From Barley Straw to Valuable Polyols: A Sustainable Process Using Ethanol/Water Mixtures and Hydrogenolysis over Ruthenium-Tungsten Catalyst.

Organosolv fractionation of barley straw followed by a hydrogenolysis reaction of the resulting organosolv pulp over a heterogeneous catalyst containing ruthenium and tungsten on activated carbon (Ru-W/AC) is a potential pathway to produce valuable chemicals from lignocellulose-based feedstock in a future biorefinery. Polyols, such as ethylene glycol, propylene glycol, or 1,2-butanediol, can be obtained with a very high yield of 70 % using organosolv barley pulp pretreated in a 50:50 wt % ethanol/water solution at 200 °C and a processing time of one hour. Moreover, we investigated the influence of several pretreatment parameters (e.g., solvent/water ratio, reaction temperature, and reaction time) on the pulp composition and product distribution obtained during the hydrogenolysis reaction to reduce the production of undesired side molecules. Finally, the optimal organosolv pretreatment conditions for straw were successfully transferred to other lignocellulose-based feedstock, namely bamboo foliage and hemp shives.