Patent ID: 7326391

Claim:
A process for the recovery of ammonia from a vaporous stream comprising contacting said stream with a first aqueous ammonium phosphate solution comprising ammonium dihydrogen phosphate and diammonium hydrogen phosphate, having a first ratio of ammonium ions (NH 4 + ) to phosphate ions (PO 4 −3 ), thereby absorbing ammonia from said stream and forming aqueous quench bottoms having increased ratio of (NH 4 + ) to (PO 4 −3 ) and a depleted vapor stream comprising residual ammonia; contacting said depleted vapor stream with a second aqueous ammonium phosphate solution comprising ammonium dihydrogen phosphate and diammonium hydrogen phosphate, and having a second ratio of ammonium ions (NH 4 + ) to phosphate ions (PO 4 −3 ) that is lower than the first ratio, thereby absorbing substantially all of said residual ammonia from said vapor stream and forming said first aqueous ammonium phosphate solution; heating said aqueous quench bottoms to an elevated temperature for a time sufficient to decompose at least a portion of the diammonium phosphate and generate a vaporous ammonia stream; and separating the ammonia from the remaining components of said vaporous ammonia stream.