Alkylation of Benzene by Propylene to Cumene 6

6.3 Reactor/Separator/Recycle Structure 183k1 = 6510exp( −52564/ RT) (6.5)in which the reaction rate is given in kmol/m 3 .s and the activation energy in kJ/kmol. Table 6.6 enables an estimation of a first - order reaction constant for theDIPB formation as:k2 = 450exp( −55000/ RT) (6.6)The above kinetic equations have been tested by the simulation of an adiabaticPFR. For an inlet temperature of 160 ° C, a benzene/propylene ratio of 7 and aspatial time WHSV of 10 a total conversion of propylene may be reached withselectivity around 90%. In conclusion, the kinetic data corresponds to a fast industrialcatalyst and may be reasonably used in design.6.3Reactor/Separator/Recycle StructureThe following reactor performance in recycle is the aim: over 99.9% per/passpropylene conversion over 88% cumene selectivity, adiabatic temperature risebelow 70 ° C, but a maximum catalyst temperature of 250 ° C. The inlet pressureshould be sufficiently high to ensure only one liquid phase. Thermodynamic calculationsat 35 bar indicate bubble temperatures of 198 and 213 ° C for propylene/benzene ratios of 1/4 and 1/7, respectively (Figure 6.5 ). The reactive mixture canbe maintained as liquid up to about 250 ° C, since the concentration of propylenediminishes gradually by reaction.In a first attempt, we simulate the reactor as an adiabatic PFR. We consider adiameter of 1.3 m and a total length of 7 m, which ensure propylene conversionover 99.9%. The feed consists of 100 kmol/h propylene at molar benzene/Figure 6.5 Reactor residence time as a function of the molar benzene/propylene ratio.