Ionic framework constructed with protic ionic liquid units for improving ammonia uptake

Abstract

In this work, an ionic framework [Ph3ImH][Tf2N]₂ constructed from protic imidazolium ionic liquid units through ionic and hydrogen bonding interactions was synthesized for selective ammonia uptake. Investigation of the NH₃ uptake mechanism indicates that the acid sites in [Ph3ImH][Tf₂N]₂ would be frustrated when contacted with NH₃, and the frustration of [Ph3ImH][Tf₂N]₂ precipitates NH₃ capture by hydrogen bonding and physical interactions, and the NH₃ could be released under mild conditions. There was no obvious decrease in capacity over 10 consecutive cycles of ammonia uptake and release.