Exploring the impact of side-reactions on triple-column reactive-extractive distillation

Background

Presently, there are no studies that examine the impact of side-reactions of ethylene oxide hydration on triple-column reactive-extractive distillation (TC-RED). This study addressed this gap by investigating how these side-reactions influence the energy consumption, total annual cost (TAC), and CO₂ emission of the TC-RED process. Two case studies, which involve the ternary separation of tetrahydrofuran (THF)/ethanol (ETOH)/water and ethyl acetate (EA)/ETOH/water were conducted here.

Results

Case studies 1 and 2 showed significant increase in energy consumption (39.68% and 16.56%), TAC (65.57% and 47.88%) and CO₂ emission (21.15% and 12.89%) resulting from side-reactions. The increase in energy consumption, TAC, and CO₂ emission is primarily a consequence of the high boiling point of higher glycol product derivatives, altered chemical equilibrium behavior and increased reactant flowrates, which necessitate larger equipment sizes and incur higher capital costs. Notwithstanding this, TC-RED with side-reactions still outperforms pressure swing distillation (PSD) for separation of THF/ETOH/water and extractive distillation (ED) for separation of EA/ETOH/water. However, it falls short of double-column reactive-extractive distillation (DC-RED) owing to the need for an additional column.

Conclusion

Our study highlights the importance of considering side-reactions in TC-RED during process design. Although the decline in performance is a result of the additional complexities brought by side-reactions, it is important to emphasize that the primary takeaway of this study is that the system model is more realistic. By incorporating side-reactions into the simulation, we can model the system more comprehensively, providing future researchers with an opportunity to explore and address potential issues resulting from side-reactions. © 2024 Society of Chemical Industry (SCI).