Mesoporous Ti-KIT-6 molecular sieves: Their catalytic activity in the epoxidation of cyclohexene

Titanium incorporated mesoporous KIT-6 molecular sieves with Si/Ti ratios 20, 50, 100, 150 and 200 were synthesized hydrothermally using triblock copolymer (Pluronic P123) as the structure directing template. The materials were characterized using XRD, BET, SEM, HR-TEM, FT-IR and UV-vis DRS. Their BET surface areas were in the range 675-780 m(2)/g. TEM images demonstrated highly porous network with well ordered arrangement of pores. Ti-KIT-6 with Si/Ti ratios 100,150 and 200 were found to contain both free TiO2 and framework Ti, whereas KIT-6 (20 and 50) contained only framework Ti. Their catalytic activity was evaluated in the epoxidation of cyclohexene with tert-butyl hydroperoxide (TBHP). Ti-KIT-6 (20 and 50) gave higher yield of cyclohexene oxide than others. This result revealed that the reaction is strongly influenced by framework titanium compared to non-framework one. The influence of solvent polarity on the epoxidation was also studied and it was found that the yield of cyclohexene oxide increased with the increase in the solvent polarity. (C) 2010 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.