Oxidative dehydrogenation of ethane over Cr/TiO2 modified by phosphorus

A series of catalysts were prepared by loading titanium dioxide with chromi um and different amounts of phosphorus. Investigation in the oxidative dehy drogenation of ethane showed that chromium notably increases the activity o f TiO2 principally toward the total oxidation of the hydrocarbon. Addition of phosphorus to the system simultaneously improved the global conversion a nd the ethylene selectivity. Moreover, a fairly good correlation between th e catalysts acidity, the P/Cr ratios and the activity in the ODH reaction w as established. It was also found that an excess of phosphorus, although it increases the acidity, decreases the conversion as if phosphorus effect wa s optimum for P/Cr ratios equal to 1.6. EPR and UV-visible characterization s of the samples before and after the catalytic tests showed that the impro vement of the catalysts performances might be due to the isolated octahedra l Cr3+ species that appear on the support.