No abstract

The amine functionalized material 1-dmen shows a record high working capacity for CO2 capture at low regeneration temperatures compared with other MOFs. Furthermore, this performance is maintained upon exposure to humidity.

A combined sonication and microwave irradiation procedure provides the most effective functionalization of ethylenediamine (en) and branched primary diamines of 1-methylethylenediamine (men) and 1,1-dimethylethylenediamine (den) onto the open metal sites of Mg (dobpdc) (1). The CO capacities of the advanced adsorbents 1-en and 1-men under simulated flue gas conditions are 19 wt % and 17.4 wt %, respectively, which are the highest values reported among amine-functionalized metal-organic frameworks (MOFs) to date. Moreover, 1-den exhibits both a significant working capacity (12.2 wt %) and superb CO uptake (11 wt %) at 3 % CO . Additionally, this framework showcases the superior recyclability; ultrahigh stability after exposure to O , moisture, and SO ; and exceptional CO adsorption capacity under humid conditions, which are unprecedented among MOFs. We also elucidate that the performance of CO adsorption can be controlled by the structure of the diamine ligands grafted such as the number of amine end groups or the presence of side groups, which provides the first systematic and comprehensive demonstration of fine-tuning of CO uptake capability using different amines.

A porous Mg 2 (dondc) framework (H 4 dondc ¼ 1,5-dioxido-2,6-naphthalenedicarboxylic acid) with open metal sites was prepared and functionalized with primary or secondary diamines (en ¼ ethylenediamine, mmen ¼ N,N 0 -dimethylethylenediamine, or ppz ¼ piperazine). The CO 2 adsorption was substantial under post-combustion flue gas conditions as compared to other reported metal-organic frameworks.Interestingly, the IR spectroscopic measurements demonstrated that the CO 2 adsorption mechanism is based on the combination of physisorption and chemisorption. The CO 2 adsorption capacity of 1-mmen was greater than that of 1-en and 1-ppz, which can likely be attributed to the basicity of the free amine groups tethered to the open coordination sites. Ultrahigh selectivity and superior dynamic separation of CO 2 over N 2 were evident in 1-ppz. Such exceptional CO 2 uptake and CO 2 /N 2 selectivity of diaminefunctionalized materials hold potential promise for post-combustion CO 2 capture applications.