Studies on catalytically active surface compounds. 11

Interaction of VOCl3 dissolved in CCl4 with silanol groups of Aerosil gives rise to reaction products, the Cl/V-ratio of which depends on thermal pretreatment of Aerosil and the amount of the vanadium fixed on the surface. Geometrically different arrangements of the silanol groups (centers) show kinetically differing behaviour, thus giving the possibility to establish a mathematical model for the interpretation of experimental data. Quantitative estimation of the population with silanol groups depending on the annealing temperature is achieved and correlated with the existence of two vanadium oxide surface species which differ with respect to their catalytic activity. (author)