Rates of oxidation of naphthalene were measured for the temperature range 300°C. to 335°C. using a thin layer of vanadium oxide-potassium sulfate-silica catalyst in a flow reactor. The amounts of naphthalene converted were determined by analysing the products for 1,4-naphthoquinone, 1,2-naphtho-quinone, and phthalic anhydride. Negligible amounts of products of complete combustion were formed.
The reaction rate data obtained at low conversions of naphthalene were correlated by the following expression, based upon a model for the reaction proposed by Hinshelwood:
From the results of experiments in which the contact time was varied, it was suggested that the reaction course consisted of two parallel, consecutive reactions in which 1,4- and 1,2-naphthoquinone are intermediates in the formation of phthalic anhydride.