Drop-in transportation fuel can be produced by dehydration of bio-butanol to produce alkenes followed by oligomerization to produce liquids. Bio-butanol, which contains n-butanol (63 wt%), acetone (29 wt%) and ethanol (8 wt%), can be produced by using Clostridia bacteria which can effectively utilize both C5 and C6 sugars from multiple lignocellulosic feedstocks. In this work the catalytic dehydration reactions of bio-butanol mixture is studied in a continuous packed bed tubular reactor. The product streams (gas, aqueous liquid, and organic liquid) are analyzed and compared with those from the individual components. Two catalysts, γ-Al2O3 and ZSM-5, are tested for their effectiveness at different temperatures. The products from the bio-butanol mixture feed are mostly unsaturated hydrocarbons in the range of C2-C15. The difference in the higher heating values (HHV) of the liquid products and infrared spectra of the gas products indicate that the products from the bio-butanol feed are different from the products from the individual feed components. This difference is attributed to the synergistic inter-component reactivity during the dehydration reactions. HHV of the liquid product increases with the residence time. A better conversion of bio-butanol in terms of liquid product quality and HHV was found in dehydration on γ-Al2O3 catalyst than on ZSM-5, when all other parameters (i.e., temperature and residence time) are kept constant. Composition analyses and yield data are obtained in this study for rationale understanding of the dehydration step.
