Synthesis and Catalytic Properties of a New Titanosilicate with the Lamellar Structure Analogous to Mww-Type Precursor

摘要

MWW-type zeolites are arousing the interest of researchers because of their unique crystalline structure. The aluminosilicate material (MCM-22) is a highly selective industrialized catalyst in benzene alkylation, while the titanosilicate analogue (Ti-MWW) proves to be more active than TS-1 and Ti-Beta for the epoxidation of linear alkenes with H_2O_2, also exhibiting a unique trans- selectivity in the epoxidation of geometric alkenes. Concerning the reactions of bulky molecules, a major advantage of MWW structure is expected to result from its supercages and side pockets. However, access to the supercages is seriously restricted by the distorted 10-membered ring (MR) openings when the three-dimensional MWW crystalline structure is formed upon clacination of its lamellar precursor. If the lamellar structure remains after the calcination, the active sites within the channels could be more accessible to bulky molecules, and consequently MWW zeolites would provide more opportunities to be applied to a wide variety of catalytic reactions in petrochemical and fine chemical industries. In this study, we report a new way to prepare such a novel catalyst by using the post-synthesis method.