Investigation of the catalytic oxidation of benzene to maleic anhydride by wave front analysis with respect to the application of periodic operation

A kinetic analysis of the partial oxidation of benzene to maleic anhydride over a Merck, Sharp and Dohme developed V 2 O 5 ‐MoO 3 /TiO 2 catalyst shows that partial oxidation proceeds through surface reduction, induction and collapse phases. In each, surface species and reactions are different. The reduction/induction phases correspond to a “ignited” state whereas the collapse phase is similar to an extinguished state familiar in the catalytic oxidation of CO. Selectivity to maleic anhydride is lower in the extinguished state. Periodic operation should offer a means to keep selectivity high provided the cycle period does not exceed just a few minutes. Improvement in selectivity of close to 100% has been attained by periodic switching of the feed composition between mixtures containing oxygen and benzene in ratios of 2.4 and 4.6 with periods between 1/2 and 6 minutes. Benzene conversion, however, is lower.