PROCEDIMENTO PER LA PREPARAZIONE DI UN CATALIZZATORE DI OSSIDAZIONE DEL LA NAFTALINA MEDIANTE IMPREGNAZIONE DI SILICE CON UNA SOLUZIONE ACQUOSA DI VOC2O4-K2SO4-KHSO4

Catalytic material is prepared by impregnating porous silica with an aqueous solution containing vanadyl oxalate (VOC2O4), potassium sulfate (K2SO4) and potassium bisulfate (KHSO4). A free-flowing dry-appearing powder is provided comprising particles having substantially all compounds deposited from the impregnating solution attached to the silica particles within pores of the particles. Subsequent calcining of the powder provides a mixture of compounds within the particle pores containing at least one oxide of vanadium and at least one sulfate of potassium. Catalytic material prepared by the disclosed process is characterized in having a substantially uniform concentration of deposited compounds within the pores of the silica support. The catalytic material is particularly useful in a process for fluid bed oxidation of naphthalene to phthalic anhydride, in which oxidation process the catalyst provides high product yield at a low catalyst attrition rate.