Chemical Engineering - Industrial Organic Chemistry

Full exam

Andrea Landella POLITECNICO DI MILANO Industrial Organic Chemistry Exam Feb 1 5, 201 7 Benzene (C 6H6) can be catalytically hydrogenated to produce cyclohexane (C 6H12), according to the following process scheme and exothermic reaction: The fresh mixture consists of C 6H12/H 2 in ratio 1:3 at 3 atm. The exit stream from the reactor consists of C 6H12, C6H6 and H 2. Assuming that: • The reacting mixture is an ideal mixture of perfect gases; • A conversion pe r pass of C 6H6 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 H 2 is recovered in the T stream; o C6H6 and C 6H12 are split according to the following molar ratios: 1. Evaluate the recycle ratio β = R/T required to achieve an overall conversion of C 6H6 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. FF R-101 C6H6 + 3H2 = C6H12 V-101 F P FA V-102 T R S T-101 6 6 6 12 6 6 6 12 0.6 0.65 C H C H C H C H PP FA FA    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 : 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 02 Δ ( )fg T A BT CT   