1) direct feeding to the reboiler SBD1 resulted in 31.93% reduction in time, and, required 2.14 times less for specific energy demand, and, 2) namely, SBD2, feeding into the column at the fixed stage resulted in the same time reduction as SBD1, and, somewhat better in specific energy demand ie. required 2.49 times less. Ferchichi et al. , introduced "varied feed location semi batch mode" namely SBD3, in contrast, the stages were divided into two sections: namely feed plates being lowest as SBD3,A, brought in almost all time intervals more energy intensive operation, for example in the second time interval even 46.44%. compared to SBD3,B , namely feed plates of the middle section. Vibhute and Jogwar , the authors first generate the best open-loop policy, to use this trajectory in the subsequent closed-loop studies where the extended Kalman filter is used as one of the most favorite estimators to provide reliable estimates in the presence of plant-model mismatch and process measurement noise. For the open-loop policy, it was the amount of product collected per unit energy consumption factor that gave the significant production maximization, ie. 83% along with significant energy savings, ie. 97%, for all purity specifications. Vibhute and Jogwar , reworked the study for the same vapor recompressed batch column, this time under total reflux so to obtain both products in high purity: the open-loop trajectory is subsequently traced by maximizing same of the key indices as previously, in closed-loop trajectory using this time a model predictive controller. Interestingly, the same as in the previous study, the authors did a test with disturbance after 100 min of time, consequently, the tray efficiency drooped by 5%, and, the total time increased by 13.84%, and the overall performance factor dropped by 14.23%.