Fluid bed reactor has been suggested for the oxidation of ethylene to ethylene oxide. The operating conditions would be 280oC and 1 atm pressure. The feed gas whose composition is C2H4 = 8% O2 = 19% and N2 73 % has a superficial velocity in the reactor 0.6 m/ s at 280 oC. The intrinsic reaction rate, g mol of ethylene oxide/ s kg catalyst is given by R = 5.0 C2H4 Two competing reactions occur: C2H4 + 0.5 O2 → C2H4O C2H4 + 3 O2 → 2CO2 + 2 H2O The selectivity of ethylene oxide with respect to carbon dioxide is independent of conversion and equal to 1.5. 

i. Calculate the conversion as a function of fluidized bed reactor height using the bubbling gas model. Neglect the catalyst concentration in the bubbles, assume that the dense phase is a well mixed batch fluid and that the gas bubbles rise in plug flow. Other properties of the fluidized bed are: Density of catalyst particles in the dense phase = 0.04 g/ cm3 Mass transfer coefficient, bubble to dense phase ( km av) = 0.30 s-1 Volume fraction occupied by gas bubbles, 1 - εd = 0.10 

ii. For comparison, calculate the conversion in a plug flow reactor and in a stirred tank reactor for the same bubble phase residence time.