High Ammonia Uptake of a Metal–Organic Framework Adsorbent in a Wide Pressure Range

Abstract

Although numerous porous adsorbents have been investigated for NH3 capture applications, these materials often exhibit insufficient NH3 uptake, low NH3 affinity at the ppm level, and poor chemical stability against wet NH3 conditions. The NH3 capture properties of M2(dobpdc) complexes (M=Mg2+, Mn2+, Co2+, Ni2+, and Zn2+; dobpdc4−=4,4‐dioxidobiphenyl‐3,3‐dicarboxylate) that contain open metal sites is presented. The NH3 uptake of Mg2(dobpdc) at 298 K was 23.9 mmol g−1 at 1 bar and 8.25 mmol g−1 at 570 ppm, which are record high capacities at both pressures among existing porous adsorbents. The structural stability of Mg2(dobpdc) upon exposure to wet NH3 was superior to that of the other M2(dobpdc) and the frameworks tested. Overall, these results demonstrate that Mg2(dobpdc) is a recyclable compound that exhibits significant NH3 affinity and capacity, making it a promising candidate for real‐world NH3‐capture applications.

Capture of toxic gases in MOFs: SO2, H2S, NH3 and NOx

“…18). 109 The NH 3 uptake of Mg 2 (dobpdc) at 298 K and 1 bar was 23.9 mmol g À1 at 1 bar and 8. 25 constant over ve breakthrough wet cycles.…”

“…25 constant over ve breakthrough wet cycles. 109 Thus, Mg 2 (dobpdc) is an exceptional MOF material that can be easily synthesised (i.e., microwave-assisted), highly recyclable (even aer exposure to a humid NH 3 ) without structural degradation or NH 3 capacity loss and holds the record for the highest NH 3 uptake at room temperature and atmospheric pressure. All of these relevant properties are possible due to the exceptional chemical stability of this Mg 2+ -based MOF material.…”

“…Due to the highly reactive nature of NO x , the uncontrolled emissions of such gases into the atmosphere are associated with a series of health and environmental issues. [114][115][116] For instance, the presence of high concentrations of NO 2 has been directly related to the formation of tropospheric ozone O 3 , 109,116 which not only is considered an important greenhouse gas; but is also associated with pulmonary and chronic respiratory diseases. 115,116 The adverse effects caused by atmospheric NO 2 have motivated an intense research for the development of NO 2 abatement technologies.…”

“…MIL-101(Cr)-4F(1%),20 are stable even aer 50 SO 2 adsorption-desorption cycles while the following MOFs are stable for different numbers of SO 2 cycles [Ni 8 (OH) 4 (H 2 O) 2 (-BDP_X) 6 ] (10 cycles),45 SIFSIX-1-Cu (4-6 cycles),51 and MFM-300(Sc) (10 cycles). 37c Furthermore, Mg-CUK-1,68 MIL-53(Al)-TDC,69 and MFM-300(Sc)70 are stable for at least ve adsorptiondesorption cycles of H 2 S while Mg 2 (dobpdc),109 Co 2 Cl 2 BBTA and Co 2 Cl 2 BTDD, 108 MFM-300(Al) (50 cycles),111 and UiO-67 112. Finally, MFM-300(Al) is not affected even by ve cycles of NO 2 124.…”

Reversible ammonia uptake at room temperature in a robust and tunable metal–organic framework

“…Metal–organic frameworks (MOFs) have emerged as a promising material for the capture of toxic chemicals such as NH 3 , 5–19 NO x , 20–23 SO x , 24–26 and volatile organic compounds 27,28 because well-ordered porosity with feasible chemical and structural tunability of pore surfaces enables such applications. Synthesis of MOFs with high structural stability toward corrosive species is a critical issue for real-world applications.…”