KINETIC MECHANISM OF REACTIONS OF CARBON-TETRACHLORIDE WITH TT-NIOBIUM OXIDE AND NIOBIUM PHOSPHATE

The rate of reaction of CCl4 with lattice oxygen atoms of the TT-phase niobium oxide (TT-Nb2O5) at 453 K was limited by the diffusion of CCl 4 through the layer of a solid reaction product, NbOCl3, formed around the outer surface of niobium oxide. This contrasts to the reaction oc curring on the amorphous niobium phosphate in which an inner niobium p hosphate participates in the reaction leading to the complete oxidatio n of CCl4 to CO2. For the reaction of CCl4 on TT-Nb2O5 at temperatures above 573 K, the chemical reaction occurring on the surface of the ni obium oxide controls the decomposition rate due to the disappearance o f the layer of NbOCl3 by its sublimation.