Makrokinetische Studien über die heterogene Gasphasenoxydation von Anthracen

Abstract

The macroscopic behaviour of the catalytic gas-phase oxidation of anthracene with air on a vanadium oxide catalyst has been investigated at temperatures between 350 and 486 °C in an integral-fixed-bed reactor. In addition to the normal oxidation products, the existence of an instable intermediate (X) was proved by isolating 2-hydroxyl-1,4-anthrachinone. The suggested kinetic model was in good agreement with the experimental results and lead to the following conclusions: anthracene is transformed in a fast step to anthrachinone, which is practically stable at reaction conditions. In a simultaneous reaction, the intermediate product (X) is formed in a step 4 to 20 times slower, depending on the oxidation temperature. From this intermediate the main part of the phthalic anhydride is obtained by a very fast consecutive reaction. The complex temperature dependence of the formation of anthrachinone is due to the influence of pore diffusion and to a subsequent sudden variation of the oxygen content of the catalytically active component.