Mesoporous Ti-SBA-15 has been postsynthesized by the titanation of pure silica SBA-15 in glycerol with the assistance of quaternary organic ammonium hydroxides, and has been extensively characterized by various techniques to investigate the mesostructural and catalytic properties, and the chemical nature of the incorporated Ti species, in comparison with those of Ti-MCM-41. To incorporate tetrahedral Ti species into the silica walls of SAB-15, the titanation needs to be carried out at elevated temperature and using an optimum amount of organic ammonium hydroxide. Ti-SBA-15 samples with a Si/Ti ratio ranging from 376 to 16 are successfully prepared with the retention of hexagonal mesostructure by elaborately conducting the titanation. The nature of the Ti species depends greatly on the Ti loading. At Si/Ti ratios higher than 50, the Ti species are mainly tetrahedrally coordinated in isolated states, while poorly dispersed Ti species of octahedral coordination are formed at higher Ti incorporation levels; however, no anatase phase is formed in all cases. The IR band at 948cm-1 due to Si-O-Ti bonds can be used to characterize the tetrahedral Ti species in mesoporous materials, but the techniques of dehydration or trimethylsilylation should be adopted to get rid of the influence of silanol groups. In an actual catalytic reaction, Ti-SBA-15 exhibits not only extremely high thermal stability but also outstanding endurance against Ti leaching not observed for Ti-MCM-41. Ti-SBA-15 is thus presumed to be a promising liquid-phase oxidation catalyst.

The catalytic properties of Ti-MWW in the epoxidation of linear cis/trans-alkenes with hydrogen peroxide has been studied extensively, and a mechanistic investigation into its unique trans-selectivity has been carried out by comparing with TS-1 and Ti-Beta. Ti-MWW exhibits a singularity never observed on conventional titanosilicates, that it selectively epoxidizes the trans-isomer to give a selectivity of ca. 80% for corresponding trans-epoxide from an alkene mixture with a cis/trans ratio of 50:50. The trans-selective nature of Ti-MWW is affected neither by the reaction conditions nor by the kinds of alkenes. Ti-MWW retains the stereochemistry for both the substrates and the epoxides during the epoxidation reactions. Liquid-phase adsorption and the epoxidation reaction with bulky organic oxidant and position-selective poisoning reagents have revealed that the unique trans-selectivity of Ti-MWW originates mainly from its sinusoidal 10-MR channels.

B-free titanosilicate with the MWW topology, Ti-MWW, has　been successfully prepared from its highly siliceous analogue　through structural interconversion and simultaneous titanium incorporation in the presence of piperidine or hexamethyleneimine.

A novel titanosilicate with MWW topology, Ti-MWW, exhibits a behavior not observed on other titanosilicates such as TS-1, TS-2 and Ti-beta, in that it selectively epoxidizes trans isomers from a mixture of cis/trans alkenes with retention of stereochemistry.

A novel titanosilicate with MWW topology, Ti-MWW, has been prepared by an acid treatment on a corresponding lamellar precursor which is hydrothermally synthesized with the coexistence of boron and titanium using piperidine (PI) or hexamethyleneimine (HM) as a structure-directing agent. TheMWWprecursor can be synthesized to have a Si/Ti ratio as low as 10 when the Si/B ratio of the gel is maintained at 0.75. Both the materials synthesized using PI and HM exhibit the crystal form of thin platelets, while the latter shows a larger crystal size. Besides the tetrahedral Ti species, the precursor always contains the octahedral Ti species showing a UV-vis band at 260nm, regardless of the Ti content. Calcination of the precursor results in a partial condensation of the octahedral Ti species to form the anatase phase, which is hardly removed by the acid treatment. MWW-type titanosilicate nearly free of both anatase and boron, however, is successively prepared by a cyclic treatment on the lamellar precursor, that is, an acid treatment, subsequent calcination, and a further acid treatment. After evacuation at 773K, the titanosilicate thus prepared shows a characteristic IR band at 960cm-1 not observed for the Ti-free sample. The intensity of the 960 cm-1 band increases linearly with the Ti content up to a level corresponding to Si/Ti) 40, indicating the limitation of incorporating Ti into the framework of MWW by the present method.