No abstract

No abstract

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.

Abstract:The biochemical production of n-butanol by fermentation is an interesting option for the sustainable production of a chemical that can be used as a fuel additive or solvent. However, n-butanol is toxic towards the production organisms, resulting in low concentrations of biobutanol in the aqueous fermentation broth. Therefore, conventional purification by distillation is very energy intensive. Extraction with ionic liquids and pervaporation as alternative separation technologies are two promising options for energy-efficient n-butanol recovery. These processes are analysed on detailed economics, including the influence of the uncertainty of the used model parameters and the sensitivity of the production costs to model parameters and design variables. It is shown that the costs for n-butanol purification by means of distillation are strongly dependent on the costs for thermal energy. For extractive recovery, the solubility of the extraction solvent in the raffinate is one of the main cost drivers as it affects the solvent loss. The costs of the pervaporation-based recovery mainly depend on the price for the membranes and are strongly dependent on the permeate fluxes. For all processes, the feed concentration has a noteworthy effect on the total downstream costs. This study allows not only an analysis of existing technologies but also helps to guide future research.

No abstract