DAMAGE DISTRIBUTION AND WAVE-GUIDE FORMATION IN CU IMPLANTED LINBO3

The influence of sodium and phosphorus on the oxidation state of vanadium and molybdenum species and on the redox process of a V-Mo-O catalyst was studied by X-ray photoelectron spectroscopy and thermal gravimetric analysis. Why the sodium doping increased activity and the phosphorus doping improved selectivity in the V-Mo-O catalyst is explained. The sodium ions in the V-Mo-O catalyst seem to decrease the dissociation energy of adsorbed oxygen molecules and therefore make it favorable to the reoxidation of reduced molybdenum and vanadium species; the sodium ions in the V-Mo-O catalyst also weaken the M=O bonds, and therefore promote the vanadium species to be reduced. In other words, the sodium doping promotes the redox process of the V-Mo-O catalyst. The phosphorus ions in the V-Mo-O catalyst tend to keep the reduced vanadium species in a V4+ state and prevent the vanadium species from being significantly reduced, which may be an important reason for improving the selectivity of the V-Mo-O catalyst. In addition, both the sodium and the phosphorus doping in the V-Mo-O catalyst seem to be also helpful in diffusing lattice oxygen.