Purifying Benzene from Thiophene by Extractive Distillation Using Columns with Side Withdrawal in the Vapor Phase

Sulfur compounds are found in crude benzene from coke production. One of these compounds is thiophene. Extractive distillation (ED) with dimethylformamide as a separating agent can be used to remove it from crude benzene. The relative volatility in the benzene–thiophene binary system increases in the presence of dimethylformamide from 1.13 to 1.46–2.18. The purpose of this work is to study the possibility of using a scheme that includes a complex extractive column (EC) with side withdrawal in the vapor phase. New schemes of ED have been synthesized and mathematical modeling and their optimization have been carried out. It is shown that the proposed scheme of ED provides a decrease in energy consumption by 29.5% and the amount of circulating extractive agent (E) by 47.8%. At the same time, the requirements for the quality of benzene purification and its losses with the thiophene fraction are met.