Integrated processing for the separation of biobutanol. Part A: experimental investigation and process modelling

n-Butanol is an important bulk chemical and a promising potential fuel additive. An alternative way to the chemical production of biobutanol from crude oil is the fermentation of biomass. However, the main drawback of this process is the toxicity of n-butanol towards the microorganisms resulting in a limited productivity. Additionally, high purification costs occur due to an energy-intensive distillation step which is used, up to now, as purification technology for the recovery of n-butanol. Therefore, alternative separation processes are discussed in this study. Extraction and pervaporation are two unit operations with high potential to overcome this problem. Because of their tuneable properties, the use of ionic liquids as extraction solvents for n-butanol recovery is a promising option; however, their economic potential is not obvious because of the relatively high costs. On the basis of those two unit operations, different potential processes to separate biobutanol from water are modelled using experimental data. Cost estimations result in purification costs of €0.230 kg-1 to €0.296 kg-1 n-butanol, which accounts for 20%–27% of the n-butanol market price in 2012