Synergistic Boosting Capture Ability of Thiophene Sulfur with a Novel Dual-Amino-Functionalized MOF-on-MOF Adsorbent

A single metal-organic framework (MOF) exhibits some drawbacks in deep adsorptive desulfurization such as insufficient functional active sites, water instability, low surface area, etc. Herein, a dual-amino-functionalized (ZIF-8-NH₂)-PVP-(Cu-BTC-NH₂) core-shell dual MOF adsorbent was first synthesized by the hydrothermal growth method. The adsorption performance of thiophene sulfur (ThS) is systematically investigated and evaluated at mild temperatures through batch tests. The (ZIF-8-NH₂)-PVP-(Cu-BTC-NH₂) exhibits good adsorption ability toward ThS, which is attributed to the associative effects of dual MOFs with structure features such as hydrogen bond, open metal active sites, suitable pore sizes and π-π conjugation, etc. Meanwhile, the (ZIF-8-NH₂)-PVP-(Cu-BTC-NH₂) embedded 25 wt % water still remains crystal intact and good adsorption desulfurization performance, which is attributed to the NH₂^- functional groups. After five recycles, more than 90% ThS uptake onto (ZIF-8-NH₂)-PVP-(Cu-BTC-NH₂) could be recovered, exhibiting good reuse performance. This study presents a new strategy for grafting MOF-on-MOF with specific functional groups to improve the abilities of desulfurization and water resistance.