1. To illustrate the effect of mass velocity on external diffusion in the oxidation of sulfur dioxide with a platinum catalyst, consider the following data, all at 480C. bs SO Mass velocity (kg/hm) 2511.8 1710.4 1197.3 Bulk partial pressures, Pb, atm SO 0.0601 0.00668 0.0599 0.00666 0.0603 0.00668 02 0.201 0.201 0.201 Global rate, re 0.1346 0.1278 0.1215 The reactor consisted of a fixed bed of 0.3175cm x 0.3175 cm cylindrical pellets. The pressure was 790 mmHg. The external area of catalyst pellet was 1.05 m/kg, and the platinum did not penetrate into the interior of the alumina particles. The external area of catalyst pellets is 1.05 m/kg material. Calculate the partial pressure difference between the bulk gas phase and the surface of the catalyst for SO2 at each mass velocity. What conclusions may be stated with regard to the importance of external diffusion? Neglect temperature differences. = 0.1339 kg/mh D = 0.2835 cm/s Pair = 0.487 kg/m 2 3 air