Selective Hydrodeoxygenation of Cyclic Vicinal Diols to Cyclic Alcohols over Tungsten Oxide–Palladium Catalysts

Abstract

Hydrodeoxygenation of cyclic vicinal diols such as 1,4-anhydroerythritol was conducted over catalysts containing both a noble metal and a group 5-7 transition-metal oxide. The combination of Pd and WOx allowed the removal of one of the two OH groups selectively. 3-Hydroxytetrahydrofuran was obtained from 1,4-anhydroerythritol in 72 and 74% yield over WOx -Pd/C and WOx -Pd/ZrO2 , respectively. The WOx -Pd/ZrO2 catalyst was reusable without significant loss of activity if the catalyst was calcined as a method of regeneration. Characterization of WOx -Pd/C with temperature-programmed reduction, X-ray diffraction, and transmission electron microscopy/energy-dispersive X-ray spectroscopy suggested that Pd metal particles approximately 9 nm in size were formed on amorphous tungsten oxide particles. A reaction mechanism was proposed on the basis of kinetics, reaction results with tungsten oxides under an atmosphere of Ar, and density functional theory calculations. A tetravalent tungsten center (W(IV) ) was formed by reduction of WO3 with the Pd catalyst and H2 , and this center served as the reductant for partial hydrodeoxygenation.

Demethoxylation of guaiacol and methoxybenzenes over carbon-supported Ru–Mn catalyst

“…Next, the Ru/C catalyst was modified by further loading of secondary metals. The modification of noble metal catalysts with secondary metals is often effective in improving the hydrodeoxygenation performances [60][61][62][63][64][65][66][67]. The performance of catalysts (molar ratio of secondary metal to Ru = 0.25) is summarized in Table 2 (2 h reactions) and Table S2 (0.5 h reactions).…”

Hydrodeoxygenation of Vicinal OH Groups over Heterogeneous Rhenium Catalyst Promoted by Palladium and Ceria Support

“…3) These systems typically use other reductants than H 2 and lower yields are obtained if H 2 is used as the reductant. [16,20] Simultaneous hydrodeoxygenation of straightchain vicinal diols over heterogeneous Re catalysts has been reported; however, the yields of alkenes ( % 50 %) were lower than those obtained with homogeneous catalysts ( % 95 %), and the TON and TOF per Re atom were very low (< 20 and < 5 h À1 , respectively; Table S1, entries [27][28][29][30]. [27,28] In addition, there are no reports on the reuse of heterogeneous catalysts for deoxydehydration without decrease in activity up to now.…”

“…1,4-AHERY is the dehydration product of biomass-derived erythritol. [29] The target product is tetrahy- [30,31] Indeed, we also tested various combinations of Group 5-7 metal (MO x ) + Pd ( Figure S1) and ReO x + noble metal ( Figure S2) using a silica support. Other combinations than ReO x -Pd showed lower activity and/or lower selectivity to THF.…”

New Reaction Schemes for the Production of Biomass-Based Chemicals Created by Selective Catalytic Hydrogenolysis: Catalysts with Noble Metal and Tungsten

“…Therefore, Pd is an ideal component for hydrogen activation. We tested Pd catalysts supported on various group 5-7 metal oxides for hydrogenolysis of 1,4-anhydro-erythritol ( cis -3,4-dihydroxytetrahydrofuran) ( Table 8.3 ) [ 49 ]. 1,4-Anhydroerythritol is easily produced by dehydration of erythritol, which is derived from glucose by fermentation [ 50 ].…”