ACIDIC AND CATALYTIC PROPERTIES OF NIOBIUM PENTAOXIDE.

Abstract

The surface acidic property of Nb//2O//5 multiplied by (times) nH//2O and its catalytic activities for the isomerization of 1-butene, the polymerization of propylene and the dehydration of 2-butanol were examined. The activities were high on Nb//2O//5 multiplied by (times) nH//2O evacuated at moderate temperatures (400 - 500 degree C) in all of the reactions and decreased drastically on evacuation at higher temperatures (400 - 500 degree C). The surface of Nb//2O//5 multiplied by (times) nH//2O showed a strong acidic character (H//o less than equivalent to -5. 6) even after heating in air at 100 degree C, but the strong acid sites disappeared on heat treatment at higher temperatures. The active sites on the cataylsts heat-treated at moderate temperatures were ascribed mainly to Broensted acid sites on the basis of the IR study of adsorbed pyridine.