93. Nahreen, Shaima; Gupta, Ram B., Conversion of the Acetone-Butanol-Ethanol (ABE) Mixture to Hydrocarbons by Catalytic Dehydration, Energy & Fuels 2013, 27(4), 2116-2125.
Acetone-butanol-ethanol (ABE) mixture, containing 62.9 wt% n-butanol, 29.3 wt% acetone and 7.8 wt% ethanol, can be produced from biomass through the well-established ABE fermentation process using genetically-modified clostridium acetobutylicum. In this work the catalytic dehydration reactions of ABE mixture is studied to deoxygenate the mixture. Feed of ABE mixture was preheated and pumped through a catalytic packed bed tubular reactor in a continuous process at pressures of 3-13 bar. Experiments were run at different operating temperatures and feed flow rates to observe the effect on the dehydration products, which are mixtures of three phases: (1) a gas phase consisting of light hydrocarbons and carbon dioxide, (2) an organic liquid phase consisting of heavy hydrocarbons , and (3) an aqueous phase with dissolved oxygenated hydrocarbons. The products were analyzed and compared to those from the dehydration of pure n-butanol, acetone and ethanol feedstocks. The conversion is examined on two different catalysts: an alumina (γ-Al2O3) and a zeolite (ZSM-5). The dehydration products from the ABE mixture are mostly unsaturated hydrocarbon chains in the range of C2-C16. Based on the higher heating values (HHV) of the liquid products and infra-red spectra of the gas products, it can be concluded that the products from the ABE feedstock are different from those from the individual components, which suggests a cross reactivity of the components during the reaction. HHV of the liquid product increases with a decrease in the feed flow rate, and γ-Al2O3 catalyst is better than ZSM-5 for getting a good conversion of ABE in terms of liquid product energy content at a moderate reaction time.