Selective decontamination of the reactive air pollutant nitrous acid via node-linker cooperativity in a metal–organic framework

Abstract

Nitrous acid (HONO) is a reservoir of NO_x and an emerging pollutant having direct impacts on air quality, both in- and outdoors, as well as on human health. In this work, the amine-functionalized metal–organic framework (MOF), UiO-66-NH₂, was investigated due to its potential to selectively decontaminate nitrous acid at environmentally relevant concentrations. UiO-66-NH₂ proved to be effective in the removal of nitrous acid from a continuous gaseous stream. This is observed via the formation of an aryl diazonium salt that subsequently converts to a phenol with a concomitant release of nitrogen gas. This process is preceded via the formation of the nitrosonium cation (likely protonation from an acidic proton on the node). Thus, UiO-66-NH₂ is capable of selectively converting the pollutant nitrous acid to benign products.