摘要
Bromine functionalization improves low-pressure CH 4 /H 2 separation in UiO-66. • UiO-66-Br 2 shows the highest CH 4 /H 2 selectivity among the three samples. • Bromination strengthens CH 4 -framework interactions and favors CH 4 adsorption. • Bromination leads to a capacity-selectivity trade-off in the UiO-66 series. Efficient separation of CH 4 /H 2 mixtures is crucial for hydrogen purification but remains challenging because of the limited adsorption contrast between the two gases in conventional porous adsorbents. Herein, UiO-66 and its brominated derivatives, UiO-66-Br and UiO-66-Br 2 , were synthesized and systematically investigated through structural characterization, adsorption measurements, ideal adsorbed solution theory (IAST), grand canonical Monte Carlo (GCMC) simulations, and density functional theory (DFT) calculations. Bromination preserved the parent UiO-66 framework while effectively regulating the pore environment and host-guest interactions. At 273 K and 1 bar, the experimental CH 4 uptake increased from 0.809 mmol g −1 for UiO-66 to 0.938 mmol g −1 for UiO-66-Br 2 . Both IAST and binary GCMC consistently demonstrated enhanced CH 4 /H 2 separation after bromination, with UiO-66-Br 2 exhibiting the best overall performance. In particular, binary GCMC simulations yielded a CH 4 /H 2 selectivity of 14.23 for UiO-66-Br 2 at 0.1 bar, representing an approximately 73 % enhancement over pristine UiO-66 (8.23). DFT calculations further revealed that the CH 4 binding energy increased from 7.097 kJ mol −1 for BDC to 26.433 kJ mol −1 for BDC-Br 2 , indicating substantially strengthened local CH 4 -linker interactions. These results demonstrate that bromine functionalization, particularly dibromination, effectively enhances CH 4 -preferential adsorption and CH 4 /H 2 separation through the synergistic regulation of pore confinement and host-guest interactions. Download: Download high-res image (401KB) Download: Download full-size image
危险品化学品经营许可证（带存储）