The production of bio-derived fuels and additives is one of the major avenues for reducing consumption of fossil fuels. Ethanol plays a central role in the bio-fuel arena as a gasoline substitute and oxygenate additive. It can also be used in the production of n-butanol, which has advantages over ethanol in terms of its applications in fuels. Such benefits include higher miscibility with gasoline, more resistance to water contamination, and chemical properties such as energy density, stoichiometric air-fuel ratio, heat of vaporization, research octane number, and motor octane number that are closer to gasoline [1][2]. The general pathway for the production of bio-butanol from bio-ethanol is known as the Guerbet reaction. There have been several studies in recent years for conducting Guerbet reaction using numerous catalysts and reaction conditions [3]. Most of these experiments were done in batch systems or gas phase continuous packed bed reactors. In this study, the previous results obtained from our research group in a batch reactor [4][5] have been extended to a condensed-phase continuous reactor using similar catalysts (8% Ni/γ-Al
2O
3 modified with La
2O
3) and varying reaction parameters such as temperature, WHSV, and feed composition. Also, the catalyst has been modified using bi-metallic (Ni-Cu, Ni-Pt, Ni-Pd, and Ni-Co), and tri-metallic catalysts. Results show that adding Cu to Ni catalyst improves reaction selectivity to higher alcohols because of reduced byproduct gas formation. i. However, a decreases in catalyst activity is observed because Cu has a lower activity for alcohol dehydrogenation that is the initial step in the Guerbet reaction. Ethanol conversion of 40% and higher alcohol selectivity of 80% were observed at optimal condition for the Ni-Cu bimetallic catalysts.
References
[1] R. L. Wingad, P. J. Gates, S. T. G. Street, and D. F. Wass, “Catalytic Conversion of Ethanol to n-Butanol Using Ruthenium P-N Ligand Complexes,†ACS Catal., vol. 5, no. 10, pp. 5822–5826, 2015.
[2] H. S. Ghaziaskar and C. (Charles) Xu, “One-step continuous process for the production of 1-butanol and 1-hexanol by catalytic conversion of bio-ethanol at its sub-/supercritical state,†RSC Adv., vol. 3, no. 13, pp. 4271–4280, 2013.
[3] D. Gabriëls, W. Y. Hernández, B. Sels, P. Van Der Voort, and A. Verberckmoes, “Review of catalytic systems and thermodynamics for the Guerbet condensation reaction and challenges for biomass valorization,†Catal. Sci. Technol., vol. 5, pp. 3876–3902, 2015.
[4] T. L. Jordison, L. Peereboom, and D. J. Miller, “Impact of Water on Condensed Phase Ethanol Guerbet Reactions,†Ind. Eng. Chem. Res., vol. 55, no. 23, pp. 6579–6585, 2016.
[5] T. L. Jordison, C. T. Lira, and D. J. Miller, “Condensed-Phase Ethanol Conversion to Higher Alcohols,†Ind. Eng. Chem. Res., vol. 54, no. 44, pp. 10991–11000, 2015.
