| 摘要 |
1,134,881. Removal of nitrous gases. SINCATSOC. INDUSTRIALE CATANESE S.p.A. 10 Nov., 1965 [11 Nov., 1964], No. 47784/65. Heading C1A. Nitrous gases are removed from a gaseous mixture by reacting it with a soln. containing sulphite and/or bisulphite ions which are oxidized by the gases to sulphate and/or bisulphate ions. Ammonium, sodium, magnesium and potassium sulphites and bisulphites may be used. The soln. may be saturated but preferably has a concn. of 0À1-10% by wt. calculated as SO 2 . The pH of the soln. may be at least 6, and preferably 6.4 to 6.9. The washing may be carried out in absorption towers packed with Raschig rings in one or more stages. The gases may be washed with a relatively weak soln. in a 1st stage, such as will oxidize all the SO 3 = or HSO 3 -, and then in a 2nd or last stage with relatively conc. soln. which may be obtained from recycled partly oxidized soln. from the same or an earlier stage. Fresh (NH 4 ) 2 SO 3 and/or NH 4 .HSO 3 soln. may be those obtained by the removal of SO 2 from the tail gases of H 2 SO 4 synthesis. The solns. of (NH 4 ) 2 SO 4 and NH 4 HSO 4 may be fed to the synthesis of (NH 4 ) 2 SO 4 by the reaction of NH 4 and H 2 SO 4 , where they are concentrated by the heat of reaction. |
