No abstract

The effect of support in Ir-ReO x catalysts for glycerol hydrogenolysis to 1,3-propanediol was investigated. Rutile TiO2 support showed high activity, even higher than previously reported SiO2 support. Anatase TiO2, C, ZrO2, CeO2, Al2O3, and MgO supports showed very low activity of supported Ir-ReO x pairs. Higher Ir-based 1,3-propanediol productivity of Ir-ReO x /rutile catalyst was obtained at the initial stage even with lower Re/Ir ratio (typical Ir loading amount, 4 wt %, nominal ratio of 0.25; actual ratio of 0.24) without addition of H2SO4 than that of Ir-ReO x /SiO2. The 1,3-propanediol productivity over Ir-ReO x catalysts showed dependency on catalyst compositions (metal loading amount), and the relationship between catalyst structure and activity was further established over Ir-ReO x /rutile. Relatively high Ir loading amount in comparison with small surface area (6 wt %, on 6 m2 g–1 rutile TiO2) showed the highest activity (Ir-based activity). From combined characterization results altogether (TPR, TEM, XPS, XAS, CO adsorption, CO FT-IR) with a kinetics study, the Ir metal particles interacted with the partially oxidized ReO x cluster (average valence of Re: +3) almost totally covering the surface of rutile TiO2 particles, and the active site was the Ir-ReO x interface. Small amounts of Ir species (∼20%) were incompletely reduced; however, such IrO x species as well as rutile TiO2 support were not directly involved in glycerol hydrogenolysis. The role of rutile support was regarded as providing a unique environment for stabilization of uniform and small Ir-ReO x particles with very high surface density on rutile TiO2, which increased the number of active sites per Re amount.

2-Furancarboxylic acid (FCA), produced by oxidation of furfural, is rarely used as a platform molecule. Metal-oxide-supported Pt-MoO x catalysts were effective for hydrodeoxygenation of FCA to valeric acid (VA) in water solvent. The highest VA yield is 51% over Pt-MoO x /TiO2 catalyst under 1.5 MPa H2 at 413 K. Other metal combinations (M-MoO x , M = Rh, Pd, Ru, Ir, Au, none; Pt-M′O x , M′= V, W, Re, none) showed very low VA yield. This catalyst system was applicable to the hydrodeoxygenation of 2,5-furandicarboxylic acid (FDCA), and adipic acid (AA) was obtained with 21% yield at 473 K.

Pt catalysts, especially supported on Al2O3, are effective for hydrogenolysis of 2-furancarboxylic acid to 5-hydroxyvaleric acid (5-HVA) and its derivatives (ester and δ-valerolactone), and the highest yield of 5-HVA derivatives was 62%.