Studies on catalytically active surface compounds, VIII. On the reaction of VCl4 with aerosil

Abstract

The preparation and hydrolysis of silica supported vanadium catalysts have been investigated using VCl4 as a paramagnetic probe. Chemical analysis shows the possibility of the VCl4 molecule to react one, two, or three hydroxy groups of the surface. The type of reaction is influenced by the temperature of pretreatment of aerosil (TPA). ESR measurements show distortions of the tetrahedral coordination of the (SiO)nVCl4−n surface complex, which is strongest for the threefold attachment (n=3) of VCl4 to the surface. Hydrolysis is accompanied by an increase of the coordination number and leads to highly mobile vanadium species.