Nanoporous Aromatic Framework with Bulky Binding Groups for Palladium Recovery

Effective extraction of palladium from secondary resources is a promising solution for the sustainable utilization of precious metals. A cyclic molecule containing four N atoms was modified on a nanoporous aromatic framework (PAF) to give PAF-1-N4, which provided a meaningful route to introduce bulky molecules with multiple coordination sites into the PAF materials. Through the interaction of multiple binding sites to Pd(II), PAF-1-N4 showed rapid and deep adsorption of Pd(II) at a low initial concentration. The maximum Pd(II) adsorption capacity of PAF-1-N4 reached 299.4 mg g–1, and PAF-1-N4 reduced the concentration of Pd(II) from 5.35 ppm to 84 ppb within 5 min and finally to 42 ppb within 60 min. After the in situ reduction, the obtained Pd@PAF-1-N4 exhibited good catalytic activity and reusability for the Suzuki–Miyaura coupling reaction in five-cycle catalytic experiments, thus realizing its sustainable utilization of palladium extracted from secondary resources.