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A synthesis strategy has been developed for the hydrothermal crystallization of microporous vanadium aluminosilicate with BEA structure. Influence of temperature, time, vanadium source and addition of alkaline metal ions on the synthesis was evaluated. XRD SEM, ICP-AES, framework IR, UV-Vis DRS, ESR and oxidation-reduction were applied to characterize these materials. It revealed that, by using vanadyl acetylacetonate as vanadium source, vanadium could be effectively incorporated into zeolite beta framework. Vanadium ions were thermally stable and atomically dispersed in zeolite beta lattice. V(IV) was the predominant oxidation state for vanadium in the as-synthesized vanadium aluminosilicate beta, while V(V) was the sole oxidation state after calcination in air. Tetrahedral or square-pyramidal coordinated V(IV) and V(V) were found over the as-synthesized vanadium aluminosilicate beta, which were incorporated into the zeolitic lattice and were stable enough against extraction with NH4Ac solution. The framework vanadium ions showed a good reversibility in the V(IV)↔V(V) redox process.

Nano-sized copper silicalite with MEL structure has been hydrothermally synthesized for the first time under static conditions. The physicochemical property of this novel material was characterized by means of XRD, TEM, FT-IR, ESR, TG-DTA and NH 3 -TPD techniques. The results revealed that the as-synthesized copper silicalite was highly thermally stable owing to its siliceous nature. This monophased crystalline material was quite uniform in size around 1×10 −8 m. Cupric ions were highly dispersed and mainly resided in distorted tetrahedral and square pyramidal environments before and after calcination. However, most of the incorporated copper ions left from the framework upon calcination and NH 4 Ac extraction, which resulted in a high density of lattice defect in the framework. Incorporation of cupric ions into the silicalite framework during crystallization also resulted in a weak acidity on this material.

Publisher Summary This chapter presents a novel method for the synthesis of chromium aluminosilicate with BEA structure. A novel method has been developed for the hydrothermal synthesis of zeolite beta with high chromium content and low aluminum content under static conditions. The crystalline phase and spectroscopic property of this material are characterized by means of X-ray diffraction (XRD), infrared (IR), electron spin resonance (ESR), and scanning electron microscopy (SEM). The results reveal that part of the chromium ions are incorporated into the zeolite framework during crystallization. Using tris(acetylacetonato) chromium(III), [Cr(C5H7O2)3], as a chromium source, chromium/silicon (Cr/Si) molar ratio can be up to 1/48 in the calcined and ion-exchanged sample. The chromium aluminosilicate exhibit a high oxidative activity in the presence of dilute hydrogen peroxide (H2O2).