One-step continuous process for the production of 1-butanol and 1-hexanol by catalytic conversion of bio-ethanol at its sub-/supercritical state

Abstract

A one-step, easy to scale-up, continuous process was developed to catalytically convert bio-ethanol into 1-butanol and 1-hexanol as chemicals or fuels, as well as some other compounds that are also useful as biogasoline. The process is novel as it employs ethanol at its sub- and supercritical states. The reactions were performed in a continuous-flow fixed-bed tubular reactor with γ-alumina supported Ni catalysts at 135–300 °C at a weight hourly space velocity of 6.4–15.6 h⁻¹ using neat ethanol. The process at 250 °C and 176 bar with an 8% Ni/γ-alumina catalyst led to ethanol conversion of 35%, with the highest selectivity of approximately 62% and 21% towards 1-butanol and 1-hexanol, respectively. In addition to 1-butanol and 1-hexanol, other minor biogasoline components such as butanal, and 2-pentanone, etc. were also synthesized from this process. The catalyst was found active for 18 h on stream in this study, and the regenerated catalysts retained their activities for the reactions.