A shape-selective catalyst for epoxidation of cyclic olefins: The nanoporous nickel phosphate VSB-5

27 FIELD Section Title:Heterocyclic Compounds (One Hetero Atom) Catalysis Center for Molecular Engineering,Korea Research Institute of Chemical Technology,Daejeon,S. Korea. FIELD URL: written in English.Nickel in the form of porous nickel phosphate VSB-5 has been used as a shape-selective catalyst for epoxidn. of cyclic olefins such as cyclohexene and cyclooctene using hydrogen peroxide. The VSB-5 showed high selectivity to cyclohexene oxide and cyclohexane diol, much higher productivity per catalyst wt. in the epoxidn. of cyclohexene, and high selectivity to cyclooctene oxide in the epoxidn. of cyclooctene. The VSB-5 behaved as a heterogeneous catalyst in the epoxidn. and can be used many times without structure degrdn., leaching of active nickel species, or significant activity loss. It has been concluded that the epoxidn. reaction with VSB-5 proceeds via a free-radical mechanism by taking into consideration a sharp activity loss in the presence of a radical scavenger, hydroquinone. The effect of radical scavengers with different mol. dimension on the catalytic activity also indicates the shape selectivity in the pores of VSB-5. [on SciFinder (R)