Conversion of the Acetone–Butanol–Ethanol (ABE) Mixture to Hydrocarbons by Catalytic Dehydration

Abstract

An 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 the ABE mixture are studied to deoxygenate the mixture. A feed of the 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-Al 2 O 3 ) and a zeolite (ZSM-5). The dehydration products from the ABE mixture are mostly unsaturated hydrocarbon chains in the range of C 2 −C 16 . On the basis of the higher heating values (HHV) of the liquid products and infrared 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 the γ-Al 2 O 3 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.

Efficient Catalytic Dehydration of High-Concentration 1-Butanol with Zn-Mn-Co Modified γ-Al2O3 in Jet Fuel Production

“…Lewis acidity does not require dehydroxylation if the basic substrates can displace water. Substrates that have sufficient basicity to compete with water can also be activated by alumina in the presence of water [14,25].…”

“…When using γ-Al 2 O 3 as a catalyst, the composition of the products is relatively easier to control, and the product distribution depends on the process temperature and strength of catalyst acidity [12,13]. It has been proven that there is more dibutylether than butenes in the products when the reaction temperature is below 310 • C, and, as the temperature rises, butenes supersede dibutylether [14]. Transition metal catalysts such as cobalt [15,16], manganese, iron [17], nickel [18], and zinc oxides [19] are often utilized for the alcohol dehydration reaction.…”

8. Conversion of lignocellulosic biomass-derived intermediates to hydrocarbon fuels

“…Another approach has been quite recently reported by Nahreen and Gupta from the Auburn University [64]. An acetone-butanol-ethanol mixture, containing 62.9 wt% n-butanol, 29.3 wt% acetone, and 7.8 wt% ethanol, was subjected to dehydration reactions in order to deoxygenate the mixture.…”

Catalytic alkylation of acetone with ethanol over Pd/carbon catalyst in flow-through system via borrowing hydrogen route

“…8 Catalytic dehydration of the ABE mixtures was studied in order to deoxygenate it, but the resulted products were mostly unsaturated hydrocarbons. 9 The obtained mixture was similarly disadvantageous as the products of thermochemical method. Anbarasan and co-workers 10 proposed a chemical route to convert fermentation ABE product into hydrocarbons that can be used for fuel.…”