The shape selectivity in the liquid-phase hydroxylation of aromatic hydrocarbons with hydrogen peroxide has been studied on two kinds of titanosilicate, the large-pore Ti-M with MOR structure and medium-pore TS-1 with MFI structure, and the liquid-phase diffusion of aromatics into both catalysts was compared in the presence of H2O and H2O2 to clarify the origin of the shape selectivity. The hydroxylation rate on TS-1 decreased monotonically with increasing molecular size in the order benzene>toluene. ethylbenzene>cumene, while Ti-M showed the maximum rate for toluene hydroxylation. The apparent diffusivity of aromatics was lowered roughly by 1 order by adding H2O2 to H2O solvent for both titanosilicates but was not affected for their Ti-free derivatives, mordenite and silicalite-1. The reduction in diffusion rate in the presence of H2O2 was more pronounced for TS-1 and for Ti-rich samples. It is concluded that a bulky Ti peroxo species (Ti-OOH) formed by the interaction of Ti site with H2O2 mainly causes a transition-state shape selectivity in the hydroxylation of bulky aromatics in titanosilicate/H2O2 systems.

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.

Highly effective formation of cyclopentanol through the liquid-phase hydration of cyclopentene has been attempted on various zeolites catalysts. MCM-22 zeolite was the most selective catalyst, which actively converted cyclopentene to cyclopentanol with a selectivity up to 99%. The effects on the hydration of catalyst preparation method, reaction atmosphere and temperature have been investigated for the MCM-22 catalysts. On the basis of the effect of reaction atmosphere, the mechanism of liquid-phase cyclopentene hydration was proposed. The thermodynamic equilibrium between cyclopentene and cyclopentanol was suggested to control greatly the cyclopentene conversion. The cyclopentene conversion was increased to 10% by increasing the water/cyclopentene ratio. Poisoning using organic amines with different molecular sizes revealed that the hydration occurred mainly in the 10-membered ring channels of MWW structure, which had an elliptic aperture smaller than that of MFI structure, exhibiting a significant shape selectivity by suppressing the etherification cyclopentanol.

The catalytic properties of Ti-MWW in the epoxidation of allyl alcohol (AAL) with hydrogen peroxide to glycidol (GLY) have been studied in detail by a comparison with those of TS-1 and pure silica Ti-Beta, and mechanical considerations have been given to the relation between the catalytic performance and the structural, acidic, and hydrophilic/hydrophobic nature of titanosilicates. Ti-MWW catalyzed the AAL epoxidation more actively and selectively than TS-1 and Ti-Beta in the presence of H2O or MeCN, and exhibited a conversion of 95% for AAL and a selectivity of 99% for GLY when the AAL epoxidation was carried out at 333K for 30min and at 12wt% of catalyst to substrate. Ti-MWWproved to be a reusable and sustainable catalyst as it stood up to Ti leaching and maintained the catalytic activity and the product selectivity in the reaction-regeneration cycles. The acidic character due to the boron framework was very weak, and thus contributed negligibly to the solvolysis of GLY. The AAL epoxidation proceeded mainly within the intralayer sinusoid 10-MR channels which supplied more steric fitness to the substrate molecules than the tunnel-like channels of TS-1 ad Ti-Beta. Ti-MWW was more hydrophilic than TS-1, but much more hydrophobic than Ti-Beta. The hydrophilicity of Ti-MWW was presumed to derive mainly from the defect sites due to the incomplete dehydroxylation between the layers and partially as a result of deboronation. The sinusoidal 10-MR channels serving as the reaction space for the AAL epoxidation were considered to be hydrophobic, thus rendering the Ti-MWWcatalyst applicable to the substrates and solvents, both of a polar nature.

A new ferrisilicate molecular sieve with the MCM-22 structure is synthesized in Al-free form and exhibits low activity as a solid-acid catalyst and significant activity for the selective catalytic reduction of NO with NH3.