The synergistic effects of Ru and WOx for aqueous-phase hydrogenation of glucose to lower diols

Aqueous-phase hydrogenation of glucose to lower diols (ethylene glycol (EG), 1, 2-propylene glycol (PG), and butanediol (BDO)) over bi-functional Ru-W supported catalysts was investigated in a continuous-flow fixed-bed reactor. A variety of catalysts based on different supports including mesoporous SiO 2 , activated carbon (AC), carbon nanofibers (CNFs), and bulk WO 3 were compared and examined by N 2 physisorption, H 2 chemisorption, XRD, TEM, ICP, H 2 -TPR, in-situ / ex-situ XPS, NH 3 -TPD, and Raman spectra. The results indicate that the lower diols yield is highly dependent on the synergistic effect of Ru metal sites and WO x acid sites, in other words, strongly depending on the competitive reactions of the glucose. Abundant W 4+ and Ru° sites on Ru-W/SiO 2 catalysts with large specific surface area effectively catalyze the selective cleavage of the C C bonds in glucose and subsequent hydrogenation to lower diols, resulting in 100% glucose conversion as well as highest diols selectivity (87.3%) over 50 h reaction at 478 K and 4 MPa H 2 . Meanwhile, the Ru/WO 3 with much lower surface area forms more W 5+ species, which is advantageous to producing more EG products (55.9%) at the same reaction conditions.