ROLE OF SURFACE-ACIDITY ON VANADIA SILICA CATALYSTS USED IN THE OXIDATIVE DEHYDROGENATION OF ETHANE

The oxidative dehydrogenation of ethane in ethene has been investigated in the 753-863 K temperature range over V2O5/SiO2 catalysts prepared by grafting or wet impregnation methods. The acidic features of fresh and used catalysts were studied by ammonia and pyridine adsorption using microcalorimetry and DRIFT spectroscopy. V2O5/SiO2 catalysts can be regarded as medium acidic materials. At the same conversion level of ethane, selectivity to ethene was favored by low V2O5. loadings. Ethane conversion increased with the vanadium content and the ammonia uptake of the V2O5/SiO2 Catalysts. Some Bronsted-type sites disappeared in the course of the catalytic reaction, leading to minor changes in the acidic character of the catalysts.