Direct capture of CO₂ from the air is a complementary technology to the capture of CO₂ from large point sources, such as power plants. It has the advantage that it can address CO₂ emissions from all sources, including mobile sources, if the technology is operated on a sufficiently large scale. Christopher Jones and colleagues, Georgia Institute of Technology, USA, have developed porous-oxide supports impregnated with polymeric amines to extract CO₂ from ultra-dilute gas streams that mimic air.

The new adsorbents offered both high adsorption capacity and improved adsorption kinetics compared to conventional adsorbents. Adsorption capacities exceeding 2 mol_CO2kg_sorbent^–1 were seen under conditions simulating ambient air (400 ppm CO₂ in inert gas). There was also an improvement in thermal stability. Under repeated adsorption/desorption cycles in dry conditions, the new absorbents showed no loss of capacity unlike unmodified adsorbents.

Image: (c) Wiley-VCH

• Amine-Tethered Solid Adsorbents Coupling High Adsorption Capacity and Regenerability for CO₂ Capture From Ambient Air
  S. Choi, M. L. Gray, C. W. Jones,
  ChemSusChem 2011.
  DOI: 10.1002/cssc.201000355