Titanium containing molecular sieves as catalysts for selective oxidation reactions with hydrogen peroxide

Titanium silicalite (TS-1) is known to be a highly-efficient and selective redox molecular sieve that has been found to catalyze a range of synthetically useful oxidation reactions with hydrogen peroxide under mild conditions. Among these reactions which are often influenced also by the shape-selective properties of the Ti-containing molecular sieve are olefin epoxidation, the oxidation of alcohols to carbonyl compounds, aromatic hydroxylations and ammoximation of cyclohexanone to cyclohexanone oxime. A critical review on the present literature on TS-1 catalysts and further Ti-containing molecular sieves is given mainly focused on the questions connected with the identification of the catalytic active titanium species and the mechanism of some of the reactions. Therefore, the procedure of the synthesis of TS-1 as well as the results obtained from the most of the physico-chemical investigations are analyzed. There are no final correlations to realize between the parameters of the synthesis, the results of characterization and the catalytic properties of TS-1.