Studies on vanadium incorporation in AFI type molecular sieves

974-982Vanadium aluminophosphatcs (VAPO-5) and vanadium silicoaluminophosphatEs (VAPSO-5) have been synthesized with different vanadium and silicon contents using tripropylamine (TPA) and hexamethyleneimine (HEM) as templates. A larger incorporation of V takes place when HEM is used. The studies reveal that vanadium replaces both phosphorous and silicon. The VAPO-5 and VAPSO-5 samples synthesized using hexamethyleneimine have been characterized by XRD, SEM, TG/DTA, FT-IR, UV-vis., ESR, and cyclic voltammetry. About three fourth of the vanadium in the samples are found to be present in a tetrahedral co-ordination and the rest in square pyramidal or distorted octahedral co-ordination. The catalytic activities of the samples in the oxidation of toluene with tertiary butyl hydroperoxide and acetalization of benzaldehyde are presented