Abstract
In the research, triblock structure directing agent (SDA) N3-(PO)5-N3Br6 with hydrophobic middle part and hydrophilic ends was applied to the synthesis of hierarchical silicalite-1 and TS-1. In addition, Ti species were grafted on the surface of silicalite-1 for propylene epoxidation. Compared with conventional MFI zeolites, materials obtained by using tri-block as SDA featured high BET surface area and hierarchical structure. In the synthesis of hierarchical TS-1 prepared by using the SDA N3-(PO)5-N3OH6, the resulted material showed considerable amount of tetrahedral Ti species, but the morphology was irregular. After selectively removing the hydrophobic part of SDA by acid treatment the hierarchical silicalite-1 could exposed the external surface of nanosheets, which was grafted with titanocene dichloride to form tetrahedrally coordinated species . We deposited gold nanoparticles onto the two hierarchical titanium-containing zeolites and used them as catalysts for propylene epoxidation. Although both samples prepared by post-grafting and direct hydrothermal synthesis did not improve the conversion of propylene compared to conventional zeolite, they exhibited greater catalytic stability in 500 minutes.