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

Abstract

Glycols are accessible via metal-catalyzed hydrogenolysis of sugar alcohols such as xylitol obtained from hemicellulose. Rubased 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 HNO 3 , NH 3 and H 2 or carbonization of organic precursors.For all N-doped materials a high glycol selectivity of �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.

Ligand-Free One-Pot Synthesis of Ru/W18O49 Self-Assembled Hierarchical Coral-Like Nanostructures for Selective Conversion of Glucose into Glycols

“…Besides, the synergistic effects of Ru and W 18 O 49 were also investigated by using XRD, Raman, BET, FESEM, HRTEM, EDS, and NH 3 -TPD analysis. To the best of our knowledge, this is the first report where unique Ru/W 18 O 49 self-assembled coral-like nanostructures were used as a nanocatalyst to study glucose hydrogenolysis, which turned out to be the first report for the lowest Ru loading of 0.03% to demonstrate the highest glucose conversion (100%) and diols selectivity (82.6%) reported to date without any further oxide, activated carbon, graphene, or cocatalyst support. − ,− ,,− …”

“…On the other hand, the 09-Ru/W NC catalyst contributes to creating more W 6+ species, which improved the yield of EG products in comparison, as exemplified in the probable reaction mechanism. The current protocol also appears promising for synthesizing other metal/W 18…”

“…18 Whereas peaks at 284.16, 285.90, and 288.06 eV were assigned to C 1s core level adventitious contamination with respect to the presence of graphitic carbon (C�C), epoxy ether carbon (C−O), and carbonyl carbon (C�O), respectively. 18,30 To avoid interference from the C 1s spectrum, the isolated Ru 3p spectrum was generally used to analyze the surface chemistry of the Ru element. As represented in Figure 4h, two prominent peaks at 460.23 and 461.63 eV were observed for Ru 3p, attributed to the metallic Ru (Ru 0 ) and surface oxidized anhydrous Ru oxide (Ru IV ) species, respectively.…”

“…Generally, bifunctional catalysts were employed to promote the glucose hydrogenolysis reaction, − among which Ru-based bifunctional catalysts have attracted particular attention because of their remarkable hydrogenation activities and highly efficient conversion ability to hydrolyze glucose to form polyols. − ,− Furthermore, it was reported that the catalytic process and the yield of polyols were influenced by the supports and their surface properties. , The tungsten-supported catalysts were among the most effective agents in promoting C–C bond cleavage . There were quite a few studies on Ru-based tungsten-supported catalysts, showing that the amount of acid sites plays a crucial role in catalyzing C–O and C–C bond breaking to tune the product distribution. ,,, Although various forms of tungsten, such as WO 3 , and WO x ( x =1–3) , with or without being further supported on SiO 2 and/or carbon and/or other oxides and/or noble metals as cocatalyst are reported. ,,,,,− Also Ru-based nanocatalysts on other supports (e.g., carbon/activated carbon, metal oxide, metal/carbon composite) are reported for hydrogenolysis of glucose to glycols, ,,− and there is only one report citing 5% Ru on 30% W 18 O 49 on graphene support for conversion of cellulose to glycols with total glycol selectivity as 77.8% . Notably, the fabrication of Ru/W 18 O 49 or Ru/WO x -based catalysts is rare ,,, and has not been reported so far for the conversion of glucose to glycols, to the best of our knowledge.…”

Synthesis and Red/Ox Reversibility of a Novel Copper‐Iron‐Aluminum Spinel Precursor for Low‐Temperature Water‐Gas‐Shift Reaction

“…DFT calculations confirm the stabilizing effect of divalent cations on intermediates. Ru-catalysts supported on N-doped activated carbon were found to be highly active and selective metal catalysts for xylitol hydrogenolysis [2]. Multiple doping methods were tested yielding glycols with high selectivity.…”