P8-4 Consider the following system of gas-phase reactions: A X rx=k,Ck2 k, = 0.004(mol/dm)12 min . A B l's=k_CA ka=0.3 min-1 A Y ry=kzc kz=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 27C. The reaction system is to be operated at 27C and 4 atm. Pure A enters the system at a volumetric flow rate of 10 dm?/min. (a) Sketch the instantaneous selectivities (SB_x, SBY, and SB/XY=FB/(Vx+ry)) as a function of the con- centration of CA. (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 max- imize SB/XY? (f) Suppose that E, = 20,000 cal/mol, E2 = 10,000 cal/mol, and Ez = 30,000 cal/mol. What tempera- ture would you recommend for a single CSTR with a space time of 10 min and an entering concen- tration of A of 0.1 mol/dm3? (g) If you could vary the pressure between 1 and 100 atm, what pressure would you choose