Properties of [Ti,Al]-beta with different titanium content

Crystallization curves of [Ti,Al]-Beta were obtained from reaction mixtures having Si/Ti ratios between 20 and 125 and Si/Al approx. 200. It was observed that practically all aluminum is incorporated into the solid during the first hours of reaction, whereas titanium and silicon are continuously incorporated. Increasing Ti content in the reaction mixture results in an increase in particle size, indicating that the presence of Ti reduces the nucleation rate. X-ray diffraction and diffuse reflectance spectra show that when the Ti content is less than 4% of the tetrahedral atoms, this element is incorporated in the sieve framework in isolated form. (C) Elsevier Science Inc. 1997.