SHAPE-SELECTIVE CATALYTIC BEHAVIORS OF NICKEL ION-EXCHANGED LAYERED POTASSIUM NIOBATE

The alcohol decomposition and olefin hydrogenation on the hydrogen-tre ated Ni ion-exchanged (exchange degree, 30%) potassium niobate (Ni-K4N b6O17) were performed. Formation of propene from i-propanol on Ni-K4Nb 6O17 was much smaller than that observed on bulk Nb2O5, while the olef in yields from ethanol and n-propanol were almost the same on both cat alysts. The 1-butene hydrogenation did not proceed on Ni-K4Nb6O17, whe reas propene hydrogenation took place rapidly on the same catalyst at 80-degrees-C. The formation of the acid sites and Ni metallic sites by hydrogen treatment at 300-degrees-C was proposed by using temperature -programmed reduction (TPR) and extended X-ray absorption fine structu re (EXAFS). These results suggest that H-2-treated Ni-K4Nb6O17 acts as a shape selective acid- and metal-catalyst at suitable reaction tempe ratures.