Chemical Engineering - Industrial Organic Chemistry

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Andrea Landella POLITECNICO DI MILANO Industrial Organic Chemistry Exam Sep 2, 2016 Styrene (STY) is industrially produced by catalytic dehydrogenation of ethy lbenzene (EB) accordin g to the following reaction: EB → STY + H 2 The reactor is fed with ethylbenzene and superheated water st eam in molar ratio of 1:10. The inle t mi xture is at 600°C and 3 bar. The exit stream consists of E B, STY, H 2, H 2O. T he reactor operates in adiabatic con ditions. By assuming that: • The reacting mi xture is an ideal mi xture of perfect gases; • The thermodynamic equilibrium is reached at the outlet of the reactor; • Pressure drops are negligible; 1. Asses s and justi fy how man y reactions have to be considered to evaluate the thermodynamic equilibrium conditions : 2. Evaluate the molar conve rsion of EB, the outlet temperature and the composition of the stream leaving the reactor: RE SUL TS: Conversion of EB Outlet temperature EB STY H2 H2O Composition 3. Assess and justify how an inc rease of reactor p ressure affects the EB conversion : Andrea Landella POLITECNICO DI MILANO Thermod ynamic data: Gib bs free energ y change of the reaction (J/m ol) as a function of temperature (K): The re ference state for calculations is perfect gas at 1 atm Specie ΔfH0(298 K) [kJ/mol] CP [J/mol/K] EB 29 .8 206.571 STY 147.5 192.597 H2 0 29.254 H2O -242.0 35.22 5 Heat capacities can be assumed constant with t emperature. Δ ( ) 127 619.9 134.02rg T T   