Construction of hydrophobic CuCl@AC–PTFE composites with an enhanced Cu(I) stability for efficient CO adsorption

Cu(I) based CO adsorbents are prone to oxidation and deactivation owing to the sensitivity of Cu⁺ ions to oxygen and moisture in the humid air. In this study, in order to improve its antioxidant performance, hydrophobic Cu(I) based adsorbents were fabricated using polytetrafluoroethylene (PTFE) for the hydrophobic modification, effectively avoiding the contact of CuCl active species with moisture, thereby inhibiting the oxidation of the Cu(I) based adsorbents. The successful introduction of PTFE into the activated carbon (AC) carrier significantly improves the hydrophobicity of the adsorbent. The optimal adsorbent CuCl(6)@AC–PTFE(0.10%) with the CuCl loading of 6 mmol·g⁻¹ and the PTFE mass concentration of 0.10% exhibits an excellent CO adsorption capacity of 3.61 mmol·g⁻¹ (303 K, 500 kPa) as well as high CO/CO₂ and CO/N₂ adsorption selectivities of 29 and 203 (303 K, 100 kPa). Particularly, compared with the unmodified adsorbents, the antioxidant performance of modified adsorbent CuCl(6)@AC–PTFE(0.10%) is significantly improved, holding 86% of CO adsorption performance of fresh one after 24 h of exposure to humid air with a relative humidity of 70%, making the fabricated composite a promising adsorbent for CO separation.