This investigation was conducted to further study the vapor-phase oxidation or o-xylene to phthalic anhydride in a fluidized bed catalytic reactor. Parameters investigated during the study were temperature, catalyst volume, and catalyst activated by use or different promoters. Two different vanadium pentoxide catalysts were used. One was a new catalyst(Catalyst I) supported on a silica base and diluted with potassium sulfate. The other catalyst(Catalyst II) was similar to the first one except that it had been used in a commercial fixed bed reactor operated by the Monsanto Company, St. Louis, Missouri, using naphthalene as a reed material. It had been suggested that this second catalyst would be activated whereas the fresh catalyst would not am the used catalyst would thus give higher yield or phthalic anhydride. Little difference in yield or phthalic anhydride was found, the used catalyst giving slightly lower yields. These studies were conducted on a laboratory scale in equipment similar to that used in earlier studies by Wang(12) but modified in several respects.
Phthalic anhydride, maleic anhydride, o-toluic aldehyde, carbon dioxide and water were obtained as oxidation products. Except water, they are all determined by quantitative analysis.
Two different amounts of Catalyst I (24 grams and 102 grams) were used at five different temperatures C320,400,450,490,520⁰C) to study the effect on the yield per cent or phthalic anhydride. It was found that the optimum reaction temperature is at 490⁰C when using either amount of catalyst. The highest yields of phthalic anhydride obtained were 21.5 per cent when using 24 grams of Catalyst I and 24.3 per cent when using 102 grams. The highest yield of phthalic anhydride was 19.6 per cent when 137 grams of Catalyst II were used at 490⁰C and the lowest yield was 9.6 per cent at 320⁰C.
The effect of the addition of bromine, phenol bromide, and 1-3 dibromo-propane, as promoters, was also investigated. These promoters were introduced into the liquid o-xylene feed in separate tests. It was again found from a number of tests at different reactor temperatures that 490⁰C gave the highest yield of phthalic anhydride, 36.2 per cent. This yield was obtained using 5 per cent by volume of liquid bromine in the feed and 102 grams of Catalyst I --Abstract, pages ii-iii
