A Universal Porous Adsorbent for the Selective Capture of Carbon Dioxide

2019-08-27T15:58:34Z (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 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.