Phase composition and catalytic properties of Ni-V oxide catalysts for dehydrotreatment of C9-aromatics.

The DTA, TG, DTG, XRD and IR techniques were employed to characterize the structure and phase composition of binary Ni-V oxide catalysts (0-100 mol.% NiO) prepared by coprecipitation from aqueous solutions of NH4VO3 and Ni(NO3)2 6H2O, followed by treatment of the precipitates obtained. The phase composition of nickel-vanadium samples calcined at 500C comprises both bulk phases of V2O5 and NiO (at NiO contents <= 75 and >= 75 mol.%, respectively) and nickel meta- and pyrovanades (~30-75 mol.% NiO). Besides that, at T > 500C, nickel orthovanadate is also appeared in nickelia-enriched samples (NiO >= 75 mol.%), its crystal structure being formed finally at T >= 700C. Catalytic activity of the NiO-V2O5 catalysts for ethylbenzene dehydrogenation has been found to be due to exclusively V2O5 phase (NiO<= 20 mol.%); other phases present in the NiO-V2O5 samples catalyze ethylbenzene cracking and dealkylation reactions mainly.