Ultramicroporous Carbon Molecular Sieve for Air Purification by Selective Adsorption Low-Concentration CO2 and VOC Molecules

The development of an ultramicroporous (<7 Å) adsorbent with a narrow pore distribution for capturing and adsorbing gas molecules has received a lot of attention. In this paper, the commercial carbon molecular sieve (CMS) was used as the precursor, and a carbon molecular sieve (CMS-A-5) with better performance was obtained by activating with potassium hydroxide (KOH). After activation, the ultramicroporous volume increased from 0.163 cm3 g–1 (CMS) to 0.329 cm3 g–1 (CMS-A-5), and the CO2 capacity increased from 42.76 to 71.92 cm3 g–1 at 298 K and 1 bar. The breakthrough experiments demonstrated that the CO2 capture ability of CMS-A-5 increased by ∼9.5 times for the respiratory air containing CO2/O2/N2 (4:20:76) and was easily regenerated and reused. CMS-A-5 was also capable of selectively capturing VOC molecules including benzene, toluene, and C8 alkyl aromatics (BTEX) with a high adsorption capacity at a low pressure. The excellent CO2 and VOC molecule adsorption capacity make CMS-A-5 a promising candidate for selective separation of the gas mixture, in particular, for air purification in confined spaces.