Programming Framework Materials for Ammonia Capture

Abstract

Ammonia serves as an essential feedstock in several large industries, including fertilizer and explosives manufacturing, and as a key coolant in large-scale applications such as ice rinks, making it one of the most important industrial gases.(1) It is also extremely corrosive and toxic, which makes its adsorption in applications such as air remediation, gas masks, and adsorption heat pumps very challenging. The current commercial adsorbent, activated carbon, suffers from low affinity for ammonia and relatively low capacity of only 11 mmol g⁻¹.(2) Although recent developments in porous materials including metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) have produced remarkable advances in the state-of-the-art sorbents for a variety of gases and even water vapor, most of these materials have been surprisingly ineffective at storing NH₃. Now, reporting in ACS Central Science, Yang et al. demonstrate systematically designed COFs that meet this challenge.(3) Through a series of programmed modifications to the pore surface (Figure 1), the authors successfully install metal ions with open coordination sites which confer exceptional affinity for ammonia.