M. Nagai et al., TPD AND XRD STUDIES OF MOLYBDENUM NITRIDE AND ITS ACTIVITY FOR HYDRODENITROGENATION OF CARBAZOLE, Catalysis today, 43(3-4), 1998, pp. 249-259
The nitrided MoO3 catalysts formed using two kinds of treatment with e
ither NH3 or He after nitriding were studied by temperature-programmed
desorption and X-ray diffraction analyses. The catalysts were cooled
to room temperature in either flowing NH3 or He (NH or HE catalyst) af
ter nitriding at 773, 973 and 1173 K with NH3. The activities of the c
atalysts were determined during the hydrodenitrogenation of carbazole
at 573 K and 10.1 MPa total pressure. MoO2, gamma-Mo2N, and Mo metal w
ere mainly formed in the NH catalysts nitrided at 773, 973 and 1173 K,
respectively. Mo oxides and metals in the NH catalysts were nitrided
to gamma-Mo2N and beta-Mo2N0.78 With low crystallinity during TPD. The
surface area of the NH and HE catalysts nitrided at 773 K increased t
o 66 and 59 m(2) g(-1) maximum from 1.1 m(2) g(-1) of fresh MoO3, resp
ectively, but decreased as the nitriding temperature increased to 973
K and 1173 K. The HE catalysts per surface area were more active than
the NH catalysts for both the overall HDN reaction and hydrogenation,
and the 1173 K-nitrided catalysts were highest. On the other hand, the
NH catalysts were more active than the HE catalysts for C-N hydrogeno
lysis and the 973 K-nitrided catalyst showed a maximum activity for C-
N hydrogenolysis. (C) 1998 Elsevier Science B.V. All rights reserved.