One-pot synthesis of acidic and basic bifunctional catalysts to promote the conversion of ethanol to 1-butanol

The conversion of ethanol to 1-butanol could allow the effective use of bioethanol as a renewable fuel, but requires a catalyst with both strongly acidic and basic sites. In the present work, a series of basic/acidic bifunctional catalysts was prepared by the calcination of KNO3 loaded onto granular coconut shell carbon (CSC) at varying temperatures. An extensive characterization using powder X-ray diffraction, scanning electron micro-scopy, surface area analysis, and NH3- and CO2-temperature programmed desorption was performed in order to understand structure-activity trends. The CSC structure was found to be well preserved following calcination and the resulting catalysts exhibited both basic and acidic properties. The decomposition of KNO3 played an important role in the formation of these sites, and it was determined that moderately basic/acidic sites were the most helpful in promoting the aldol coupling of ethanol. These new materials show significant potential for application to the ethanol-to-1-butanol reaction, with the highest-performing specimen (made with 10 wt% KNO3 and calcined at 500 degrees C) exhibiting 60% C4 products selectivity at 50% ethanol conversion.