Synthesis and characterization of ferrisilicate zeolite of pentasil group

Synthesis of ‘ferrisilicate’ a crystalline zeolite containing iron and silicon in the zeolite lattice positions and possessing remarkable molecular sieving properties and catalytic activity has been reported. The ferrisilicate was characterized by XRD, i.r., t.g./d.t.a., SEM, XPS, EPR, chemical analysis and water and hydrocarbon sorption measurement. The infrared spectra of ferrisilicate zeolite, in the mid infrared region indicated that Fe3+ ions were present in the zeolite framework. The presence of a signal at g = 4.3 in the EPR spectra was assigned to Fe3+ ions isomorphously substituted in the tetrahedral positions. The fact that Fe3+ ions in ferrisilicate zeolite were in trivalent state and indeed situated at the lattice sites was confirmed by XPS study. The catalytic activity of the ferrisilicate zeolite for xylene isomerization was lower than for its aluminium analogue, probably due to low concentration as well as the strength of strong acid sites.