The benzene–toluene–xylene (BTX) system represents an energy-intensive petrochemical process with various industrial applications. Global climate changes have forced modern industry to act toward environmental safety, which requires technological changes. Thus, the divided wall column (DWC) represents a significant advancement in multicomponent mixture separation. To assess the impact of the conventional BTX process and its intensification proposal based on DWC technology, it is necessary to integrate an eco-efficiency approach that jointly analyzes the economic and environmental variables influencing the system, such as water consumption, CO₂ emissions, and utility costs. An auxiliary utility plant was also considered for more realistic results in terms of energy and water consumption, which was identified as a lack in many research studies that performed an overall sustainability analysis. The results showed that the DWC scheme is 37.5% more eco-efficient than the conventional counterpart, mainly due to a 15.6% and 30.3% savings on energy and water consumption, respectively, which provided a 15.5% and 16.7% reduction on CO₂ emissions and utility costs, respectively. In addition, all other environmental and safety indicators based on the waste algorithm reduction (WAR) were reduced by approximately 16%. Thus, the DWC proved to be a convenient technology with economic attractiveness and environmental friendliness.

Propionic acid (PA) is a valuable chemical with wide industrial applications, and its sustainable production via microbial fermentation has gained increasing attention. This study aimed to develop and improve a bioprocess for PA production using Acidipropionibacterium acidipropionici DSM 4900 and renewable carbon sources, namely xylose and glycerol. Shake-flask and bioreactor experiments were conducted to evaluate the effects of substrate ratios and operational strategies on process performance. Among the tested conditions, the fed-batch bioreactor using glycerol as the main substrate showed the best results, reaching a final PA concentration of 24.5 g/L, productivity of 0.18 g/(L·h), yield of 0.57 g/g, and bioconversion efficiency of 71%. These findings highlight the potential of optimizing substrate composition and feeding strategies to enhance microbial catalysis and process efficiency. This work advances current knowledge by revealing the synergy between xylose and glycerol co-utilization and demonstrating that integrated process design, combining redox-balanced substrates with fed-batch operation, can overcome end-product inhibition and enhance carbon flux toward propionic acid synthesis. Overall, this study demonstrates the feasibility of using low-cost, renewable feedstocks for PA production, contributing to the development of sustainable and circular biorefinery platforms in line with green chemistry and process intensification principles.

For the separation of the close-boiling 1,2-propanediol and ethylene glycol mixture, several process intensification (PI) schemes have been proposed for the two-column configurations. However, no PI technology has yet been investigated for the challenging single-column design operating at atmospheric pressure (SCD). The previously published improvements include the economically modified single-column design (MSCD) as well as high-pressure configurations with (HPDHI) and without (HPD) feed-preheating heat integration. Therefore, this study proposes a partial vapor recompression (SCD-PVR) configuration to intensify this separation using UniSim Design software. Economic and environmental performances were evaluated through total annualized cost (TAC) and CO₂ emissions. When directly compared with the SCD, MSCD, HPD, and HPDHI schemes, the SCD-PVR achieved CO₂ emission reductions of 67.9%, 68.6%, 61.2%, and 56.0%, respectively. Considering a 5-year payback period, SCD-PVR outperformed the SCD and MSCD schemes, decreasing TAC by 9.7% and 11.2%. For a 10-year payback period, the benefits became more significant, with TAC reductions of 31.4%, 32.7%, 17.2%, and 9.3% relative to SCD, MSCD, HPD, and HPDHI. These findings demonstrate that SCD-PVR provides a more energy-efficient, environmentally sustainable, and economically attractive alternative for retrofitting existing plants.

Purification of isobutane remains a fundamental step in the production of a cleaner alkylated gasoline, and the distillation operation employed for this separation is notoriously energy-intensive and a significant contributor to environmental impacts. To address these challenges, this work proposes vapor recompression (VR) as an intensified alternative process to fully electrify the conventional column–reactor configuration used in n-butane isomerization and separation. An external VR scheme was designed and globally optimized with the objective of minimizing total annualized cost. The optimized VR configuration showed a clear economic advantage, achieving an approximate 13.83% reduction in costs over a 10-year horizon with a break-even time of 7.13 years. Additionally, overall energy demand was reduced by 74%, and operational safety was enhanced, as the boiler is required only during plant start-up and shutdown. To account for economic uncertainty, a sensitivity analysis was conducted to evaluate the effects of fluctuations in electricity and steam prices. Environmental performance was further assessed through CO₂ emissions using different national electricity emission factors. While emission reductions depend strongly on grid carbon intensity, regions with low-carbon electricity mixes show significant mitigation potential. Overall, VR emerges as a promising strategy to improve the economic and environmental sustainability of industrial processes.