsorbent for CO2 that sequesters CO2 from a broad palette of gas streams with record selectivities over competing gases. The position of the CO2 molecules captured in the framework pores was determined crystallographically to illustrate how complementary noncovalent interactions envelop the guest molecules. The pore environment has a low affinity for all other gases, which underpins the benchmark selectivity of MUF-16 for CO2 over methane, hydrogen and acetylene. 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, easily regernarable and recyclable adsorbent that is universally applicable to the removal of CO2 from sources such as natural gas, syngas and chemical feedstocks.