Vanadium pentoxide, isotopic oxygen

B g. 3. The effect of isotopic composition of molecular oxygen on rate of exchange with oxygen of vanadium pentoxide after Jirff and Novakova (21). 

Fio. 4. Activity of vanadium pentoxide promoted with sulfates of alkali metals in respect to isotopic exchange in molecular oxygen. 

For this reaction the comparison of activity of various oxides cannot be carried out because most of them transform in reaction conditions into nonactive sulfates. The exception is vanadium pentoxide whose activity strongly increases when promoted by sulfates of alkali metals. As is clear from Fig. 15, the catalytic activity of vanadium catalysts, with the addition of different sulfates of alkali metals, changes identically in reactions of isotopic exchange in molecular oxygen and in the oxidation of sulfur dioxide. 

Roiter and co-workers have investigated with the aid of 0 , the participation of vanadium pentoxide oxygen in reactions of oxidation. In the oxidation of naphthalene (51) on vanadium pentoxide enriched with 0 , no decrease of the content of this isotope in catalyst was discovered within the accuracy of measurements ( 10%). If all oxygen required for oxidation of naphthalene was removed from the vanadium pentoxide surface and the intermixing of oxygen inside catalyst were full, then the final content of in vanadium pentoxide should decrease to up to 10-30% of the original content. The authors have concluded from this... 

When reaction of oxidation of sulfur dioxide (32) is realized on vanadium pentoxide enriched with 0 , one could observe the decrease in the content of this isotope in catalyst, but it is still not a greater decrease than in the exchange with oxygen in similar conditions. If the oxidation of sulfur dioxide proceeded at the expense of surface oxygen of vanadium pentoxide then the extraction of from catalyst should be considerably accelerated in the process of reaction. The doubt as to the insufficient mobility of catalyst oxygen, in this case, due to high temperature of experiments (500-610°) is out of the question. The data obtained by Kasatkina for the transition in the process of catalysis of O - from vanadium pentoxide into the formed sulfur trioxide are in some contradiction to these results. 

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