d-Glucose hydrogenation/hydrogenolysis reactions on noble metal (Ru, Pt)/activated carbon supported catalysts

• Glucose hydrogenation/hydrogenolysis at harsh conditions (180 °C, 3–12 h, 1.6 MPa H2).
• Pt/AC is highly selective for glucose hydrogenation to sorbitol.
• Single crystal Ru(0) nanoparticles (2–4 nm) favor sorbitol hydrogenolysis to arabinitol.
• Ru content and reduction method (NaBH4 or H2) affect selectivity to C3–C6 sugar alcohols.

In the present work we studied the hydrogenation/hydrogenolysis of d-glucose over Pt and Ru catalysts supported on activated micro/mesoporous carbon (AC), under low hydrogen pressure (1.6 MPa) and relatively high reaction temperature, i.e. 180 °C. We also studied the effect of metal content (1–5 wt.%), method of metal pre-treatment/reduction (H2 at 350 °C or NaBH4) and reaction time (1–12 h). All the Ru and Pt/AC catalysts were very active (conversion ≥97%) with the Pt/AC catalysts being also very selective toward sorbitol (sel. ≥90%) irrespective of metal content, method of reduction and reaction time (up to 12 h). On the other hand, the Ru/AC catalysts exhibited a wide range of sorbitol selectivity values (55–93%) having various C3–C6 sugar alcohols (1,2,5,6-hexanetetrol, arabinitol, threitol, glycerol and 1,2-propanediol) as main by-products. The formation of by-products was dependent on the crystalline/amorphous nature of Ru and Ru(O)xδ+ nanoparticles which were in turn affected by the Ru content and the method of reduction.

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