REACTION-ENGINEERING SIMULATIONS OF A FLUIDIZED-BED REACTOR FOR SELECTIVE OXIDATION OF FLUORENE TO 9-FLUORENONE

The catalytic oxidation of fluorene to 9-fluorenone in a fluidized-bed reactor was investigated by modeling of the reactor and simulation of its performance. The ''Bubble Assemblage Model'' of Kato and Wen, the ''Bubbling Bed Model'' of Kunii and Levenspiel and the ''Countercurre nt Backmixing Model'' of Potter were applied. From a comparison of sim ulation results obtained by the various fluidized-bed models and a fix ed-bed model conclusions were drawn about the influence of interphase mass transfer and gas backmixing on the conversion of fluorene and sel ectivity of 9-fluorenone formation. Furthermore, the dependence of con version and selectivity on temperature and hydrodynamic conditions was investigated. In particular, the implications of a change of hydrodyn amic conditions for scale-up were analysed. The highest yield of 9-flu orenone predicted for a bench-scale fluidized bed amounted to 88% (X(F ) = 97%, S(NON) = 91%). This yield was lower than in a fixed-bed react or (Y(NON) = 92%, X(F) = 99%, S(NON) = 93%). A further drop of the yie ld was predicted when scaling-up from a bench-scale reactor to a comme rcial size unit (Y(NON) = 54%, X(F) = 86%, S(NON) = 63%).