an no abatement process wherein an no - containing fluid is contacted with a polymeric cobalt dioxygen diamine complex . the aqueous solution is recovered , purified by membrane separation to remove low molecular weight reaction products , optionally electrolytically regenerated , and recycled for the no - containing gas contact . the cobalt is complexed with an amine - containing polymer such as polyethyleneimine free of acidic , e . g . carboxylate , chelating groups .