THF-FER (ferrierite) zeolite was synthesized in the reactant system of tetrahydrofuran (THF)-Na-20-Si0-2-AlO-3-H2O. H-FER with very low content of sodium was prepared by two means, ion-exchange-detemplate by calcination ( I ) and detemplate by calcination-ion-exchange ( II ) . The structural stability and the effect of de-aluminum in the framework of H-FER zeolite were investigated by XRD,~ 27A1 and Si MAS NMR as well as the adsorption of nitrogen at 77 K. The framework of H- FER zeolite exhibits very high stability, even calcined at 1273 K for 2 h and treated at 1073 K for 10 h in air flow saturated with water vapor. The H-FER zeolite prepared by means of ( II ) includes the treatment with saturated water vapor at high temperature, Si(2Al) in the framework of H-FER zeolite was easily removed from the framework, whereas the content of Si(lAl) was relatively unchanged. The perfection and the opening of the porous structure for H-FER zeolite still remain after thermal and hydrothermal treatment at high temperatu

Key words: ZEOLITE, TETRAHYDROFURAN, CRYSTAL STRUCTURE, STABILITY, NMR, HYDRO-THERMAL REACTION, SODIUM OXIDE, SILICON OXIDE, ALUMINIUM OXIDE, WATER