The behavior of modifying metallic ions Zn2+, Ga3+ etc. in HZSM-5 is studied with high-resoln. solid-state NMR using 129Xe, 29Si, 27Al as probes. Experimental results indicate that ion Ga3+ is located mainly on the exterior of HZSM-5 and cannot stabilize the framework, but ion Zn2+ exists inside the channel, replaces the proton's position and stabilizes the framework. Both ions Zn2+ and Ga3+ do not enter into the zeolites framework. The framework dealumination is in accordance with the following order: GaHZSM-5 > HZSM-5 > ZnHZSM-5 ?BaHZSM-5 x CaHZSM-5.

Key words: ZINC, CHEMICAL MODIFICATION, ADSORPTION, NMR SPECTROMETRY, THERMAL STABILITY, GALLIUM, SILICONE ISOTOPES, XENON ISOTOPE, CATALYTIC ACTIVITY, ALUMINIUM ISOTOPES