This work deals with the improvement of the current process of alkylation of benzene (B) with propylene (P) to produce cumene (IPB). Due to high energy consumption brought by high feeding molar ratio of benzene to propylene (B/P), an optimized process design has been developed and is presented. First, a side-stream was added to the diisopropylbenzene (DIPB) distillation column in order to recover some trisopropylbenzene (TIPB), resulting in a decrease of the energy consumption per product. The total heat duty on condensers and reboilers per product decreased by 5.5 and 4.3%, respectively. On the other hand, if the original fixed-bed reactor is replaced by a bubble-point reactor, the total heat duty on condensers and reboilers will decrease by 18.5 and 22.8%, respectively. Using the above two schemes together, they decreased up to 19.4 and 23.6% per product, respectively. Then, using a fixed-bed catalytic distillation (FCD) column for producing cumene, the calculated results showed that a much lower energy consumption was required, and the total heat duty on condensers and reboilers per product decreased by 36.4 and 23.6%. The improvement of FCD column was done by carrying out alkylation and transalkylation reactions simultaneously in a single column for producing cumene, with the result that investment of equipment for transalkylation is reduced and the process is simplified. Finally, with the combination of the improved DIPB column and FCD process, the heat duty was found to be the lowest.