Incorporation of titanium into polymorph C for catalytic epoxidation of cyclohexene

Abstract

Incorporation of titanium into the framework of polymorph C of zeolite beta was attempted in a hydrothermal system using different titanium precursors of various contents in the synthesis gel. Samples were characterized using X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), inductive-coupled plasma-atomic emission spectrometer (ICP-AES), X-ray photoelectron spectroscope (XPS), and X-ray absorption near edge structure (XANES) techniques. Characterization results revealed that the incorporation of titanium into the framework of polymorph C can be achieved using Ti(NH4)2F6 as the titanium precursor without significantly affecting the crystalline structure of polymorph C. The sample synthesized with a Si/Ti molar ratio of 20 was found to possess the highest catalytic activity while the sample synthesized with a Si/Ti molar ratio of 5 was observed to display the highest selectivity in the epoxidation of cyclohexene. © 2009 Elsevier Inc. All rights reserved.