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Tert-butylation of phenol with different alkylating agents, i.e., iso-butylene, MTBE and tert-butyl alcohol (TBA), was studied over various molecular sieve catalysts. It revealed that the reactivity followed the order of Hβ > HY > HZSM-5 ≈ HAlMCM-41 in the catalysts and of iso-butylene > MTBE > TBA in the alkylating agents. The selectivity of the product depended not only on the nature of the catalysts but also on the reaction conditions. p-TBP is a more favorable primary product than o-TBP owing to its less steric hindrance in the transition state, and the amount of o-TBP is always trace in the product. o-TBP may play a less important role than p-TBP in the formation of 2,4-DTBP.

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.

The shape-selective alkylation of phenol with isobutylene to para-tert-butyl phenol (p-TBP) and 2,4-di-tert-butyl phenol (2,4-DTBP) has been studied over zeolite beta. The influence of reaction parameters as well as thermal treatment and pyridine poisoning of zeolite beta on the tert-butylation of phenol was evaluated. The surface acidity of the catalysts was characterized by means of NH3-TPD and pyridine adsorbed IR (Py-IR) techniques. It revealed that the fresh H-form zeolite beta was highly active and shape-selective in alkylation of phenol with isobutylene. p-TBP and 2,4-DTBP were the predominant alkylation products. Reaction temperature, reactant molar ratio, space velocity and surface acidity showed different impact on the alkylation. High temperature calcination of zeolite beta benefited the selective formation of 2,4-DTBP at the expense of p-TBP. In the present work, adsorption of pyridine on zeolite beta at low content up to 3 wt% resulted in little change in the phenol conversion and the product distribution, while at high content the phenol conversion and the p-TBP selectivity decreased. Medium and weak acid sites were the active centers for the alkylation of phenol with isobutylene. Alumina as bondant at a content up to 30 wt% showed almost no effect on the conversion of phenol.

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).