A STUDY ON THE STRUCTURE AND THERMAL-PROPERTY OF CU2-EXCHANGED ZEOLITE A( AND NH4+ ION)

The frameworks of (Cu(NH3)3OH+)x(NH4+)12-x-A.zH2O which were prepared by the ion-exchange of zeolite A with ammoniac cupric nitrate solution are more stable than those of CuxNa12-2x-A obtained by the ion exchan ge with aqueous cupric nitrate solution are more stable than those of CuxNa12-2x-A obtained by the ion exchange with aqueous cupric nitrate solution. An energetic calculation was made on the relatively stable ( CuOH+)2(NH4)10-A.2H2O prepared by the partial evacuation of (Cu(NH3)3O H+)2(NH4)10-A.zH2O. The mean stabilization energies of water, OH-, and NH4+ ions are - 30.23 kcal/mol, -60.24 kcal/mol, and -16.65 kcal/mol, respectively. The results of calculation were discussed in terms of f ramework stability. The (Cu(NH3)3OH+)2(NH3+)10-A.zH2O zeolite shows tw o step deammoniation reactions. The first deammoniation around 210-deg rees-C (third DSC peak) was attributed to the decomposition of [Cu(NH3 )3OH)]+ ion and the second one around 380-degrees-C (fourth DSC peak) was ascribed to the decomposition of NH4+ ion. The activation energies of the first and second deammoniation reactions were 99.75 kJ/mol and 176.57 kJ/mol, respectively.