Investigations on the selective deoxygenation of sugar alcohols over heterogeneous catalysts

In this PhD thesis, the industrial potential for selective deoxygenation (-C-O- bond cleavage) of biomass-derived polyols was investigated over heterogeneous catalysts. Standard commercial hydrogenation catalysts based on Ru, Ni and Cu were applied for the hydrogenolysis of various sugars and sugar alcohols, including sucrose, glucose, sorbitol, mannitol, and xylitol. The effect of the active metal and support material were investigated with regards to compare -C-O- vs. -C-C- bond cleavage properties. For this purpose, reaction intermediates were identified and isolated to better understand the mechanisms involved in the selective -C-O- bond cleavage over Cu catalysts. Furthermore, different reaction pathways for -C-C- bond cleavage (degradation of the carbon chain) were evaluated such as retro-aldol reactions, decarbonylation and decarboxylation. Finally, the separation of deoxygenated C6 polyols from short-chain compounds such as glycols and glycerol were investigated by comparing standard industrial downstream processes: ion-exchange chromatography and liquid-liquid extraction using non-soluble polar solvents