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Biobutanol is receiving great interest from both the academia and industry sectors, and some companies are already focusing on revamping bioethanol plants to produce biobutanol. The recovery of fuel grade butanol by distillation was proven not to be economically sustainable. On the other side, hybrid flowsheets, obtained with the combination of liquid−liquid extraction and distillation, were proposed as a more convenient alternative. Divided wall columns (DWCs), 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. At the same time, also the controllability was improved compared to the hybrid liquid−liquid-assisted simple column distillation sequence considered as a reference.

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This paper presents a multiobjective optimization to obtain the optimal planning of butanol production, considering the optimal selection of feedstock and the correct ratio of fermentable sugars. This multiobjective methodology was applied during both the fermentation and purification process of butanol. The multiobjective optimization problem considers minimizing the total annual cost and environmental impact as objective function. The economic objective function takes into account the availability of bioresources, the cost of feedstocks, the fermentation conditions, and the separation units. On the other hand, the environmental assessment includes the overall impact measured through the eco-indicator 99 which is based on a life cycle analysis methodology. Both objective functions were applied to a case study for the optimal planning to produce biobutanol in Mexico. After the optimization process, we generated a set of solutions represented by a Pareto curve that identifies a group of optimal solutions for both objectives. Considering the best compromise of both targets, the best solution involves initially a raw material with a moderate content of sugars followed by a separation unit designed as a hybrid separation process. This hybrid process considers the inclusion of a liquid–liquid extraction column followed by three thermally coupled distillation columns.

Currently furfural production has increased the interest because of it is a bio-based chemical able to compete with fossil-based chemicals. Furfural is characterized by flammability, explosion and toxicity properties. Improper handling and process design can lead to catastrophic accidents. Hence it is of utmost importance to use inherent safety concepts during the design stage. This work is the first to present several new downstream separation processes for furfural purification, which are designed using an optimization approach that simultaneously considers safety criteria in addition to the total annual cost and the eco-indicator 99. The proposed schemes include: thermally coupled configuration, thermodynamic equivalent configuration, dividingwall column, and a heat integrated configuration. These are compared with the traditional separation process of furfural known as Quaker Oats Process. The results show that due to a large amount of water present in the feed, similar values are obtained for total annual cost and eco-indicator 99 in all cases. Moreover, the topology of the processes has an important role in the safety criteria, the thermodynamic equivalent configuration resulted as the safest alternative with a 40% of reduction of the inherent risk with respect to the Quaker Oats Process and thus it is the safest option to purify furfural.

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BACKGROUND: Butanol produced from fermentation has attracted the interest of research groups because its physicochemical properties show several enhancements over bioethanol. Recent studies have proposed alternative methods to separate and purify biobutanol from a fermentation broth. These alternatives offer energy and economic savings; in addition, a reduction in environmental impact is observed. However few studies have analyzed the control properties of the process which involves separation of an acetone-butanol-ethanol (ABE) mixture.

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