Consider the following system of gas-phase reactions:
A→XrX=k1CA1/2k1=0.004(mol/dm3)1/2⋅min−1A→BrB=k2CAk2=0.3 min−1A→YrY=k3CA2k3=0.25 dm3/mol⋅min
B is the desired product, and X and Y are foul pollutants that are expensive to get rid of. The specific reaction rates are at 27°C. The reaction system is to be operated at 27°C and 4 atm. Pure A enters the system at a volumetric flow rate of 10 dm³/min.
a. Sketch the instantaneous selectivities (S_B/X, S_B/XY = r_B/(r_X + r_Y)) as a function of the concentration of C_A.
b. Consider a series of reactors. What should be the volume of the first reactor?
c. What are the effluent concentrations of A, B, X, and Y from the first reactor?
d. What is the conversion of A in the first reactor?
e. If 99% conversion of A is desired, what reaction scheme and reactor sizes should you use to maximize SB/XY?
f. Suppose that E₁ = 20000 cal/mol, E₂ = 10000 cal/mol, and E₃ = 30000 cal/mol. What temperature would you recommend for a single CSTR with a space time of 10 min and an entering concentration of A of 0.1 mol/dm³?
g. If you could vary the pressure between 1 and 100 atm, what pressure would you choose?