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

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