Liquid-phase oxidation process using titanosilicate catalysts with mordenite structure.

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Titanosilicate with mordenite structure was prepared by Atom-planting method using dealuminated mordenite and TiCl_4. A strong absorption at 220 nm in UV spectra indicated tetrahedral coordination of Ti species. An absorption band also appeared at 963 cm^<-1> in IR spectra. Its absorbance was in proportion to the concentration of Ti. This was an evidence of framework incorporation of all the Ti species. A TiCl_4 reacts with a defect site, hydroxyl nest, to form four Ti-O-Si bonds.Liquid-phase hydroxylation of toluene with hydrogen peroxide was carried out on titanosilicate. Cresol isomers were produced with selectivity higher than 99%. Turnover number (TON) increased with increasing hydrophobisity of catalyst by dealumination. Benzene, ethylbenzene and cumene gave almost the same TON as toluene, while TON in the hydroxylation of t-butylbenzene was much lower. On MFI-type titanosilicate, however, only benzene was reacted with the same TON ; the others showed much less reactivity. It was revealed that titanosilicate with mordenite structure is effective catalyst for the hydroxylation of large aromatic molecules compared with that with MFI structure. The framework Ti species in titanosilicate catalyzes ammoximation of ketones with ammonia and hydrogen peroxide, because absorbance of the 963 cm^<-1> IR band was in proportion to the reaction rate of ammoximation. Dealumination of the parent mordenite caused the increase in oxime selectivity as well as activity through the increase in hydrophobic nature of the catalyst.