RELATIONSHIP BETWEEN THE ACIDITY OF NICKEL PHOSPHATE (NIP) CATALYSTS AND THEIR ACTIVITY IN ETHYLBENZENE OXYDEHYDROGENATION

A nickel phosphate catalyst was prepared from nickel nitrate and ammonium phosphate solutions by a precipitation method. The activities of the catalyst samples were examined in a flow reactor at various time intervals from the start of an ethylbenzene oxidative dehydrogenation reaction. Total and Bronsted acid surface sites concentration on the catalysts were determined from the adsorption of pyridine and 2,4,6-trimethylpyridine respectively, at those intervals. The relationship between styrene yield and catalyst surface acidity has been discussed. Styrene yield proved to be well correlated only with the concentration of Lewis type acid sites on the surface of the catalyst samples.