Dual templates synthesis of Ti-containing hollownest-structure zeolite with efficiently catalytic activity

Ti-containing hollownest-structured zeolite (Ti-HSZ), constructed by the highly intergrowth of MWW lamellar crystals, has been proven to show excellent catalytic performance in the epoxidation of alkenes due to its highly exposed Ti catalytic active sites and unique hollownest morphology. However, up to date, only piperidine is reported to act as the structure directing agent of MWW crystalline phase for the formation of Ti-HSZ, which has limited its application in a wider range. In this work, Ti-HSZ has been successfully synthesized by using dual templates, including hexamethyleneimine as main template and dicyclohexylamine (or piperidine) as secondary template. Systematical experiments, including composition of synthetic gel, rotation rate of autoclave, and time of crystallization, have been conducted to explore the optional synthesis conditions of Ti-HSZ catalyst with high catalytic performance. It is found that, compared with HMI as solely template, the usage of dual templates HMI/PI or HMI/DCHA is important for the synthesis of Ti-HSZ material, which has important influence on its catalytic performance. In addition, the ratio of main template and secondary template also plays an important role on the catalytic activity of Ti-HSZ catalyst. Moreover, Ti-HSZ material prepared by dual templates owes good recycling stability. This work provides a new route to synthesize Ti-HSZ materials with high catalysis activity.