Synthesis of titanium-containing mesoporous molecular sieves with a cubic structure

Abstract

Recently a new family of mesoporous molecular sieves named “M41S” was discovered by the researchers at Mobil. The M41S family is classified into several members: MCM-41 (hexagonal), MCM-48 (cubic), and other species. These materials have uniform pore, and the pore size are able to be tailored in the range 16Å to 100 Å through the choice of surfactant, auxiliary chemicals, and reaction conditions. Because of the favorable uniformity and size of the pore, synthesis and utilization of mesoporous materials have been investigated by numbers of researchers. Some circumstantial reports about the synthesis have been made. Adsorption property and catalytic activity of silica-based and Al-containing MCM-41 have also been reported. Ti-, V-, B-, Fe- and Mn-substituted MCM-41, and Ti-substituted hexagonal mesoporous silica (Ti-HMS) have also been synthesized. These Ti- and V-substituted mesoporous molecular sieves pioneered the potential to oxidize bulky molecules which cannot enter into the micropores of zeolites such as TS-1, TS-2 and Ti-beta. MCM-48, characterized by a three-dimensional channel system, may have several advantages over MCM-41 with a one-dimensional channel system when applied to catalytic reactions: for instance, the three-dimensional pore system should be more resistant to blockage by extraneous materials than the one-dimensional pore system. This chapter reports the synthesis of Ti-MCM-48 and its use as a catalyst for epoxidation of alkenes and unsaturated alcohols. The effects of gel composition and the gel preparation method on the structure of mesoporous materials are also reported in the chapter.