Surfactant-assisted synthesis of defective UiO-67(Zr) framework and its application for CO adsorption and CO/N2 separation

The Cu+-based pi-complex adsorbent is a promising material for storing and separating carbon monoxide (CO) from various industrial gas emission sources. Herein, defective Cu+@UiO-67(Zr) materials were developed and exploited for the adsorptive separation of CO. First, a defective UiO-67(Zr) framework was prepared using cetyltrimethylammonium bromide (CTAB) as a modulator (UiO-67-CT). Then, Cu2+ was reduced to defective UiO-67(Zr)-CT at 150 degrees C to obtain Cu+@UiO-67-CT adsorbents. Results indicated that CTAB-created UiO-67 contained defects with the ligand deficiency of ca. -2.05 per Zr6 unit, enhancing their porosity and giving beneficiation for loading Cu+. The gas adsorption experiments showed that the Cu+@UiO-67-CT adsorbents exhibited enhanced CO adsorption compared to the parent MOF, and their adsorption ability depends on the Cu+ load. The optimal 25Cu+@UiO-67-CT had CO uptake capacity and CO/N2 selectivity of ca. -2.91 mmol g-1 and -318 at 100 kPa and 27 degrees C, respectively, exceeding many reported adsorbents, such as CuCl/Al2O3, CuCl/MCM-41, CuZSM-5, and Cu(I)/polymer. Furthermore, the prepared defective Cu+@UiO-67-CT showed good CO/N2 separation under dynamic flow mixture conditions. The study provides a strategy for developing efficient pi-complex adsorbents for CO recovery and separation.