A method for the removal of F2 and/or OF2 from gases is described where in a gas comprising F2 and/or OF2 optionally also containing HF is contacted with a liquid comprising a base and a dissolved thiosulfate salt or alkali metal nitrite, preferably the respective Na compounds. Preferred bases are alkali metal hydroxides and alkali metal carbonates, especially the respective Potassium compounds. The method is very suitable to treat gas from industrial processes in which F2 is applied or formed, example in gases resulting from the manufacture of semiconductors, photovoltaic cells or TFTs. It can be applied, for example, for gases comprising F2 resulting from emergency events, from the start-up phase of F2 production, for waste gases from semiconductor etching apparatus including chamber cleaning waste gases and for gases comprising out-of-spec F2. The method allows the removal of F2 without formation of a significant level of OF2 in the treated gas.
Authors: Eicher, Johannes; Feys, Francis; Morelle, Philippe; Diana, Oliviero; Predikant, Peter M.; Uenveren, Ercan; Pernice, Holger; Schwarze, Thomas; Kalbreyer, Wolfgang; Rau, Helge. ;Full Source: PCT Int. Appl. WO 2012 35,000 (Cl. B01D53/68), 22 Mar 2012, EP Appl. 2011/165,500, 10 May 2011; 42pp. ;