Biobutanol Purification by Liquid-Liquid Extraction Assisted Divided Wall Columns

Abstract

Biobutanol is receiving a great interest from both academia and industry sectors, and some companies are already focused on revamping bioethanol plants to produce biobutanol. The recovery of fuel grade butanol by distillation was proved to be not economically sustainable. On the other side, hybrid flowsheets, obtained combining liquid-liquid extraction and distillation, were proved to be a valid alternative. Divided wall columns, as one of the most promising intensified distillation alternatives, were here explored in combination with liquid-liquid extraction. A multiple objective function taking into account the economy, the environmental impact and the process controllability was defined to screen the alternatives. Among all the configurations considered, liquid-liquid extraction combined with a DWC equipped with two reboilers and a side rectifier, reached 22% and 18% reduction of the economy and environmental index respectively in comparison with conventional schemes. At the same time, also the controllability was improved compared to the hybrid liquid-liquid assisted simple column distillation sequence considered as a reference.