OXIDATION OF ETHENE IN A WALL-COOLED PACKED-BED REACTOR

The selective oxidation of ethene over a silver on a-alumina catalyst was studied in a pilot plant with a wall-cooled tubular packed bed rea ctor. Gas and solid temperatures in the catalyst bed were measured at different axial and radial positions as well as concentrations at diff erent axial position. Total pressure, inlet mole fraction ethene, mass flow rate and wall temperature were varied. The experiments are compa red with model calculations. A pseudo-homogeneous model and a heteroge neous two-dimensional model were used for the calculations. Kinetics a nd heat transport parameters in the model have been determined indepen dently in separate studies. The work is distinctive in the accuracy pa id to a large number of experimental details. The models correspond re asonably well with the experiments at all operating conditions. The ma in problem in the description of the reactor is the inability of the k inetic expressions to predict the reaction rates over the entire range of partial pressures. As a result some systematic deviations are foun d, in particular in the predicted temperature profiles. The heterogene ous model gives better agreement with the experiments although systema tically larger temperature differences are calculated on the basis of available correlations in literature than has been measured. On the ba sis of this work it is difficult to determine directly whether an infl uence of chemical reaction is present on the values of the heat transp ort parameters.