Zeolite titanium beta: A versatile epoxidation catalyst. Solvent effects

The essentially aluminum-free titanium containing analogue of zeolite beta was synthesized using di(cyclohexylmethyl)dimethylammonium (DCDMA) as the template. The titanium zeolite beta was found to exhibit Bronsted acidic properties when alcohols were employed as the solvent, which is explained by the Lewis acid character of the titanium site, which on coordination of an alcohol yields a mild Bronsted acid site. The use of alcohol/acetonitrile mixtures as the solvent showed a clear maximum in activity in 1-octene epoxidation, depending on the type and amount of alcohol used. A catalytic species is proposed in which an alcohol as well as a hydroperoxo group is coordinated to a framework connected titanium atom.