DECOMPOSITION OF NITROUS OXIDE ON RARE-EARTH SESQUIOXIDES AND RELATED OXIDES

The decomposition of N2O, catalyzed by 15 M2O3 oxides, including 11 of the rare-earth-C crystal structure, is represented with reasonable accuracy at 10-20 cm by the equation -[ d(N2O) dt] = K[ (N2O) (O2) 1 2], where the parentheses represent gas pressures. The desorption of molecular oxygen is an important rate-determining step: this is also the rate-determining step in the isotopic exchange between O2 gas and the oxide surface, by a dissociative process on the surface, which has recently been measured for this series of oxides. A strong correlation exists between both A0 and E in the Arrhenius expression for the exchange reaction and the corresponding functions for N2O decomposition. Since these functions vary in a regular manner with lattice parameter (for instance the molecular volume or the nearest M-O or nearest O-O distances) for the exchange reaction so too do A0 and E for the decomposition of N2O. No correlation is found for such properties as the magnetic moment of the M3+ ion which do not vary regularly with the lattice parameter. © 1969.