Thermally reversible polymeric sorbents for acid gases, IV. Affinity tuning for the selective dry sorption of NOx

We have found that amino-functional polymers absorb and readily bind nitrogen oxides (NO_x) namely NO₂ and NO. Our previous results showed that the reaction of NO_x with polymer-grafted primary and secondary amines yielded stable products, subsequently identified as nitrite and nitrosamine derivatives, which cannot be thermally degraded to regenerate the original amino-polymer and thereby release the absorbed NO_x. Consequently, we have prepared and evaluated polymers carrying pendant sterically hindered tertiary amines with the proper electron donor-acceptor properties to bind specifically NO_x. The results of thermogravimetric analysis experiments showed that dipropylamine-functional polymers absorb and bind NO₂ effectively and reversibly while they remain almost/completely inert when exposed to relatively weaker acid gases such as SO₂ or CO₂.