MFI zeolite as adsorbent for selective recovery of hydrocarbons from ABE fermentation broths Abrar Faisal • Agata Zarebska • Pardis Saremi • Danil Korelskiy • Lindsay Ohlin • Ulrika Rova • Jonas Hedlund • Mattias Grahn Received: 19 May 2013 / Accepted: 11 September 2013 Ó Springer Science+Business Media New York 2013 Abstract 1-Butanol and butyric acid are two interesting compounds that may be produced by acetone, butanol, and ethanol fermentation using e.g. Clostridium acetobutyli- cum. The main drawback, restricting the commercialization potential of this process, is the toxicity of butanol for the cell culture resulting in low concentrations of this com- pound in the broth. To make this process economically viable, an efficient recovery process has to be developed. In this work, a hydrophobic MFI type zeolite with high silica to alumina ratio was evaluated as adsorbent for the recovery of butanol and butyric acid from model solutions. Dual component adsorption experiments revealed that both butanol and butyric acid showed a high affinity for the hydrophobic MFI zeolite when adsorbed from aqueous model solutions. Multicomponent adsorption experiments using model solutions, mimicking real fermentation broths, revealed that the adsorbent was very selective to the target compounds. Further, the adsorption of butyric and acetic acid was found to be pH dependent with high adsorption below, and low adsorption above, the respective pKa val- ues of the acids. Thermal desorption of butanol from MFI type zeolite was also studied and a suitable desorption temperature was identified. Keywords Butanol  Adsorption  Zeolites  Langmuir  Butyric acid  MFI List of symbols Variables ABE Acetone, Butanol and Ethanol C Concentration V Volume b Langmuir adsorption parameter (L/g) q max Saturation loading (g/g) Subscripts i Adsorbate specie i e Equilibrium 1 Introduction Energy demands of the world are ever increasing in this industrial era. With the depleting reservoirs of fossil fuel, the need for new, sustainable fuels and chemicals is more urgent than ever. In the future, biofuels will likely emerge as one of the key replacements of fossil fuels in the transportation market. To replace gasoline and diesel used, biofuels with approximately the same physical and chem- ical properties are desired. 1-butanol (or simply butanol) produced from renewable resources is a very promising fuel in this sense. For instance, butanol has higher energy density than ethanol, and it is also less polar than ethanol diminishing the problem of water dissolving in the fuel (Durre 1998). Butanol is also an important industrial chemical, which can be used as solvent for paints, dyes, coating, varnishes etc. It is also a precursor or intermediate for chemical synthesis of many plastics and chemicals e.g. hydraulic fluids and safety glass (Jin et al. 2011). Currently, butyric acid is produced industrially by chemical synthesis, by the oxidation of butyraldehyde obtained from crude oil derived propylene (Cascone 2008). It is an important A. Faisal  A. Zarebska  D. Korelskiy  L. Ohlin  J. Hedlund  M. Grahn (&) Chemical Technology, Lulea ˚ University of Technology, 971 87 Lulea ˚, Sweden e-mail: mattias.grahn@ltu.se P. Saremi  U. Rova Biochemical and Chemical Process Engineering, Lulea ˚ University of Technology, 971 87 Lulea ˚, Sweden 123 Adsorption DOI 10.1007/s10450-013-9576-6