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

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)_x ^δ+ nanoparticles which were in turn affected by the Ru content and the method of reduction.