Large pore Ti-zeolites and mesoporous Ti-silicalites as catalysts for selective oxidation of organic sulfides

The oxidation of bulky thioethers has been carried out on Ti-Beta and Ti-MCM-41 catalysts, using H2O2 and t-butyl hydroperoxide (TBHP) as oxidants. The intrinsic activity of Ti-Beta was higher than that of Ti-MCM-41 for the oxidation of methyl phenyl sulfide which can penetrate in the pores of Beta, while in the case of the larger isopentyl phenyl sulfide, which diffuses more slowly in Ti-Beta zeolite, Ti-MCM-41 gives a larger activity. Ti-Beta is able to perform better for the more demanding oxidation of sulfoxides to sulfones giving, therefore, higher selectivities to sulfones than Ti-MCM-41. Similar results were obtained when using either H2O2 or TBHP as oxidants. However, the sterical effects were enhanced when TBHP was used as oxidant.