AN HY-HZSM-5 ZEOLITE SYSTEM MODIFIED WITH NICKEL

Zeolite systems NH(4)NaY(x)ZSM-5(100-x) (1) and (HNaY(x)ZSM-5(100-x))( 3) (II) exchanged or impregnated with Ni(NO3)(2) solution were investi gated with IR, XRD and MAS NMR spectroscopies. Zeolite mixtures I, exc hanged with Ni2+, showed only slightly better hydrothermal stability ( lower degree of dehydroxylation). Zeolite mixtures II stabilized and e xchanged with Ni2+ were stable to water vapour under test conditions. Samples I and II impregnated with Ni(NO3)(2) solution underwent far-re aching dehydroxylation by the first heating, but the same samples trea ted with ammonia water preserved the OH groups, because in the case NO 3- anion did not act as a dehydroxylating agent. The final pH by impre gnation is an important factor in obtaining catalysts with Ni having a high concentration of Bronsted acid sites.