Problem 14.14: (Fall 2001) The gas-phase dehydrogenation of propane is carried out according to the reaction
C3 H8 (g) = C3 H6 (g) + H2 (g).
The reaction takes place in the presence of a catalyst in an isothermal reactor that is maintained at 5 bar.
a) Calculate the equilibrium constant at 25 °C.
b) Calculate the standard enthalpy of reaction at 25 °C. Is the reaction exothermic or endothermic?
c) The reactor feed contains pure propane. If the desired conversion of propane is 95%, at what temperature should you run the reaction? Assume the reaction reaches equilibrium.
d) Due to upstream process modifications, the reactor feed has now changed from pure propane into a mixture that contains 50% nitrogen (by mol). If the reactor pressure remains at 5 bar, how should you adjust the temperature to achieve 95% conversion?
e) Just as you finished adjusting the temperature to handle the propane/nitrogen feed of the previous part, the compressor malfunctions and the reactor pressure drops to 1 bar. How should you adjust the temperature to achieve 95% conversion?
f) Clearly state all the assumptions.