Hydrogenolysis of Cellulose over Cu-Based Catalysts-Analysis of the Reaction Network

• Published in: ChemSusChem 2014-05, Vol.7 (5), p.1311-1317
• Main Authors: Tajvidi, Kameh, Hausoul, Peter J. C., Palkovits, Regina
• Format: Article
• Language: English
• Subjects: Aluminum Oxide - chemistry; Biofuels; biomass; Catalysis; cellulose; Cellulose - chemistry; Conservation of Energy Resources; copper; Copper - chemistry; Hot Temperature; hydrogenolysis; mechanism; Zinc Oxide - chemistry
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.201300978

A series of polyols, carbohydrates, and cellulose were tested in the aqueous, CuO/ZnO/Al2O3‐catalyzed hydrogenolysis reaction at 245 °C and 50 bar H2. The compositions of liquid‐phase products were analyzed; based on these results a unified reaction mechanism is proposed that accounts for the observed product distribution. Elementary transformations such as dehydration, dehydrogenation/hydrogenation, Lobry de Bruyn–van Ekenstein isomerization and retro‐aldol cleavage were identified as most important for controlling the selectivity of simple polyols and carbohydrates. For cellulose the product distribution is considerably different than for glucose or sorbitol, indicating a change in the reaction pathway. Therefore, next to the traditional hydrolysis of the glycosidic bond, an additional depolymerization mechanism involving only the reducing ends of cellulose oligomers is proposed to account for this observation. In the web: A series of polyols and carbohydrates with increasing carbon‐chain length as well as cellulose are screened in the CuO/ZnO/Al2O3‐catalyzed hydrogenolysis reaction. Analysis of the obtained product mixtures provides insight into the reaction network. For cellulose, an additional depolymerization mechanism is proposed to account for the observed product distribution.