Continuous Gas‐Phase Condensation of Bioethanol to 1‐Butanol over Bifunctional Pd/Mg and Pd/Mg–Carbon Catalysts

• Published in: ChemSusChem Vol. 11; no. 19; pp. 3502 - 3511
• Main Authors: López‐Olmos, Cristina, Morales, Maria Virtudes, Guerrero‐Ruiz, Antonio, Ramirez‐Barria, Carolina, Asedegbega‐Nieto, Esther, Rodríguez‐Ramos, Inmaculada
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 11.10.2018
• Subjects: alcohols; basicity; Butanol; Catalysis; Catalysts; Condensates; Dehydrogenation; Ethanol; gas-phase reactions; Heat treatment; Helium; heterogeneous catalysis; Hydrogen storage; Magnesium hydroxide; Moisture content; Nanoparticles; Palladium; palladium; alcohols; basicity; gas-phase reactions; heterogeneous catalysis
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.201801381

The condensation of ethanol to 1‐butanol in the presence of different catalyst systems based on a Pd dehydrogenating/hydrogenating component and magnesium hydroxide‐derived materials as basic ingredient was studied in a fixed‐bed reactor. The metal was incorporated by wetness impregnation, and the resulting material was then reduced in situ with hydrogen at 573 K for 1 h before reaction. The bifunctional catalysts were tested in a fixed‐bed reactor operated in the gas phase at 503 K and 50 bar with a stream of helium and ethanol. A bifunctional catalyst supported on a synthetic composite based on Mg and high surface area graphite (HSAG) was also studied. Improved catalytic performance in terms of selectivity towards 1‐butanol and stability was shown by the Pd catalyst supported on the Mg–HSAG composite after thermal treatment in helium at 723 K, presumably due to the compromise between two parameters: adequate size of the Pd nanoparticles and the concentration of strongly basic sites. The results indicate that the optimal density of strongly basic sites is a key aspect in designing superior bifunctional heterogeneous catalyst systems for the condensation of ethanol to 1‐butanol. A good compromise: A high‐performance Pd/MgO bifunctional catalyst for the continuous gas‐phase condensation of bioethanol to 1‐butanol is designed. An optimum compromise between the number of metal atoms and the amount of strongly basic sites exposed on the surface of the catalyst is found to result in the highest 1‐butanol yield.