1. You are asked to carry out the gas-phase hydrogenation of benzene to cyclohexane.
a) What conditions of pressure and temperature (high/low) would result in maximum conversion?
b) Determine the equilibrium composition of a mixture that contains 30% benzene (by mole) and 70% hydrogen at 200 °C, 5 bar.
2. Benzene is formed from the gas-phase dehydrogenation of cyclohexane according to the reaction:
C6 H12 (g) = C6 H6 (g) + 3H2 (g).
a) Calculate the standard heat of reaction and the equilibrium constant at 25 °C.
b) A stream that contains 50% by mole cyclohexane in nitrogen is fed to a reactor that operates a constant pressure and temperature. The reactor pressure is 5 bar and the desired conversion of cyclohexane is 85%. Determine the amount of heat per mol in the feed that must be added or removed from the reactor in order to maintain the temperature constant.
c) Determine the composition of all species at the exit of the reactor.
d) Assuming the reaction reaches equilibrium, determine the reactor temperature.
e) It has been suggested that conversion could be increased by operating at different pressure. You may vary the reactor pressure between 1 and 10 bar. If temperature and inlet conditions remain the same, at what pressure would you operate the reactor? Explain your answer.
f) List all of your assumptions and explain where each assumption was used.