Ru on N-doped Carbon for the Selective Hydrogenolysis of Sugars and Sugar Alcohols

Glycols are accessible via metal-catalyzed hydrogenolysis of sugar alcohols such as xylitol obtained from hemicellulose. Ru-based catalysts are highly active but also catalyze side-reactions such as decarbonylation and deoxygenation. To achieve high selectivity, these reactions need to be suppressed. In our study, we introduce heteroatom doped carbon materials as catalyst supports providing high selectivity. Heteroatom doping with nitrogen and oxygen was achieved by treating activated carbon with HNO3, NH3 and H2 or carbonization of organic precursors. For all N-doped materials a high glycol selectivity of (Formula presented.) 80 % for sorbitol and xylitol and 44 % for xylose and glucose was reached. XPS analysis confirms the presence of different nitrogen species at the carbon surface and varying ligand effects for oxygen and nitrogen. Oxygen has an electron withdrawing effect on ruthenium and leads to a decreased activity. Nitrogen has weaker electron withdrawing properties, resulting in an enhanced selectivity.