Timoshenko A., Anokhina E., Akishin A., Remizova A., 2018, Benzene Purification from Thiophene by Extractive Distillation with Dimethylformamide, Chemical Engineering Transactions, 69, 877-882.
Thiophene (T) is the one of the main sulfur-containing impurities in the composition of crude benzene by coke production. The effective way to remove the main amount of thiophene from crude benzene is an extractive distillation (ED) with dimethylformamide (DMF) when the relative volatility of the benzene-thiophene pair increases from 1.13 to 1.8–2.18. The aim of this work is to investigate the possibility to increase benzene yield from the initial fraction and to reduce ED heat demand of B-T mixture with DMF as entrainer by using an extractive distillation system with partially thermally coupled distillation columns (PTCEDS). To achieve the goal, the conventional extractive distillation (CED) and the PTCEDS were subjected to parametric optimization. The total energy consumption in the column reboilers (Qreb) was selected as a criterion. It was found that the same yield of benzene is achieved in PTCEDS at lower heat demand in the columns' boilers than in CED. With an increase in the yield of benzene, energy savings are increased compared to conventional ED. Also, the production of the thiophene fraction in the side section of the PTCEDS requires a significantly smaller reflux ratio (1.0 – 2.28) than in the recovery column of the CED (7.17 – 73.13).
