Hydrogenolysis of Cellulose over Cu‐Based Catalysts—Analysis of the Reaction Network

Abstract

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.

Hemicellulose arabinogalactan hydrolytic hydrogenation over Ru-modified H-USY zeolites

“…Since in the literature it is often reported [3] that hydrolytic hydrogenation can result in cleavage of carbon-carbon bond, retention times for several polyols with a shorter carbon chain were measured, confirming formation of ethylene glycol, observed also in the literature [42,43] for transformations of cellulose. Interestingly no enough formation of other alcohols and polyols mentioned in the literature [42,43] such as methanol, glycerol, 1,2-propanediol, and meso-erythritol could be confirmed. Moreover there also was no formation of levulinic acid.…”

Mechanism and Kinetic Analysis of the Hydrogenolysis of Cellulose to Polyols

“…Palkovits and coworkers investigated hydrolytic hydrogenation of cellulose over a CuO/ZnO/Al 2 O 3 catalyst at 518 K and 50 bar H 2 and proposed a unified reaction mechanism according to the observed product distribution [144]. As shown in Fig.…”

Ethylene glycol production from glucose over W‐Ru catalysts: Maximizing yield by kinetic modeling and simulation

“…The direct catalytic conversion of lignocellulose to EG (DLEG process) was first reported in 2008 and has been intensively studied in the following years, providing a novel route for the synthesis of EG from biomass . Among a variety of effective catalysts, tungstenic catalysts have shown the highest yields of EG, up to 76% . The catalytic functions of active sites and the reaction pathways over tungstic catalysts were elucidated for tuning the distribution of polyol products .…”