SYNTHESIS AND PHYSICOCHEMICAL CHARACTERIZATION OF ZSM-5 METALLOSILICATE ZEOLITES PREPARED BY ISOMORPHOUS SUBSTITUTION PROCESS

Abstract

Metal ions-containing ZSM-5 materials were prepared by isomrphous substitution of purely ZSM-5 using different metal ions, namely Co(II), Ni(II) and Cu(II). The metal modified ZSM-5 samples were synthesized hydrothermally in the presence of tetrapropyl ammonium bromide (TPABr) as the template and n-propyl amine (n-PrNH2) as the mobilizing agent. The structure, morphology, particle-size distribution, surface texture and acidity of these materials have been investigated and compared with ZSM-5 prepared by direct hydrothermal synthesis. The apparent effect of the substitution of Al by Co(II) ions on the crystal size results in a structural arrangement of the gel during aging-favoring nucleation.Thesurfacearea, degree of crystallinity and particle size of Co/ZSM-5 increase at the expense of pore radius, though Ni(II) and Cu(II) ions substituted ZSM-5 cause lesser effects. The M/ZSM-5 catalyst in the presence H2O2/UV is an active system for the oxidative color removal of Direct blue-1 in aqueous heterogeneous suspensions with a very low M(II)/substrate ratio. The high phase heterogeneity of Co/ZSM-5 catalyst account for the increased values of the activity than the corresponding Ni/ and Cu/ZSM-5 ones.