Continuous upgrading of methanol and ethanol to isobutanol by heterogeneous catalysis over Cu-CeO2/AC catalyst and the combination

Isobutanol has the highest octane value among several types of butanols and is the most ideal fuel substitute. Developing an efficient continuous production system for synthesis of isobutanol from methanol and ethanol is the key to industrialization. The existing heterogeneous catalysts were all applied to batch reactor systems. The first heterogeneous catalyst, activated carbon supported Cu-CeO2 (Cu-CeO2/AC), with excellent performance for the continuous synthesis system of isobutanol from methanol and ethanol was revealed in this paper. Through XRD, TEM, H2-TPR, CO2-TPD, and FT-IR, it was demonstrated that CeO2 not only enhanced the stability of Cu nanoparticles, but also provided a large number of hydroxyl aldehyde condensation active sites. Cu provided dehydrogenation active sites. The synergy of Cu active sites and CeO2 active sites completed the Guerbet reaction cycle. 3Cu-CeO2/AC exhibited a high ethanol conversion rate (81.6 %) and isobutanol selectivity (54.0 %). Finally, based on the analysis of reaction thermodynamics and dynamics, a catalyst combination mode of dehydrogenation + aldol condensation + hydrogenation was proposed, which improved the conversion of ethanol (81 % to 85%) and selectivity of isobutanol (54% to 65%).