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Andrea Landella POLITECNICO DI MILANO Industrial Organic Chemistry Exam Feb 15, 2017 Benzene (C6H6) can be catalytically hydrogenated to produce cyclohexane (C6H12), according to the following process scheme and exothermic reaction: FF R-101 C6H6 + 3H2 = C6H12 V-101 F P FA V-102 T R S T-101 The fresh mixture consists of C6H12/H2 in ratio 1:3 at 3 atm. The exit stream from the reactor consists of C6H12, C6H6 and H2. Assuming that: • The reacting mixture is an ideal mixture of perfect gases; • A conversion per pass of C6H6 equal to 30% is achieved in the reactor; • Pressure drops across the reactor are negligible; • The separation unit operates with the following specifications: o The whole H2 is recovered in the T stream; o C6H6 and C6H12 are split according to the following molar ratios: 6 6 6 12 6 6 6 12 0.6 0.65 C H C H C H C H PP FA FA    1. Evaluate the recycle ratio β = R/T required to achieve an overall conversion of C6H6 equal to 35%, and the C6H12 leaving the plant in the P stream. RESULTS: Recycle ratio β C6H12 in the P stream 2. By assuming that the stream leaving the reactor is at the thermodynamic equilibrium, assess and justify if the temperature of the FA stream could be 600 K or 569 K. Andrea Landella POLITECNICO DI MILANO Thermodynamic data: The Gibbs free energy of formation for the species (kJ/mol) depends on temperature (K), using a reference state of perfect gas at 1 atm: 02Δ ( )fg T A BT CT   Species A B C H2 0 0 0 C6H6 8.1512E+01 1.5282E-01 2.6552E-05 C6H12 -1.2792E+02 5.2032E-01 4.4706E-05