A COMPARATIVE-STUDY ON THE CATALYTIC INFLUENCE OF CU(II), CO(II), AG(I) AND NI(II) ON OXIDATION OF (NH4)(2)SO3 USING O-2 GAS

The kinetics of oxidation of ammonium sulfite using gaseous oxygen wer e studied in an autoclave at 373K. Kinetic equations for various catal ysts such as Cu(II), Co(II) and Ag(I) were determined. The reaction ra te at 373K was found to be 2.0 order with respect to initial sulfite c oncentration and 0.5 order with respect to pO(2). The order was found to be 0.35, 0.25 and 0.175 with respect to Cu(II), Co(II) and Ag(I), r espectively. At higher concentrations, order of dependence for Cu(II) decreased to 0.05, while for Co(II) and Ag(I), no change in order was observed. Ni(II) does not influence the kinetics of sulfite oxidation. Activation energy was found to be 21.27 kJ . mol(-1) in the absence o f metal ion, where, as in the presence of Cu(II), Co(II) and Ag(I), th ese were found to be 25.83, 22.65, 23.25 kJ . mol(-1), respectively. T he catalytic activity was in the order Cu(II)>Co(II)>Ag(I).