Hydrothermal Synthesis of Titanium Silicalite-1 Structurally Directed by Hexamethyleneimine

Abstract

Titanium silicalite-1 (TS-1) with the MFI topology has been synthesized successfully in the absence of alkali metal ions with the cooperative effects of active seeds and the structure-directing agent hexamethyleneimine (HMI). The physicochemical properties and structures of the products were characterized by various techniques. The coexistence of HMI and primary and/or secondary building units of the MFI structure in the synthesitic gels was essential for the nucleation and crystallization of TS-1. The nature and preparation conditions of the seed precursors had a great influence on the crystallization process and the incorporation of titanium atoms into the framework. It was found that a synergistic effect between HMI and the precursor seeds led to the full crystallization of TS-1. Other synthesis parameters such as boron addition, silicon source, and crystallization time were also investigated. Moreover, the present synthesis system is also applicable to the preparation of other MFI analogues.