Synthesis of Zeolite Beta by the Vapour-Phase Transport Method Using Tetraethylammonium Bromide as the Organic Template

Abstract

Abstract The synthesis of zeolite beta by the vapour-phase transport method using tetraethylammonium bromide (TEABr) as a cheap organic template was studied. With TEABr being solid state at room temperature, the materials were mixed directly, and the preparing xerogel was not necessary. The products were characterized using X-ray diffraction, scanning electron microscopy, and infrared spec-troscopy. The crystallization process of zeolite beta was investigated. The results indicated that zeolite beta can be synthesized when the ratio of n(SiO2)/n(Al2O3) was 15–200, n(NaOH)/n(Al2O3) was 0.35–0.55, and n(TEABr)/n(SiO2) was more than 0.12. The solvent of the synthesis system was a little, which just came from vapour. The concentrations of TEA+ and Na+ were high, and the crystallization speed was fast. At 423 K, the crystallization process was completed after 10 h. The alkalinity of the system has a very important impact on the crystallization process, affecting crystallization speed and particle size. Too long time and too high temperature were disadvantageous to the crystallization of zeolite beta. The zeolite beta synthesis followed the liquid phase synthesis mechanism. At the initial crystallization stage, the morphology of the products was ellipse, and at the last crystallization stage, the products were transformed into polyhedron. The particle sizes were mostly 0.3 μm and the distribution range of sizes was narrow. The vapour-phase transport method was more promising and economical than the traditional hydrothermal method, and it can simplify the synthetic process and reduce the cost.